CN114640255A - Series resonant converter and control method thereof - Google Patents

Series resonant converter and control method thereof Download PDF

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Publication number
CN114640255A
CN114640255A CN202210285002.4A CN202210285002A CN114640255A CN 114640255 A CN114640255 A CN 114640255A CN 202210285002 A CN202210285002 A CN 202210285002A CN 114640255 A CN114640255 A CN 114640255A
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power switch
switch tube
voltage
vin
output voltage
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陈景文
毛磊
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Shaanxi University of Science and Technology
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Shaanxi University of Science and Technology
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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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L53/00—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • 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
    • H02M3/33592—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 having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2207/00—Indexing scheme relating to details of circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J2207/20—Charging or discharging characterised by the power electronics converter
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/7072—Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02T90/10—Technologies relating to charging of electric vehicles
    • Y02T90/14—Plug-in electric vehicles

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

Abstract

A series resonant converter comprises an input voltage source Vin, a first power switch tube S1A second power switch tube S2The third power switch tube S3The fourth power switch tube S4Transformer, first diode D1A second diode D2Resonant inductor LRResonant capacitor CRDC blocking capacitor CBAn output capacitor COAnd an output load RO(ii) a The control method comprises the following steps: 1) assembling a series resonant converter; 2) the driving signals of the first power switch tube and the fourth power switch tube are complementary with the driving signals of the second power switch tube and the third power switch tube; the switching tube on the secondary side of the transformer is in a synchronous rectification state; 3) using conventional frequency-modulated control, switching frequency fSWith output voltage VOUTIs decreased and increased(ii) a 4) Output voltage VOUTBy controlling the boost duty cycle DBTo adjust; 5) regulating the output voltage V by controlling the duty ratio of the fourth power switch tubeOUT(ii) a Has the characteristics of simple operation and high efficiency.

Description

Series resonant converter and control method thereof
Technical Field
The invention belongs to the technical field of isolated direct current electric energy conversion, and particularly relates to a series resonant converter and a control method thereof.
Background
In recent years, with the implementation of the "two-carbon" policy and the more widespread existence of electric vehicles, the charging of electric vehicles is becoming more and more important. Two main protocols of the current electric vehicle charger are CHArge remove and Combined Charging System, and the two protocols have different voltage ranges for the rechargeable battery. Generally, the CHArge deMOve covers the battery with relatively low voltage, and the maximum voltage can reach 500V, while the Combined Charging System covers the battery with relatively high voltage, and the maximum voltage can reach 950V. Therefore, in order to be compatible with most electric vehicles adopting the two mainstream protocols, an electric vehicle charger covering a very large battery voltage range is required, so that high efficiency can be realized in the whole output voltage range.
Series Resonant Converters (SRC) and LLC converters have the advantage of a small number of soft switches and components and are widely used in various applications. Both SRC and LLC converters use series resonant inductance and capacitance as the main resonant elements. The main difference between the SRC and LLC converters is the size of the magnetizing inductance of the transformer. The transformer excitation inductance of the SRC converter is larger than that of the LLC converter, the circulation loss of the SRC is smaller, and the efficiency is higher at a resonant frequency. SRC only provides a step-down conversion ratio, the LLC converter obtains a gain when the switching frequency is reduced, the circulating current is stored in the resonant capacitor, and energy is delivered to the output terminal in the next switching period. Therefore, the SRC has a small circulation current, but the gain range is limited. If a larger gain range can be achieved in the SRC, both a small circulating current and a large gain range can be achieved.
In order to solve the disadvantages of the series resonant converter, a Pulse Width Modulation (PWM) adaptive resonant converter is adopted in the prior art. In this way, the PWM signal will increase the resonant current, so that the resonant converter achieves an increased gain. A wider voltage conversion ratio range can be covered by a narrower switching frequency range, the switching frequency range is reduced, and the size of the magnetic element is reduced. However, when the high boost gain is needed, the resonance current with a large peak value needs to be considered, and the resonance current can cause huge root mean square current and turn-off loss; reconfiguration of the inverting or rectifying structure is achieved by controlling a certain switching device. For example, a full-bridge inverter may also act as a half-bridge inverter by fully opening a switch. When the full-bridge or half-bridge inverter is operated, the gain of the converter can be reduced by half, so that the converter can have a wider gain range. However, sudden changes of the converter structure can cause problems of sudden drop and expansion of output voltage.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a series resonant converter and a control method thereof, which have the characteristics of simple operation and high efficiency.
