Three-phase-shift control method and system of DAB converter

Abstract

The invention discloses a three-phase-shift control method and system of a DAB converter, and relates to the technical field of converter control. Comprising the steps that a primary side voltage steady-state value, a secondary side voltage steady-state value and an expected value X * of a high-frequency transformer Tr in a target DAB converter and a sampling value X fed back by the output end of the target DAB converter are acquired; performing proportional integral on a difference value between the sampling value X and the expected value X * to obtain unit transmission power Y; determining the voltage ratio # imgabs0 # of the two sides of the inductor, and determining a first phase shift angle D1, a second phase shift angle D2 and a third phase shift angle D3 according to the unit transmission power Y and the voltage ratio # imgabs1 # of the two sides of the inductor; and performing signal modulation through the first phase shift angle D1, the second phase shift angle D2, the third phase shift angle D3 and the switching frequency fs to obtain a driving signal to control the target DAB converter. Design and implementation of a control strategy are greatly simplified, and the control method is clear in mechanism and easy to control.

Description

Technical Field

[0001] The present invention relates to the technical field of converter control, and in particular to a three-phase shift control method and system for a DAB converter. Background Art

[0002] With the development of renewable energy, electric vehicles and energy storage industries, the demand for efficient DC / DC converters that safely and reliably support bidirectional energy transmission has increased. Dual-Active-Bridge (DAB) DC / DC converters have attracted widespread attention due to their advantages such as bidirectional energy transmission, electrical isolation, soft switching, high energy conversion efficiency, and high power density.

[0003] DAB converter mainly adopts phase shift control, which can be divided into single-phase-shift (SPS) control, extended phase-shift (EPS) control, dual-phase-shift (DPS) control and triple-phase-shift (TPS) control according to the number of phase-shift degrees of freedom. TPS control has three degrees of freedom. Single-phase control SPS, extended phase control EPS and dual-phase control DPS can be regarded as special cases of triple-phase control TPS. Accordingly, TPS control is the best and most complex control method.

[0004] The defects of the above-mentioned prior art are: TPS control can maximize the soft switching range and eliminate the backflow power, thereby improving the energy conversion efficiency of the converter, but due to its high control complexity, the current TPS control algorithm has problems such as complex control process, poor dynamic performance or low energy transmission efficiency, which limits the application and development of DAB converters. Summary of the invention

[0005] Based on this, it is necessary to provide a three-phase shift control method and system for a DAB converter in order to solve the above technical problems.

[0006] The embodiment of the present invention provides a three-phase shift control method of a DAB converter, wherein the DAB converter includes an inductor L , high frequency transformer T r And through the inductor L and high frequency transformer T r Two coupled active full-bridge circuits, each of which includes four switches; including: Obtain the target DAB converter medium and high frequency transformer T r The steady-state value of the primary voltage , Steady-state value of secondary voltage , Expected value X* and the sampled value fed back from the output of the target DAB converter X ; The sampled value is controlled by the PI controller X and expected value X* The difference is proportionally integrated to obtain the unit transmission power used to control the energy transfer of the target DAB converter. Y ; According to the steady-state value of the primary voltage , Steady-state value of secondary voltage and transformer ratio n , determine the voltage ratio on both sides of the inductor ; According to the unit transmission power Y The voltage ratio across the inductor , determine the first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 ; Through the first phase shift angle D 1 , the second phase shift angle D 2 , the third phase shift angle D 3 and the switching frequency of each switch f s Signal modulation is performed to obtain driving signals for eight switches in an active full-bridge circuit to control the target DAB converter.

[0007] Optionally, in the DAB converter, an inductor will be included L One side acts as a high frequency transformer T r The primary side does not include the inductor L One side acts as a high frequency transformer T r The secondary side of the transformer; the ratio of the number of turns of the primary winding to the number of turns of the secondary winding is taken as the transformer ratio n .

