A three-phase-shift control method and system for a DAB converter

Abstract

The application discloses a three-phase shift control method and system of a DAB converter, and relates to the technical field of converter control. T r The application discloses a three-phase shift control method and system of a DAB converter, and relates to the technical field of converter control. X* The application discloses a three-phase shift control method and system of a DAB converter, and relates to the technical field of converter control. X The application discloses a three-phase shift control method and system of a DAB converter, and relates to the technical field of converter control. X The application discloses a three-phase shift control method and system of a DAB converter, and relates to the technical field of converter control. X* The application discloses a three-phase shift control method and system of a DAB converter, and relates to the technical field of converter control. Y The application discloses a three-phase shift control method and system of a DAB converter, and relates to the technical field of converter control. Y The application discloses a three-phase shift control method and system of a DAB converter, and relates to the technical field of converter control. D 1 The application discloses a three-phase shift control method and system of a DAB converter, and relates to the technical field of converter control. D 2 The application discloses a three-phase shift control method and system of a DAB converter, and relates to the technical field of converter control. D 3 The application discloses a three-phase shift control method and system of a DAB converter, and relates to the technical field of converter control. D 1 The application discloses a three-phase shift control method and system of a DAB converter, and relates to the technical field of converter control. D 2 The application discloses a three-phase shift control method and system of a DAB converter, and relates to the technical field of converter control. D 3 The application discloses a three-phase shift control method and system of a DAB converter, and relates to the technical field of converter control. f s The application discloses a three-phase shift control method and system of a DAB converter, and relates to the technical field of converter control.

Description

Technical Field

[0001] This invention relates to the field of converter control technology, and in particular to a three-phase shift control method and system for a DAB converter. Background Technology

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

[0003] DAB converters primarily employ phase-shift control, which can be categorized based on the number of phase-shift degrees of freedom: Single-phase-shift (SPS) control, Extending phase-shift (EPS) control, Dual-phase-shift (DPS) control, and Triple-phase-shift (TPS) control. TPS control possesses three degrees of freedom, and SPS, EPS, and DPS can be considered special cases of TPS. Correspondingly, TPS control offers the best performance but is also the most complex control method.

[0004] The shortcomings of the existing technology are: TPS control can maximize the soft switching range and eliminate backflow power, thereby improving the energy conversion efficiency of the converter. However, due to its high control complexity, the current TPS control algorithm has problems such as complex control process, poor dynamic performance, or low energy transfer efficiency, which limits the application and development of DAB converters. Summary of the Invention

[0005] Therefore, it is necessary to provide a three-phase shift control method and system for a DAB converter to address the aforementioned technical problems.

[0006] This invention provides a three-phase shift control method for a DAB converter, the DAB converter including an inductor. L High-frequency transformers T r And through inductors L and high frequency transformer T r Two coupled active full-bridge circuits, each including four switches; including:

[0007] Obtain the high-frequency transformer in the target DAB converter T r primary voltage steady-state value , the secondary side voltage steady-state value , the expected value X* , and the sampling value of the target DAB converter output end feedback X ;

[0008] The difference between the sampling value X and the expected value X* is proportional and integral by the PI controller to obtain the unit transmission power Y for controlling the energy transmission of the target DAB converter.

[0009] According to the primary side voltage steady-state value , the secondary side voltage steady-state value , and the transformer turns ratio n , the inductance voltage ratio on both sides is determined ;

[0010] According to the unit transmission power Y and the inductance voltage ratio on both sides , the first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 are determined.

[0011] The driving signals of the eight switches in the active full-bridge circuit are obtained by signal modulation 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 to control the target DAB converter.

[0012] Optionally, in the DAB converter, one side containing the inductor L is taken as the primary side of the high-frequency transformer T r , and the side not containing the inductor L is taken as the secondary side of the high-frequency transformer T r ; the ratio of the primary side winding turns to the secondary side winding turns is taken as the transformer turns ratio n .

