Backflow power optimization control method and system for dual-active bridge DC-DC converter

Abstract

The invention discloses a backflow power optimization control method and system for a dual-active bridge DC-DC converter, and the method comprises the steps: determining a transmission power range of the dual-active bridge DC-DC converter in each working mode based on a voltage conversion ratio, determining the working mode of the dual-active bridge DC-DC converter according to a real-time calculated transmission power per unit value, and carrying out the optimization control of the backflow power of the dual-active bridge DC-DC converter. And finally, inputting the current optimal phase shifting ratio combination into a PWM (Pulse Width Modulation) generator of the dual-active bridge DC-DC converter, generating a control pulse wave of a switch tube, controlling the on-off of the switch tube, and optimizing the backflow power of the dual-active bridge DC-DC converter in real time. According to the invention, the working mode of the dual-active bridge DC-DC converter can be determined in real time, power control is directly carried out on the dual-active bridge DC-DC converter, large backflow power generated in the working process of the dual-active bridge DC-DC converter is effectively reduced, the loss of a converter switch is reduced, and the response speed and the dynamic performance of a system are improved.

Description

Technical Field

[0001] The invention belongs to the field of DC-DC converters, and in particular relates to a method and system for optimizing the control of reflux power of a dual active bridge DC-DC converter. Background Art

[0002] Dual-active-bridge (DAB) DC-DC converters have the characteristics of bidirectional energy transfer, symmetrical topology, high power density, easy soft switching, electrical isolation, etc., and are widely used in power electronic transformers, new energy vehicles, distributed power generation, DC distribution networks, etc. However, under phase-shift control, especially when the voltage does not match, the dual-active-bridge DC-DC converter will generate a large amount of reflux power. In order to compensate for this reflux power, the power supply will generate more power, which will cause a large circulating current and power consumption, thereby accelerating the loss of the converter. Therefore, in order to make the converter work reliably under the condition of changing working environment, it is also particularly important to improve the dynamic performance of the converter while optimizing efficiency. Summary of the invention

[0003] The object of the present invention is to provide a dual active bridge DC-DC converter reflux power optimization control method and system in view of the above problems existing in the prior art.

[0004] To achieve the above objectives, the technical solution of the present invention is as follows:

[0005] In a first aspect, the present invention provides a dual active bridge DC-DC converter backflow power optimization control method, comprising:

[0006] S1. Determine the transmission power range of the dual active bridge DC-DC converter in each working mode based on the voltage conversion ratio;

[0007] S2. Based on the real-time calculated transmission power per unit value, determine the working mode of the dual active bridge DC-DC converter, so as to determine the current optimal shift ratio combination;

[0008] S3. Input the current optimal shift phase combination into the PWM generator of the dual active bridge DC-DC converter to generate a control pulse wave of the switch tube, control the on and off of the switch tube, and optimize the reflux power of the dual active bridge DC-DC converter in real time.

[0009] In S1, the transmission power range in each working mode includes:

[0010] The transmission power range of working mode 1 is

[0011] The transmission power range of working mode 2 is

[0012] The transmission power range of working mode 3 is

[0013] In the above formula, K is the voltage conversion ratio of the dual active bridge DC-DC converter.

[0014] The optimal shift ratio combination in S2 includes:

[0015] The optimal shift ratio combination of working mode 1 is calculated using the following formula:

[0016]

[0017] In the above formula, D 1.opt , D 2.opt are the optimal inward shift ratio and the optimal outward shift ratio of the dual active bridge DC-DC converter, respectively. K is the voltage conversion ratio of the dual active bridge DC-DC converter. is the per-unit value of the transmission power of the dual active bridge DC-DC converter;

[0018] The optimal shift ratio combination of working mode 2 is calculated using the following formula:

[0019]

[0020] The optimal shift ratio combination of working mode 3 is calculated using the following formula:

[0021]

[0022] In a second aspect, the present invention proposes a dual active bridge DC-DC converter reflux power optimization control system, including a transmission power range determination module, an optimal shift ratio combination determination module, and a reflux power optimization module;

[0023] The transmission power range determination module is used to determine the transmission power range of the dual active bridge DC-DC converter in each working mode based on the voltage conversion ratio;

[0024] The optimal shift ratio combination determination module is used to determine the working mode of the dual active bridge DC-DC converter based on the transmission power per unit value calculated in real time, so as to determine the current optimal shift ratio combination;

[0025] The reflux power optimization module is used to input the current optimal shift phase combination into the PWM generator of the dual active bridge DC-DC converter, generate a control pulse wave of the switch tube, control the on and off of the switch tube, and optimize the reflux power of the dual active bridge DC-DC converter in real time.