[0008] Optionally, determining a first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 , specifically including: If the energy is transferred forward during the operation of the target DAB converter, the domain is expressed as: ; If the energy is reversely transferred during the operation of the DAB converter, the voltage ratio on both sides of the inductor α Take the reciprocal, unit transmission power Y Take the absolute value; then determine the first phase shift angle using the same calculation method as the forward energy transmission D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 Then, the first phase shift angle D 1 and the third phase shift angle D 3 The value of the second phase shift angle is exchanged D 2 Take the opposite number to get the first phase shift angle of reverse energy transmission D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 .

[0009] Optionally, the first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 Specifically: When the first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 When greater than 0, the first phase shift angle D 1 express g 4 Hysteresis g 1 Unit phase shift angle, first phase shift angle D 1 The angle is equal to g 4 Hysteresis g 1 The angle is divided by 180 degrees; the second phase shift angle D 2 express g 5 Hysteresis g 1 The unit phase shift angle; the third phase shift angle D 3 express g8 Hysteresis g 5 The unit phase shift angle of When the first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 When it is less than 0, the first phase shift angle D 1 express g 4 Ahead of the times g 1 Unit phase shift angle, first phase shift angle D 1 The angle is equal to g 4 Ahead of the times g 1 The angle is divided by 180 degrees; the second phase shift angle D 2 express g 5 Ahead of the times g 1 The unit phase shift angle; the third phase shift angle D 3 express g 8 Ahead of the times g 5 The unit phase shift angle of in, g x Indicates the switches of the DAB converter S x , x =The corresponding driving signal of 1~8.

[0010] Optionally, by a first phase shift angle D 1 , the second phase shift angle D 2 , the third phase shift angle D 3 and the switching frequency of each switch f s Perform signal modulation, including: g 1~8 The duty cycle is 50% and the frequency is the switching frequency. f s The square wave signal of the same half bridge is complementary to the upper and lower switch signals. g 1 and g 2 , g3 and g 4 , g 5 and g 6 , g 7 and g 8 complementary; by g 1 is the reference signal, g 4 Lagging reference signal D 1 T h time, g 5 Lagging reference signal D 2 T h time, g 8 Lagging reference signal ( D 2 + D 3 ) T h time; g 2 , g 3 , g 6 and g 7 They are g 1 , g 4 , g 5 and g 8 The complementary signal has a phase difference of 180 degrees. in, T h is half of the switching period, T h =0.5 / f s .

[0011] Optionally, the target DAB converter is controlled by driving signals of eight switches in the active full-bridge circuit, and the target DAB converter completely eliminates the backflow power. The power transfer characteristic is expressed as: ; in, L Indicates the inductance value, fs represents the switching frequency, Y represents the unit transmission power; if Y Greater than 0 means that power is transmitted from the primary side to the secondary side, in the positive direction; if Y If it is less than 0, it means that the power is transmitted from the secondary side to the primary side and in the reverse direction; The energy transfer efficiency is expressed as: ; Among them, Cond It represents the conduction loss coefficient when the return power is completely eliminated, Г Sw Indicates the switching loss coefficient when the return power is completely eliminated; The voltage ratio of the two sides of the inductor The calculation formula is: ; in, Y represents the unit transmission power, t off,p represents the switching time of the primary switch, t off,s represents the switching time of the secondary switch, R e Represents the equivalent parasitic resistance of the power transmission loop, It represents the voltage ratio on both sides of the inductor. V s represents the secondary voltage, V p Represents the primary voltage, n Indicates the transformer ratio.