[0013] Optionally, the first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 are determined, specifically including:

[0014] If the energy is transmitted forward in the process of controlling the target DAB converter to work, the domain is represented as:

[0015] ;

[0016] If the energy is transmitted backward in the process of controlling the target DAB converter to work, the voltage ratio of the inductance on both sides is α Take the reciprocal, the unit transmission power Y Take the absolute value; and the first phase shift angle is determined according to the same calculation method as the energy forward transmission D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 After that, the values of the first phase shift angle D 1 and the third phase shift angle D 3 are exchanged, and the second phase shift angle D 2 Take the opposite number to get the first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 .

[0017] Alternatively, the first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 Specifically:

[0018] When the first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 are greater than 0, the first phase shift angle D 1 represents g 4 the unit phase shift angle of lag g 1 , and the angle of the first phase shift angle D 1 is equal to g 4 the angle of lag g 1 divided by 180 degrees; the second phase shift angle D 2denotes g 5 lagging g 1 unit phase shift angle; third phase shift angle D 3 denotes g 8 lagging g 5 unit phase shift angle

[0019] when the first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 are smaller than 0, the first phase shift angle D 1 denotes g 4 leading g 1 unit phase shift angle, the angle of the first phase shift angle D 1 is equal to g 4 leading g 1 the angle divided by 180 degrees; the second phase shift angle D 2 denotes g 5 leading g 1 unit phase shift angle; third phase shift angle D 3 denotes g 8 leading g 5 unit phase shift angle

[0020] wherein g x denotes the respective switch S x of the DAB converter, x = the corresponding drive signal of 1 to 8.

[0021] Optionally, the signal is modulated 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 the respective switch f s , in particular comprising:

[0022] g1~8 are both 50% duty cycle, frequency is switching frequency f s of square wave signals; 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 are complementary;

[0023] with g 1 as the reference signal, g 4 the reference signal is delayed by D 1 T h time, g 5 the reference signal is delayed by D 2 T h time, g 8 the reference signal is delayed by D 2 + D 3 ) T h time; g 2 , g 3 , g 6 and g 7 are respectively g 1 , g 4 , g 5 and g 8 complementary signals of

[0024] wherein, T h is half of the switching period, T h = 0.5 / f s .

[0025] Optionally, the target DAB converter is controlled by the driving signals of the 8 switches in the active full-bridge circuit, and the target DAB converter completely eliminates the backflow power, and the expression formula of the power transmission characteristic is:

[0026] ;

[0027] wherein, L represents the inductance value, f s represents the switching frequency, Y represents the unit transmission power; if Y is greater than 0, it indicates that the power is transmitted from the primary side to the secondary side, and the forward transmission; if Y is less than 0, it indicates that the power is transmitted from the secondary side to the primary side, and the reverse transmission;

[0028] The expression formula of the energy transmission efficiency is:

[0029] ;

[0030] wherein, Г Cond represents the conduction loss coefficient under the condition of completely eliminating the backflow power, and Г Sw represents the switching loss coefficient under the condition of completely eliminating the backflow power;

[0031] The calculation formula of the voltage ratio of the inductance on both sides is:

[0032] ;

[0033] wherein, Y represents the unit transmission power, t off,p represents the switching time of the primary side switch, t off,s represents the switching time of the secondary side switch, R e represents the equivalent parasitic resistance of the power transmission loop, represents the voltage ratio of the inductance on both sides, V s represents the secondary side voltage, V p represents the primary side voltage, n represents the transformer ratio.

[0034] The embodiment of the application further provides a three-phase shift control system of a DAB converter, comprising:

[0035] An acquisition module is configured to acquire a steady-state value of a primary side voltage of a high-frequency transformer T r in a target DAB converter​ Secondary voltage steady-state value Expected value X* The sampled value fed back from the output of the target DAB converter X ;

[0036] The parameter calculation module is used to process sampled values ​​via a PI controller. X and expected value X* The difference is proportionally integrated to obtain the unit transfer power used to control the energy transfer of the target DAB converter. Y Based on the steady-state values ​​of the primary voltage, secondary voltage, and transformer turns ratio n Determine the voltage ratio across the inductor ;

[0037] Modulation module, used to adjust based on unit transmission power Y voltage ratio across the inductor Determine the first phase shift angle D 1 Second phase shift angle D 2 and the third phase shift angle D 3 ; through the first phase shift angle D 1 Second phase shift angle D 2 Third phase shift angle D 3 and the switching frequency of each switch f s Signal modulation is performed to obtain the drive signals for the eight switches in the active full-bridge circuit to control the target DAB converter.

