CN112653332B - Control method and device of bidirectional DC/DC conversion system and controller - Google Patents
Control method and device of bidirectional DC/DC conversion system and controller Download PDFInfo
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- CN112653332B CN112653332B CN202011442710.1A CN202011442710A CN112653332B CN 112653332 B CN112653332 B CN 112653332B CN 202011442710 A CN202011442710 A CN 202011442710A CN 112653332 B CN112653332 B CN 112653332B
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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
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac 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
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac 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
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac 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 with automatic control of output voltage or current, e.g. switching regulators
- H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac 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 with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
- H02M3/1584—Conversion of dc power input into dc power output without intermediate conversion into ac 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 with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load with a plurality of power processing stages connected in parallel
-
- 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
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac 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
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac 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
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac 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 with automatic control of output voltage or current, e.g. switching regulators
- H02M3/157—Conversion of dc power input into dc power output without intermediate conversion into ac 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 with automatic control of output voltage or current, e.g. switching regulators with digital control
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- Dc-Dc Converters (AREA)
Abstract
The application provides a control method, a device and a controller of a bidirectional DC/DC conversion system, when the scheme detects that the bidirectional DC/DC conversion system operates in a two-stage modulation mode, the switching frequency of the conversion system is controlled to be gradually adjusted to a first target frequency; when the conversion system is switched from the double-stage modulation mode to the single-stage modulation mode, the switching frequency of the conversion system is controlled to gradually increase to a second target frequency matched with the single-stage modulation mode. According to the scheme, when the conversion system is detected to operate in a two-stage modulation mode, the switching frequency of the conversion system is changed through software to change the cut-off frequency of the system, so that the cut-off frequency of the system avoids the resonant frequency of a CLC filter circuit formed by an external circuit of the system, and finally the system is prevented from resonating. The switching frequency of the conversion system is controlled in a software mode without adding a hardware device, so that the hardware cost is reduced, and the control logic for controlling the switching frequency of the conversion system is simple and easy to implement.
Description
Technical Field
The invention belongs to the technical field of power electronics, and particularly relates to a control method, a control device and a control device of a bidirectional DC/DC conversion system.
Background
The bidirectional DC/DC conversion system is used for realizing bidirectional flow of direct current electric energy, and can operate in a single-stage modulation mode or a double-stage modulation mode according to the requirement of voltage difference between the input end and the output end. Under a single-stage modulation mode, a high-voltage side switching tube works in a chopping state; in the two-stage modulation mode, the switching tubes on the high-voltage side and the low-voltage side are in a chopping state.
When the two sides of the bidirectional DC/DC conversion system are respectively connected with a battery and a DC/AC converter, a bus capacitor of the DC/DC conversion system, a bus capacitor of the DC/AC converter and transmission line inductance form a CLC filter circuit, and the CLC filter circuit has fixed resonant frequency. When the bidirectional DC/DC conversion system is operated in a dual-stage modulation mode, the cut-off frequency of the system is close to the resonant frequency of the CLC filter circuit, so that the whole system is in resonance.
In a resonance suppression mode of a bidirectional DC/DC conversion system in the related art, a filter capacitance value in a CLC filter circuit is changed by switching a parallel capacitor, so that the resonance frequency of the CLC filter circuit is changed, the resonance frequency of the CLC filter circuit is different from the cut-off frequency of the bidirectional DC/DC conversion system, and the system resonance is finally eliminated. However, in this way, the resonant frequency is changed by changing the filter capacitance value, and a hardware switching device is added, so that the hardware cost is increased, and the hardware switching control process is complicated.
Disclosure of Invention
In view of the above, an object of the present invention is to provide a method, an apparatus and a controller for controlling a bidirectional DC/DC conversion system, so as to solve the technical problems of high hardware cost and complex hardware switching control process in a manner of changing a resonant frequency by changing a filter capacitance, and a specific technical solution thereof is as follows:
in a first aspect, the present application provides a method for controlling a bidirectional DC/DC conversion system, including:
when the bidirectional DC/DC conversion system is detected to operate in a two-stage modulation mode, controlling the switching frequency of a switching tube in the bidirectional DC/DC conversion system to be gradually adjusted to a first target frequency; when the bidirectional DC/DC conversion system operates at the first target frequency, the cut-off frequency of the bidirectional DC/DC conversion system does not resonate with a filter circuit formed by an external circuit of the bidirectional DC/DC conversion system;
when the modulation mode of the bidirectional DC/DC conversion system is detected to be switched from the double-stage modulation mode to the single-stage modulation mode, the switching frequency of the DC/DC conversion system is controlled to be gradually increased to a second target frequency matched with the single-stage modulation mode, and the second target frequency is larger than the first target frequency.