In order to achieve the purpose, the invention adopts the technical scheme that:
a series resonant converter comprises an input voltage source Vin, a first power switch tube S1A second power switch tube S2The third power switch tube S3The fourth power switch tube S4The turn ratio is NP:N S1, a first diode D1A second diode D2Resonant inductor LRResonant capacitor CRDC blocking capacitor CBAn output capacitor COAnd an output load RO；
The positive pole of the input voltage source Vin and the first power switch tube S1Is connected with the drain electrode of the second power switch tube S2Source electrode and resonant capacitor CRThe second ends of the two are connected; first power switch tube S1Source electrode of and the second power switch tube S2Drain electrode and resonant inductor LRAre all connected; resonant inductor LRSecond terminal of and transformer primary NPIs connected with the first end of the first connecting pipe; transformer primary NPSecond terminal and resonant capacitor CRIs connected with the first end of the first connecting pipe; secondary N of transformerSFirst terminal of and first diode D1And a third power switch tube S3The drain electrodes of the two are all connected; secondary N of transformerSSecond terminal and DC blocking capacitor CBIs connected with the first end of the first connecting pipe; blocking capacitor CBSecond terminal and fourth power switch tube S4And a second diode D2The anodes of the two are all connected; first diode D1And a second diode D2Cathode and output capacitor COFirst terminal and output load ROAre all connected; third power switch tube S3Source electrode of and fourth power switch tube S4Source and output capacitor COAnd the output load ROAre all connected.
The first power switch tube, the second power switch tube, the third power switch tube and the fourth power switch tube are all SiC MOSFET switch tubes.
The first power switch tube, the second power switch tube, the third power switch tube and the fourth power switch tube are all provided with diodes connected in parallel.
The duty ratio of the first power switch tube and the duty ratio of the second power switch tube are both equal to 0.5 and are driven by complementary pulses.
And the third power switch tube, the fourth power switch tube, the first diode and the second diode form a full-bridge synchronous rectifier on the secondary side of the transformer.
When the fourth power switch tube is completely opened, the full-bridge rectifier is converted into a voltage-doubling rectifier.
A control method using a series resonant converter, comprising the steps of:
step one, the positive pole of an input voltage source Vin and a first power switch tube S1Is connected with the drain electrode of the second power switch tube S2Source and resonant capacitor CRThe second ends of the two are connected; first power switch tube S1Source electrode of and the second power switch tube S2Drain electrode of (2) and resonant inductor LRAre all connected; resonant inductor LRSecond terminal of and transformer primary NPIs connected with the first end of the first connecting pipe; transformer primary NPSecond terminal of (2) and resonant capacitor CRIs connected with the first end of the first connecting pipe; secondary N of transformerSFirst terminal of (2) and first diode D1And a third power switch tube S3The drain electrodes of the two are all connected; secondary N of transformerSSecond terminal and DC blocking capacitor CBIs connected with the first end of the first connecting pipe; blocking capacitor CBA second end ofFourth power switch tube S4And a second diode D2The anodes of the anode groups are all connected; first diode D1And a second diode D2Cathode and output capacitor COFirst terminal and output load ROAre all connected; third power switch tube S3Source electrode of and fourth power switch tube S4Source and output capacitor COAnd the output load ROThe second ends of the two are connected;
step two, when the switching frequency f of the series resonance converterSEqual to the resonant frequency fRWhen the driving signals of the first power switch tube and the fourth power switch tube are the same and the duty ratio is 0.5, the driving signals of the second power switch tube and the third power switch tube are also the same and the duty ratio is 0.5, and meanwhile, the driving signals of the first power switch tube and the fourth power switch tube are complementary with the driving signals of the second power switch tube and the third power switch tube; at the moment, the switching tubes on the secondary side of the transformer are in a synchronous rectification state, and output voltage VOUTIs Vin/2n, wherein n is the turns ratio of the transformer;
