CN114696619A - Direct current converter, electronic equipment and control method of direct current converter - Google Patents

Direct current converter, electronic equipment and control method of direct current converter Download PDF

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Publication number
CN114696619A
CN114696619A CN202011627553.1A CN202011627553A CN114696619A CN 114696619 A CN114696619 A CN 114696619A CN 202011627553 A CN202011627553 A CN 202011627553A CN 114696619 A CN114696619 A CN 114696619A
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voltage
circuit
output
input
conversion unit
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Inventor
朱勇发
丁涛
曾智强
陈晓威
张敬阳
王平华
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Huawei Technologies Co Ltd
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Huawei Technologies Co Ltd
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Priority to PCT/CN2021/133101 priority patent/WO2022142898A1/en
Publication of CN114696619A publication Critical patent/CN114696619A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33507—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters
    • H02M3/33523—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters with galvanic isolation between input and output of both the power stage and the feedback loop
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The application provides a direct current converter, an electronic device and a control method of the direct current converter, which are used for improving the efficiency of the direct current converter. The method comprises the following steps: calculating a target transformation ratio, wherein the target transformation ratio is a transformation ratio between the input voltage of the direct current converter and the target output voltage of the direct current converter; determining a first transformation ratio of the LLC resonance conversion unit from a plurality of voltage conversion gears of the LLC resonance conversion unit according to the target transformation ratio and the minimum transformation ratio of the first voltage regulation circuit; and determining a second transformation ratio of the first voltage regulating circuit according to the first transformation ratio and the target transformation ratio.

Description

Direct current converter, electronic equipment and control method of direct current converter
Technical Field
The present disclosure relates to circuit technologies, and more particularly, to a dc converter, an electronic device, and a control method of the dc converter.
Background
LLC resonant conversion circuits are a common dc-dc voltage conversion circuit, with which it is possible to implement switching tube soft switches for use in voltage converters in many types of power systems. For example, voltage converters in power systems such as power management systems, photovoltaic power generation systems, communication power supply systems, and data centers of electric/hybrid vehicles often need to use an LLC resonant conversion circuit to realize voltage conversion.
Generally, the LLC resonant conversion circuit mainly includes: the inverter circuit is used for converting direct-current voltage received by the input end into alternating current and outputting the alternating current to the resonant circuit, the resonant circuit is used for achieving soft switching of the inverter circuit, the transformer is used for outputting the alternating current output by the resonant circuit to the rectifying circuit, and the rectifying circuit is used for converting the alternating current output by the transformer into direct current and outputting the direct current.
In practical use, according to the requirement of load voltage regulation, the input voltage of the voltage converter can fluctuate within a certain range, and the voltage conversion ratio of the voltage converter is adjustable. In order to realize soft switching of a switching tube in the inverter circuit and improve conversion efficiency, the conduction time sequence of the switching tube of the inverter circuit is fixed, and the switching frequency of the switching tube is consistent with the resonant frequency of the resonant circuit, so that the voltage conversion ratio of the voltage conversion circuit of the LLC resonant conversion circuit is fixed, and the LLC resonant conversion circuit is difficult to meet the voltage conversion requirement of the voltage converter.
In order to meet the voltage conversion requirement of the voltage converter, a two-stage converter architecture is proposed to meet the requirement of the voltage converter. As shown in fig. 1, the LLC resonant conversion circuit converts and outputs the voltage received by the input terminal of the voltage converter, and then the voltage regulator circuit regulates the dc voltage output by the LLC resonant conversion circuit to output a voltage meeting the requirements of the voltage converter.
However, when the scheme is implemented, the overall efficiency of the two-stage series connection architecture is equal to the multiplication of the two-stage efficiency, and the conversion efficiency of the direct current converter is directly reduced due to the low conversion efficiency of the voltage regulating circuit. In order to solve the problem, a two-stage converter architecture of quasi-parallel conversion is proposed, as shown in fig. 2, an input end of an LLC resonant conversion circuit receives most of the input voltage and converts the received voltage into the voltage required by the voltage converter, and an input end of a voltage regulation circuit receives a small portion of the input voltage and converts the received voltage into the voltage required by the voltage converter.
During specific implementation, the total efficiency of the voltage converter is a weighted average of conversion efficiency of the two circuits and the ratio of input voltage, when the input voltage of the voltage converter is increased or the output voltage of the voltage converter is reduced, the voltage conversion ratio of the LLC resonance conversion circuit is fixed, and only the voltage received by the input end of the voltage regulating circuit can be increased, so that the conversion efficiency of the voltage converter is directly reduced.
Disclosure of Invention
The application provides a direct current converter, electronic equipment and a control method of the direct current converter, which are used for improving the conversion efficiency of the direct current converter.
In a first aspect, the present application provides a control method for a dc converter, where the control method is applied to the dc converter. The direct current converter comprises an LLC resonance conversion unit and a first voltage regulating circuit, the LLC resonance conversion unit is provided with a plurality of voltage conversion gears, the LLC resonance conversion unit comprises a first input end, a second input end, a first output end and a second output end, the first voltage regulating circuit comprises a third input end, a fourth input end, a third output end and a fourth output end, and the second input end is connected with the third input end. The first output end is connected with the third output end, and the second output end is connected with the fourth output end. Specifically, the control method mainly comprises the following steps:
calculating a target transformation ratio, wherein the target transformation ratio is a transformation ratio between the input voltage of the direct current converter and the output voltage of the direct current converter; determining a first transformation ratio of the LLC resonance conversion unit from a plurality of voltage conversion gears of the LLC resonance conversion unit according to the minimum transformation ratio of the target transformation ratio and the first regulating voltage; and determining a second transformation ratio of the first voltage regulating circuit according to the target transformation ratio and the first transformation ratio.
By adopting the method, the LLC resonance conversion unit is connected with the input end of the first voltage regulating circuit in series, the output end of the LLC resonance conversion unit is connected in parallel, the two conversion devices respectively convert part of the input voltage, because the conversion efficiency of the LLC resonance conversion unit is greater than that of the first voltage regulating circuit, the first transformation ratio of the LLC resonance conversion circuit can be increased as much as possible under the condition that the target conversion ratio of the DC converter and the minimum transformation ratio of the first voltage regulating circuit are determined, because the input voltage of the LLC resonance conversion circuit is fixed, the larger the first transformation ratio is, the more input voltage can be received by the input end of the LLC and more power can be transmitted, and the conversion efficiency of the whole DC converter is ensured.
In one possible design, when a first transformation ratio of the LLC resonance conversion unit is determined according to a target transformation ratio and a minimum transformation ratio of a voltage regulating circuit, a value range of a voltage conversion gear of the LLC resonance conversion unit is determined according to the minimum transformation ratio of the target transformation ratio and a first voltage regulating voltage; and determining the maximum voltage conversion gear within the value range of the voltage conversion gear of the LLC resonance conversion circuit as a first transformation ratio.
By adopting the method, the efficiency of the LLC resonance conversion unit is higher, the efficiency of the switching power supply is further improved, the maximum transformation ratio which can be realized by the LLC resonance conversion unit can be found according to the minimum transformation ratio of the voltage regulating circuit, and the maximum transformation ratio is used as the first transformation ratio of the LLC resonance conversion, so that the LLC resonance conversion unit can transmit more power.
In one possible implementation, determining the second transformation ratio using the target transformation ratio and the first transformation ratio includes: calculating a target input voltage of the LLC resonance conversion unit when the LLC resonance conversion circuit is in a first transformation ratio; calculating a first voltage difference between the input voltage of the direct current converter and a target input voltage; and determining a transformation ratio between the first voltage difference and the output voltage of the direct current converter as a second transformation ratio.
By adopting the method, under the condition that the maximum variable ratio which can be realized by the LLC resonance conversion unit is determined to realize that the LLC resonance conversion unit transmits more power, the difference voltage between the maximum variable ratio of the LLC resonance conversion unit and the total input voltage is transmitted by using the first voltage regulating circuit, so that the voltage fine tuning is realized.
Specifically, the LLC resonance conversion unit is controlled to be in a first transformation ratio, and the first voltage regulating circuit is controlled to be in a second transformation ratio.
In one possible implementation, the LLC resonant conversion unit includes: inverter circuit, resonant circuit, transformer and rectifier circuit control LLC resonance conversion unit and be in first transformation ratio, include:
and sending a driving signal to the inverter circuit to control the LLC resonance conversion unit to be in a first transformation ratio. After the inverter circuit receives the driving signal, the period of the alternating voltage output by the inverter circuit is the same as the resonance period of the resonance circuit.
By adopting the scheme, the efficiency of the LLC resonance conversion unit can be improved only when the period of the alternating current output by the inverter circuit in the LLC resonance conversion unit is consistent with the resonance period of the resonance circuit, and in order to realize the adjustable transformation ratio of the LLC resonance conversion unit, the transformation ratio range of the LLC resonance conversion unit can be expanded by changing the conduction time sequence of the switching tube through changing the driving signal under the condition that the period of the alternating current output by the inverter circuit is consistent with the resonance period of the resonance circuit.
In a second aspect, an embodiment of the present application provides a dc converter, which mainly includes an LLC resonant conversion unit and a first voltage regulation circuit.
The LLC resonance conversion unit comprises a first input end, a second input end, a first output end and a second output end, and the first voltage regulation circuit comprises a third input end, a fourth input end, a third output end and a fourth output end. The second input end is connected with the third input end, the first output end is connected with the third output end, and the second output end is connected with the fourth output end. The LLC resonance conversion unit can comprise an inverter circuit, a resonance circuit, a transformer and a rectification circuit.
Specifically, the inverter circuit is configured to convert a first input voltage received through the first input terminal and the second input terminal into an ac voltage, transmit the ac voltage to the rectifier circuit through the resonant circuit and the transformer, convert the ac voltage output by the transformer into an output voltage of the dc converter through the rectifier circuit, and output the output voltage of the dc converter through the first output terminal and the second output terminal; the LLC resonance conversion unit is provided with a plurality of voltage conversion gears; the first voltage regulating circuit is used for converting a second input voltage received through the third input end and the fourth input end into an output voltage of the direct current converter and outputting the output voltage of the direct current converter through the third output end and the fourth output end, and the total input voltage of the converting circuit comprises a first input voltage and a second input voltage.
In the above-described dc converter configuration, the LLC resonant conversion unit is connected in series with the input side and the output side of the first voltage regulation circuit in parallel. Assuming that the efficiency of the LLC resonant conversion unit is a% and the efficiency of the first voltage regulating circuit is b%, since the efficiency of the LLC resonant conversion unit is higher than the efficiency of the first voltage regulating circuit, the efficiency of the dc converter provided in the embodiments of the present application can be expressed as
Figure BDA0002879504370000031
Because the larger the transformation ratio of the LLC resonance conversion unit is, the higher the efficiency of the DC converter is, the maximum transformation ratio is realized by adjusting the voltage conversion gear of the LLC resonance conversion unit, and the efficiency of the DC converter is favorably improved.
In one possible design, when the LLC resonant conversion unit is in any one of the multiple voltage conversion gears, the period of the ac voltage output by the inverter circuit is the same as the resonant period of the resonant circuit, and the output voltage of the LLC resonant conversion unit is greater than zero.
In a possible implementation manner, the voltage conversion efficiency of the LLC resonant conversion unit is greater than the voltage conversion efficiency of the first voltage regulating circuit, the voltage conversion efficiency of the LLC resonant conversion unit is a ratio of the output power of the LLC resonant conversion unit to the input power of the LLC resonant conversion unit, and the voltage conversion efficiency of the first voltage regulating circuit is a ratio of the output power of the first voltage regulating circuit to the input power of the first voltage regulating circuit.
In one possible implementation, a controller.
The controller is used for controlling the LLC resonance conversion unit to convert the first input voltage into the output voltage of the direct-current converter and controlling the first voltage regulating circuit to convert the second input voltage into the output voltage of the direct-current converter; and adjusting the voltage conversion gear of the LLC resonance conversion unit according to the target transformation ratio of the DC converter. Wherein the target transformation ratio is a ratio between the total input voltage and a target output voltage of the direct current converter.