Optionally, the method further comprises:
in the process of controlling the switching frequency to change, judging whether the risk of losing the duty ratio of the control signal of the switching tube exists or not;
and when the duty ratio of the control signal is lost, continuously adjusting the amplitude of the modulation wave in the same direction according to the amplitude change direction of the carrier wave until the switching frequency reaches the corresponding target frequency, so that the amplitude of the carrier wave is crossed with the amplitude of the modulation wave, wherein the modulation wave and the carrier wave are used for generating the control signal.
Optionally, the determining whether there is a risk of losing a duty cycle of the control signal of the switching tube includes:
when the phase of the carrier wave is a synchronous phase, acquiring a difference absolute value between the amplitude of the carrier wave and the amplitude of the modulation wave;
determining that there is a risk of loss of the duty cycle of the control signal when the absolute value of the difference is less than or equal to a first threshold;
determining that there is no risk of loss of the duty cycle of the control signal when the absolute value of the difference is greater than the first threshold.
Optionally, the adjusting the amplitude of the modulated wave in the same direction according to the amplitude variation direction of the carrier wave includes:
When the amplitude of the carrier wave is increased, controlling the amplitude of the modulated wave to be increased by a second threshold value, wherein the second threshold value is larger than the first threshold value;
when the amplitude of the carrier wave decreases, the amplitude of the modulated wave is controlled to decrease by the second threshold.
Optionally, the controlling the switching frequency of the switching tube in the bidirectional DC/DC conversion system to gradually adjust to the first target frequency includes:
the frequency of the control carrier wave is gradually adjusted to the first target frequency according to a first preset frequency step, and the carrier wave and the modulation wave are used for generating a control signal for controlling the switching tube;
the controlling the switching frequency of a switching tube in the DC/DC conversion system to gradually increase to a second target frequency matched with the single-stage modulation mode comprises the following steps:
and controlling the frequency of the carrier wave to gradually increase to the second target frequency according to a second preset frequency step length.
Optionally, the gradually adjusting the frequency of the control carrier to the first target frequency according to a first preset frequency step includes:
controlling the carrier wave period counter to be gradually adjusted to a first target value matched with the first target frequency according to a first numerical value;
the controlling the frequency of the carrier wave to gradually increase to the second target frequency according to a second preset frequency step includes:
And controlling the cycle counter of the carrier wave to be reduced to a second target value matched with the second target frequency according to a second value.
In a second aspect, the present application also provides a control device for a bidirectional DC/DC conversion system, including:
the first frequency conversion module is used for controlling the switching frequency of a switching tube in the bidirectional DC/DC conversion system to be gradually adjusted to a first target frequency when the bidirectional DC/DC conversion system is detected to operate in a two-stage modulation mode; when the bidirectional DC/DC conversion system operates at the first target frequency, the cut-off frequency of the bidirectional DC/DC conversion system does not resonate with a filter circuit formed by an external circuit of the bidirectional DC/DC conversion system;
and the second frequency conversion module is used for controlling the switching frequency of the DC/DC conversion system to gradually increase to a second target frequency matched with the single-stage modulation mode when the modulation mode of the bidirectional DC/DC conversion system is detected to be switched from the double-stage modulation mode to the single-stage modulation mode, wherein the second target frequency is greater than the first target frequency.
Optionally, the apparatus further comprises:
the risk judgment module is used for judging whether the risk of losing the duty ratio of the control signal of the switching tube exists in the process of controlling the switching frequency to change;
And the modulation wave amplitude optimization module is used for continuously adjusting the amplitude of the modulation wave in the same direction according to the amplitude change direction of the carrier wave until the switching frequency reaches the corresponding target frequency when the risk of losing the duty ratio of the control signal exists, so that the amplitude of the carrier wave and the amplitude of the modulation wave are crossed, wherein the modulation wave and the carrier wave are used for generating the control signal.
Optionally, the risk determining module includes:
an amplitude difference obtaining sub-module, configured to obtain an absolute value of a difference between the amplitude of the carrier and the amplitude of the modulated wave when the phase of the carrier is a synchronous phase;
a first determination sub-module configured to determine that there is a risk of loss of the duty cycle of the control signal when the absolute value of the difference is less than or equal to a first threshold;
a second determining submodule, configured to determine that there is no risk of losing the duty cycle of the control signal when the absolute value of the difference is greater than the first threshold.
Optionally, the modulation wave amplitude optimization module includes:
a first amplitude adjustment submodule, configured to control an amplitude of the modulation wave to increase by a second threshold when the amplitude of the carrier increases, where the second threshold is greater than the first threshold;
And a second amplitude adjustment submodule configured to control the amplitude of the modulated wave to decrease by the second threshold when the amplitude of the carrier decreases.
In a third aspect, the present application further provides a controller, including a memory and a processor;
the memory has stored therein program instructions;
the processor is configured to call program instructions stored in the memory to execute the control method of the bidirectional DC/DC converter according to any one of the possible implementation manners of the first aspect.