[0026] In the transmission power range determination module, the transmission power range in each working mode includes:

[0027] The transmission power range of working mode 1 is

[0028] The transmission power range of working mode 2 is

[0029] The transmission power range of working mode 3 is

[0030] In the above formula, K is the voltage conversion ratio of the dual active bridge DC-DC converter.

[0031] The optimal shift ratio combination in the optimal shift ratio combination determination module includes:

[0032] The optimal shift ratio combination of working mode 1 is calculated using the following formula:

[0033]

[0034] In the above formula, D 1.opt , D 2.opt are the optimal inward shift ratio and the optimal outward shift ratio of the dual active bridge DC-DC converter, respectively. K is the voltage conversion ratio of the dual active bridge DC-DC converter. is the per-unit value of the transmission power of the dual active bridge DC-DC converter;

[0035] The optimal shift ratio combination of working mode 2 is calculated using the following formula:

[0036]

[0037] The optimal shift ratio combination of working mode 3 is calculated using the following formula:

[0038]

[0039] In a third aspect, the present invention provides a dual active bridge DC-DC converter backflow power optimization control device, comprising a processor and a memory;

[0040] The memory is used to store computer program code and transmit the computer program code to the processor;

[0041] The processor is used to execute the aforementioned dual active bridge DC-DC converter backflow power optimization control method according to the instructions in the computer program code.

[0042] In a fourth aspect, the present invention provides a computer storage medium having a computer program stored thereon;

[0043] When the computer program is executed by the processor, the steps of the aforementioned dual active bridge DC-DC converter backflow power optimization control method are implemented.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The present invention proposes a dual active bridge DC-DC converter reflux power optimization control method and system. The method first determines the transmission power range of the dual active bridge DC-DC converter in each working mode based on the voltage conversion ratio, and then determines the working mode of the dual active bridge DC-DC converter according to the transmission power per unit value calculated in real time, thereby determining the current optimal shift ratio combination, and finally inputting the current optimal shift ratio combination into the PWM generator of the dual active bridge DC-DC converter to generate a control pulse wave of the switch tube, control the on and off of the switch tube, and optimize the reflux power of the dual active bridge DC-DC converter in real time. The method can determine the working mode of the dual active bridge DC-DC converter in real time, directly control the power of the converter, effectively reduce the large reflux power generated by the dual active bridge DC-DC converter during operation, reduce the loss of the converter switch, and speed up the response speed and dynamic performance of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is the working waveform diagram of Mode 1 of the present invention.

[0047] Figure 2 This is the working waveform diagram of Mode 3 of the present invention.

[0048] Figure 3 This is a topological diagram of the dual active bridge DC-DC converter described in Example 1.

[0049] Figure 4 This is a power optimization control block diagram of the dual active bridge DC-DC converter described in Example 1.

[0050] Figure 5 The figure is an overall flow chart of the method of the present invention.

[0051] Figure 6 This is a comparison chart of the efficiency characteristics described in Example 1.

[0052] Figure 7 This is a reflux power waveform diagram of Example 1 without adopting this solution.

[0053] Figure 8 This is a reflux power waveform diagram of the present solution as described in Example 1.

[0054] Fig. 9 This is a load mutation waveform diagram described in Example 1 without adopting this solution.

[0055] Fig.10 This is a load mutation waveform diagram of the present solution as described in Example 1.

[0056] Fig.11 This is a voltage drop waveform diagram in Example 1 without using this solution.

[0057] Fig.12 This is a voltage drop waveform diagram using the solution described in Example 1.

[0058] Fig.13 The structure diagram of the system of the present invention is shown in FIG.

[0059] Fig.14 This is a structural diagram of the device described in Example 3. DETAILED DESCRIPTION

[0060] The present invention is further described in detail below in conjunction with specific implementations and drawings.

[0061] The present invention proposes a dual-active bridge DC-DC converter reflux power optimization control method and system, collects relevant data of the dual-active bridge DC-DC converter, takes minimizing the reflux power of the dual-active bridge DC-DC converter as the goal, establishes an optimization control model of the dual-active bridge DC-DC converter in each working mode, and divides the transmission power of the dual-active bridge DC-DC converter into segments by solving the optimization control model of the dual-active bridge DC-DC converter, determines the transmission power range of the dual-active bridge DC-DC converter in each working mode, selects and switches the working mode according to the transmission power range where the real-time transmission power per unit value is located, obtains the optimal shift phase combination of the corresponding working mode, and inputs it into a PWM generator to generate a control pulse wave of a switch tube, controls the on and off of the switch tube, optimizes the reflux power of the dual-active bridge DC-DC converter in real time, effectively reduces the large reflux power generated by the dual-active bridge DC-DC converter in the working process, reduces the switching loss, improves the system efficiency and realizes the rapid response of the system.