That is, the adjustment of the states of the circuits in the dc converter is realized under the control of the controller.
In one possible implementation, the LLC resonant conversion unit includes: the circuit comprises an inverter circuit, a resonance circuit, a transformer and a rectification circuit.
The two input ends of the inverter circuit form a first input end and a second input end respectively, one output end of the inverter circuit is connected with one end of the resonant circuit, and the other output end of the inverter circuit is connected with one end of a primary winding of the transformer; the other end of the resonant circuit is connected with the other end of the primary winding of the transformer; two ends of the secondary winding of the transformer are respectively connected with two input ends of the rectifying circuit; the two output ends of the rectifying circuit form a first output end and a second output end respectively.
The inverter circuit has a plurality of voltage conversion ratios, and the plurality of voltage conversion ratios are in one-to-one correspondence with a plurality of voltage conversion steps of a plurality of voltage conversion units of the LLC resonance conversion unit.
By adopting the structure for realizing the LLC resonance conversion circuit, the conversion ratio of the LLC resonance conversion unit can be adjusted by adjusting the conversion ratio of the inverter circuit, so that the LLC resonance conversion unit can be controlled to be in a larger conversion ratio, more power is transmitted, and the efficiency of the direct current converter is further improved.
Specifically, there are at least the following possible implementations of the inverter circuit:
the inverter circuit has the following implementation mode:
the inverter circuit includes: an H-bridge circuit and a first capacitor.
The first end of a first bridge arm of the H-bridge circuit forms a first input end, the second end of the first bridge arm is connected with one end of the resonant circuit, the first end of a second bridge arm of the H-bridge circuit forms a second input end, the first end of the second bridge arm and the resonant circuit form a second input end, the second end of the second bridge arm is connected with the second end of the first bridge arm, and the H-bridge circuit is used for receiving a first driving signal and adjusting a voltage conversion gear of the LLC resonant conversion unit according to the first driving signal; a first capacitor is connected between the middle node of the first bridge arm and the middle node of the second bridge arm in a bridging mode.
By adopting the inverter circuit structure, the conduction time sequence of the switch tube in the H-bridge circuit can be controlled through the received driving signal to control the first capacitor to be charged and discharged, so that the inverter circuit can output different voltage values, and the transformation ratio of the LLC resonance conversion unit can be adjusted.
Implementation mode two of the inverter circuit:
the inverter circuit includes: the flying capacitor type multi-level half-bridge inverter circuit comprises a flying capacitor type multi-level half-bridge inverter circuit, a first switch tube and a second switch tube.
The first input end of the flying capacitor type multilevel half-bridge inverter circuit is formed as the first input end, the second input end of the flying capacitor type multilevel half-bridge inverter circuit is formed as the second input end, the first output end of the flying capacitor type multilevel half-bridge inverter circuit is connected with the first end of the first switch tube, the second output end of the flying capacitor type multilevel half-bridge inverter circuit is connected with the first end of the second switch tube, and the flying capacitor type multilevel half-bridge inverter circuit is used for receiving the second driving signal and adjusting the voltage conversion gear of the LLC resonance conversion unit according to the second driving signal; the second end of the first switching tube is connected with one end of the resonant circuit; the second end of the second switch tube is connected with the second end of the first switch tube.
By adopting the inverter circuit structure, the conduction time sequence of the switching tube in the flying capacitor type multilevel half-bridge inverter circuit can be controlled through the received driving signal, so that a plurality of flying capacitors are controlled to be charged and discharged, the inverter circuit is realized to output different voltage values, and the transformation ratio of the LLC resonance conversion unit is adjusted.
In a possible design, in a case that the transformation ratio of a single LLC resonant conversion unit is limited, in order to further improve the conversion efficiency of the dc converter, the LLC resonant conversion unit includes N LLC resonant conversion circuits. Wherein, each LLC resonance converting circuit in N LLC resonance converting circuits all has a plurality of voltage conversion gear. Wherein N is an integer greater than or equal to 2.
The input ends of the N LLC resonance conversion circuits are connected in series to form a first input end and a second input end, and the output ends of the N LLC resonance conversion circuits are connected in parallel to form a first output end and a second output end.
In one possible design, the dc converter may further include: a plurality of third switching tubes, a plurality of fourth switching tubes and a plurality of fifth switching tubes.
Each third switching tube is bridged between first end points of input ends of two adjacent LLC resonance conversion circuits; each fourth switching tube is bridged between second end points of the input ends of the two adjacent LLC resonant conversion circuits; one end of each fifth switching tube is connected with the second end point of the input end of the first LLC resonance conversion unit in the two adjacent LLC resonance conversion circuits, and the other end of each fifth switching tube is connected with the first end point of the input end of the second LLC resonance conversion unit in the two adjacent LLC resonance conversion circuits. The first end point is one end of the LLC resonance conversion circuit receiving high level, and the second end point is one end of the LLC resonance conversion circuit receiving low level.
By adopting the structure of the direct current converter, when the voltage of the input voltage and the voltage of the output voltage are changed to cause the target transformation ratio of the direct current converter to be changed, the input sides of the LLC resonance conversion circuits can be changed from series connection to parallel connection, so that the transformation ratio of the LLC resonance conversion units is adjusted, namely the transformation ratio is adjusted in real time along with the application scene.
In one possible design, when the maximum transformation ratio of the LLC resonant conversion unit is much smaller than the target transformation ratio, in order to improve the efficiency of the dc converter, the dc converter further includes: and the second voltage regulating circuit has higher conversion efficiency.
The input end of the second voltage regulating circuit is respectively connected with the input end of the first voltage regulating circuit and the input end of the LLC resonance conversion unit in series to form a first input end and a second input end, and the output end of the second voltage regulating circuit is respectively connected with the output end of the first voltage regulating circuit and the output end of the LLC resonance conversion unit in parallel to form a first output end and a second output end.
In one possible design, the first voltage regulating circuit may be a Buck circuit.
In a third aspect, an embodiment of the present application provides a dc converter, which mainly includes an LLC resonant conversion unit and a first voltage regulation circuit.
The LLC resonance conversion unit comprises a first input end, a second input end, a first output end and a second output end. The first voltage regulating circuit comprises a third input end, a fourth input end, a third input end and a fourth output end. The LLC resonance conversion unit comprises an inverter circuit, a resonance circuit, a transformer and a rectification circuit.
Specifically, the second output terminal is connected to the third output terminal, the first input terminal is connected to the third input terminal, and the second input terminal is connected to the fourth input terminal.
The inverter circuit can be used for converting input voltage of the direct current converter received through the first input end and the second input end into alternating current voltage, the alternating current voltage is transmitted to the rectifier circuit through the resonance circuit and the transformer, and the rectifier circuit converts the alternating current voltage output by the transformer into first output voltage and outputs the first output voltage through the first output end and the second output end; the LLC resonance conversion unit is provided with a plurality of voltage conversion gears; the first voltage regulating circuit is used for converting input voltage of the direct current converter received through the third input end and the fourth input end into second output voltage and outputting the second output voltage through the third input end and the fourth output end, and the total output voltage of the direct current converter comprises first output voltage and second output voltage.
By adopting the structure of the direct current converter, the LLC resonance conversion unit and the input side of the first voltage regulation circuit are connected in parallel, and the output side is connected in series, so that the direct current converter is mainly used in a boosting application scene and has the technical effect similar to that of the second aspect, the technical effect of the corresponding scheme in the third aspect can refer to the technical effect which can be obtained by the corresponding scheme in the second aspect, and repeated parts are not detailed.
In one possible design, when the LLC resonant conversion unit is in any one of the multiple voltage conversion gears, the period of the ac voltage output by the inverter circuit is the same as the resonant period of the resonant circuit, and the output voltage of the LLC resonant conversion unit is greater than zero.
In one possible design, the voltage conversion efficiency of the LLC resonant conversion unit is greater than the voltage conversion efficiency of the voltage regulation circuit, the voltage conversion efficiency of the LLC resonant conversion unit is the ratio of the output power of the LLC resonant conversion unit to the input power of the LLC resonant conversion unit, and the voltage conversion efficiency of the voltage regulation circuit is the ratio of the output power of the voltage regulation circuit to the input power of the voltage regulation circuit.
In one possible design, the dc-to-dc converter further includes: and a controller.
The controller is used for controlling the LLC resonance conversion unit to convert the input voltage of the direct current converter into a first output voltage and controlling the voltage regulation circuit to convert the input voltage of the direct current converter into a second output voltage; and adjusting the voltage conversion gear of the LLC resonance conversion unit according to the target transformation ratio of the DC converter. The target transformation ratio is the ratio of the input voltage to the target output voltage.
In a fourth aspect, embodiments of the present application provide a conversion system, which mainly includes a dc converter and a controller.
Specifically, the direct current converter mainly comprises an LLC resonant conversion unit and a first voltage regulating circuit, the LLC resonant conversion unit has a plurality of voltage conversion gears, the LLC resonant conversion unit comprises a first input terminal, a second input terminal, a first output terminal and a second output terminal, and the first voltage regulating circuit comprises a second input terminal, a third output terminal and a fourth output terminal. The LLC resonance conversion unit comprises an inverter circuit, a resonance circuit, a transformer and a rectification circuit.
Specifically, the second input terminal is connected to the third input terminal, the first output terminal is connected to the third output terminal, and the second output terminal is connected to the fourth output terminal.
Wherein, the controller is connected with LLC resonance converting unit and first regulator circuit respectively, and the controller can be used for: the control inverter circuit converts a first input voltage received through a first input end and a second input end into an alternating current voltage, the alternating current voltage is transmitted to the rectifying circuit through the resonant circuit and the transformer, the rectifying circuit converts the alternating current voltage output by the transformer into an output voltage of a system, and the output voltage of the direct current converter is output through a first output end and a second output end; and controlling the first voltage regulating circuit to convert a second input voltage received through the third input end and the fourth input end into an output voltage of the conversion system, and outputting the output voltage of the direct current converter through the third output end and the fourth output end, wherein the total input voltage of the direct current converter comprises a first input voltage and a second input voltage.
By adopting the structure of the conversion system, the controller can configure the proper maximum transformation ratio for the LLC resonance conversion unit from a plurality of voltage conversion gears, so that the LLC resonance conversion unit transmits more power, and the efficiency of the LLC resonance conversion unit is higher than that of the voltage regulation circuit, thereby being beneficial to improving the efficiency of the conversion system.
In a fifth aspect, embodiments of the present application provide an electronic device, which may include a power supply and the dc converter provided in the foregoing embodiments.
The dc converter may be connected to a power supply, and may convert a voltage output by the power supply into a supply voltage of a load.
Alternatively, the electronic device may switch power.
Alternatively, the electronic device may be an in-vehicle charger.
By adopting the electronic equipment, the efficiency of the electronic equipment can be improved through the direct current converter.
These and other aspects of the present application will be more readily apparent from the following description of the embodiments.