step three, when the output voltage VOUTWhen the voltage is less than Vin/2n, the series resonant converter is in a voltage reduction zone; when the output voltage V isOUTWhen the voltage is larger than Vin/2n, the series resonant converter is in a voltage boosting area; when the series resonant converter is in the buck region, conventional frequency modulation control is adopted, and the switching frequency fSWith output voltage VOUTDecrease and increase;
step four, when the output voltage VOUTSwitching frequency f equal to Vin/2nSAt a resonance frequency fRThe series resonant converter reaches a first resonance point; when the series resonant converter is in the boost region, the output voltage VOUTBy controlling the boost duty cycle DBRegulation is carried out, wherein the boost duty cycle DBThe time obtained by subtracting the turn-off time of the first switching tube from the turn-off time of the fourth switching tube accounts for the duty ratio of the whole switching period;
step five, when the output voltage VOUTGreater than Vin/2n and output voltage VOUTWhen the voltage is less than Vin/n, the boosting duty ratio DBHas a value range of 0-0.5 and a switching frequency fSMaintained at resonant frequency fRIncreasing the duty ratio of the fourth power switch tube, and regulating the output voltage V by controlling the duty ratio of the fourth power switch tubeOUTThis region is defined as the PWM1 region.
Further, when the output voltage V isOUTAt Vin/n, the boost duty ratio DBWhen the voltage is equal to 0.5, the fourth power switch tube keeps a conducting state, the full-bridge synchronous rectifier is converted into a voltage multiplier, and the series resonant converter reaches a second resonant point; when the output voltage V isOUTWhen the voltage is larger than Vin/n, the boosting duty ratio DBAnd if the duty ratio of the third power switching tube is more than 0.5, increasing the duty ratio of the third power switching tube, and regulating the output voltage V by controlling the duty ratio of the third power switching tubeOUTDefining the section as a PWM2 area; in the voltage boosting region, the switching frequency fSIs always maintained at the resonant frequency fRAt output voltage V of the series resonant converterOUTThe two resonance working points are equal to Vin/2n and Vin/n, the series resonance converter has higher efficiency when working at the resonance points, and therefore the series resonance converter has two highest efficiency points in a wider gain range.
The resonant frequency is fRIs composed of
Figure DEST_PATH_IMAGE002
Wherein L isRIs a resonant inductor, CRIs a resonant capacitor.
Compared with the prior art, the invention has the following beneficial effects:
the efficiency of the traditional PWM resonant converter is reduced along with the increase of output voltage, when larger voltage gain is needed, the efficiency of a system can be remarkably reduced, the traditional PWM resonant converter can be far away from a resonance point to work along with the increase of the voltage gain, when higher voltage gain is needed, a resonant current waveform can present sawtooth waves, the peak value and the root mean square are large, the conduction loss and the magnetic core loss are large, and the turn-off loss caused by the turn-off of a switching tube and the large peak current is increased. The series resonant converter of the invention has two resonance points, when the output voltage is increased from Vin/2n to Vin/n, the series resonant converter works close to the second resonance point, thereby limiting the large peak value and the root-mean-square current caused by the increase of the PWM gain. Meanwhile, the switching frequency of the series resonant converter in the boost region is constant, so that the control is simpler to operate, the efficiency optimization is easier to realize, and the series resonant converter can realize higher efficiency in the whole output voltage range.
Drawings
Fig. 1 is a topology structure diagram of a series resonant converter of the present invention.
Fig. 2 is a control conceptual diagram of a series resonant converter according to the present invention.
FIG. 3 shows the output voltage VOUTKey waveform in PWM1 region equal to Vin/2 n.
FIG. 4 shows the output voltage VOUTAnd key waveform diagram in PWM1 area when the key waveform is larger than Vin/2n and smaller than Vin/n.
Fig. 5 is a schematic diagram of the operation mode 1 of the series resonant converter of the present invention in the PWM1 region.
Fig. 6 is a schematic diagram of the operation mode 2 of the series resonant converter of the present invention in the PWM1 region.