[0062] The transmission power range in each working mode of the present invention can be determined in the following manner:

[0063] 1. According to the size relationship between the internal and external shifts of the dual active bridge DC-DC converter, the dual active bridge is initially divided into two working modes. With the goal of minimizing the reflux power of the dual active bridge DC-DC converter, an optimization control model for each working mode of the dual active bridge DC-DC converter is established;

[0064] According to the KKT condition method, with the goal of minimizing the return power, the return power per unit value is the optimization function, the transmission power per unit value is the equality constraint, and the zero voltage turn-on condition is the inequality constraint, the optimization control model of each working mode of the dual active bridge DC-DC converter is established;

[0065] The standard form of the KKT conditional method is:

[0066] min F(x);

[0067]

[0068] In the above formula, F(x) is the optimization function of the KKT conditional method, h i (x) is the i-th equality constraint, g j (x) is the jth inequality constraint;

[0069] The general expression of the objective function under KKT conditions is:

[0070]

[0071] In the above formula, L is the general expression of the objective function under KKT conditions, λ i h i (x) The corresponding constraint coefficient, μ j g j (x) The corresponding constraint coefficient;

[0072] When the magnitude relationship between the inner and outer shift phases of the dual active bridge DC-DC converter satisfies 0≤D1≤D2≤1, the dual active bridge DC-DC converter operates in mode 1. At this time:

[0073] The return power per unit value is calculated using the following formula:

[0074]

[0075] In the above formula, is the return power per unit value of the dual active bridge DC-DC converter, K is the voltage conversion ratio of the dual active bridge DC-DC converter, D1 and D2 are the inward shift phase ratio and outward shift phase ratio of the dual active bridge DC-DC converter respectively;

[0076] The transmission power per unit value is calculated using the following formula:

[0077]

[0078] In the above formula, is the per-unit value of the transmission power of the dual active bridge DC-DC converter;

[0079] Zero voltage turn-on condition, the inductor current satisfies i L (t1)≤0,i L (t3)≥0, calculated using the following formula:

[0080]

[0081] Select working mode 1 as Figure 1The working waveform shown is used as a representative, and the optimization control model of working mode 1 is established as follows:

[0082]

[0083] In the above formula, L1 is the objective function of the optimization control model under working mode 1, λ1 is the coefficient of the equality constraint corresponding to the per-unit value of the transmission power under working mode 1, μ1, μ2, μ3, μ4, μ5, μ6, and μ7 are the coefficients of the inequality constraint corresponding to the zero voltage switching condition respectively;

[0084] When the magnitude relationship between the inner and outer shift phases of the dual active bridge DC-DC converter satisfies 0≤D2≤D1≤1, the dual active bridge DC-DC converter operates in mode 3. At this time:

[0085] The return power per unit value is calculated using the following formula:

[0086]

[0087] The transmission power per unit value is calculated using the following formula:

[0088]

[0089] Zero voltage turn-on condition, the inductor current satisfies i L (t1)≤0,i L (t2)≥0, calculated using the following formula:

[0090]

[0091] Select working mode 3 as follows Figure 2 The working waveform shown is used as a representative, and the following optimization control model of working mode 3 is established:

[0092]

[0093] In the above formula, L2 is the objective function of the optimization control model under working mode 3, λ2 is the coefficient of the equality constraint corresponding to the per-unit value of the transmission power under working mode 3, and μ1, μ2, μ3, μ4, and μ5 are the coefficients of the inequality constraint corresponding to the zero voltage switching condition.