Drawings
FIG. 1 is a first schematic diagram of a two-stage converter architecture;
FIG. 2 is a diagram illustrating a two-stage converter architecture;
FIG. 3 is a schematic diagram of a structure of an LLC resonant conversion unit;
fig. 4 is a first schematic structural diagram of a dc converter according to an embodiment of the present disclosure;
fig. 5 is a schematic structural diagram of a dc converter according to an embodiment of the present application;
fig. 6 is a flowchart illustrating a method for adjusting a conversion ratio of a dc converter according to an embodiment of the present application;
fig. 7 is a flowchart illustrating a specific method for adjusting a conversion ratio of a dc converter according to an embodiment of the present application;
FIG. 8 is a schematic diagram of a transformation ratio change determination process provided in an embodiment of the present application;
fig. 9 is a schematic structural diagram of an LLC resonant conversion unit provided in an embodiment of this application;
FIG. 10 is a schematic diagram of a driving signal provided by an embodiment of the present application;
fig. 11 is a schematic diagram of a switching state of an LLC resonant converting unit provided in the embodiment of the present application;
fig. 12 is an equivalent circuit schematic diagram of an LLC resonant conversion unit provided in the embodiments of the present application;
fig. 13 is a schematic diagram of a switching state of an LLC resonant conversion unit provided in the embodiment of the present application;
fig. 14 is an equivalent circuit schematic diagram of an LLC resonant conversion unit provided in the embodiments of the present application;
fig. 15 is a schematic diagram of a switching state of an LLC resonant conversion unit provided in the embodiment of the present application;
fig. 16 is an equivalent circuit schematic diagram of an LLC resonant conversion unit provided in an embodiment of the present application;
FIG. 17 is a schematic diagram of a driving signal provided in an embodiment of the present application;
fig. 18 is a schematic diagram of a switching state of an LLC resonant conversion unit provided in the embodiments of the present application;
fig. 19 is an equivalent circuit schematic diagram of an LLC resonant conversion unit provided in the embodiments of the present application;
fig. 20 is a schematic structural diagram of an LLC resonant conversion unit provided in an embodiment of the present application;
fig. 21 is a schematic structural diagram of an LLC resonant conversion unit provided in an embodiment of this application;
fig. 22 is a schematic structural diagram of an LLC resonant conversion unit provided in this application;
fig. 23 is a schematic structural diagram of an LLC resonant conversion unit provided in this application;
FIG. 24 is a schematic diagram of a driving signal provided in an embodiment of the present application;
fig. 25 is a schematic structural diagram of an LLC resonant conversion unit provided in an embodiment of the present application;
fig. 26 is a schematic structural diagram of a first voltage regulating circuit according to an embodiment of the present disclosure;
fig. 27 is a schematic structural diagram of a first voltage regulating circuit according to an embodiment of the present application;
fig. 28 is a schematic structural diagram of an LLC resonant conversion unit provided in this application;
fig. 29 is a schematic structural diagram of an LLC resonant conversion unit provided in an embodiment of this application;
fig. 30 is a schematic structural diagram of an LLC resonant conversion unit provided in an embodiment of the present application;
fig. 31 is a schematic structural diagram of another dc converter according to an embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more clear, the present application will be further described in detail with reference to the accompanying drawings. The particular methods of operation in the method embodiments may also be applied to apparatus embodiments or system embodiments. It is to be noted that "at least one" in the description of the present application means one or more, where a plurality means two or more. In view of this, the "plurality" may also be understood as "at least two" in the embodiments of the present invention. "and/or" describes the association relationship of the associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" generally indicates that the preceding and following related objects are in an "or" relationship, unless otherwise specified. In addition, it is to be understood that the terms first, second, etc. in the description of the present application are used for distinguishing between the descriptions and not necessarily for describing a sequential or chronological order.
It is to be noted that "connected" in the embodiments of the present application refers to an electrical connection, and the connection of two electrical components may be a direct or indirect connection between the two electrical components. For example, a and B may be connected directly, or a and B may be connected indirectly through one or more other electrical elements, for example, a and B may be connected, or a and C may be connected directly, or C and B may be connected directly, and a and B are connected through C.
It should be noted that the "transformation ratio" of the conversion circuit in the embodiment of the present application refers to a ratio between a larger voltage of the input voltage and the output voltage of the conversion circuit and a smaller voltage of the input voltage and the output voltage. If the conversion circuit performs the step-down conversion, the output voltage of the conversion circuit is smaller than the input voltage of the conversion circuit, and the conversion ratio of the conversion circuit is input voltage/output voltage. If the conversion circuit performs the step-up conversion, the output voltage of the conversion circuit is greater than the input voltage of the conversion circuit, and the conversion ratio of the conversion circuit is output voltage/input voltage.
With the development of the power electronic field, the switching converter has been widely used, and accordingly, the design of the switching converter also meets the requirements of comprehensive performances such as high power density, high efficiency, fast dynamic characteristics, and the like. In order to achieve higher power density, the size of the magnetic elements such as capacitors, inductors, and transformers in the converter is usually reduced by increasing the switching frequency, but the increase in the switching frequency leads to an increase in the switching loss, thereby reducing the efficiency of the switching converter.
Soft switching technology is one of the important technologies for realizing high conversion efficiency of a switching type converter. Among them, LLC resonant converters are widely studied and used. As shown in fig. 3, the LLC resonant converter mainly includes: the circuit comprises an inverter circuit, a resonance circuit, a transformer and a rectification circuit. The first output end of the inverter circuit is connected with one end of the resonant circuit, and the other output end of the inverter circuit is connected with one end of the primary winding of the transformer; the other end of the resonant circuit is connected with the other end of the primary winding of the transformer; two ends of the secondary winding of the transformer are respectively connected with two input ends of the rectifying circuit.
When the inverter works specifically, a switching tube in the inverter circuit usually works at a switching frequency with a duty ratio of 50%, and the transformation ratio of the whole LLC resonant converter can be controlled by adjusting the switching frequency of the switching tube. When operating at the resonant frequency of the resonant circuit, the LLC resonant converter can achieve soft switching and low conduction losses, when it has maximum efficiency. LLC resonant converters are less efficient when the switching frequency deviates more from the open resonant frequency.
During specific implementation, in order to ensure the efficiency of the LLC resonant converter, the conduction time sequence and the switching frequency of a switching tube in an inverter circuit are fixed, the switching frequency of the switching tube in the inverter is consistent with the resonant frequency of the resonant circuit, and the maximum efficiency is achieved.
In practical power supply application, various different output voltages are required to be adjusted, an input voltage can also adapt to a certain wide range, the converter needs to output different transformation ratios to meet the requirement that a power supply runs at different transformation ratios, the transformation ratio of the single-stage LLC resonant conversion converter is difficult to meet the power supply requirement of the power supply, and therefore a power supply framework of the two-stage converter is arranged.
See fig. 2 for a schematic diagram of a two-stage converter power supply architecture. The LLC resonant converter is provided with a fixed voltage conversion gear, and the Buck circuit is used for converting the voltage which cannot be converted by the LLC resonant converter to realize voltage adjustment.
For example, the LLC resonant converter has an efficiency of 97%, the Buck circuit has an efficiency of 88%, the LLC resonant converter has a transformation ratio of 30, the input voltage of the two-stage converter power supply architecture shown in fig. 2 varies in the range of [40-60] V, and the output voltage varies in the range of [0.6-1.2] V.
When the input voltage of the two-stage converter power supply architecture is 40V and the output voltage is 1.2V, the input voltage of the LLC resonant converter is 36V, the output voltage of the LLC resonant converter is 1.2V, the input voltage of the Buck circuit is 4V, and the output voltage of the Buck circuit is 1.2V, wherein the total efficiency of the two-stage converter power supply architecture is 36/40 + 97% +4/40 + 88% ≈ 96%; when the input voltage of the two-stage converter power supply architecture is 60V and the output voltage is 0.6V, the output voltage of the LLC resonant converter is 18V, the output voltage is 0.6V, the input voltage of the Buck circuit is 42V, and the output voltage is 0.6V, at this time, the total efficiency of the two-stage converter power supply architecture is 18/60 × 97% +42/60 × 88% ≈ 91%. Therefore, in the converter structure shown in fig. 2, the lower the ratio of the input voltage received by the LLC resonant converter to the input voltage of the two-stage converter power supply architecture, the lower the efficiency of the converter.
In view of this, the present application provides a dc converter, which can be applied to a switching power supply, and not only can meet the transformation ratio requirement of the switching power supply, but also is beneficial to improving the efficiency of the switching power supply.
As shown in fig. 4, the dc converter 400 provided in the embodiment of the present application mainly includes an LLC resonant conversion unit 401 and a first voltage regulation circuit 402. Therein, the LLC resonant conversion unit 401 includes a first input terminal 11, a second input terminal 12, a first output terminal 13 and a second output terminal 14. The first voltage regulating circuit 402 comprises a third input 21, a fourth input 22, a third output 23 and a fourth output 24.
The LLC resonant converting unit 401 has a first input terminal 11 and a second input terminal 12 for receiving a first input voltage Vi1 of the dc converter 400, and a third input terminal 21 and a fourth input terminal 22 of the first voltage regulating circuit 402 for receiving a second input voltage Vi2 of the dc converter 400. The first input voltage Vi1 and the second output voltage Vi2 constitute a total input voltage Vi of the dc converter 400. I.e. the input sides (the first input terminal 11 and the second input terminal 12) of the LLC resonant conversion unit 401 are connected in series with the input sides (the third input terminal 21 and the fourth input terminal 22) of the first voltage regulating circuit 402.
Since the input side of the LLC resonance conversion unit 401 and the input side of the first voltage regulation circuit 402 are connected in series, the LLC resonance conversion unit 401 and the first voltage regulation circuit 402 have the same input current. Meanwhile, as shown in fig. 4, the voltage between the input terminals 11 and 12 is Vi1, the voltage between the input terminal 21 and the input terminal 22 is Vi2, and the sum of the input voltage Vi1 and the input voltage Vi2 is the total input voltage Vi of the dc converter 400.
In the embodiment of the present application, both the LLC resonant conversion unit 401 and the first voltage regulation circuit 402 can implement a voltage conversion function. The LLC resonant conversion unit 401 can convert the input voltage Vi1, and output the converted voltage through the output terminal 13 and the output terminal 14. The first voltage regulating circuit 402 may convert the input voltage Vi2 and output the converted voltage through the output terminal 23 and the output terminal 24. The LLC resonant conversion unit 401 includes an inverter circuit, a resonant circuit, a transformer, and a rectifier circuit.
When the LLC resonance conversion unit is used for converting the input voltage Vi1, the inverter circuit converts the input voltage Vi1 received by the input ends 11 and 12 into alternating current voltage, the alternating current voltage is transmitted to the rectifier circuit through the resonance circuit and the transformer, and the rectifier circuit converts alternating current output by the transformer into direct current voltage and outputs the direct current voltage.
As shown in fig. 4, the output terminal of the LLC resonance converting unit 401 is connected to the output terminal of the first voltage regulating circuit 402, the output terminal 13 of the LLC resonance converting unit 401 is connected to the output terminal 23 of the first voltage regulating circuit 402, and the output terminal 14 of the LLC resonance converting unit 401 is connected to the output terminal 24 of the first voltage regulating circuit 402, that is, the output sides (the first output terminal 13 and the second output terminal 14) of the LLC resonance converting unit 401 are connected in parallel to the output sides (the third output terminal 23 and the fourth output terminal 24) of the first voltage regulating circuit 402, so that the output voltages Vo of the LLC resonance converting unit 401 and the first voltage regulating circuit 402 are the same, that is, the output voltage of the dc converter 400.
The dc converter 400 provided by the embodiment of the present application has high conversion efficiency. For example, assume that the input current of the dc converter 400 is Ii and the output current is Io. The output current of the LLC resonant conversion unit 401 is Io1, and the output current of the first voltage regulation circuit 402 is Io 2. Since the output side of the LLC resonant conversion unit 401 and the output side of the first voltage regulating circuit 402 are connected in parallel, the sum of the output current Io1 of the LLC resonant conversion unit 401 and the output current Io2 of the first voltage regulating circuit 402 is the output current Io of the dc converter 400, i.e., Io1+ Io2 is Io.
Assuming that the efficiency of the LLC resonant conversion unit 401 is a%, the efficiency a% of the LLC resonant conversion unit 401 may be understood as the ratio (expressed in percentage terms) of the output power of the LLC resonant conversion unit 401 to the input power of the LLC resonant conversion unit 401, and a may be any value greater than or equal to 0 and less than or equal to 100. The efficiency of the LLC resonant conversion unit satisfies the following formula one:
(N1 Vo) Ii a ═ Vo Io1 (formula one)
Where N1 is a transformation ratio of the LLC resonant conversion unit 401, which is hereinafter referred to as the first transformation ratio N1, N1 Vo Vi1, and Vi1 is an input voltage of the LLC resonant conversion unit.