[0038] The three-phase shift control method and system for a DAB converter provided in this invention have the following advantages compared with the prior art:

[0039] The three-phase shift control method for DAB converters proposed in this invention can be applied to any control system of DAB converters, such as constant voltage control, constant current control, and constant power control, and can also be applied to control systems for bidirectional energy transmission.

[0040] More importantly, this invention only requires adjustments to the phase shift angle. D 1 , D 2 , D 3 and switching frequency f sThe signal modulation can obtain the driving signals of 8 switches in the active full-bridge circuit; compared with the complex multi-variable control system, the modulation method based on a few key parameters not only greatly simplifies the design and implementation of the control strategy, and the control method mechanism is clear and simple to control; and the rapid adjustment of the parameters can quickly respond to the load change, and the dynamic performance is good, and the energy transmission efficiency of the soft switching can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 A DAB converter topology diagram of a three-phase shift control method of a DAB converter provided in an embodiment;

[0042] Figure 2 A typical waveform diagram of a three-phase shift control method of a DAB converter provided in an embodiment;

[0043] Figure 3 A DAB converter closed-loop control strategy diagram of a three-phase shift control method of a DAB converter provided in an embodiment;

[0044] Figure 4 A calculation process diagram of a three-phase shift control method of a DAB converter provided in an embodiment. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0046] In an embodiment, a DAB converter is provided, Figure 1 The topology diagram of the DAB converter is shown. It includes an inductor L、 A high-frequency transformer T r and two active full-bridge circuits coupled by the inductor L and the high-frequency transformer T r Each active full-bridge circuit includes 4 switches. The capacitor C p and C s in the active bridge has a filtering and voltage stabilizing effect, maintaining the stability of the voltage on both sides of the DAB converter. The side with the inductor L is called the primary side of the transformer, and the other side is called the secondary side, i.e. V p represents the primary side voltage, I p represents the primary side current, V sIndicates the secondary voltage. I s This represents the secondary current. Transformer turns ratio. n It is also defined as the ratio of the number of turns in the primary winding to the number of turns in the secondary winding.

[0047] In one embodiment, a three-phase shift control method for a DAB converter is provided, the method comprising:

[0048] Obtain the high-frequency transformer in the target DAB converter T r primary voltage steady-state value Secondary voltage steady-state value Expected value X* The sampled value fed back from the output of the target DAB converter X .

[0049] The sampled value is processed by a PI controller. X and expected value X* The difference is proportionally integrated to obtain the unit transfer power used to control the energy transfer of the target DAB converter. Y .

[0050] Based on the steady-state value of the primary voltage Secondary voltage steady-state value and transformer turns ratio n Determine the voltage ratio across the inductor .

[0051] Based on unit transmission power Y voltage ratio across the inductor Determine the first phase shift angle D 1 Second phase shift angle D 2 and the third phase shift angle D 3 .

[0052] Through the first phase shift angle D 1 Second phase shift angle D 2 Third phase shift angle D 3 and the switching frequency of each switch f s Signal modulation is performed to obtain the drive signals for the eight switches in the active full-bridge circuit to control the target DAB converter.

[0053] Typical waveforms of a DAB converter using TPS control are also shown. Figure 2 Drive signals for all switches of the DAB converter g x (x =1~8) are all square wave signals with a 50% duty cycle, and the signals of the upper and lower bridge arms are complementary. T h This represents half a switching cycle, and its value is equal to 0.5 / f s First phase shift angle D 1 Second phase shift angle D 2 and the third phase shift angle D 3 The definition can be found by referring to Figure 2 When the first phase shift angle D 1 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 Lag g 1 The unit phase shift angle, the first phase shift angle D 1 Angle equal to g 4 Lag g 1 Divide the angle by 180 degrees. Second phase shift angle. D 2 express g 5 Lag g 1 The unit phase shift angle, the third phase shift angle D 3 express g 8 Lag g 5 The unit phase shift angle.