[0012] The embodiment of the present invention further provides a three-phase shift control system of a DAB converter, comprising: Acquisition module, used to acquire the high frequency transformer of the target DAB converter T r The steady-state value of the primary voltage , Steady-state value of secondary voltage , Expected value X* and the sampled value fed back from the output of the target DAB converter X ; Parameter calculation module, used to calculate the sampled value through PI controller X and expected value X* The difference is proportionally integrated to obtain the unit transmission power used to control the energy transfer of the target DAB converter. Y ; According to the steady-state value of the primary voltage, the steady-state value of the secondary voltage and the transformer ratio n , determine the voltage ratio on both sides of the inductor ; Modulation module, used to transmit power according to the unitY The voltage ratio across the inductor , determine the first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 ; Through the first phase shift angle D 1 , the second phase shift angle D 2 , the third phase shift angle D 3 and the switching frequency of each switch f s Signal modulation is performed to obtain driving signals for eight switches in an active full-bridge circuit to control the target DAB converter.

[0013] Compared with the prior art, the three-phase shift control method and system of the DAB converter provided by the embodiment of the present invention have the following beneficial effects: The three-phase shift control method of the DAB converter proposed in the present invention can be applied to any control system of the DAB converter, such as constant voltage control, constant current control and constant power control, and can also be applied to a control system for bidirectional energy transmission.

[0014] More importantly, the present invention only needs to D 1 , D 2 , D 3 and switching frequency f s By performing signal modulation, the driving signals of the eight switches in the active full-bridge circuit can be obtained. Compared with complex multivariable control systems, this modulation method based on a few key parameters not only greatly simplifies the design and implementation of the control strategy, but also has a clear control method mechanism and simple control. Moreover, the rapid adjustment of parameters can quickly respond to load changes, has good dynamic performance, and can improve the energy transmission efficiency of the soft switch. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A topological structure diagram of a DAB converter of a three-phase shift control method of a DAB converter provided in an embodiment; Figure 2 A typical waveform diagram of a three-phase shift control method for a DAB converter provided in an embodiment; Figure 3 A schematic diagram of a closed-loop control strategy of a DAB converter of a three-phase shift control method of a DAB converter provided in an embodiment; Figure 4The figure is a schematic diagram of a calculation process of a three-phase shift control method for a DAB converter provided in an embodiment. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0017] In one embodiment, a DAB converter is provided. Figure 1 The topology diagram of the DAB converter is shown. Including the inductor L、 High frequency transformer T r And through the inductor L and high frequency transformer T r Two active full-bridge circuits are coupled, each of which includes four switches. Among them, the capacitor in the active bridge C p and C s It plays the role of filtering and stabilizing voltage, maintaining the stability of the voltage on both sides of the DAB converter. L One side of the transformer is called the primary side, and the other side is called the secondary side. V p Represents the primary voltage, I p represents the primary current, V s represents the secondary voltage, I s Indicates the secondary current. Transformer ratio n It is also defined as the ratio of the number of primary turns to the number of secondary turns.

[0018] In one embodiment, a three-phase shift control method for a DAB converter is provided, the method comprising: Obtain the target DAB converter medium and high frequency transformer T r The steady-state value of the primary voltage , Steady-state value of secondary voltage , Expected value X* and the sampled value fed back from the output of the target DAB converter X .

[0019] The sampled value is controlled by the PI controller X and expected value X* The difference is proportionally integrated to obtain the unit transmission power used to control the energy transfer of the target DAB converter. Y .

[0020] According to the steady-state value of the primary voltage , Steady-state value of secondary voltage and transformer ratio n , determine the voltage ratio on both sides of the inductor .

[0021] According to the unit transmission power Y The voltage ratio across the inductor , determine the first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 .

[0022] Through the first phase shift angle D 1 , the second phase shift angle D 2 , the third phase shift angle D 3 and the switching frequency of each switch f s Signal modulation is performed to obtain driving signals for eight switches in an active full-bridge circuit to control the target DAB converter.

[0023] Typical waveforms of a DAB converter using TPS control are also shown. Figure 2 , the driving signal of all switches of the DAB converter g x ( x =1~8) are all square wave signals with a duty cycle of 50%, and the signals of the upper bridge arm and the lower bridge arm are complementary. T h Represents half a switching cycle, which is equal to 0.5 / f s The first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 The definition can be found in Figure 2 When the first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 When greater than 0, the first phase shift angle D 1 express g 4 Hysteresis g 1Unit phase shift angle, first phase shift angle D 1 The angle is equal to g 4 Hysteresis g 1 The angle is divided by 180 degrees. The second phase shift angle D 2 express g 5 Hysteresis g 1 The unit phase shift angle, the third phase shift angle D 3 express g 8 Hysteresis g 5 The unit phase shift angle.