In a fourth aspect, the present application further provides a storage medium, on which a program is stored, and the program is loaded by a processor and executed to implement the control method of the bidirectional DC/DC converter according to any one of the possible implementation manners of the first aspect.
According to the control method of the bidirectional DC/DC conversion system, when the bidirectional DC/DC conversion system is detected to operate in a two-stage modulation mode, the switching frequency of the conversion system is controlled to be gradually adjusted to a first target frequency; when the conversion system is switched from the double-stage modulation mode to the single-stage modulation mode, the switching frequency of the conversion system is controlled to gradually increase to a second target frequency matched with the single-stage modulation mode. According to the scheme, when the conversion system is detected to operate in a two-stage modulation mode, the switching frequency of the conversion system is changed through software to change the cut-off frequency of the system, so that the cut-off frequency of the system avoids the resonant frequency of a CLC filter circuit formed by an external circuit of the system, and finally the system is prevented from resonating. The switching frequency of the conversion system is controlled in a software mode without adding a hardware device, so that the hardware cost is reduced, and the control logic for controlling the switching frequency of the conversion system is simple and easy to implement.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a topology diagram of a bidirectional DC/DC converter provided by an embodiment of the present application;
FIG. 2 is a schematic diagram of a CLC filter circuit formed by a bidirectional DC/DC converter and a DC/AC converter connected with the bidirectional DC/DC converter according to an embodiment of the present application;
fig. 3 is a flowchart of a control method of a bidirectional DC/DC conversion system according to an embodiment of the present application;
fig. 4 is a waveform diagram of key signals when there is a risk of losing the duty cycle of the control signal according to an embodiment of the present application;
fig. 5 is a flowchart of another control method for a bidirectional DC/DC conversion system according to an embodiment of the present disclosure;
fig. 6 is a flowchart of a process for determining whether there is a risk of losing a duty ratio in a control signal of a switching tube in a conversion system according to an embodiment of the present disclosure;
Fig. 7 is a waveform diagram of each key signal after control optimization is performed on a system where there is a risk of loss of the duty cycle of a control signal according to an embodiment of the present disclosure;
fig. 8 is a block diagram of a control device of a bidirectional DC/DC conversion system according to an embodiment of the present application;
fig. 9 is a block diagram of a control device of another bidirectional DC/DC conversion system according to an embodiment of the present application.
Detailed Description
Referring to fig. 1, a topology diagram of a bidirectional DC/DC converter provided in an embodiment of the present application is shown, when two sides of the bidirectional DC/DC converter are respectively connected to a battery and a DC/AC converter, a bus-side capacitor of the DC/DC converter, a bus capacitor of the DC/AC converter, and a line equivalent inductor form a CLC filter circuit, as shown in fig. 2, in a case where a hardware parameter is determined, the CLC filter circuit has a fixed resonant frequency. When the DC/DC converter operates in a two-stage modulation mode, the equivalent switching frequency is increased, so that the system cut-off frequency is close to the resonant frequency of the external CLC filter circuit, and system resonance is generated. The application provides a control method of a bidirectional DC/DC conversion system for restraining resonance, which controls the switching frequency to gradually adjust to a first target frequency when the bidirectional DC/DC conversion system operates in a double-stage modulation mode, and controls the switching frequency of the conversion system to gradually increase to a second target frequency matched with the single-stage modulation mode when the conversion system is switched from the double-stage modulation mode to the single-stage modulation mode. According to the scheme, when the conversion system is detected to operate in a two-stage modulation mode, the switching frequency of the conversion system is changed through software to change the cut-off frequency of the system, so that the cut-off frequency of the system avoids the resonant frequency of a CLC filter circuit formed by an external circuit of the system, and finally the system is prevented from resonating. In addition, the switching frequency of the conversion system is controlled in a software mode, and a hardware device is not required to be added, so that the hardware cost is reduced, and the control logic for controlling the switching frequency of the conversion system is simple and easy to implement.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
Referring to fig. 3, a flowchart of a control method of a bidirectional DC/DC conversion system provided in an embodiment of the present application is shown, where the method is applied to a controller of the bidirectional DC/DC conversion system, and as shown in fig. 3, the method may include the following steps:
and S110, when the bidirectional DC/DC conversion system is detected to operate in a double-stage modulation mode, controlling the switching frequency of a switching tube in the bidirectional DC/DC conversion system to be gradually adjusted to a first target frequency.
When the modulation modes of the bidirectional DC/DC conversion system comprise a single-stage modulation mode and a double-stage modulation mode, the corresponding rated switching frequency f of the systemNAnd when the bidirectional DC/DC conversion system operates in a two-stage modulation mode, the equivalent switching frequency of the system is greater than the rated switching frequency f NResulting in a cut-off frequency of the system close to the natural resonant frequency of the external CLC filter circuit, which in turn results in the system resonating.