[0054] When the first phase shift angle D 1 Second phase shift angle D 2 and the third phase shift angle D 3 When less than 0, the first phase shift angle D 1 express g 4 Advanced g 1 The unit phase shift angle, the first phase shift angle D 1 Angle equal to g 4lead g 1 of the angle divided by 180 degrees. The second phase shift angle D 2 represents g 5 lead g 1 of the unit phase shift angle, the third phase shift angle D 3 represents g 8 lead g 5 of the unit phase shift angle. Wherein, g x represents the respective switch of the DAB converter S x , x =1~8 corresponding drive signal.

[0055] g 1~8 are all duty cycle of 50%, the frequency of the switching frequency f s square wave signal. The same half-bridge upper and lower complementary switch signal, g 1 and g 2 , g 3 and g 4 , g 5 and g 6 , g 7 and g 8 complementary. In g 1 reference signal, g 4 lag reference signal D 1 T h time, g 5 lag reference signal D 2 T h time, g 8 lag reference signal( D 2 + D 3 ) T h time. g 2, g 3 、 g 6 and g 7 are the complementary signals of g 1 、 g 4 、 g 5 and g 8 with a phase difference of 180 degrees. Wherein, T h is half of the switching period, T h =0.5 / f s .

[0056] The target DAB converter is controlled by the driving signals of the 8 switches in the active full-bridge circuit, and the target DAB converter completely eliminates the backflow power, and the expression formula of the power transmission characteristic is:

[0057] ;

[0058] Wherein, L represents the inductance value, f s represents the switching frequency, Y represents the unit transmission power; if Y is greater than 0, it indicates that the power is transmitted from the primary side to the secondary side, that is, forward transmission; if Y is less than 0, it indicates that the power is transmitted from the secondary side to the primary side, that is, reverse transmission. Since the reverse transmission is the inverse process of the forward transmission, the following derivation process takes the forward transmission as an example.

[0059] The energy transmission efficiency under the condition of completely eliminating the backflow power can be expressed as:

[0060] ;

[0061] Wherein, Г Cond represents the conduction loss coefficient under the condition of completely eliminating the backflow power, and Г Sw represents the switching loss coefficient under the condition of completely eliminating the backflow power, which represents the ratio of the corresponding loss to the transmission power. The calculation formula of the voltage ratio of the inductance on both sides is:

[0062] ;

[0063] Wherein, Y represents the unit transmission power, t off,p represents the switching time of the primary side switch,t off,s the switching time of the secondary side switch, R e the equivalent parasitic resistance of the power transfer loop, the voltage ratio across the inductor, V s the secondary side voltage, V p the primary side voltage, n the transformer turns ratio.

[0064] The definition domain of forward transmission can be expressed as:

[0065] ;

[0066] It can be found by derivation that the third phase shift angle D 3 is smaller, the loss is lower, and the energy transfer efficiency is higher. Therefore, the phase shift angle at the highest efficiency under NC-TPS control can be calculated by Table I.

[0067] Table I

[0068]

[0069] The closed-loop control system using NC-TPS control can be expressed in Figure 3 . The difference between the sampling value X and the expected value X* is proportional and integrated by the PI controller to obtain the required unit transmission power Y . According to the primary side voltage steady-state value , the secondary side voltage steady-state value , and the transformer turns ratio n , the voltage ratio across the inductor is determined . Then, according to Table I, the unit transmission power Y , and the voltage ratio across the inductor , the first phase shift angle D 1 , the second phase shift angle D 2 , and the third phase shift angle D 3 are determined. Then, 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 , the driving signals of the 8 switches in the active full-bridge circuit are obtained by signal modulation, and then the target DAB converter is controlled according to the driving signals.