[0024] When the first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 When it is less than 0, the first phase shift angle D 1 express g 4 Ahead of the times g 1 Unit phase shift angle, first phase shift angle D 1 The angle is equal to g 4 Ahead of the times g 1 The angle is divided by 180 degrees. The second phase shift angle D 2 express g 5 Ahead of the times g 1 The unit phase shift angle, the third phase shift angle D 3 express g 8 Ahead of the times g 5 The unit phase shift angle is . g x Indicates the switches of the DAB converter S x , x =The corresponding driving signal of 1~8.

[0025] g 1~8 The duty cycle is 50% and the frequency is the switching frequency. f sThe upper and lower switch signals of the same half bridge are complementary. g 1 and g 2 , g 3 and g 4 , g 5 and g 6 , g 7 and g 8 Complementary. g 1 is the reference signal, g 4 Lagging reference signal D 1 T h time, g 5 Lagging reference signal D 2 T h time, g 8 Lagging reference signal ( D 2 + D 3 ) T h time. g 2 , g 3 , g 6 and g 7 They are g 1 , g 4 , g 5 and g 8 The complementary signal of is 180 degrees in phase difference. T h is half of the switching period, T h =0.5 / f s .

[0026] The target DAB converter is controlled by the driving signals of the eight switches in the active full-bridge circuit. The target DAB converter completely eliminates the backflow power. The expression formula of the power transfer characteristic is: ; in, L Indicates the inductance value, f s represents the switching frequency, Y represents the unit transmission power; if Y Greater than 0 means that power is transmitted from the primary side to the secondary side, that is, forward transmission; if Y If it is less than 0, it means that the power is transmitted from the secondary side to the primary side, that is, reverse transmission. Since reverse transmission is the reverse process of forward transmission, the following derivation process takes forward transmission as an example.

[0027] The energy transfer efficiency when the return power is completely eliminated can be expressed as: ; Among them, Cond It represents the conduction loss coefficient when the return power is completely eliminated, Г Sw Indicates the switching loss coefficient when the return power is completely eliminated. They represent the ratio of the corresponding loss to the transmission power. The calculation formula is:

[0028] ; in, Y represents the unit transmission power, t off,p represents the switching time of the primary switch, t off,s represents the switching time of the secondary switch, R e Represents the equivalent parasitic resistance of the power transmission loop, It represents the voltage ratio on both sides of the inductor. V s represents the secondary voltage, V p Represents the primary voltage, n Indicates the transformer ratio.

[0029] The domain of forward transmission can be expressed as: ; By derivation, it can be found that within the definition domain, the third phase shift angle D 3 The smaller the loss, the lower the energy transmission efficiency, and the higher the phase shift angle when the efficiency is highest under NC-TPS control can be calculated by Table I.

[0030] Table I The closed-loop control system using NC-TPS control can be expressed in Figure 3 . The sampled value is controlled by the PI controllerX and expected value X* The required unit transmission power is obtained by proportionally integrating the difference Y , according to the steady-state value of the primary voltage , Steady-state value of secondary voltage and transformer ratio n , determine the voltage ratio on both sides of the inductor Then according to Table I, the unit transmission power Y The voltage ratio across the inductor , determine the first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 Then, by the first phase shift angle D 1 , the second phase shift angle D 2 , the third phase shift angle D 3 and the switching frequency of each switch f s Signal modulation is performed to obtain driving signals of eight switches in the active full-bridge circuit, and then the target DAB converter is controlled according to the driving signals.