Assuming that the efficiency of the first voltage regulating circuit 402 is b%, the efficiency b% of the first voltage regulating circuit 402 can be understood as the ratio (expressed in percentage) of the output power of the first voltage regulating circuit 402 to the input power of the first voltage regulating circuit 402, and b can be any value greater than or equal to 0 and less than or equal to 100. The efficiency of the first voltage regulating circuit satisfies the following formula two:
(Vi-N1 Vo) Ii i b% ═ Vo Io2 (formula two)
As can be seen from the combination of equation one and equation two, the efficiency of the dc converter 400 satisfies the following equation three:
Figure BDA0002879504370000091
where η represents the efficiency of dc converter 400. From equation three, the following equation four can be further obtained:
Figure BDA0002879504370000092
as can be seen from the formula four, when the efficiency a% of the LLC resonant conversion unit 401 is greater than the efficiency b% of the first voltage regulating circuit 402,
Figure BDA0002879504370000093
is positive, and the efficiency η of the dc converter is larger when the value of N1 is larger.It can be seen that, compared to the two-stage converter structure shown in fig. 2, the dc converter 600 shown in fig. 4 of the present application can achieve greater efficiency by adjusting the voltage conversion gear of the LLC resonant conversion unit 401. Wherein each voltage conversion step corresponds to a transformation ratio of the LLC resonant conversion unit 401.
It should be noted that, in order to achieve the efficiency of the LLC resonant conversion unit, when the LLC resonant conversion unit is in any one of the multiple voltage conversion gears, the period of the ac voltage output by the inverter circuit is the same as the resonant period of the resonant circuit, and the output voltage of the LLC resonant conversion unit is greater than zero.
In a specific implementation, the LLC resonant conversion unit 401 and the first voltage regulation circuit 402 may be composed of devices such as a switching tube, a diode, an inductor, and a capacitor. The operation states of the LLC resonance conversion unit 401 and the first voltage regulation circuit 402 can be adjusted by adjusting the operation states of these devices (e.g., switching tubes) to adjust the transformation ratio of the LLC resonance conversion unit 401 and the first voltage regulation circuit 402.
In the present application, the adjustment of the above-mentioned operating state can be realized by a controller. That is, the dc converter 400 may further include a controller 403, as shown in fig. 5, the controller 403 is respectively connected to the LLC resonance converting unit 401 and the first voltage regulating circuit 402, and may be configured to control the LLC resonance converting unit 401 to convert the first input voltage Vi1 into the output voltage V0 of the dc converter 400, control the first voltage regulating circuit 402 to convert the second input voltage Vi2 into the output voltage Vo of the dc converter 400, and adjust the voltage conversion step of the LLC resonance converting unit 401 according to the target conversion ratio of the dc converter. Wherein the target transformation ratio is a ratio between the total input voltage and a target output voltage of the direct current converter.
Specifically, if the switching transistors in each circuit of the dc converter 400 are Metal Oxide Semiconductor (MOS) transistors, the controller 403 may be connected to the gates of the MOS transistors, so as to control the on/off of the MOS transistors to implement voltage conversion for the dc converter 400; if the switching transistors in each circuit of the dc converter 400 are Bipolar Junction Transistors (BJTs), the controller 403 may be connected to bases of the BJTs, so as to control the on/off of the BJTs to implement voltage conversion of the dc converter 400.
In a specific implementation, the controller 403 may be any one of a Micro Controller Unit (MCU), a Central Processing Unit (CPU), and a Digital Signal Processor (DSP). Of course, the specific form of the controller 403 is not limited to the above example.
In addition, since the LLC resonance converting unit 401 and the first voltage regulating circuit 402 perform voltage conversion independently in the embodiment of the present application, the switching frequencies of the LLC resonance converting unit 401 and the first voltage regulating circuit 402 do not need to be kept consistent.
As can be seen from the formula four, the efficiency a% of the LLC resonant conversion unit 401 is greater than the efficiency b% of the first voltage regulating circuit 402, and the larger the value of the first transformation ratio N1 is, the higher the efficiency of the dc converter 400 is. When the output voltage Vo is fixed, the larger the value of N1 is, the larger the input voltage Vi1(Vi1 — N1 Vo) of the LLC resonant conversion unit 402 is, and more voltage is transmitted. Therefore, when the efficiency a% of the LLC resonant conversion unit 401 is greater than the efficiency b% of the first voltage regulating circuit, the controller 403 may make the LLC resonant conversion unit 401 have a larger transformation ratio and make the first voltage regulating circuit 402 have a smaller transformation ratio.
Ideally, if the first voltage regulating circuit 402 has a step-down function, the ratio of the voltage N2 of the first voltage regulating circuit 402 may be 1, that is, Vo may be Vi 2. That is, the first regulator circuit 402 performs only voltage transmission and does not perform voltage conversion. Since the loss of the first regulator circuit 402 is mainly generated during the voltage conversion process, when the second conversion ratio N2 is 1, the loss of the first regulator circuit 402 can be considered to be the minimum and less power can be transmitted.
If the first voltage regulating circuit 402 has a boosting function, the voltage regulating range of the first voltage regulating circuit can be increased. Ideally, the transformation ratio N2 of the first voltage regulating circuit 402 can be made less than 1 and close to 0, i.e., the smaller the input voltage Vi2 of the first voltage regulating circuit 402, the less power the first voltage regulating circuit 402 transmits.
As described above, when the efficiency a% of the LLC resonant conversion unit 401 is greater than the efficiency b% of the first voltage regulation circuit 402, a larger transformation ratio is configured for the LLC resonant conversion unit 402, which enables the LLC resonant conversion unit 401 to transmit more power, and is beneficial to further improving the efficiency of the dc converter 400. However, since the application scenario of the dc converter 400 is not very stable, such as the battery voltage fluctuates, the operating voltage of the load changes, and the like, the transformation ratio of the LLC resonant conversion unit 401 often needs to change dynamically with the change of the application scenario.
In one possible implementation, the first transformation ratio N1 and the second transformation ratio N2 are adjustable in the embodiments of the present application. In the embodiment of the present application, the controller 403 may also detect the current total input voltage Vi and the target output voltage Va of the dc conversion. Here, the present total input voltage Vi may be an output voltage of a battery to which the dc converter 400 is connected, and the target output voltage Va of the dc converter 400 may be an operating voltage currently required by the load. As previously described, the battery voltage gradually decreases during the discharge of the connected battery. In particular, the load connected to the output 13 and the output 14 may have a plurality of operating states, in which different operating voltages are required. For example, the load may be a GPU or a battery, and the voltage across the battery gradually increases during the charging process of the battery.
It is to be understood that the output voltage Vo of the dc converter 400 may be the same as the target output voltage Va, or may be different from the target output voltage Va. When the output voltage Vo of the dc converter is different from the target output voltage Va, the controller may adjust a transformation ratio of the dc converter to adjust the output voltage Vo of the dc converter to the desired target output voltage Va. Wherein, the target output voltage is the voltage actually needed by the load.
Illustratively, the controller 403 may detect the current output voltage Vo and the total input voltage Vi. When the present output voltage Vo is different from the target output voltage Va of the dc converter 400, the controller 403 may adjust the transformation ratios of the LLC resonant conversion unit 401 and the first voltage regulation circuit 402 according to the total input voltage Vi, thereby adjusting the output voltage Vo of the dc converter 400 to the target output voltage Va.
Specifically, the controller 403 may execute a control method shown in fig. 6 to adjust the transformation ratio between the LLC resonant conversion unit 401 and the first voltage regulation circuit 402 in fig. 4, so as to improve the conversion efficiency of the dc converter 400, and mainly includes the following steps:
s601: a target transformation ratio is calculated, which is a transformation ratio between the input voltage of the dc converter 400 and the target output voltage of the dc converter. The target transformation ratio is Na ═ Vi/Va.
S602: and determining a first transformation ratio of the LLC resonance conversion unit from a plurality of voltage conversion gears of the LLC resonance conversion unit according to the target transformation ratio and the minimum transformation ratio of the first voltage regulating circuit.
The first transformation ratio N1 is less than or equal to the difference between the target transformation ratio Na and the minimum transformation ratio of the first voltage regulating circuit 402, and is less than or equal to the maximum transformation ratio of the LLC resonant conversion unit 401.
Generally, the controller 403 may change the voltage shift of the LLC resonant conversion unit 401 by controlling the timing of the driving signal of the switching tube in the inverter circuit of the LLC resonant conversion unit 401 and the switching frequency, thereby achieving the adjustment of the first transformation ratio N1. The controller determines that the specific value of N1 is related to the structure of the LLC resonance conversion unit, and the controller can flexibly select the implementation mode for setting the transformation ratio of the LLC resonance conversion unit according to the specific structure of the LLC resonance conversion unit.
S603: a second transformation ratio N2 of the first voltage regulating circuit 402 is determined based on the first transformation ratio N1 and the target transformation ratio.
Specifically, the controller 402 may determine the input voltage Vi1 after adjusting the transformation ratio of the LLC resonant conversion unit 401 according to the set first transformation ratio N1, i.e., the adjusted input voltage Vi1 is the product between the set first transformation ratio N1 and the target output voltage Va (Vi1 — N1 — Va).
The controller 403 may then determine the adjusted input voltage Vi2 of the first voltage adjustment circuit 402 according to the current total input voltage Vi, i.e., Vi2 — Vi1 — Vi-N1 — Va. That is, the second variation ratio N2 should be set to N2 ═ Vi-N1 × Va)/Va. The controller can flexibly select the implementation mode for setting the transformation ratio of the first voltage regulating circuit 402 according to the specific structure of the first voltage regulating circuit 402.
For convenience of understanding, in the following description of the embodiment of the present application, a control method shown in fig. 6 is described by taking a case where the efficiency of the LLC resonant conversion unit is a% and the efficiency of the first voltage regulation circuit is b% as an example.
In the embodiment of the present application, the first transformation ratio N1 has a plurality of discontinuous adjustable transformation ratios, and each transformation ratio corresponds to a first voltage conversion gear of the LLC resonant conversion unit 401.
As mentioned above, the efficiency a% of the LLC resonant conversion unit 401 is greater than the efficiency b% of the first voltage regulating circuit 402, the input voltage Vi1 of the LLC resonant conversion unit 401 should be increased as much as possible. Therefore, in the case where the LLC resonant conversion unit 401 has a plurality of adjustable ratios which are discontinuous, the first ratio N1 may be an adjustable ratio which is smaller than the difference between the target ratio Na and the minimum ratio of the first voltage regulating circuit 402 and is closest to the target ratio Na among the plurality of adjustable ratios in the LLC resonant conversion unit.
Taking the values of the plurality of adjustable transformation ratios of the LLC resonant conversion unit 402 as consecutive integers (e.g. the adjustable transformation ratios are 4, 3, 2, 1), the controller 403 may adjust the first transformation ratio N1 and the second transformation ratio N2 by using the method shown in fig. 7. As shown in fig. 7, the method mainly comprises the following steps:
s701: the current total input voltage Vi and the target output voltage Va are detected.
S702: the controller calculates a target transformation ratio Na. The target transformation ratio Na is a ratio between the total input voltage Vi and the target output voltage Va, that is, Na is Vi/Va.
S703: whether the first voltage regulating circuit has a boosting function is detected, if yes, 704 is executed, otherwise, 705 is executed.
S704: if the first voltage regulating circuit has a boosting function, the value range of the voltage conversion gear is less than or equal to the target transformation ratio Na. Wherein each voltage conversion step corresponds to a first voltage transformation ratio N1.
If the first voltage regulating circuit has a boosting function, the second transformation ratio N2 of the first voltage regulating circuit can be close to 0 in an ideal situation. At this time, Vi2< Va, and the first conversion ratio N1 ═ Vi-Vi2)/Va ≈ Na. That is, in the ideal case, the second conversion ratio N2 ≈ 0. Therefore, the value range of the first transformation ratio N1 is N1< Na, and N1 is smaller than or the maximum voltage of the LLC resonance conversion unit shifts.