[0094] 2. By solving the optimization control model of the two working modes of the dual active bridge DC-DC converter, the corresponding transmission power range and minimum return power value in each working mode are determined;

[0095] By solving the optimization control model of working mode 1, the optimal shift phase combination in this mode is obtained as follows:

[0096]

[0097] In the above formula, D 1.opt , D 2.opt are the optimal inward shift ratio and the optimal outward shift ratio of the dual active bridge DC-DC converter, respectively. K is the voltage conversion ratio of the dual active bridge DC-DC converter. is the per-unit value of the transmission power of the dual active bridge DC-DC converter;

[0098] According to the optimal shift ratio combination under working mode 1, which satisfies the relationship between the inner and outer shift ratios of 0≤D1≤D2≤1, the transmission power range under working mode 1 is:

[0099] The minimum return power within this transmission power range is calculated using the following formula:

[0100]

[0101] In the above formula, is the minimum return power of the dual active bridge DC-DC converter;

[0102] By solving the optimization control model of working mode 3, the optimal shift phase combination in this mode is obtained as follows:

[0103]

[0104] According to the optimal shift ratio combination under working mode 3, which satisfies the inner and outer shift ratio size relationship of 0≤D2≤D1≤1, the transmission power range of working mode 3 is obtained as follows:

[0105] The minimum return power within this transmission power range is calculated using the following formula:

[0106]

[0107] According to the transmission power range and minimum return power of the dual active bridge DC-DC converter in the two working modes, the minimum return power is proportional to the transmission power per unit value in the corresponding mode, that is, the minimum return power increases monotonically with the transmission power per unit value. Therefore, there is a return power intersection point, that is, the working mode 2 of the dual active bridge DC-DC converter, which makes the return power continuous.

[0108] The crossover point of the return power is calculated using the following formula:

[0109]

[0110] The transmission power range of working mode 2 is

[0111] At this time, the optimal solution of the phase shift and the minimum return power are calculated using the following formulas:

[0112]

[0113] Embodiment 1:

[0114] The topology of the dual active bridge DC-DC converter of this embodiment is as follows: Figure 3 As shown, it includes input side voltage V1, input side support capacitor C1, output side voltage V2, output side support capacitor C2, primary side full bridge circuit H1, secondary side full bridge circuit H2, u AB 、u CD They are the AC side voltages of bridge H1 and bridge H2, high-frequency transformer T, with a transformation ratio of n:1, and transformer leakage inductance L, u L is the leakage inductance voltage, i L is the inductor current; wherein, the primary side full bridge circuit is composed of four groups of switch tubes and four groups of diodes connected in anti-parallel therewith, namely, the first switch tube S1 and the first anti-parallel diode D1, the second switch tube S2 and the second anti-parallel diode D2, the third switch tube S3 and the third anti-parallel diode D3, the fourth switch tube S4 and the fourth anti-parallel diode D4; the secondary side full bridge circuit is composed of four groups of switch tubes and four groups of diodes connected in anti-parallel therewith, namely, the fifth switch tube S5 and the fifth anti-parallel diode D5, the sixth switch tube S6 and the sixth anti-parallel diode S6, the seventh switch tube S7 and the seventh anti-parallel diode D7, the eighth switch tube S8 and the eighth anti-parallel diode D8, the control block diagram of the power optimization of the dual active bridge DC-DC converter is as shown in Figure 4 As shown, the proportional coefficient of the PI controller is 0.5 and the integral coefficient is 50.

[0115] like Figure 5 As shown, a dual active bridge DC-DC converter backflow power optimization control method is performed in the following steps:

[0116] 1. Construct the control parameter table of each working mode of the dual active bridge DC-DC converter, as shown in Table 1;

[0117] Table 1 Control parameters of each working mode of dual active bridge DC-DC converter

[0118]

[0119] 2. Use the following formula to calculate the voltage conversion ratio, and refer to Table 1 to determine the transmission power range of the dual active bridge DC-DC converter in each working mode;

[0120]

[0121] In the above formula, K is the voltage conversion ratio, V1 and V2 are the input voltage and output voltage respectively, and n is the transformation ratio of the high-frequency transformer T.

[0122] 3. Based on the real-time calculated transmission power per unit value, refer to Table 1 to select and switch the working mode, determine the working mode of the dual active bridge DC-DC converter, and thus determine the current optimal shift ratio combination;

[0123] The following formula is used to calculate the per-unit value of the dual active bridge DC-DC converter transmission power in real time:

[0124]

[0125] p=V 2ref (I v +I2);

[0126]

[0127] In the above formula, is the real-time transmission power per unit value of the dual active bridge DC-DC converter, p is the real-time transmission power, P N is the power reference value, V 2ref is the reference voltage, I v is the output current compensation amount, I2 is the output current, L is the sum of the inductance of the transformer leakage inductance L, f s The switching frequency set for the converter.