[0031] Since the forward and reverse transmissions are slightly different, Figure 3 The parameter calculation process in is slightly different. Figure 4 The flowchart in the figure further introduces the parameter calculation process. When calculating the parameters, first calculate α , and then determine whether the energy is transmitted in the reverse direction. If the energy is transmitted in the reverse direction, α Take the reciprocal, Y Take the absolute value; then determine the first phase shift angle using the same calculation method as the forward energy transmission D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 Then, the first phase shift angle D 1 and the third phase shift angle D 3 The value of the second phase shift angle is exchanged D 2 Take the opposite number to get the first phase shift angle of the final energy reverse transmission D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 .

[0032] Based on the same inventive concept, an embodiment of the present invention further provides a three-phase shift control system of a DAB converter, the system comprising: Acquisition module, used to acquire the high frequency transformer of the target DAB converter T r The steady-state value of the primary voltage , Steady-state value of secondary voltage , Expected value X* and the sampled value fed back from the output of the target DAB converter X .

[0033] Parameter calculation module, used to calculate the sampled value through PI controller X and expected value X* The difference is proportionally integrated to obtain the unit transmission power used to control the energy transfer of the target DAB converter. Y ; According to the steady-state value of the primary voltage , Steady-state value of secondary voltage and transformer ratio n , determine the voltage ratio on both sides of the inductor .

[0034] Modulation module, used to transmit power according to the unit Y The voltage ratio across the inductor , determine the first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 ; Through the first phase shift angle D 1 , the second phase shift angle D 2 , the third phase shift angle D 3 and the switching frequency of each switch f s Signal modulation is performed to obtain driving signals for eight switches in an active full-bridge circuit to control the target DAB converter.

[0035] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A three-phase shift control method for a DAB converter, the DAB converter comprising an inductor L , high frequency transformer T r And through the inductor L and high frequency transformer T r Two coupled active full-bridge circuits, each active full-bridge circuit includes 4 switches; characterized in that, include: Obtain the target DAB converter medium and high frequency transformer T r The steady-state value of the primary voltage , Steady-state value of secondary voltage , Expected value X* and the sampled value fed back from the output of the target DAB converter X ; The sampled value is controlled by the PI controller X and expected value X* The difference is proportionally integrated to obtain the unit transmission power used to control the energy transfer of the target DAB converter. Y ; According to the steady-state value of the primary voltage , Steady-state value of secondary voltage and transformer ratio n , determine the voltage ratio on both sides of the inductor ; According to the unit transmission power Y The voltage ratio across the inductor , determine the first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 ; Through the first phase shift angle D 1 , the second phase shift angle D 2 , the third phase shift angle D 3 and the switching frequency of each switch f s Signal modulation is performed to obtain driving signals for eight switches in an active full-bridge circuit to control the target DAB converter.

2. A three-phase shift control method for a DAB converter as claimed in claim 1, characterized in that: In the DAB converter, the inductor will be included L One side acts as a high frequency transformer T r The primary side does not include the inductor L One side acts as a high frequency transformer T r The secondary side; The ratio of the number of turns of the primary winding to the number of turns of the secondary winding is taken as the transformer ratio n .

3. The three-phase shift control method of a DAB converter as claimed in claim 1, characterized in that: Determining the first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 , specifically including: If the energy is transferred forward during the operation of the target DAB converter, the domain is expressed as: ； If the energy is reversely transferred during the operation of the DAB converter, the voltage ratio on both sides of the inductor α Take the reciprocal, unit transmission power Y Take the absolute value; then determine the first phase shift angle using the same calculation method as the forward energy transmission D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 Then, the first phase shift angle D 1 and the third phase shift angle D 3 The value of the second phase shift angle is exchanged D 2 Take the opposite number to get the first phase shift angle of reverse energy transmission D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 .