S705: if the first voltage regulating circuit has a voltage reduction function, the value range of the voltage conversion gear is smaller than the target transformation ratio Na-1.
If the first voltage regulating circuit has a voltage reduction function, the second transformation ratio N2 of the first voltage regulating circuit can reach 1 under ideal conditions. In this case, Vi2 is Va, and first conversion ratio N1 is (Vi-Vi2)/Va is Na-1. That is, in an ideal case, the first conversion ratio N1 is Na-1. Therefore, the value range of the first transformation ratio N1 is N1 ≦ Na-1 and is less than or equal to the maximum voltage shift position of the LLC resonant conversion unit.
S706: and determining the maximum voltage conversion gear within the value range of the voltage conversion gear of the LLC resonance conversion unit as the first transformation ratio.
For example, assume that the LLC resonant conversion unit has three voltage conversion steps of 3, 2, and 1. As shown in fig. 8, the total input voltage Vi is 3.4V, and the target output voltage Va is 1V. At this time, the target conversion Na is 3.4, and if the first voltage regulating circuit 402 has the voltage step-down function, N1 ≦ Na-1 — 2.4, so the voltage shift stage of the LLC resonance conversion unit 401 may be 1 or 2, and N1max is 2, so the controller 403 may set the first conversion N1 to 2. If the first voltage regulating circuit has a boosting function, N1< Na ≈ 3.4, so the voltage shift stage of the LLC resonance converting unit may be 1, 2, or 3, and N1max ═ 3, so the controller may set the first conversion ratio N1 to 3.
S707: and calculating a target input voltage of the LLC resonance conversion unit when the LLC resonance conversion unit is in the first transformation ratio.
S708: a first voltage difference between the input voltage of the DC converter and a target input voltage is calculated.
S709: determining a transformation ratio between the first voltage difference and the output voltage of the DC converter as the second transformation ratio.
As described above, as the input voltage is as shown in fig. 8, the controller may set the first conversion ratio N1 to 3, and further set the input voltage Vi1 to 3V, and set the input voltage Vi2 to Vi-Vi1 to 0.4V, and set the second conversion ratio N2 to Vi2/Vo to 0.4/1 to 0.4.
As can be seen from the foregoing embodiments, based on the dc converter 400 provided in the embodiments of the present application, the controller 403 may flexibly adjust the transformation ratio between the LLC resonant conversion unit 401 and the first voltage regulation circuit according to the total input voltage Vi and the target output voltage Va of the dc converter, so that under different application scenarios of the total input voltage Vi and the target output voltage Va, the LLC resonant conversion unit 401 may receive a larger input voltage Vi1 as far as possible while adapting to the application scenarios. Combining the above formula, it can be seen that, when the efficiency a% of the LLC resonant conversion unit, the efficiency b% of the first voltage regulating circuit, and the output voltage Vo are fixed, the efficiency of the dc converter also increases when the input voltage Vi1 of the LLC resonant conversion unit is increased by N1 Vo. Therefore, the method for setting the first conversion ratio N1 and the second conversion ratio N2 shown in fig. 6 and fig. 8 in the embodiment of the present application is beneficial to further improving the efficiency of the dc converter 400.
In an implementation manner, in the process of supplying power to the load by using the dc converter provided in the embodiment of the present application, if the output voltage Vo deviates from the target output voltage Va due to the voltage received by the input side or the load change on the output side, the transformation ratios of the LLC resonant conversion unit 401 and the first voltage regulating circuit may be reconfigured by setting the first transformation ratio N1 and the second transformation ratio N2 as shown in fig. 6 and fig. 8.
In another implementation manner, in the process of supplying power to the load by using the dc converter provided in the embodiment of the present application, if the output voltage Vo deviates from the target output voltage Va due to the voltage received by the input side or the load change on the output side, the output voltage Vo and the target output voltage Va may be achieved by adjusting the transformation ratio of the first voltage regulating circuit 402.
In an example, when the dc converter provided in the embodiment of the present application is used to supply power to a load, if the loads connected to the output terminals 13 and 14 of the dc converter are increased, and the output voltage Vo of the dc converter is smaller than the target output voltage Va, the duty ratio of the switching tube in the first voltage regulating circuit 402 may be adjusted to achieve adjustment of the transformation ratio N2 of the first voltage regulating circuit 402, so as to achieve adjustment of the output voltage Vo until the output voltage Vo is equal to the target output voltage Va.
In an example, when the dc converter provided in the embodiment of the present application is used to supply power to a load, if a storage battery is connected to the input side of the dc converter, during the power supply to the load, the voltage of the storage battery gradually decreases, which causes the voltage Vo output by the dc converter to deviate from the target output voltage Va, and the duty ratio of the switching tube in the first voltage regulating circuit 402 may be adjusted to adjust the transformation ratio N2 of the first voltage regulating circuit 402, so as to adjust the output voltage Vo until the output voltage Vo is equal to the target output voltage Va.
As disclosed in the embodiments of the present application, there are many possible implementation structures of the LLC resonant conversion unit 401. Next, the embodiment of the present application further exemplifies the dc converter 400 provided in the embodiment of the present application by the following examples.
Example of the dc converter:
the embodiment of the present application provides a dc converter 400, as shown in fig. 9. Wherein, the inverter circuit in the LLC resonance conversion unit 401 includes: a first capacitor C1 and a first H-bridge circuit composed of four switching tubes S1, S2, S3 and S4. The resonance circuit mainly includes: the resonant inductor includes Lr and a resonant capacitor Cr. The primary winding of the transformer is connected in series with the resonant inductor Lr and the resonant capacitor Cr, and the secondary winding of the transformer is connected with a rectifying circuit composed of a second H-bridge circuit. The second H-bridge circuit mainly comprises switching tubes S5, S6, S7 and S8. The resonant inductor Lr may be an independent inductor or a leakage inductance of the primary winding of the transformer, or the resonant inductor Lr includes a part of the independent inductor and a part of the leakage inductance of the primary winding of the transformer. Wherein Lm is the excitation winding of the transformer.
The S1 and the S2 are connected in series to form a first bridge arm of the first H-bridge circuit, the S3 and the S4 are connected in series to form a second bridge arm of the first H-bridge circuit, and the C1 is connected between a middle node of the first bridge arm and a middle node of the second bridge arm. That is, the second end of S2 is connected to the first end of S1 and the one end of C1, respectively, and the second end of S4 is connected to the first end of S3 and the other end of C2, respectively. Specifically, the first terminal of S1 is connected to input terminal 11, and the first terminal of S3 is connected to input terminal 12.
The S5 and the S6 are connected in series to form a first bridge arm of a second H-bridge circuit, and the S7 and the S8 are connected in series to form a second bridge arm of the second H-bridge circuit. That is, the second end of S6 is connected to the first end of S5, the second end of S8 is connected to the first end of S7, the first ends of S7 and secondary winding of transformer are connected to the first end of S5, and the second ends of S6 are connected to the second end of S8 and the other end of secondary winding of transformer. Specifically, the intermediate node of the first arm and the intermediate node of the second arm of the second H-bridge circuit are connected to the output terminal 12 and the output terminal 14, respectively. That is, the second terminal of S5 is connected to the output terminal 13, and the second terminal of S7 is connected to the output terminal 14.
The second end of S2 and the second end of S4 are both connected to one end of a resonant capacitor Cr, the other end of Cr is connected to one end of a resonant inductor Lr, the other end of Lr is connected to one end of the primary winding of the transformer, and the other end of the primary winding of the transformer is connected to the input terminal 12.
In a specific implementation, the first H-bridge circuit has a plurality of voltage conversion ratios, which are one-to-one with a plurality of voltage conversion stages of the LLC resonance conversion unit 401, and which are one-to-one with a plurality of driving signals. The driving signals are used for controlling the conduction timing of the switching tubes S1, S2, S3 and S4 in the first H-bridge circuit. The voltage conversion gear represents a ratio relation between an input voltage of the LLC resonant conversion unit and an output voltage of the LLC resonant conversion unit, and the ratio relation is the first transformation ratio N1 in the embodiment of the present application. It should be noted that, in the dc converter provided in the present application, the LLC resonant conversion unit has a plurality of voltage conversion steps, which means that there are a plurality of ratio relationships between the input voltage of the LLC resonant conversion unit and the output voltage of the LLC resonant conversion unit, for example, the plurality of ratio relationships are 1:1, 1.2:1, 1.5:1, and 2:1, etc. The output voltage of the LLC resonant conversion unit is different for the same input voltage in different voltage conversion gears.
In one possible implementation, as shown in fig. 9, the dc converter 400 may further include an input capacitor Cin1 and an input capacitor Cin 2. One end of the input capacitor Cin1 is connected to the input terminal 11, the other end of the input capacitor Cin1 is connected to the input terminal 12, and the input capacitor Cin1 may filter the first input voltage Vi 1. Input voltage Cin2 may be connected at one end to input 21 and input voltage Cin2 may be connected at the other end to input 22, and Cin2 may filter second input voltage Vi 2.
In one possible implementation, as shown in fig. 9, the dc converter 400 may further include an output capacitor Cout. One end of the output capacitor Cout is connected to the output end 13 of the LLC resonance converting unit 401, and the other end of the output capacitor Cout is connected to the output end 14 of the LLC resonance converting unit 401. The output capacitor Cout can filter the output voltage Vo and reduce the fluctuation of the output voltage Vo.
Referring to fig. 9, taking the period of the ac output from the inverter circuit as T as an example, when the switching tubes S1, S2, S3, and S4 receive corresponding different driving signals, the transformation ratio of the LLC resonant conversion unit satisfies the following relationship:
N1＝2Nh*NL(formula five)
Nh is Vi1/Vh (formula six)
Where Vh is the peak-to-peak value of the output voltage of the inverter circuit. N is a radical ofhThe conversion ratio between the input voltage Vi1 and the peak-to-peak value of the output voltage of the inverter circuit is shown, and NL is the conversion ratio of the number of turns of the primary winding and the secondary winding of the transformer.
For convenience of calculation and understanding, in the embodiments of the present application, NL of the transformer is equal to 1 for example, which is not described again in the following.
It should be noted that, since the period of the alternating current output by the inverter circuit is consistent with the resonance period of the resonance circuit, the soft switching of the switching tube can be realized, and the efficiency of the LLC resonance conversion unit 401 is ensured.
When the switching tubes S1, S2, S3 and S4 in the LLC resonant converting circuit shown in fig. 9 receive different driving signals, the LLC resonant converting circuit is in different states and has different transformation ratios. When S1, S2, S3 and S4 receive different driving signals, the corresponding relationship between the driving signals and the output voltage of the first H-bridge circuit can be as shown in table one.
Watch 1
S1 S2 S3 S4 C1 Vh
State 1 0 0 1 1 -- 0
State II 1 0 1 0 Charging of electricity Vi1/2
State (c) 0 1 0 1 Discharge of electricity Vi1/2
State iv 1 1 0 0 -- 1Vi1
When the LLC resonant conversion unit 401 shown in fig. 9 adopts the states of the driving signals shown in table one to drive the switching tubes S1, S2, S3, and S4, the LLC resonant conversion unit has at least two adjustable conversion ratios of 4 and 2. It should be noted that the adjustable transformation ratio is a transformation ratio that the LLC resonant conversion unit 401 can theoretically achieve, and is limited by parasitic resistance, parasitic inductance, and the like, and there may be some deviation between the actual transformation ratio of the LLC resonant conversion unit 401 and the adjustable transformation ratio, but the implementation of the technical solution of the present application is not affected.
The following describes the ratio change process in two voltage conversion steps of the LLC resonant conversion unit 401 in detail with reference to the example.
The first implementation mode comprises the following steps: the first transformation ratio N1 is 4.
Assume that the switching tubes in the LLC resonant conversion unit 401 are all turned on at high voltage and turned off at low voltage. When the controller 403 provides the driving signals shown in fig. 10 to the respective switching tubes in the LLC resonant conversion unit 401, the first transformation ratio N1 is 4. The controller sends driving signals according to the state of the switch tube, and the switch tube is controlled to switch states.