Wherein the rated switching frequency fNThe method is set according to the control bandwidth requirement and the inductance in the system when a bidirectional DC/DC conversion system is designed.
In order to avoid the resonance of the system, when the conversion system runs in a two-stage modulation mode, the switching frequency is reduced to a first target frequency fM. After the switching frequency of the conversion system is reduced, the cut-off frequency of the system is reduced, so that the cut-off frequency avoids the natural resonant frequency of the CLC filter circuit, and finally resonance is avoided.
Wherein, fM＜fN，fMMay be fN100% -70%, the specific value is as followsAccording to the actual hardware parameters of the system.
In addition, the equivalent switching frequency of the conversion system in the two-stage modulation mode is increased, and therefore, the ripple of the reactor is not increased by reducing the switching frequency. Moreover, the switching loss of the system can be optimized by reducing the switching frequency, and the system efficiency is improved.
And S120, when the modulation mode of the bidirectional DC/DC conversion system is detected to be switched from the double-stage modulation mode to the single-stage modulation mode, controlling the switching frequency of the DC/DC conversion system to gradually increase to a second target frequency matched with the single-stage modulation mode.
When the conversion system is switched from the double-stage modulation mode to the single-stage modulation mode, the switching frequency of the system is restored to the rated switching frequency fNThus, the ripple of the reactor in the system can be reduced.
In one embodiment of the present application, the frequency of the control signal of the switching tube in the system is changed, and thus the switching frequency of the switching tube is changed, usually by changing the frequency of the carrier wave. In order to ensure the stability and accuracy of the system, the carrier frequency is switched in a gradual manner, for example, the carrier frequency is controlled to increase or decrease a preset frequency step at regular intervals, and the carrier frequency is switched to the set frequency after a certain time.
In one possible implementation, the carrier frequency is incremented or decremented by incrementing or decrementing a carrier period counter, e.g., the carrier period counter is controlled to increment when a decrease in the carrier frequency is required and to decrement when an increase in the carrier frequency is required. For example, the carrier cycle counter is controlled to increment or decrement a preset value, such as 1, each time.
In the control method of the bidirectional DC/DC conversion system provided in this embodiment, when it is detected that the conversion system operates in the dual-stage modulation mode, the switching frequency of the conversion system is changed by software to change the cut-off frequency of the system, so that the cut-off frequency of the system avoids the resonant frequency of the CLC filter circuit formed by the external circuit of the system, and finally the system is prevented from resonating. The switching frequency of the conversion system is controlled in a software mode, and a hardware device is not required to be added, so that the hardware cost is reduced, and the control logic is simple and easy to implement. In addition, the scheme improves the stability of the frequency conversion process of the system and the accuracy of frequency conversion by controlling the switching frequency to be slowly changed.
If the conversion system directly switches the carrier frequency during operation, which may cause the control signal to be abnormal, as shown in fig. 4, at the carrier synchronization phase, if the amplitude of the modulation wave is relatively close to the amplitude of the carrier at this time, the situation that the duty ratio of the control signal is lost due to the fact that the amplitude of the modulation wave and the amplitude of the carrier cannot be compared may occur. If the duty ratio of the control signal is abnormal, the bidirectional DC/DC conversion system is easy to be triggered to be stopped due to faults, and the system operation can be influenced due to the stop. Therefore, in order to ensure that the bidirectional DC/DC conversion system does not stop and carry out frequency conversion, another control method embodiment of the bidirectional DC/DC conversion system is provided.
Referring to fig. 5, a flowchart of another control method for a bidirectional DC/DC conversion system according to an embodiment of the present application is shown, where the method further includes the following steps based on the embodiment shown in fig. 3:
s210, judging whether the risk of losing the duty ratio of the control signal of the switching tube exists or not in the process of controlling the switching frequency to change; if yes, go to S220; if not, the process of adjusting the switching frequency is continuously executed.
The duty cycle loss of the control signal generally occurs when the carrier signal is synchronized, and therefore, in an embodiment of the present application, as shown in fig. 6, the process of determining whether there is a risk of the duty cycle loss of the control signal may include the following steps:
And S211, when the phase of the carrier wave is the synchronous phase, acquiring the absolute value of the difference between the amplitude of the carrier wave and the amplitude of the modulation wave.
As shown in fig. 1, the bidirectional DC/DC conversion system includes a plurality of switching transistors, such as Q1-Q8, wherein different switching transistors use different control signals, for example, Q1 and Q2 use the same control signal for control, Q3 and Q4 use the same control signal for control, Q5 and Q6 use the same control signal for control, and Q7 and Q8 use the same control signal for control. Different control signals are respectively generated by different carrier waves and modulation waves, but different carrier signals need to be synchronized with the main carrier signal at certain intervals, so that different carrier signals are synchronized, and further different control signals are kept synchronized. The synchronization phase here refers to an initial phase when the carrier and the main carrier are synchronized.