4. A three-phase shift control method for a DAB converter as claimed in claim 3, characterized in that: The first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 Specifically: When the first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 When greater than 0, the first phase shift angle D 1 express g 4 Hysteresis g 1 Unit phase shift angle, first phase shift angle D 1 The angle is equal to g 4 Hysteresis g 1 The angle is divided by 180 degrees; the second phase shift angle D 2 express g 5 Hysteresis g 1 The unit phase shift angle; the third phase shift angle D 3 express g 8 Hysteresis g 5 The unit phase shift angle of When the first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 When it is less than 0, the first phase shift angle D 1 express g 4 Ahead of the times g 1 Unit phase shift angle, first phase shift angle D 1 The angle is equal to g 4 Ahead of the times g 1 The angle is divided by 180 degrees; the second phase shift angle D 2 express g 5 Ahead of the times g 1 The unit phase shift angle; the third phase shift angle D 3 express g 8 Ahead of the times g 5 The unit phase shift angle of in, g x Indicates the switches of the DAB converter S x , x =1~8 corresponding driving signal.

5. A three-phase shift control method for a DAB converter as claimed in claim 4, characterized in that: The first phase shift angle D 1 , the second phase shift angle D 2 , the third phase shift angle D 3 and the switching frequency of each switch f s Perform signal modulation, including: g 1~8 The duty cycle is 50% and the frequency is the switching frequency. f s The square wave signal of the same half bridge is complementary to the upper and lower switch signals. g 1 and g 2 , g 3 and g 4 , g 5 and g 6 , g 7 and g 8 complementary; by g 1 is the reference signal, g 4 Lagging reference signal D 1 T h time, g 5 Lagging reference signal D 2 T h time, g 8 Lagging reference signal ( D 2 + D 3 ) T h time; g 2 , g 3 , g 6 and g 7 They are g 1 , g 4 , g 5 and g 8 The complementary signal has a phase difference of 180 degrees. in, T h is half of the switching period, T h =0.5 / f s .

6. A three-phase shift control method for a DAB converter as claimed in claim 1, characterized in that: The target DAB converter is controlled by the driving signals of the eight switches in the active full-bridge circuit. The target DAB converter completely eliminates the reflux power. The expression formula of the power transfer characteristic is: ； in, L Indicates the inductance value, f s represents the switching frequency, Y represents the unit transmission power; if Y If it is greater than 0, it means that the power is transmitted from the primary side to the secondary side in the positive direction. Y If it is less than 0, it means that the power is transmitted from the secondary side to the primary side and in the reverse direction; The energy transfer efficiency is expressed as: ； Among them, Cond It represents the conduction loss coefficient when the return power is completely eliminated, Г Sw Indicates the switching loss coefficient when the return power is completely eliminated; The voltage ratio of the two sides of the inductor The calculation formula is: ； in, Y represents the unit transmission power, t off,p represents the switching time of the primary switch, t off,s represents the switching time of the secondary switch, R e Represents the equivalent parasitic resistance of the power transmission loop, It represents the voltage ratio on both sides of the inductor. V s represents the secondary voltage, V p Represents the primary voltage, n Indicates the transformer ratio.

7. A three-phase shift control system based on the three-phase shift control method of a DAB converter according to any one of claims 1 to 6, characterized in that: include: Acquisition module, used to acquire the high frequency transformer of the target DAB converter T r The steady-state value of the primary voltage , Steady-state value of secondary voltage , Expected value X* and the sampled value fed back from the output of the target DAB converter X ; Parameter calculation module, used to calculate the sampled value through PI controller X and expected value X* The difference is proportionally integrated to obtain the unit transmission power used to control the energy transfer of the target DAB converter. Y ; According to the steady-state value of the primary voltage , Steady-state value of secondary voltage and transformer ratio n , determine the voltage ratio on both sides of the inductor ; Modulation module, used to transmit power according to the unit Y The voltage ratio across the inductor , determine the first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 ; Through the first phase shift angle D 1 , the second phase shift angle D 2 , the third phase shift angle D 3 and the switching frequency of each switch f s Signal modulation is performed to obtain driving signals for eight switches in an active full-bridge circuit to control the target DAB converter.

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