As shown in fig. 10, the period of the alternating current is T, and the switching tubes S1, S2, S3 and S4 respectively correspond to different driving signals.
In the time period from 0 to T/2, the states of the respective switching tubes may be as shown in fig. 11. The switching tube S1 and the switching tube S3 are conducted, and the switching tubes S2 and S4 are disconnected.
In this case, the switch tube S1, the capacitor C1, the switch tube S3, Cr, Lr and Lm constitute a path, and an equivalent circuit can be as shown in fig. 12. At this time, V h1/2Vi 1.
In the period from T/2 to T, the states of the respective switching tubes may be as shown in fig. 13. The switching tubes S3 and S4 are turned on, and the switching tubes S1 and S2 are turned off.
In this case, the switch tube S3, the switch tube S4, Cr, Lr and Lm constitute a path, and an equivalent circuit can be as shown in fig. 14. Since the first capacitor is open and the output of the first H-bridge circuit is directly connected to the input terminal 12, Vh is 0.
In the time period from T to T3/2, the state of each switch tube may be as shown in fig. 15. The switching tubes S2 and S4 are turned on, and the switching tubes S1 and S3 are turned off.
In this case, switch tubes S4, Cr, S2, Lr and Lm constitute a path, and an equivalent circuit can be as shown in FIG. 16, when capacitor C1 discharges, since both ends of C1 have been charged to 1/2Vi1 in the time period from 0 to T/2, and therefore V ish1/2Vi1, the description is not repeated here.
In the period from 3/2T to 2T, the state of each switch tube may be as shown in fig. 13. The switching tubes S1 and S2 are turned on, and the switching tubes S3 and S4 are turned off.
In this case, the switch tube S3, the switch tube S4, Cr, Lr, and Lm constitute a path, and an equivalent circuit may be as shown in fig. 14. Since there is a direct connection between the output of the first H-bridge circuit and the input 12, Vh is 0.
It should be noted that when the switching tubes are driven by the driving signals shown in fig. 10 to drive the switching tubes S1, S2, S3 and S4, the output voltage of the inverter circuit is converted between 0 and 1/2Vi1 in two cycles of the alternating current, and then the peak-to-peak value of the output voltage of the inverter circuit is Vi1/2, which is substituted into the fifth formula and the sixth formula, so that the transformation ratio N1 of the LLC resonance converting unit 401 is 4 at this time.
It should be noted that, at this time, the switching tube performs switching once according to the sequence of (c), and in each switching period of the switching tube, the switching tube outputs alternating current of two periods, that is, the switching period of the switching tube is twice of the resonance period of the resonance circuit.
The second implementation mode comprises the following steps: the first conversion ratio N1 is 2.
Suppose that each switch tube in the LLC resonant conversion unit is turned on at a high voltage and turned off at a low voltage. When the controller 403 provides the driving signals shown in fig. 17 to the respective switching tubes in the LLC resonant conversion unit 401, the first transformation ratio N1 is 2. The controller sends driving signals according to the sequence of the state (r), so that the switching tube is controlled to switch the states.
In the time period from 0 to T/2, the state of each switching tube may be as shown in fig. 18. The switching tube S1 and the switching tube S2 are conducted, and the switching tubes S3 and S4 are disconnected.
In this case, the switch tube S1, the switch tube S2, Cr, Lr, and Lm form a path, and an equivalent circuit can be as shown in fig. 19, since C1 does not perform charging, and the first H-bridge circuit is connected across the input terminals 11 and 12, so Vh is Vi 1.
In the period from T/2 to T, the states of the respective switching tubes may be as shown in fig. 13. The switching tubes S3 and S4 are turned on, and the switching tubes S1 and S2 are turned off.
In this case, the switch tube S3, the switch tube S4, Cr, Lr, and Lm constitute a path, and an equivalent circuit can be as shown in fig. 14. Since the first capacitor is open and the output of the first H-bridge circuit is directly connected to the input terminal 12, Vh is 0.
It should be noted that when the switching tubes are driven by the driving signals shown in fig. 17 to drive the switching tubes S1, S2, S3, and S4, the output voltage of the inverter circuit is converted from 0 to Vi1 in the whole cycle of the alternating current, and the peak-to-peak value of the output voltage of the inverter circuit is Vi1, which is substituted into the formula five and the formula six, so that the transformation ratio of the LLC resonance conversion unit 401 at this time is 2.
In this case, the switching tube is switched once in the sequence of (r), and an alternating current is output for one cycle in each switching cycle of the switching tube, that is, the switching cycle of the switching tube is the same as the resonance cycle of the resonance circuit.
In practical use, the states of other driving signals in table one may also be adopted for combination, so as to obtain other adjustable transformation ratios of the LLC resonant conversion unit, which is described in detail herein. When the states of the other drive signals are combined, the number of times of charging and discharging the first capacitor C1 is the same for each combination.
It should be noted that, depending on the type of the load, the rectifier circuit may have other circuit configurations in addition to the configuration of the second H-bridge circuit described above. For example, the rectifier circuit uses a half-bridge rectifier circuit with a center tap to supply power to the load, and in this case, the dc conversion circuit may use the circuit structure shown in fig. 20.
In one example, referring to fig. 21, to address device cost and size, a diode may be used to replace the switching tube in the second H-bridge circuit.
In an example, referring to fig. 22, the resonant capacitor in the resonant circuit can be split into two resonant capacitors C2 and C3 for realizing resonance with the resonant inductor Lr. Wherein the sum of the capacity values of C1 and C2 is the capacity value of Cr.
Example two of the LLC resonant conversion units:
the embodiment of the present application provides a dc converter, as shown in fig. 23. The inverter circuit in the LLC resonant conversion unit 401 mainly includes a first switch tube S1, a second switch tube S2, and a flying capacitor type multilevel half-bridge inverter circuit composed of N first switch tubes, N second switch tubes, and N flying capacitors. The resonant circuit mainly comprises a resonant inductor Lr and a resonant capacitor Cr. The primary winding of the transformer is connected with the resonant inductor Lr and the resonant capacitor Cr in series, and the secondary winding of the transformer is connected with a rectifying circuit consisting of an H bridge. The H-bridge circuit mainly comprises switching tubes S3, S4, S5 and S6. N is an integer greater than 1.
The first converting switch tube is connected in series between the input end 11 and the first end of the switch tube S1. That is, the second end of the ith first transfer switch tube Si1 is connected to the first end of the (i +1) th first transfer switch tube S (i +1)1, the first end of the ith first transfer switch tube Si1 is connected to the second end of the (i-1) th first transfer switch tube S (i-1)1, and i sequentially takes a value from 2 to N. Similarly, the 1 st to nth second transfer switch tubes are sequentially connected in series between the input end 11 and the first end of the switch tube S2. The first end of the 1 st first transfer switch tube S11 is connected to the input terminal 11, and the first end of the first second transfer switch tube S12 is connected to the input terminal 12.
The second end of the S2 and the second end of the S1 are both connected to one end of the resonant capacitor Cr, the other end of the Cr is connected to one end of the resonant inductor Lr, the other end of the Lr is connected to one end of the primary winding of the transformer, and the other end of the primary winding of the transformer is connected to the input end 12.
The S3 and the S4 are connected in series to form a first bridge arm of the H-bridge circuit, and the S5 and the S6 are connected in series to form a second bridge arm of the H-bridge circuit. That is, the second terminal of S4 is connected to the first terminal of S3, the second terminal of S6 is connected to the first terminal of S5, the first terminals of S5 and the one terminal of the secondary winding of the transformer are connected to the first terminals of S3, and the second terminals of S4 are connected to the second terminal of S6 and the other terminal of the secondary winding of the transformer. Specifically, the intermediate node of the first leg and the intermediate node of the second leg of the H-bridge circuit are connected to output terminal 12 and output terminal 14, respectively. That is, the second terminal of S3 is connected to the output terminal 13, and the second terminal of S5 is connected to the output terminal 14.
The ith first transfer switch tube Si1 and the ith second transfer switch tube Si2 in the inverter circuit form a switch combination, and the inverter circuit may include N switch combinations. And the two switching tubes in each switching combination are conducted complementarily.
The following description will be given taking the value of N as 2 as an example with reference to fig. 23. In this case, the flying capacitor mainly includes C1 and C2, first transfer switch tubes S11 and S21, and second transfer switch tubes S12 and S22.
The switch tube S21 and the output switch tube S22 belong to the same switch combination, S11 and S12 belong to the same switch combination, and S1 and S2 belong to the same output combination.
When the switching tubes in the LLC resonant conversion circuit shown in fig. 23 receive different driving signals, the switching tubes in the LLC resonant conversion unit are in different states and have different transformation ratios. When receiving different driving signals, the corresponding relationship between the driving signals and the output voltage of the flying capacitor type multilevel half-bridge inverter circuit can be shown in table two.
Watch two
Figure BDA0002879504370000161
Figure BDA0002879504370000171
When the LLC resonant conversion unit shown in fig. 23 uses the driving signal shown in table two to drive the switches in the flying capacitor type multilevel half-bridge inverter circuit to operate, the LLC resonant conversion unit has at least three adjustable transformation ratios of 6, 3 and 2.
When the states of S11& -S12 in table two are 0, it indicates that the switching tube S11 is turned off, and the switching tube S12 is turned on. Similarly, when the states of S11& -S12 in table two above are 1, it indicates that the switching tube S11 is turned on, and the switching tube S12 is turned off.
Next, the transformation ratios in the three voltage conversion stages of the LLC resonance conversion unit 401 will be described in detail with reference to fig. 23 and table two.
The first implementation mode comprises the following steps: the first transformation ratio N1 is 6.
Suppose that each switch tube in the LLC resonant conversion unit is turned on at a high voltage and turned off at a low voltage. When the controller 403 provides the driving signals shown in fig. 24 to the respective switching tubes in the LLC resonant conversion unit 401, the first transformation ratio N1 is 6. Wherein, the driving signals are switched according to the sequence of the states of the fourth, fifth and sixth.
When the flying capacitor type multi-level half-bridge inverter circuit drives the switches by using the driving signals shown in fig. 24, in three periods of the alternating current, the output voltage of the inverter circuit is switched from 2Vi1/3 to Vi1/3 in the three periods of the alternating current output by the inverter circuit, the peak-to-peak value of the output voltage of the inverter circuit is Vi1/3, and the fifth formula and the sixth formula are substituted, so that the transformation ratio N1 of the LLC resonance conversion unit 401 at the moment is 6.
It should be noted that, at this time, the switching tube performs switching once according to the sequence of (a), (b), (c), (d) and (d).
The second implementation mode comprises the following steps: the first transformation ratio N1 is 3.
Suppose that each switch in the LLC resonant converting unit is turned on at a high voltage and turned off at a low voltage. When the controller 403 switches the states of the respective switching tubes in the LLC resonant conversion unit 401 in the order of the state (r), (c), (d) and (d) b).
When the flying capacitor type multi-level half-bridge inverter circuit drives the switches by using the driving signals, in three periods of alternating current, the output voltage of the inverter circuit is switched from 2Vi1/3 to 0 in the three periods of the alternating current output by the inverter circuit, the peak-to-peak value of the output voltage of the inverter circuit is 2Vi1/3, the five formula and the six formula are substituted, and the transformation ratio N1 of the LLC resonance conversion unit 401 at the moment is 3.
It should be noted that, at this time, the switching tube is switched once according to the sequence of (r), (c), and in each switching period of the switching tube, three periods of alternating current are output, that is, the switching period of the switching tube is three times of the resonant frequency period of the resonant circuit.
The third implementation mode comprises the following steps: the first transformation ratio N1 is 2.
Suppose that each switch tube in the LLC resonant conversion unit is turned on at a high voltage and turned off at a low voltage. When the controller 403 switches the states of the respective switching tubes in the LLC resonance conversion unit 401 in the order of the state ((r)), the LLC resonance conversion unit becomes 2.