The bidirectional DC/DC conversion system can cause control abnormity by directly switching carrier frequency in the modulation operation process, wherein the control signal of the switching tube obtains the duty ratio of the control signal by comparing the amplitude of the modulation wave with the amplitude of the carrier wave.
And acquiring a difference absolute value of the amplitudes of the carrier wave and the modulation wave at the carrier synchronization phase, and judging whether the risk of losing the duty ratio of the control signal exists according to the difference absolute value.
And S212, when the absolute value of the difference value is less than or equal to the first threshold value, determining that the risk of losing the duty ratio of the control signal exists.
If the absolute value of the difference between the modulation wave and the carrier amplitude is less than or equal to the first threshold, it is considered that there is a risk that the duty ratio of the control signal is lost for the following reasons:
if the absolute value of the difference between the amplitude of the modulated wave and the amplitude of the carrier wave is smaller than or equal to the first threshold value in the initial phase of carrier synchronization, the amplitude of the carrier wave is suddenly changed when the frequency of the carrier wave is adjusted, and the risk that the amplitude of the modulated wave cannot be compared with the amplitude of the carrier wave and the risk that the duty ratio of the control signal is lost are likely to occur at the moment when the amplitude of the carrier wave disappears in the process of sudden change of the amplitude of the carrier wave.
The first threshold is determined according to a change step of a corresponding cycle counter when the carrier frequency is converted, for example, if the carrier cycle counter is incremented or decremented by n, the first threshold is n + 1.
And S213, when the absolute value of the difference value is larger than the first threshold value, determining that the risk of losing the duty ratio of the control signal does not exist.
And when the absolute value of the difference value between the modulation wave and the carrier amplitude is larger than the first threshold value, the process of adjusting the switching frequency is continuously executed.
S220, the amplitude of the modulation wave is adjusted in the same direction according to the amplitude change direction of the carrier wave until the switching frequency reaches the corresponding target frequency, and the amplitude of the modulation wave is controlled to be restored to the initial value before adjustment.
In one embodiment of the present application, as shown in fig. 6, S220 may include the following steps:
and S221, when the amplitude of the carrier wave is reduced, controlling the amplitude of the modulation wave to be reduced by a second threshold value. Wherein the second threshold is greater than the first threshold.
As shown in fig. 7, the carrier synchronization phase is in the phase of decreasing the amplitude of the carrier, and there is a risk that the amplitude comparison between the carrier and the modulation wave is lost, which results in the loss of the duty cycle of the control signal, in this case, the amplitude of the modulation wave is reduced by a second threshold, where the second threshold is greater than the first threshold, for example, the second threshold is about 2 times the first threshold, e.g., the first threshold is 2, and the second threshold is 4, which can ensure that the carrier crosses the modulation wave in the decreasing process, thereby avoiding the loss of the duty cycle of the control signal, and finally realizing the non-stop frequency conversion.
S222, when the amplitude of the carrier wave increases, controlling the amplitude of the modulation wave to increase by a second threshold.
If the carrier synchronization phase is in a phase of increasing the carrier amplitude, and the carrier and the modulation wave are at a risk of losing the duty ratio of the control signal due to the loss of amplitude comparison, in this case, the amplitude of the modulation wave is increased by the second threshold.
And S223, when the carrier frequency reaches the target frequency value, not adjusting the amplitude of the modulation wave.
The amplitude of the modulated wave is maintained at the amplitude after increasing or decreasing the second threshold value in one carrier cycle. Usually, the amplitude adjustment process of the modulated wave lasts for a plurality of carrier cycles, and the amplitude of the modulated wave is updated once per carrier cycle, so that the second threshold value is increased or decreased according to the change direction of the carrier wave on the basis of the updated amplitude of the modulated wave per cycle when the amplitude of the modulated wave is adjusted until the carrier frequency reaches the target frequency value, and the amplitude of the modulated wave is not adjusted according to the change direction of the amplitude of the carrier wave. As shown in fig. 7, at t1, the carrier frequency reaches the target frequency at t2, and the amplitude of the modulated wave is maintained at the amplitude increased or decreased by the second threshold value at the stage from t1 to t 2.
According to the control method of the bidirectional DC/DC conversion system provided by the embodiment, when the risk of losing the duty ratio of the control signal is detected, the amplitude of the modulation wave is adjusted, so that the amplitude of the modulation wave is compared with the amplitude of the carrier wave at the synchronous phase of the carrier wave, the condition of losing the duty ratio of the control signal is further avoided, the non-stop frequency conversion of the bidirectional DC/DC conversion system is realized, and the stability of the conversion system in the frequency conversion process is improved.