Fig. 7 is a schematic diagram of mode 3 operation of the series resonant converter of the present invention in the PWM1 region.
FIG. 8 shows the output voltage VOUTKey waveform in the PWM2 region at Vin/n.
FIG. 9 shows the output voltage VOUTAnd when the voltage is larger than Vin/n, the key waveform in the PWM2 area is shown.
Fig. 10 is a schematic diagram of the operation mode 1 of the series resonant converter of the present invention in the PWM2 region. Wherein: FIG. 10 is an operational mode 1; FIG. 11 is an operational mode 2; FIG. 12 is operating mode 3;
fig. 11 is a schematic diagram of the operation mode 2 of the series resonant converter of the present invention in the PWM2 region.
Fig. 12 is a schematic diagram of mode 3 operation of the series resonant converter of the present invention in the PWM2 region.
In the figure: vin is an input voltage source; s1 is a first power switch tube; s2 is a second power switch tube; s3 is a third power switch tube; s4 is a fourth power switch tube; LR is resonance inductance; CR is a resonance capacitor; NP is the number of turns of the primary side coil of the transformer; NS is the number of turns of the secondary side coil of the transformer; CB is a blocking capacitor, CO is an output capacitor; d1 is a first diode; d2 is a second diode; RO is a load; VOUT is the output voltage.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings and embodiments, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in other sequences than those illustrated or described herein. Moreover, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The invention is described in further detail below with reference to the accompanying drawings:
referring to fig. 1, the series resonant converter of the present invention includes an input voltage source Vin; a first power switch tube S1; a second power switch tube S2; a third power switch tube S3; a fourth power switch tube S4; turns ratio of NP:NSA transformer of = n: 1; a first diode D1; a second diode D2; a resonant inductance LR; resonant capacitor CR(ii) a Blocking capacitor CB(ii) a Output capacitor COAndoutput load RO；
The positive pole of the input voltage source Vin and the first power switch tube S1Is connected with the drain electrode of the second power switch tube S2Source and resonant capacitor CRThe second ends of the two are connected; first power switch tube S1Source electrode of and the second power switch tube S2Drain electrode and resonant inductor LRAre all connected; resonant inductor LRSecond terminal of and transformer primary NPIs connected; transformer primary NPSecond terminal and resonant capacitor CRIs connected with the first end of the first connecting pipe; secondary N of transformerSFirst terminal of and first diode D1And a third power switch tube S3The drain electrodes of the two transistors are connected; secondary N of transformerSSecond terminal and DC blocking capacitor CBIs connected with the first end of the first connecting pipe; blocking capacitor CBSecond terminal and fourth power switch tube S4And a second diode D2The anodes of the two are all connected. First diode D1And a second diode D2Cathode and output capacitor COFirst terminal and output load R ofOAre all connected; third power switch tube S3Source electrode of and fourth power switch tube S4Source and output capacitor COAnd the output load ROAre all connected.
Referring to fig. 2, the method for controlling a series resonant converter of the present invention is performed when the switching frequency f of the series resonant converter isSAt a resonance frequency fRWhile, the first power switch tube S1And the fourth power switch tube S4The second power switch tube S has the same driving signal and the duty ratio is 0.52And the third power switch tube S3Is also the same and has a duty cycle of 0.5, and at the same time the first power switch S1And the fourth power switch tube S4And the second power switch tube S2And the third power switch tube S3Are complementary to each other. At the moment, the switching tubes on the secondary side of the transformer are in a synchronous rectification state, and output voltage VOUTIs Vin/2n, wherein n is variable voltageThe turns ratio of the device. When the output voltage V isOUTAnd when the voltage is less than Vin/2n, the series resonant converter is in a voltage reduction zone. When the output voltage V isOUTAnd when the voltage is larger than Vin/2n, the series resonant converter is in a voltage boosting area. When the series resonant converter is in the buck region, conventional frequency modulation control is adopted, and the switching frequency fSWith output voltage VOUTIs increased. When the output voltage V isOUTSwitching frequency f equal to Vin/2nSAt a resonance frequency fRThe series resonant converter reaches a first resonance