[0128] 4. Input the current optimal phase shift ratio combination into the PWM generator of the dual active bridge DC-DC converter. The internal phase shift ratio determines the phase shift angle between the switches on the primary side of the dual active bridge DC-DC converter. The external phase shift ratio determines the phase shift angle between the primary and secondary sides of the converter. The on and off of the switches are controlled. The power of the dual active bridge DC-DC converter is directly controlled to speed up its response speed and dynamic performance, and the reflux power of the dual active bridge DC-DC converter is optimized in real time.

[0129] In order to verify the effectiveness of this scheme, the main circuit parameters of the dual active bridge DC-DC converter are set as shown in Table 2;

[0130] Table 2 Main circuit parameters are shown in Table

[0131] parameter Numeric parameter Numeric <![CDATA[Input voltage V1 / V]]> 50 <![CDATA[Reference output voltage V2 / V]]> 40 Transformer ratio n 1 Transformer leakage inductance L / μH 22 <![CDATA[Primary side buffer capacitor C1 / μF]]> 1360 <![CDATA[Secondary side support capacitor C2 / μF]]> 1360 <![CDATA[Switching frequency f5 / kHz]]> 20 - -

[0132] Through simulation verification, the efficiency characteristics of this scheme and the SPS control method are compared. Figure 6 As shown in the figure, it can be seen that the conversion efficiency of the dual active bridge DC-DC converter using this solution is improved, especially in the low power range, the improvement effect is significant;

[0133] When this solution is not adopted, the return power waveform of the dual active bridge DC-DC converter is as follows: Figure 7 As shown, the converter's reflux power waveform when this solution is adopted is as follows Figure 8 As shown, Figure 7 The circled part in the figure is the reflux power generated by the converter, which is an important factor affecting the converter efficiency. It can be seen from the figure that the reflux power under this scheme is significantly smaller than the reflux power when this scheme is not adopted;

[0134] At 0.1s, the load resistance R is set to drop from 10Ω to 5Ω. The waveform of the dual active bridge DC-DC converter without this solution is as follows: Fig. 9 As shown in Figure 1, the output voltage also drops when the load suddenly decreases, and it takes a long time to recover to a stable state. The waveform of the converter using this solution is as follows: Fig.10 As shown in the figure, the output voltage remains almost unchanged when the load suddenly decreases, and quickly returns to stability;

[0135] At 0.1s, the reference output voltage is set to drop from 40V to 30V. The waveform of the dual active bridge DC-DC converter without this solution is as follows: Fig.11 As shown in the figure, the converter has a large overshoot when the output reference voltage suddenly decreases, and it takes a long time to recover to stability. The waveform of the converter using this solution is as follows Fig.12 As shown in the figure, the converter has a small overshoot when the output reference voltage suddenly decreases, and can quickly return to stability.

[0136] Embodiment 2:

[0137] like Fig.13 As shown, a dual active bridge DC-DC converter backflow power optimization control system includes a transmission power range determination module, an optimal shift ratio combination determination module, and a backflow power optimization module;

[0138] The transmission power range determination module is used to determine the transmission power range of the dual active bridge DC-DC converter in each working mode based on the voltage conversion ratio;

[0139] The optimal shift ratio combination determination module is used to determine the working mode of the dual active bridge DC-DC converter based on the transmission power per unit value calculated in real time, so as to determine the current optimal shift ratio combination;

[0140] The reflux power optimization module is used to input the current optimal shift phase combination into the PWM generator of the dual active bridge DC-DC converter, generate a control pulse wave of the switch tube, control the on and off of the switch tube, and optimize the reflux power of the dual active bridge DC-DC converter in real time.

[0141] In the transmission power range determination module, the transmission power range in each working mode includes:

[0142] The transmission power range of working mode 1 is

[0143] The transmission power range of working mode 2 is

[0144] The transmission power range of working mode 3 is

[0145] In the above formula, K is the voltage conversion ratio of the dual active bridge DC-DC converter.

[0146] The optimal shift ratio combination in the optimal shift ratio combination determination module includes:

[0147] The optimal shift ratio combination of working mode 1 is calculated using the following formula:

[0148]

[0149] In the above formula, D 1.opt , D 2.opt are the optimal inward shift ratio and the optimal outward shift ratio of the dual active bridge DC-DC converter, respectively. K is the voltage conversion ratio of the dual active bridge DC-DC converter. is the per-unit value of the transmission power of the dual active bridge DC-DC converter;

[0150] The optimal shift ratio combination of working mode 2 is calculated using the following formula:

[0151]

[0152] The optimal shift ratio combination of working mode 3 is calculated using the following formula:

[0153]

[0154] Embodiment 3:

[0155] like Fig.14 As shown, a dual active bridge DC-DC converter backflow power optimization control device includes a processor and a memory;

[0156] The memory is used to store computer program code and transmit the computer program code to the processor;

[0157] The processor is used to execute the dual active bridge DC-DC converter backflow power optimization control method described in Example 1 according to the instructions in the computer program code.