[0070] Because forward and reverse transmissions are slightly different, therefore Figure 3 The parameter calculation process is slightly different in some cases, and will be explained below. Figure 4 The flowchart further illustrates the parameter calculation process. During parameter calculation, the parameters are first calculated as follows: α Then determine if energy is being transferred in the reverse direction. If energy is being transferred 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 for forward energy transfer. D 1 Second phase shift angle D 2 and the third phase shift angle D 3 Then, shift the first phase angle. D 1 and the third phase shift angle D 3 The values ​​are swapped, the second phase shift angle. D 2 Taking the opposite number yields the first phase shift angle for the final reverse energy transfer. D 1 Second phase shift angle D 2 and the third phase shift angle D 3 .

[0071] Based on the same inventive concept, embodiments of the present invention also provide a three-phase shift control system for a DAB converter, the system comprising:

[0072] The acquisition module is used to acquire the high-frequency transformer in the target DAB converter. T r primary voltage steady-state value Secondary voltage steady-state value Expected value X* The sampled value fed back from the output of the target DAB converter X .

[0073] The parameter calculation module is used to process sampled values ​​via a PI controller. X and expected value X* The difference is proportionally integrated to obtain the unit transfer power used to control the energy transfer of the target DAB converter. Y According to the steady-state value of the primary voltage Secondary voltage steady-state value and transformer turns ratio n Determine the voltage ratio across the inductor .

[0074] Modulation module, used to adjust based on unit transmission powerY and inductance voltage ratio , determine the first phase shift angle D 1 , the second phase shift angle D 2 and the third phase shift angle D 3 ; 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, get the driving signal of 8 switches in active full-bridge circuit to control target DAB converter.

[0075] The above-described embodiments only express several embodiments of the present application, which are described in detail and specifically, but cannot be understood as the limitation of the scope of the patent. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which belong to the protection scope of the present application.

Claims

1. A three-phase shift control method for a DAB converter, the DAB converter including an inductor L High-frequency transformers T r And through inductors L and high frequency transformer T r Two coupled active full-bridge circuits, each including four switches; characterized in that, include: Obtain the high-frequency transformer in the target DAB converter T r primary voltage steady-state value Secondary voltage steady-state value Expected value X* The sampled value fed back from the output of the target DAB converter X ; The sampled value is processed by a PI controller. X and expected value X* The difference is proportionally integrated to obtain the unit transfer power used to control the energy transfer of the target DAB converter. Y ; Based on the steady-state value of the primary voltage Secondary voltage steady-state value and transformer turns ratio n Determine the voltage ratio across the inductor ; Based on unit transmission power Y voltage ratio across the inductor Determine the first phase shift angle D 1 Second phase shift angle D 2 and the third phase shift angle D 3 ; The determination of the first phase shift angle D 1 Second phase shift angle D 2 and the third phase shift angle D 3 Specifically, it includes: If energy is transferred in the forward direction during the operation of the target DAB converter, the domain is defined as follows: ； If energy is transferred in the reverse direction during the operation of the target DAB converter, the voltage across the inductor will be higher than that of the target DAB converter. 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 for forward energy transfer. D 1 Second phase shift angle D 2 and the third phase shift angle D 3 Then, shift the first phase angle. D 1 and the third phase shift angle D 3 The values ​​are swapped, and the second phase shift angle is... D 2 Taking the opposite number yields the first phase shift angle for reverse energy transfer. D 1 Second phase shift angle D 2 and the third phase shift angle D 3 ; Through the first phase shift angle D 1 Second phase shift angle D 2 Third phase shift angle D 3 and the switching frequency of each switch f s Signal modulation is performed to obtain the drive signals for the eight switches in the active full-bridge circuit to control the target DAB converter; The target DAB converter is controlled by drive signals from eight switches in the active full-bridge circuit. The target DAB converter completely eliminates backflow power, and the power transfer characteristics are expressed by the following formula: ； in, L Indicates the inductance value. f s Indicates the switching frequency. Y Indicates unit transmission power; if Y A value greater than 0 indicates that power is transmitted from the primary side to the secondary side, which is a forward transmission; if Y A value less than 0 indicates that power is transmitted from the secondary side to the primary side, or in the reverse direction. The formula for energy transfer efficiency is: ； Among them, Г Cond Γ represents the conduction loss coefficient when the return power is completely eliminated. Sw This represents the switching loss factor when the return power is completely eliminated. The voltage ratio across the inductor The calculation formula is: ； in, Y Indicates unit transmission power, t off,p This indicates the switching time of the primary-side switch. t off,s Indicates the switching time of the secondary switch. R e This represents the equivalent parasitic resistance of the power transmission circuit. This represents the voltage ratio across the inductor. V s Indicates the secondary voltage. V p Represents the primary voltage. n This indicates the transformer turns ratio.