point. When the series resonant converter is in a boost region, outputting a voltage VOUTBy controlling the boost duty cycle DBRegulating, wherein the boost duty cycle DBThe time obtained by subtracting the turn-off time of the first switching tube from the turn-off time of the fourth switching tube accounts for the duty ratio of the whole switching period. When the output voltage V isOUTGreater than Vin/2n and output voltage VOUTWhen the voltage is less than Vin/n, the boosting duty ratio DBHas a value range of 0-0.5 and a switching frequency fSMaintained at resonant frequency fRIncreasing the duty ratio of the fourth power switch tube, and regulating the output voltage V by controlling the duty ratio of the fourth power switch tubeOUTThis section is defined as a PWM1 region. When the output voltage V isOUTWhen Vin/n is equal, the boosting duty ratio DBAnd when the voltage is equal to 0.5, the fourth power switch tube keeps a conducting state, the full-bridge synchronous rectifier is converted into a voltage doubler, and the series resonant converter reaches a second resonance point. When the output voltage V isOUTWhen the voltage is larger than Vin/n, the boosting duty ratio DBAnd if the duty ratio of the third power switching tube is more than 0.5, increasing the duty ratio of the third power switching tube, and regulating the output voltage V by controlling the duty ratio of the third power switching tubeOUTThis region is defined as the PWM2 region. In the voltage boosting region, the switching frequency fSAlways maintained at the resonant frequency fRSaid series resonant converter being at an output voltage VOUTEqual to Vin/2n and Vin/n, two resonance working points are provided, the series resonance converter has higher efficiency when working at the resonance points, and therefore, the series resonance converter has wider gain rangeThere may be two points of maximum efficiency.
The series resonant converter mainly works in a boosting area, and a rectifier on the secondary side of a transformer of the series resonant converter is gradually converted into a voltage-multiplying rectifier from a full-bridge rectifier through simple PWM control along with the increase of output voltage. When operating in the boost region, the switching frequency fSResonant frequency f always kept constantRThe series resonant converter realizes two resonant working points through the full-bridge rectifier and the voltage-multiplying rectifier, and because the two resonant working points limit the efficiency of the series resonant converter in a wider gain range to be reduced, the series resonant converter can realize higher efficiency in the wider gain range, and simultaneously used devices are fewer and are simple to control.
See FIG. 3, which is a graph showing the output voltage VOUTKey waveform in PWM1 region equal to Vin/2 n;
see FIG. 4, which is a graph showing the output voltage VOUTKey waveform diagram in PWM1 area when greater than Vin/2n and less than Vin/n;
the working process of the invention is described below:
in order to obtain maximum gain and minimum loop current, the boost region is mainly considered. When the output voltage V isOUTAt Vin/2n, the series resonant converter operates in a conventional half-bridge series resonant converter and a full-bridge rectifier. When the output voltage V isOUTWhen the voltage is larger than Vin/2n and smaller than Vin/n, the secondary side of the series resonant converter transformer is used as a voltage-boosting duty ratio DBThe full bridge rectifier of (1).
As shown in fig. 5 to 7, there are 3 different operating modes of PWM1, and in order to simplify the circuit analysis of the converter, the following assumptions are made: 1) the semiconductor elements in all converters are considered ideal; 2) all the capacitors are large enough, the voltage of all the capacitors is kept unchanged in one switching period, and the voltage ripples of all the capacitors are ignored;
working mode 1: as shown in fig. 5, at this time, the first power switch tube S1Is turned on, at which point the current i on the resonant inductorLRIs zero. The above-mentionedThe resonant inductor starts to have current, and the resonant element is the resonant inductor LRAnd a resonance capacitor CRResonant current iLRThrough the transformer and the first diode D on the secondary side of the transformer1And the fourth power switch tube S4To the output capacitor CO. The fourth power switch tube S4Conducting as a synchronous rectifier. The working mode 1 lasts for half a resonance period, and at the resonance frequency, the first power switch tube S1And the second power switch tube S2Operating at a drive signal with a duty cycle of 0.5. Current i in resonant inductorLRZero again, the first power switch tube S1Off and operational mode 1 ends.