When the flying capacitor type multi-level half-bridge inverter circuit drives the switches by using the driving signals in the mode, the output voltage of the inverter circuit is converted from 0 to Vi1 in the whole cycle of alternating current, the peak-to-peak value of the output voltage of the inverter circuit is Vi1, the peak-to-peak value is substituted into a fifth formula and a sixth formula, and the transformation ratio of the LLC resonance conversion unit 401 at the moment is 2.
In this case, the switching tube is switched once in the order of (r), and an alternating current is output for one cycle in each switching cycle of the switching tube, that is, the switching cycle of the switching tube is the same as the resonant frequency cycle of the resonant circuit.
It should be noted that other states may be combined to obtain a plurality of other transformation ratios, and this application will be described in detail herein. When the flying capacitors are combined in a state in which other driving signals are used, the flying capacitors C1 and C2 are charged and discharged the same number of times in each combination.
In practical use, in order to increase the transformation ratio range of the LLC resonant conversion unit, the inverter circuit may include a first flying capacitor type multilevel half-bridge inverter circuit and a second flying capacitor type multilevel half-bridge inverter circuit for increasing the transformation ratio type of the LLC resonant conversion unit.
Referring to fig. 25, in the first flying capacitor type multi-level half-bridge inverter circuit, a first switch tube is sequentially connected in series between an input end 11 and a first end of a switch tube S1, a second switch tube is sequentially connected in series between an input end 12 and a first end of a switch tube S2, and a second end of S1 and a second end of S2 are both connected to one end of a resonant circuit.
In the second flying capacitor type multi-level half-bridge inverter circuit, the first conversion switch tube is sequentially connected in series between the input end 11 and the first end of the switch tube S7, the second conversion switch tube is sequentially connected in series between the input end 12 and the first end of the switch tube S8, and the second end of S1 and the second end of S2 are both connected with the other end of the resonant circuit.
The process of changing the transformation ratio of the LLC resonant conversion unit 401 by using the driving signal is the same as that of example two of the LLC resonant conversion unit of this application, and this application will not be described repeatedly here.
In the embodiment of the present application, there are many possible implementations of the first voltage regulating circuit 402. Generally, in the case where the efficiency of the first voltage regulating circuit 402 is low, the first voltage regulating circuit may focus on finely regulating the output voltage Vo.
Example one of the first voltage regulating circuit:
the first voltage regulation may be a Buck (Buck) circuit. Illustratively, as shown in fig. 9, the first voltage-regulating voltage mainly includes a switching tube SH, a switching tube SL and an inductor L1. A first end of the switching tube SH may be used as an input end 21 of the first voltage regulating circuit, and is connected to the input end 12 of the LLC resonance converting circuit 401. The second end of the switching tube SH is connected to the first end of the switching tube SL and one end of the second regulating inductor L2, respectively, and the second end of the switching tube SL may serve as the output end 24, is connected to the input end 22, and is grounded. The other end of the second regulating inductance L2 may be connected as an output terminal 23 to the output terminal 13 of the LLC resonant conversion unit 401.
When the first voltage regulating circuit is in the continuous mode, for example, the following relationship is satisfied between the duty ratio DH and the second conversion ratio N2:
Figure BDA0002879504370000181
it should be noted that, when the first voltage regulating circuit is in the continuous mode, the inductor L1 switches between storing energy and releasing energy for a long time, that is, the current flowing through the inductor L1 is in a changing state for a long time.
Example two of the first voltage regulating circuit 402:
the first voltage regulating circuit 402 may also be a Buck-Boost circuit. Illustratively, as shown in fig. 26, the first voltage regulating circuit 402 mainly includes a switching tube Sa, a switching tube Sb, a switching tube Sc, a switching tube Sd, and a regulating inductor L1. A first end of the switching tube Sa may be connected to the connection end 12 of the LLC resonant conversion unit 401 as a connection end 21 of the first voltage regulating circuit. The second end of the switching tube Sa may be connected to the first end of the switching tube Sb and one end of the regulating inductor L1, respectively. The other end of the regulating inductor L1 is connected to the second end of the switching tube Sc and the first end of the switching tube Sd, respectively. A first end of the switching tube Sc may be connected as an output 23 to the output 13 of the LLC resonant conversion unit 401. A second terminal of the switching tube Sb and a second terminal of the switching tube Sd may be grounded as the input terminal 22 and the output terminal 24.
Example four of the first voltage regulation circuit 402:
the first voltage regulating circuit 402 may also be a cuk chopper circuit. Illustratively, as shown in fig. 27, the first voltage regulating circuit mainly includes a switching tube Sa, a switching tube Sb, a regulating capacitor C2, a regulating capacitor C3, a regulating inductor L1, and a regulating inductor L2.
One end of the regulating inductor L1 may be used as the input end 21 of the first voltage regulating circuit, and is connected to the input end 12 of the LLC resonant converting unit. The other end of the regulating inductor L1 is connected to the first end of the switching tube Sa and one end of the regulating capacitor C2, respectively. The other end of the adjusting capacitor C2 is connected to one end of the adjusting inductor L2 and the first end of the switch tube Sb. The other end of the regulating inductor L2 is connected to one end of the regulating capacitor C3. The other end of the adjusting capacitor C3, the second end of the switch tube Sa and the second end of the switch tube Sb are grounded.
It should be noted that, in the foregoing embodiment, the first voltage regulating circuit 402 is provided as a non-isolated conversion circuit having a voltage boosting function or a voltage dropping function, and in actual use, the first voltage regulating circuit 402 may also be an isolated conversion circuit having a voltage boosting function or a voltage dropping function. The first voltage regulating circuit 402 may be, but is not limited to, an isolated converter such as a flyback converter, a forward converter, a half-bridge converter, a full-bridge converter, a push-pull converter, or a resonant switching converter.
The above examples show possible implementations of the LLC resonant conversion unit 401 and the first voltage regulation circuit 402 in the dc converter. As described above, the dc converter 400 provided in the embodiments of the present application is beneficial to improving the efficiency of the dc converter.
In an implementation, if the transformation ratio N1 of a single LLC resonant conversion unit is much smaller than the target transformation ratio Na, see fig. 28, the resonant conversion unit in this case may be a combination of N resonant conversion circuits. Wherein N ≧ 2.
Wherein each LLC resonance conversion circuit of the N LLC resonance conversion circuits has a plurality of voltage conversion steps.
Specifically, the input ends of the N LLC resonant conversion circuits are connected in series to form the input end 11 and the input end 12, and the output ends of the K LLC resonant conversion circuits are connected in parallel to form the output end 13 and the output end 14.
It should be noted that the structure of each LLC resonant conversion circuit may be the same as the circuit structure shown in fig. 9 or fig. 23, and the operation principle thereof will not be described repeatedly in this application.
In a specific implementation, if the LLC resonant conversion unit shown in fig. 28 is used to supply power to a connected battery, during a charging process, a voltage of the battery is increased to decrease a target transformation ratio Na, and at this time, a transformation ratio of the output of the dc converter is equal to the target transformation ratio Na, the dc converter provided in the embodiment of the present application further includes: a plurality of third switching tubes S3, a plurality of fourth switching tubes S4, and a plurality of fifth switching tubes S5.
Referring to fig. 29, each of the third switching tubes S3 is connected across a first end point of the input terminals of two adjacent LLC resonant conversion circuits; each fourth switching tube is connected between the second end points of the input ends of the two adjacent LLC resonant conversion circuits in a bridging mode; one end of each fifth switching tube is connected with the second end point of the input end of the first LLC resonance conversion unit in the two adjacent LLC resonance conversion circuits, and the other end of each fifth switching tube is connected with the first end point of the input end of the second LLC resonance conversion unit in the two adjacent LLC resonance conversion circuits.
In actual use, when the third switching tubes S3 and S4 are turned on and the switching tube S5 is turned off, the input sides of the K LLC resonance converting units are connected in parallel and the output sides are connected in parallel. When the third switching tubes S3 and S4 are turned off and the switching tube S5 is turned on, the input sides of the K LLC resonant conversion units are connected in series and the output sides are connected in parallel.
When the input sides of the plurality of LLC resonant conversion circuits are connected in parallel and the output sides are connected in parallel, the input voltages of the plurality of LLC resonant conversion circuits are the same, and the conversion ratios of the plurality of LLC resonant conversion circuits connected in parallel on the input sides are the same in order to achieve the output target output voltage Va.
In a specific implementation, the switching tubes S3, S4, and S5 are all connected to the controller 403, and the adjustment state is realized by the driving signal sent by the controller 403.
As can be seen from the above embodiments, based on the dc converter 400 provided in the embodiments of the present application, the controller 403 can flexibly adjust the switching tubes S3, S4, and S5 according to the target transformation ratio Na of the dc converter, so as to adjust the transformation ratio of the LLC resonant conversion unit 401.
In another implementation, the dc converter may further include a second regulated voltage 404.
Referring to fig. 30, the input end of the second voltage regulating circuit 404 is respectively connected in series with the input end of the first voltage regulating circuit and the input end of the LLC resonant converting unit to form the first input end and the second input end, and the output end of the second voltage regulating circuit is respectively connected in parallel with the output end of the first voltage regulating circuit and the output end of the LLC resonant converting unit to form the first output end and the second output end.
In a specific implementation, the second voltage regulating circuit may be an LLC resonant conversion circuit or other conversion circuit with high efficiency, and is used to increase the transformation ratio range of the dc converter.
In the above example, the LLC resonant conversion circuit and the first voltage regulation circuit in the dc converter are connected in series on the input side and in parallel on the output side. Based on the same technical concept, the LLC resonance conversion circuit and the input side of the first voltage regulating circuit can be connected in parallel, and the output side of the LLC resonance conversion circuit and the input side of the first voltage regulating circuit are connected in series.
In this case, as shown in FIG. 31, the input 11 of the LLC resonant circuit may be taken as the output 11, the output 13 of the LLC resonant conversion unit may be taken as the input 13, and the output 14 of the LLC resonant conversion unit may be taken as the input 14. Similarly, the output 23 of the first voltage regulator circuit may serve as input 23 and the output 24 of the first voltage regulator circuit may serve as input 24.
That is, the input sides (the input terminals 13 and 14) of the LLC resonance converting unit and the input sides (the input terminals 23 and 24) of the first voltage regulating circuit are connected in parallel, and the output sides (the output terminals 11 and 12) of the LLC resonance converting unit 401 and the output sides (the output terminals 21 and 22) of the first voltage regulating circuit 402 are connected in series.
The input 13 and the input 14 of the LLC resonant conversion unit may receive the input voltage Vi, and the output 11 and the output 12 of the LLC resonant conversion unit 401 may output the output voltage Vo1 of the LLC resonant conversion unit. The input 23 and the input 24 of the first voltage regulating circuit 402 may receive the input voltage Vi of the dc converter, and the output 21 and the output 22 of the first voltage regulating circuit may output the output voltage Vo2 of the first voltage regulating circuit. The voltage between the output end 11 and the output end 22 is the output voltage Vo of the dc converter, which is Vo — Vo1+ Vo 2.
It should be noted that when the input sides of the dc converters are connected in parallel and the output sides are connected in series, the dc converters are boost circuits. In this case, the first conversion ratio N1 can be understood as the ratio between the output voltage Vo1 and the input voltage Vi, i.e., N1 — Vo 1/Vi. The second transformation ratio N2 can be expressed as N2 ═ Vo2/Vi in the same manner.
It should be noted that, when the dc converter provided in the embodiment of the present application is used as a boost circuit, the LLC resonant conversion unit and the first voltage regulation circuit may also adopt any of the above examples provided in the embodiment of the present application, and details are not described again.
To further improve the efficiency of the dc converter, in one possible implementation, when the efficiency of the LLC resonant conversion unit is greater than the efficiency of the first voltage regulating circuit, Vo1 of the LLC resonant conversion unit is greater than the second output voltage Vo 2. The detailed analysis is the same as that of the dc converter shown in fig. 4, and the detailed description thereof is omitted.
The structures of the LLC resonant converting unit and the first voltage regulating circuit can be referred to the foregoing embodiments, and are not described in detail herein.