2. The three-phase shift control method for a DAB converter as described in claim 1, characterized in that, In a DAB converter, an inductor will be included. L One side serves as a high-frequency transformer T r The original side will not include inductance. L One side serves as a high-frequency transformer T r The secondary side; The ratio of the number of turns in the primary winding to the number of turns in the secondary winding is used as the transformer turns ratio. n .

3. The three-phase shift control method for a DAB converter as described in claim 1, characterized in that, The first phase shift angle D 1 Second phase shift angle D 2 and the third phase shift angle D 3 Specifically: When the first phase shift angle D 1 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 Lag g 1 The unit phase shift angle, the first phase shift angle D 1 Angle equal to g 4 Lag g 1 Divide the angle by 180 degrees; second phase shift angle D 2 express g 5 Lag g 1 The unit phase shift angle; the third phase shift angle D 3 express g 8 Lag g 5 The unit phase shift angle; When the first phase shift angle D 1 Second phase shift angle D 2 and the third phase shift angle D 3 When less than 0, the first phase shift angle D 1 express g 4 Advanced g 1 The unit phase shift angle, the first phase shift angle D 1 Angle equal to g 4 Advanced g 1 Divide the angle by 180 degrees; second phase shift angle D 2 express g 5 Advanced g 1 The unit phase shift angle; the third phase shift angle D 3 express g 8 Advanced g 5 The unit phase shift angle; in, g x Indicates the individual switches of the DAB converter S x , x =1~8 corresponding drive signals.

4. The three-phase shift control method for a DAB converter as described in claim 3, characterized in that, The first phase shift angle D 1 Second phase shift angle D 2 Third phase shift angle D 3 and the switching frequency of each switch f s Signal modulation specifically includes: g 1~8 All have a duty cycle of 50% and a frequency equal to the switching frequency. f s The square wave signal; the upper and lower switching 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; by g 1 As a reference signal, g 4 Lag reference signal D 1 T h time, g 5 Lag reference signal D 2 T h time, g 8 Lag 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 signals have a phase difference of 180 degrees; in, T h It is half of the switching cycle. T h =0.5 / f s .

5. A three-phase shift control system based on the three-phase shift control method of the DAB converter according to any one of claims 1-4, characterized in that, include: The acquisition module is used to acquire the high-frequency transformer in the target DAB converter. T r primary voltage steady-state value Secondary voltage steady-state value Expected value X* The sampled value fed back from the output of the target DAB converter X ; The parameter calculation module is used to process sampled values ​​via a PI controller. X and expected value X* The difference is proportionally integrated to obtain the unit transfer power used to control the energy transfer of the target DAB converter. Y According to the steady-state value of the primary voltage Secondary voltage steady-state value and transformer turns ratio n Determine the voltage ratio across the inductor ; Modulation module, used to adjust based on unit transmission power Y voltage ratio across the inductor Determine the first phase shift angle D 1 Second phase shift angle D 2 and the third phase shift angle D 3 ; through the first phase shift angle D 1 Second phase shift angle D 2 Third phase shift angle D 3 and the switching frequency of each switch f s Signal modulation is performed to obtain the drive signals for the eight switches in the active full-bridge circuit to control the target DAB converter.

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