The working mode 2 is as follows: as shown in fig. 6, the current on the resonant inductor is 0 at this time. The fourth power switch tube is in a conducting state due to the boosting duty ratio DBThe current of the resonant inductor is rapidly increased after the extension, and the duration of the working mode 2 is DBTSWhen the current in the resonant inductor increases to a certain level, the fourth power switch tube is turned off, and the operation mode 2 is ended.
Working mode 3: as shown in fig. 7, at this time, the second diode and the third power switch tube are turned on, the current in the resonant inductor is sent to the output terminal, the current in the resonant inductor starts to decrease, until the current in the resonant inductor decreases to zero, the second diode and the third power switch tube are turned off, and the operation mode 3 is ended.
Referring to FIG. 8, when the output voltage V is shownOUTKey waveform in PWM2 region equal to Vin/n;
refer to FIG. 9, which shows the output voltage VOUTKey waveform diagram in PWM2 area when greater than Vin/n;
when the output voltage V isOUTWhen Vin/n is equal, DBAnd 0.5, gradually converting the secondary side of the transformer of the series resonant converter from a full-bridge rectifier to a voltage-doubling rectifier. When the output voltage VOUT is larger than Vin/n, the secondary side rectifier works as a voltage doubling rectifier, and the resonant current is increased. As shown in FIGS. 10-12, the PWM2 region has 3 different operating modes, and the PWM1 regionThe 3 modes of operation are similar.
Example 1
A control method using a series resonant converter, comprising the steps of:
step one, the positive pole of an input voltage source Vin and a first power switch tube S1Is connected with the drain electrode of the second power switch tube S2Source electrode and resonant capacitor CRThe second ends of the two are connected; first power switch tube S1Source electrode of and the second power switch tube S2Drain electrode and resonant inductor LRAre all connected; resonant inductor LRSecond terminal of and transformer primary NPIs connected with the first end of the first connecting pipe; transformer primary NPSecond terminal and resonant capacitor CRIs connected; secondary N of transformerSFirst terminal of and first diode D1And a third power switch tube S3The drain electrodes of the two are all connected; secondary N of transformerSSecond terminal and DC blocking capacitor CBIs connected with the first end of the first connecting pipe; blocking capacitor CBSecond terminal and fourth power switch tube S4And a second diode D2The anodes of the two are all connected; first diode D1And a second diode D2Cathode and output capacitor COFirst terminal and output load ROAre all connected; third power switch tube S3Source electrode of and fourth power switch tube S4Source and output capacitor COAnd the output load ROThe second ends of the two are connected;
step two, when the switching frequency f of the series resonance converterSEqual to the resonance frequency fRWhen the driving signals of the first power switch tube and the fourth power switch tube are the same and the duty ratio is 0.5, the driving signals of the second power switch tube and the third power switch tube are also the same and the duty ratio is 0.5, and meanwhile, the driving signals of the first power switch tube and the fourth power switch tube are complementary with the driving signals of the second power switch tube and the third power switch tube; at the moment, the switching tubes on the secondary side of the transformer are in a synchronous rectification state, and output voltage VOUTIs Vin/2n, wherein n is the turns ratio of the transformer;
step three, when the output voltage VOUTWhen the voltage is less than Vin/2n, the series resonant converter is in a voltage reduction zone; when the output voltage V isOUTWhen the voltage is larger than Vin/2n, the series resonant converter is in a boosting area; when the series resonant converter is in the buck region, conventional frequency modulation control is adopted, and the switching frequency fSWith output voltage VOUTDecrease and increase;
step four, when the output voltage VOUTSwitching frequency f equal to Vin/2nSAt a resonance frequency fRThe series resonant converter reaches a first resonance point; when the series resonant converter is in the boost region, the output voltage VOUTBy controlling the boost duty cycle DBRegulation is carried out, wherein the boost duty cycle DBThe time obtained by subtracting the turn-off time of the first switching tube from the turn-off time of the fourth switching tube accounts for the duty ratio of the whole switching period;
step five, when the output voltage VOUTGreater than Vin/2n and output voltage VOUTWhen the voltage is less than Vin/n, the boosting duty ratio DBHas a value range of 0-0.5 and a switching frequency fSMaintained at resonant frequency fRIncreasing the duty ratio of the fourth power switch tube, and regulating the output voltage V by controlling the duty ratio of the fourth power switch tubeOUTThis region is defined as the PWM1 region.