Corresponding to the control method embodiment of the bidirectional DC/DC conversion system, the application also provides a control device embodiment of the bidirectional DC/DC conversion system.
Referring to fig. 8, a block diagram of a control apparatus of a bidirectional DC/DC conversion system according to an embodiment of the present disclosure is shown, and as shown in fig. 8, the apparatus may include a first frequency conversion module 110 and a second frequency conversion module 120.
The first frequency conversion module 110 is configured to control a switching frequency of a switching tube in the bidirectional DC/DC conversion system to gradually adjust to a first target frequency when it is detected that the bidirectional DC/DC conversion system operates in the two-stage modulation mode.
When the bidirectional DC/DC conversion system operates at the first target frequency, the cut-off frequency of the bidirectional DC/DC conversion system does not resonate with a filter circuit formed by an external circuit of the bidirectional DC/DC conversion system.
In an embodiment of the present application, the process of the first frequency conversion module 110 for controlling the switching frequency to gradually adjust to the first target frequency may specifically be: and the frequency of the control carrier wave is gradually adjusted to a first target frequency according to a first preset frequency step length. The carrier wave and the modulation wave are used for generating a control signal for controlling the switch tube.
In one possible implementation, the process of adjusting the carrier frequency may be: and controlling the cycle counter of the carrier wave to be gradually adjusted to a first target value matched with the first target frequency according to a first value.
A second frequency conversion module 120, configured to control the switching frequency of the DC/DC conversion system to gradually increase to a second target frequency matching the single-stage modulation mode when the modulation mode of the bidirectional DC/DC conversion system is detected to be switched from the dual-stage modulation mode to the single-stage modulation mode. Wherein the second target frequency is greater than the first target frequency.
In an embodiment of the present application, the second frequency conversion module 120 is configured to, when the switching frequency of the DC/DC conversion system is gradually increased to a second target frequency matched with the single-stage modulation mode, specifically: and controlling the frequency of the carrier wave to gradually increase to the second target frequency according to a second preset frequency step.
In one possible implementation, the cycle counter of the carrier is controlled to decrease by a second value to a second target value that matches the second target frequency.
When the control device of the bidirectional DC/DC conversion system provided in this embodiment detects that the conversion system operates in the dual-stage modulation mode, the switching frequency of the conversion system is changed by software to change the cut-off frequency of the system, so that the cut-off frequency of the system avoids the resonant frequency of the CLC filter circuit formed by the external circuit of the system, and finally the system is prevented from resonating. The switching frequency of the conversion system is controlled in a software mode, and a hardware device is not required to be added, so that the hardware cost is reduced, and the control logic is simple and easy to implement. In addition, the scheme improves the stability of the frequency conversion process of the system and the accuracy of frequency conversion by controlling the switching frequency to be slowly changed.
Referring to fig. 9, a block diagram of a control device of another bidirectional DC/DC conversion system provided in the embodiment of the present application is shown, where the control device further includes, on the basis of the embodiment shown in fig. 8:
and a risk judging module 210, configured to judge whether there is a risk that a duty ratio of a control signal of the switching tube is lost in a process of controlling the switching frequency to change.
In one embodiment of the present application, the risk determining module 210 shown in fig. 8 may include:
an amplitude difference obtaining sub-module 211, configured to obtain an absolute value of a difference between the amplitude of the carrier wave and the amplitude of the modulated wave when the phase of the carrier wave is a synchronous phase.
A first determination submodule 212 for determining that there is a risk of loss of the duty cycle of the control signal when the absolute value of the difference is smaller than or equal to a first threshold.
A second determining submodule 213, configured to determine that there is no risk of losing the duty cycle of the control signal when the absolute value of the difference is greater than the first threshold.
And a modulated wave amplitude optimization module 220, configured to, when there is a risk that the duty cycle of the control signal is lost, continuously adjust the amplitude of the modulated wave in the same direction according to the amplitude change direction of the carrier wave until the switching frequency reaches a corresponding target frequency, so that the amplitude of the carrier wave and the amplitude of the modulated wave intersect, where the modulated wave and the carrier wave are used to generate the control signal.
In one embodiment of the present application, as shown in fig. 8, the modulation wave amplitude optimization module 220 may include:
the first amplitude adjustment sub-module 221 is configured to control the amplitude of the modulated wave to increase by a second threshold when the amplitude of the carrier increases, where the second threshold is greater than the first threshold.
A second amplitude adjustment sub-module 222, configured to control the amplitude of the modulated wave to decrease by the second threshold when the amplitude of the carrier wave decreases.
According to the control method of the bidirectional DC/DC conversion system provided by the embodiment, when the risk of losing the duty ratio of the control signal is detected, the amplitude of the modulation wave is adjusted, so that the amplitude of the modulation wave is compared with the amplitude of the carrier wave at the synchronous phase of the carrier wave, the condition of losing the duty ratio of the control signal is further avoided, the non-stop frequency conversion of the bidirectional DC/DC conversion system is realized, and the stability of the conversion system in the frequency conversion process is improved.