In one possible implementation manner, the dc converter may further include a controller, and the controller may be configured to control the LLC resonant conversion unit to convert an input voltage of the dc converter into a first output voltage, and control the voltage regulation circuit to convert the input voltage of the dc converter into a second output voltage; and adjusting a voltage conversion gear of the LLC resonance conversion unit.
Based on the same technical concept, the embodiment of the application also provides a conversion system. The conversion system may include the aforementioned dc converter and a controller.
The direct current converter comprises an LLC resonance conversion unit and a first voltage regulating circuit, the LLC resonance conversion unit is provided with a plurality of voltage conversion gears, the LLC resonance conversion unit comprises a first input end, a second input end, a first output end and a second output end, and the first voltage regulating circuit comprises a second input end, a third output end and a fourth output end. The LLC resonance conversion unit comprises an inverter circuit, a resonance circuit, a transformer and a rectification circuit.
Specifically, the second input terminal is connected to the third input terminal, the first output terminal is connected to the third output terminal, and the second output terminal is connected to the fourth output terminal.
Specifically, the controller is connected to the LLC resonant conversion unit and the first voltage regulation circuit, and the controller is configured to: controlling the LLC resonance conversion unit to convert a first input voltage received through the first input terminal and the second input terminal into an output voltage of the conversion system, and to output the output voltage of the dc converter through the first output terminal and the second output terminal; and controlling the first voltage regulating circuit to convert a second input voltage received through the third input end and the fourth input end into an output voltage of the conversion system, and outputting the output voltage of the direct current converter through the third output end and the fourth output end, wherein the total input voltage of the direct current converter comprises the first input voltage and the second input voltage.
It should be noted that, the specific circuit structure of the dc converter can be referred to the foregoing embodiments, and the detailed description is not provided herein.
Based on the same concept, the embodiment of the application also provides an electronic device, and the electronic device can comprise a power supply and the direct current converter.
The direct current converter can be connected with a power supply and converts the voltage output by the power supply into the supply voltage of the load.
Wherein the power source may be, but is not limited to, a battery or an onboard power source.
Alternatively, the electronic device may be a switching power supply, which is connected to the battery and to the load, respectively. The switching power supply can receive the battery voltage provided by the battery, convert the battery voltage into the working voltage of the load and output the working voltage to the load.
Alternatively, the electronic device may be an onboard charger, and the electronic device may be connected to a powered device. The direct current converter can receive the voltage provided by the vehicle-mounted power supply, convert the voltage output by the vehicle-mounted power supply into the power supply voltage of the electric equipment and output the power supply voltage to the electric equipment.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.

Claims (17)

1. A direct current converter is characterized by comprising an LLC resonance conversion unit and a first voltage regulating circuit, wherein the LLC resonance conversion unit comprises a first input end (11), a second input end (12), a first output end (13) and a second output end (14), and the first voltage regulating circuit comprises a third input end (21), a fourth input end (22), a third output end (23) and a fourth output end; the second input end is connected with the third input end, the first output end is connected with the third output end, the second output end is connected with the fourth output end, and the LLC resonance conversion unit is provided with a plurality of voltage switching gears; wherein: the LLC resonance conversion unit comprises: the device comprises an inverter circuit, a resonance circuit, a transformer and a rectification circuit;
the inverter circuit is used for converting a first input voltage (Vi1) received by the first input end and the second input end into an alternating current voltage, transmitting the alternating current voltage to the rectifier circuit through the resonance circuit and the transformer, converting the alternating current voltage output by the transformer into an output voltage (Vo) of the direct current converter by the rectifier circuit, and outputting the output voltage of the direct current converter through the first output end (13) and the second output end (14);
the first voltage regulating circuit is used for converting a second input voltage (Vi2) received through the third input end (21) and the fourth input end (22) into an output voltage (Vo) of the direct current converter, and outputting the output voltage of the direct current converter through the third output end and the fourth output end, and a total input voltage (Vi) of the converting circuit comprises the first input voltage and the second input voltage.
2. The DC converter according to claim 1, wherein when the LLC resonant conversion unit is in any one of the plurality of voltage conversion steps, the inverter circuit outputs an AC voltage having a period equal to a resonant period of the resonant circuit and the LLC resonant conversion unit outputs a voltage greater than zero.
3. The DC converter according to claim 1 or 2, wherein the voltage conversion efficiency of the LLC resonant conversion unit is greater than the voltage conversion efficiency of the first voltage regulating circuit, the voltage conversion efficiency of the LLC resonant conversion unit is the ratio of the output power of the LLC resonant conversion unit to the input power of the LLC resonant conversion unit, and the voltage conversion efficiency of the first voltage regulating circuit is the ratio of the output power of the first voltage regulating circuit to the input power of the first voltage regulating circuit.
4. The dc converter of claim 2, further comprising: a controller;
the controller is used for controlling the LLC resonance conversion unit to convert the first input voltage into the output voltage of the DC converter, and controlling the first voltage regulating circuit to convert the second input voltage into the output voltage of the DC converter; and
adjusting a voltage conversion gear of the LLC resonance conversion unit according to the target transformation ratio of the DC converter; the target transformation ratio is a ratio between the total input voltage and a target output voltage of the direct current converter.
5. The DC converter according to any one of claims 1-4,
two input ends of the inverter circuit respectively form the first input end and the second input end, one output end of the inverter circuit is connected with one end of the resonance circuit, and the other output end of the inverter circuit is connected with one end of the primary winding of the transformer;
the other end of the resonant circuit is connected with the other end of the primary winding of the transformer;
two ends of the secondary winding of the transformer are respectively connected with two input ends of the rectifying circuit;
the two output ends of the rectifying circuit respectively form the first output end and the second output end;
the inverter circuit has a plurality of voltage conversion ratios that are one-to-one with a plurality of voltage conversion steps of the LLC resonant conversion unit.
6. The direct current converter according to any one of claims 1 to 5, wherein the inverter circuit includes: an H-bridge circuit and a first capacitor;
a first end of a first bridge arm of the H-bridge circuit forms the first input end, a second end of the first bridge arm is connected with one end of the resonant circuit, a first end of a second bridge arm of the H-bridge circuit forms the second input end, a first end of the second bridge arm forms the second input end, a second end of the second bridge arm is connected with a second end of the first bridge arm, and the H-bridge circuit is used for receiving a first driving signal and adjusting a voltage conversion gear of the LLC resonant conversion unit according to the first driving signal;
the first capacitor is connected between the middle node of the first bridge arm and the middle node of the second bridge arm in a bridge connection mode.
7. The direct current converter according to any one of claims 1 to 6, wherein the inverter circuit includes: the flying capacitor type multi-level half-bridge inverter circuit comprises a flying capacitor type multi-level half-bridge inverter circuit, a first switch tube and a second switch tube;
a first input end of the flying capacitor type multilevel half-bridge inverter circuit forms the first input end, a second input end of the flying capacitor type multilevel half-bridge inverter circuit forms the second input end, a first output end of the flying capacitor type multilevel half-bridge inverter circuit is connected with a first end of the first switch tube, a second output end of the flying capacitor type multilevel half-bridge inverter circuit is connected with a first end of the second switch tube, and the flying capacitor type multilevel half-bridge inverter circuit is used for receiving a second driving signal and adjusting a voltage conversion gear of the LLC resonance conversion unit according to the second driving signal;
the second end of the first switching tube is connected with one end of the resonant circuit;
the second end of the second switch tube is connected with the second end of the first switch tube.
8. A direct current converter according to any one of claims 1-7, wherein the LLC resonant conversion unit comprises N LLC resonant conversion circuits; wherein each of the N LLC resonant conversion circuits has a plurality of voltage conversion steps: n is an integer greater than or equal to 2;
the input ends of the N LLC resonance conversion circuits are connected in series to form the first input end and the second input end, and the output ends of the N LLC resonance conversion circuits are connected in parallel to form the first output end and the second output end.
9. The dc converter of claim 8, further comprising: a plurality of third switching tubes, a plurality of fourth switching tubes and a plurality of fifth switching tubes;
each third switching tube is bridged between first end points of input ends of two adjacent LLC resonance conversion circuits, and the first end point is one end of the LLC resonance conversion circuit receiving high level;
each fourth switching tube is bridged between second end points of input ends of two adjacent LLC resonance conversion circuits, and the second end point is one end of the LLC resonance conversion circuit receiving low level;
one end of each fifth switching tube is connected with the second end point of the input end of the first LLC resonance conversion unit in the two adjacent LLC resonance conversion circuits, and the other end of each fifth switching tube is connected with the first end point of the input end of the second LLC resonance conversion unit in the two adjacent LLC resonance conversion circuits.
10. The dc converter according to any one of claims 1-9, further comprising: a second voltage regulating circuit;
the input end of the second voltage regulating circuit is respectively connected with the input end of the first voltage regulating circuit and the input end of the LLC resonance conversion unit in series to form the first input end and the second input end, and the output end of the second voltage regulating circuit is respectively connected with the output end of the first voltage regulating circuit and the output end of the LLC resonance conversion unit in parallel to form the first output end and the second output end.
11. A dc converter according to any of claims 1 to 10, wherein the first voltage regulating circuit is a Buck circuit.
12. An electronic device comprising a power supply and a dc converter according to any one of claims 1 to 11;
the direct current converter is connected with the power supply and is used for converting the voltage output by the power supply into the power supply voltage of the load.
13. A control method of a direct current converter is applied to the direct current converter, and is characterized in that the direct current converter comprises an LLC resonance conversion unit and a first voltage regulation circuit, the LLC resonance conversion unit is provided with a plurality of voltage conversion gears, the LLC resonance conversion unit comprises a first input end, a second input end, a first output end and a second output end, the first voltage regulation circuit comprises a third input end, a fourth input end, a third output end and a fourth output end, the second input end is connected with the first third input end, the first output end is connected with the third output end, and the second output end is connected with the fourth output end, and the control method comprises the following steps:
calculating a target transformation ratio, wherein the target transformation ratio is a transformation ratio between the input voltage of the direct current converter and the target output voltage of the direct current converter;
determining a first transformation ratio of the LLC resonance conversion unit from a plurality of voltage conversion gears of the LLC resonance conversion unit according to a target transformation ratio and the minimum transformation ratio of the first voltage regulation circuit;
and determining a second transformation ratio of the first voltage regulating circuit according to the first transformation ratio and the target transformation ratio.
14. The method of claim 13, wherein the determining a first transformation ratio of the LLC resonant conversion unit is based on a target transformation ratio and a minimum transformation ratio of the voltage regulation circuit;
determining the value range of a voltage conversion gear of the LLC resonant conversion circuit according to the minimum transformation ratio of the target transformation ratio and the first voltage regulation voltage;
and determining the maximum voltage conversion gear within the value range of the voltage conversion gear of the LLC resonance conversion circuit as the first transformation ratio.
15. The method of claim 13 or 14, wherein said determining the second transformation ratio using the target transformation ratio and the first transformation ratio comprises:
calculating a target input voltage of the LLC resonance conversion unit when the LLC resonance conversion circuit is in the first transformation ratio;
calculating a first voltage difference between the input voltage of the direct current converter and the target input voltage;
determining a transformation ratio between the first voltage difference and an output voltage of the DC converter as the second transformation ratio.
16. The method of any one of claims 13-15, further comprising: and controlling the LLC resonance conversion unit to be in the first transformation ratio, and controlling the first voltage regulating circuit to be in the second transformation ratio.
17. The method of claim 16, wherein the LLC resonant conversion unit comprises: inverter circuit, resonant circuit, transformer and rectifier circuit, control LLC resonance conversion unit is in first transformation ratio includes:
sending a driving signal to the inverter circuit, and controlling the LLC resonance conversion unit to be in the first transformation ratio;
after the inverter circuit receives the driving signal, the period of the alternating current voltage output by the inverter circuit is the same as the resonance period of the resonance circuit.
CN202011627553.1A 2020-12-31 2020-12-31 Direct current converter, electronic equipment and control method of direct current converter Pending CN114696619A (en)

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