Further, when the output voltage V isOUTAt Vin/n, the boost duty ratio DBWhen the voltage is equal to 0.5, the fourth power switch tube keeps a conducting state, the full-bridge synchronous rectifier is converted into a voltage multiplier, and the series resonant converter reaches a second resonant point; when the output voltage V isOUTWhen the voltage is larger than Vin/n, the boosting duty ratio DBAnd if the duty ratio of the third power switching tube is more than 0.5, increasing the duty ratio of the third power switching tube, and regulating the output voltage V by controlling the duty ratio of the third power switching tubeOUTDefining the section as a PWM2 area; in the voltage boosting region, the switching frequency fSAlways maintained at the resonant frequency fRAt output voltage V of the series resonant converterOUTThere are two resonance points equal to Vin/2n and Vin/n, the series resonant converter has higher efficiency when working at the resonance points, therefore, the series resonance becomesThe converter has two points of highest efficiency over a wide range of gain.
The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.

Claims (8)

1. A series resonant converter is characterized by comprising an input voltage source Vin and a first power switch tube S1A second power switch tube S2The third power switch tube S3The fourth power switch tube S4The turn ratio is NP:NS1, a first diode D1A second diode D2Resonant inductor LRResonant capacitor CRDC blocking capacitor CBOutput capacitor COAnd an output load RO；
The positive pole of the input voltage source Vin and the first power switch tube S1Is connected with the drain electrode of the first power switch tube S, and the cathode of the first power switch tube S2Source electrode and resonant capacitor CRThe second ends of the two are connected; first power switch tube S1Source electrode of and the second power switch tube S2Drain electrode and resonant inductor LRAre all connected; resonant inductor LRSecond terminal of and transformer primary NPIs connected; transformer primary NPSecond terminal and resonant capacitor CRIs connected with the first end of the first connecting pipe; secondary N of transformerSFirst terminal of and first diode D1And a third power switch tube S3The drain electrodes of the two are all connected; secondary N of transformerSSecond terminal and DC blocking capacitor CBIs connected with the first end of the first connecting pipe; blocking capacitor CBSecond terminal and fourth power switch tube S4And a second diode D2The anodes of the two are all connected; first diode D1And a second diode D2Cathode and output capacitor COFirst terminal and output load R ofOAre all connected; third power switch tube S3Source and secondFour-power switch tube S4Source and output capacitor COAnd an output load ROAre connected.
2. The series resonant converter according to claim 1, characterized in that the first power switch, the second power switch, the third power switch and the fourth power switch are all SiC MOSFET switches.
3. A series resonant converter according to claim 1 wherein the first, second, third and fourth power switches are provided with diodes connected in parallel.
4. A series resonant converter according to claim 1 wherein the duty cycle of the first and second power switches is equal to 0.5 and driven by complementary pulses.
5. A series resonant converter according to claim 1, wherein said third power switch, fourth power switch, first diode, second diode form a full bridge synchronous rectifier on the secondary side of the transformer.
6. A series resonant converter as set forth in claim 1 wherein the full bridge rectifier is converted to a voltage doubler rectifier when the fourth power switch is fully on.