In another aspect, the present application provides a controller comprising a processor and a memory having stored therein a program executable on the processor. The processor implements the above-described control method of the bidirectional DC/DC conversion system when running the program stored in the memory.
In still another aspect, the present application further provides a storage medium executable by a computing device, the storage medium storing a program, the program when executed by the computing device implementing the control method of the bidirectional DC/DC conversion system described above.
In yet another aspect, the present application also provides a computer program product adapted to perform a control method initialized with the above-mentioned bidirectional DC/DC conversion system when executed on a controller.
While, for purposes of simplicity of explanation, the foregoing method embodiments have been described as a series of acts or combination of acts, it will be appreciated by those skilled in the art that the present invention is not limited by the illustrated ordering of acts, as some steps may occur in other orders or concurrently with other steps in accordance with the invention. Further, those skilled in the art should also appreciate that the embodiments described in the specification are preferred embodiments and that the acts and modules referred to are not necessarily required by the invention.
It should be noted that technical features described in the embodiments in the present specification may be replaced or combined with each other, each embodiment is mainly described as a difference from the other embodiments, and the same and similar parts between the embodiments may be referred to each other. For the device-like embodiment, since it is basically similar to the method embodiment, the description is simple, and for the relevant points, reference may be made to the partial description of the method embodiment.
The steps in the method of each embodiment of the present application may be sequentially adjusted, combined, and deleted according to actual needs.
The device and the modules and sub-modules in the terminal in the embodiments of the present application can be combined, divided and deleted according to actual needs.
In the several embodiments provided in the present application, it should be understood that the disclosed terminal, apparatus and method may be implemented in other manners. For example, the above-described terminal embodiments are merely illustrative, and for example, the division of a module or a sub-module is only one logical division, and there may be other divisions when the terminal is actually implemented, for example, a plurality of sub-modules or modules may be combined or integrated into another module, or some features may be omitted or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or modules, and may be in an electrical, mechanical or other form.
The modules or sub-modules described as separate parts may or may not be physically separate, and parts that are modules or sub-modules may or may not be physical modules or sub-modules, may be located in one place, or may be distributed over a plurality of network modules or sub-modules. Some or all of the modules or sub-modules can be selected according to actual needs to achieve the purpose of the solution of the present embodiment.
In addition, functional modules or sub-modules in the embodiments of the present application may be integrated into one processing module, or each module or sub-module may exist alone physically, or two or more modules or sub-modules are integrated into one module. The integrated modules or sub-modules can be implemented in the form of hardware, and can also be implemented in the form of software functional modules or sub-modules.
Finally, it should also be noted that, in this document, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in the process, method, article, or apparatus that comprises the element.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and amendments can be made without departing from the principle of the present invention, and these modifications and amendments should also be considered as the protection scope of the present invention.
Claims (12)
1. A control method of a bidirectional DC/DC conversion system, comprising:
when the bidirectional DC/DC conversion system is detected to operate in a double-stage modulation mode, controlling the switching frequency of a switching tube in the bidirectional DC/DC conversion system to be gradually adjusted to a first target frequency; when the bidirectional DC/DC conversion system operates at the first target frequency, the cut-off frequency of the bidirectional DC/DC conversion system cannot resonate with a filter circuit formed by an external circuit of the bidirectional DC/DC conversion system;
When detecting that the modulation mode of the bidirectional DC/DC conversion system is switched from the double-stage modulation mode to a single-stage modulation mode, controlling the switching frequency of the DC/DC conversion system to gradually increase to a second target frequency matched with the single-stage modulation mode, wherein the second target frequency is greater than the first target frequency;
under the single-stage modulation mode, a high-voltage side switching tube of the bidirectional DC/DC conversion system works in a chopping state; in the two-stage modulation mode, the switching tubes on the high-voltage side and the low-voltage side of the bidirectional DC/DC conversion system are in a chopping state.
2. The method of claim 1, further comprising:
in the process of controlling the switching frequency to change, judging whether the risk of losing the duty ratio of the control signal of the switching tube exists or not;
and when the duty ratio of the control signal is lost, continuously adjusting the amplitude of the modulation wave in the same direction according to the amplitude change direction of the carrier wave until the switching frequency reaches the corresponding target frequency, so that the amplitude of the carrier wave is crossed with the amplitude of the modulation wave, wherein the modulation wave and the carrier wave are used for generating the control signal.