[0158] Embodiment 4:

[0159] A computer storage medium having a computer program stored thereon;

[0160] When the computer program is executed by the processor, the steps of the dual active bridge DC-DC converter backflow power optimization control method described in this solution are implemented.

Claims

1. A dual active bridge DC-DC converter backflow power optimization control method, characterized in that: The method comprises: S1. Determine the transmission power range of the dual active bridge DC-DC converter in each working mode based on the voltage conversion ratio; S2. Based on the real-time calculated transmission power per unit value, determine the working mode of the dual active bridge DC-DC converter, so as to determine the current optimal shift ratio combination; S3. Input the current optimal shift phase combination into the PWM generator of the dual active bridge DC-DC converter to generate a control pulse wave of the switch tube, control the on and off of the switch tube, and optimize the reflux power of the dual active bridge DC-DC converter in real time.

2. The method for optimizing the control of the reflux power of a dual active bridge DC-DC converter according to claim 1, characterized in that: In S1, the transmission power range in each working mode includes: The transmission power range of working mode 1 is The transmission power range of working mode 2 is The transmission power range of working mode 3 is In the above formula, K is the voltage conversion ratio of the dual active bridge DC-DC converter.

3. The method for optimizing the control of the reflux power of a dual active bridge DC-DC converter according to claim 1, characterized in that: The optimal shift ratio combination in S2 includes: The optimal shift ratio combination of working mode 1 is calculated using the following formula: In the above formula, D 1.opt , D 2.opt are the optimal inward shift ratio and the optimal outward shift ratio of the dual active bridge DC-DC converter, respectively. K is the voltage conversion ratio of the dual active bridge DC-DC converter. is the per-unit value of the transmission power of the dual active bridge DC-DC converter; The optimal shift ratio combination of working mode 2 is calculated using the following formula: The optimal shift ratio combination of working mode 3 is calculated using the following formula:

4. A dual active bridge DC-DC converter backflow power optimization control system, characterized in that: The system includes a transmission power range determination module, an optimal shift ratio combination determination module, and a return power optimization module; The transmission power range determination module is used to determine the transmission power range of the dual active bridge DC-DC converter in each working mode based on the voltage conversion ratio; The optimal shift ratio combination determination module is used to determine the working mode of the dual active bridge DC-DC converter based on the transmission power per unit value calculated in real time, so as to determine the current optimal shift ratio combination; The reflux power optimization module is used to input the current optimal shift phase combination into the PWM generator of the dual active bridge DC-DC converter, generate a control pulse wave of the switch tube, control the on and off of the switch tube, and optimize the reflux power of the dual active bridge DC-DC converter in real time.

5. A dual active bridge DC-DC converter backflow power optimization control system according to claim 4, characterized in that: In the transmission power range determination module, the transmission power range in each working mode includes: The transmission power range of working mode 1 is The transmission power range of working mode 2 is The transmission power range of working mode 3 is In the above formula, K is the voltage conversion ratio of the dual active bridge DC-DC converter.

6. A dual active bridge DC-DC converter backflow power optimization control system according to claim 4, characterized in that: The optimal shift ratio combination in the optimal shift ratio combination determination module includes: The optimal shift ratio combination of working mode 1 is calculated using the following formula: In the above formula, D 1.opt , D 2.opt are the optimal inward shift ratio and the optimal outward shift ratio of the dual active bridge DC-DC converter, respectively. K is the voltage conversion ratio of the dual active bridge DC-DC converter. is the per-unit value of the transmission power of the dual active bridge DC-DC converter; The optimal shift ratio combination of working mode 2 is calculated using the following formula: The optimal shift ratio combination of working mode 3 is calculated using the following formula:

7. A dual active bridge DC-DC converter backflow power optimization control device, characterized in that: including a processor and a memory; The memory is used to store computer program code and transmit the computer program code to the processor; The processor is used to execute the dual active bridge DC-DC converter backflow power optimization control method according to any one of claims 1 to 3 according to the instructions in the computer program code.

8. A computer storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of a dual active bridge DC-DC converter backflow power optimization control method according to any one of claims 1 to 3 are implemented.

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