7. A control method of a series resonant converter according to claim 1, comprising the steps of:
step one, the positive pole of an input voltage source Vin and a first power switch tube S1Is connected with the drain electrode of the first power switch tube S, and the cathode of the first power switch tube S2Source electrode and resonant capacitor CRThe second ends of the two are connected; first power switch tube S1Source and secondPower switch tube S2Drain electrode and resonant inductor LRAre all connected; resonant inductor LRSecond terminal of and transformer primary NPIs connected with the first end of the first connecting pipe; transformer primary NPSecond terminal and resonant capacitor CRIs connected with the first end of the first connecting pipe; secondary N of transformerSFirst terminal of and first diode D1And a third power switch tube S3The drain electrodes of the two are all connected; secondary N of transformerSSecond terminal and DC blocking capacitor CBIs connected with the first end of the first connecting pipe; blocking capacitor CBSecond terminal and fourth power switch tube S4And a second diode D2The anodes of the two are all connected; first diode D1And a second diode D2Cathode and output capacitor COFirst terminal and output load ROAre all connected; third power switch tube S3Source electrode of and fourth power switch tube S4Source and output capacitor COAnd the output load ROThe second ends of the two are connected;
step two, when the switching frequency f of the series resonance converterSEqual to the resonant frequency fRWhen the driving signals of the first power switch tube and the fourth power switch tube are the same and the duty ratio is 0.5, the driving signals of the second power switch tube and the third power switch tube are also the same and the duty ratio is 0.5, and meanwhile, the driving signals of the first power switch tube and the fourth power switch tube are complementary with the driving signals of the second power switch tube and the third power switch tube; at the moment, the switching tubes on the secondary side of the transformer are in a synchronous rectification state, and output voltage VOUTIs Vin/2n, wherein n is the turns ratio of the transformer;
step three, when the output voltage VOUTWhen the voltage is less than Vin/2n, the series resonant converter is in a voltage reduction zone; when the output voltage V isOUTWhen the voltage is larger than Vin/2n, the series resonant converter is in a voltage boosting area; when the series resonant converter is in the buck region, conventional frequency modulation control is adopted, and the switching frequency fSWith output voltage VOUTDecrease and increase;
step four, when the output voltage VOUTSwitching frequency f equal to Vin/2nSAt a resonance frequency fRThe series resonant converter reaches a first resonance point; when the series resonant converter is in the boost region, the output voltage VOUTBy controlling the boost duty cycle DBRegulation is carried out, wherein the boost duty cycle DBThe time obtained by subtracting the turn-off time of the first switching tube from the turn-off time of the fourth switching tube accounts for the duty ratio of the whole switching period;
step five, when the output voltage VOUTGreater than Vin/2n and output voltage VOUTWhen the voltage is less than Vin/n, the boosting duty ratio DBHas a value range of 0-0.5 and a switching frequency fSMaintained at resonant frequency fRIncreasing the duty ratio of the fourth power switch tube, and regulating the output voltage V by controlling the duty ratio of the fourth power switch tubeOUTThis region is defined as the PWM1 region.
8. The method according to claim 7, wherein when the output voltage V is lower than the predetermined valueOUTAt Vin/n, the boost duty ratio DBWhen the voltage is equal to 0.5, the fourth power switch tube keeps a conducting state, the full-bridge synchronous rectifier is converted into a voltage multiplier, and the series resonant converter reaches a second resonant point; when the output voltage V isOUTWhen the voltage is larger than Vin/n, the boosting duty ratio DBAnd if the output voltage V is larger than 0.5, increasing the duty ratio of the third power switch tube, and regulating the output voltage V by controlling the duty ratio of the third power switch tubeOUTDefining the section as a PWM2 area; in the voltage boosting region, the switching frequency fSAlways maintained at the resonant frequency fRAt output voltage V of the series resonant converterOUTEqual to Vin/2n and Vin/n, there are two resonant operating points, and the series resonant converter has higher efficiency when operating at the resonant points, so the series resonant converter has two highest efficiency points in a wider gain range.
CN202210285002.4A 2022-03-23 2022-03-23 Series resonant converter and control method thereof Pending CN114640255A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116388588A (en) * 2023-05-29 2023-07-04 成都市易冲半导体有限公司 Rectifying control circuit, electric energy receiving device and electronic equipment
WO2024031552A1 (en) * 2022-08-11 2024-02-15 华为数字能源技术有限公司 Direct-current converter, communication device and photovoltaic system

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024031552A1 (en) * 2022-08-11 2024-02-15 华为数字能源技术有限公司 Direct-current converter, communication device and photovoltaic system
CN116388588A (en) * 2023-05-29 2023-07-04 成都市易冲半导体有限公司 Rectifying control circuit, electric energy receiving device and electronic equipment
CN116388588B (en) * 2023-05-29 2023-08-18 成都市易冲半导体有限公司 Rectifying control circuit, electric energy receiving device and electronic equipment

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