3. The method of claim 2, wherein the determining whether there is a risk of losing a duty cycle of the control signal of the switching tube comprises:
when the phase of the carrier wave is a synchronous phase, acquiring a difference absolute value between the amplitude of the carrier wave and the amplitude of the modulation wave;
determining that there is a risk of loss of duty cycle of the control signal when the absolute value of the difference is less than or equal to a first threshold;
determining that there is no risk of loss of the duty cycle of the control signal when the absolute value of the difference is greater than the first threshold.
4. The method according to claim 3, wherein said adjusting the amplitude of the modulated wave in the same direction according to the direction of change in the amplitude of the carrier wave comprises:
when the amplitude of the carrier wave is increased, controlling the amplitude of the modulation wave to increase by a second threshold value, wherein the second threshold value is larger than the first threshold value;
when the amplitude of the carrier wave decreases, the amplitude of the modulated wave is controlled to decrease by the second threshold.
5. The method according to any one of claims 1-4, wherein said controlling the switching frequency of the switching tubes in the bidirectional DC/DC conversion system to gradually adjust to a first target frequency comprises:
The frequency of a control carrier wave is gradually adjusted to the first target frequency according to a first preset frequency step length, and the carrier wave and a modulation wave are used for generating a control signal for controlling the switching tube;
the step of gradually increasing the switching frequency of a switching tube in the DC/DC conversion system to a second target frequency matched with the single-stage modulation mode comprises the following steps:
and controlling the frequency of the carrier wave to gradually increase to the second target frequency according to a second preset frequency step.
6. The method of claim 5, wherein gradually adjusting the frequency of the control carrier to the first target frequency according to a first preset frequency step comprises:
controlling a cycle counter of the carrier wave to be gradually adjusted to a first target value matched with the first target frequency according to a first numerical value;
the controlling the frequency of the carrier wave to gradually increase to the second target frequency according to a second preset frequency step includes:
and controlling the cycle counter of the carrier wave to be reduced to a second target value matched with the second target frequency according to a second value.
7. A control device for a bidirectional DC/DC conversion system, comprising:
the first frequency conversion module is used for controlling the switching frequency of a switching tube in the bidirectional DC/DC conversion system to be gradually adjusted to a first target frequency when the bidirectional DC/DC conversion system is detected to operate in a two-stage modulation mode; when the bidirectional DC/DC conversion system operates at the first target frequency, the cut-off frequency of the bidirectional DC/DC conversion system does not resonate with a filter circuit formed by an external circuit of the bidirectional DC/DC conversion system;
A second frequency conversion module, configured to control a switching frequency of the bidirectional DC/DC conversion system to gradually increase to a second target frequency matching the single-stage modulation mode when detecting that the modulation mode of the bidirectional DC/DC conversion system is switched from the dual-stage modulation mode to the single-stage modulation mode, where the second target frequency is greater than the first target frequency;
under the single-stage modulation mode, a high-voltage side switching tube of the bidirectional DC/DC conversion system works in a chopping state; in the two-stage modulation mode, the switching tubes on the high-voltage side and the low-voltage side of the bidirectional DC/DC conversion system are in a chopping state.
8. The apparatus of claim 7, further comprising:
the risk judgment module is used for judging whether the risk of losing the duty ratio of the control signal of the switching tube exists in the process of controlling the switching frequency to change;
and the modulation wave amplitude optimization module is used for continuously adjusting the amplitude of the modulation wave in the same direction according to the amplitude change direction of the carrier wave when the risk of losing the duty ratio of the control signal exists so as to enable the amplitude of the carrier wave to be crossed with the amplitude of the modulation wave, wherein the modulation wave and the carrier wave are used for generating the control signal.
9. The apparatus of claim 8, wherein the risk assessment module comprises:
an amplitude difference value obtaining submodule configured to obtain an absolute value of a difference value between the amplitude of the carrier wave and the amplitude of the modulated wave when the phase of the carrier wave is a synchronous phase;
a first determination sub-module for determining that there is a risk of loss of the duty cycle of the control signal when the absolute value of the difference is less than or equal to a first threshold;
a second determination submodule for determining that there is no risk of loss of the duty cycle of the control signal when the absolute value of the difference is greater than the first threshold.
10. The apparatus of claim 9, wherein the modulation wave amplitude optimization module comprises:
a first amplitude adjustment submodule, configured to control an amplitude of the modulation wave to increase by a second threshold when the amplitude of the carrier increases, where the second threshold is greater than the first threshold;
and the second amplitude adjusting submodule is used for controlling the amplitude of the modulation wave to be reduced by the second threshold when the amplitude of the carrier wave is reduced.
11. A controller comprising a memory and a processor;
The memory has stored therein program instructions;
the processor is configured to invoke program instructions stored in the memory to perform the method of controlling the bi-directional DC/DC converter of any of claims 1-6.
12. A storage medium having a program stored thereon, wherein the program is loaded by a processor and executed to implement the method of controlling a bidirectional DC/DC converter according to any one of claims 1 to 6.
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