Multi-objective parameter optimization design method for three-phase bidirectional AC / DC converter based on dual active full-bridge

Abstract

The invention discloses a multi-objective parameter optimization design method based on a dual-active full-bridge three-phase bidirectional AC / DC converter, wherein the energy transmission inductance value, high-frequency transformer turns ratio and phase shift ratio are selected as three parameters to be optimized and determined as optimization objects; the ratio of reactive power to active power of the high-frequency transformer, the effective value of the energy transmission inductance current and the peak-to-peak value of the current are selected as optimization objects, and the expressions of each optimization object and the optimization object are calculated; the constraints between the energy transmission inductance value, the high-frequency transformer turns ratio and the phase shift ratio are determined; the expressions of each optimization object are synthesized into a single-objective optimization function according to the weight coefficient; a method combining a genetic algorithm and a chaotic search is used to perform iterative optimization, obtain several groups of optimal solutions, and then a loss analysis is performed according to the actual hardware circuit to select the energy transmission inductance value, the high-frequency transformer turns ratio and the phase shift ratio when the circuit loss is minimized. The optimization algorithm of the invention is simple and the optimization effect is good.

Description

Technical Field

[0001] The invention relates to a three-phase bidirectional AC / DC converter technology, and in particular to a multi-objective parameter optimization design method based on a dual active full-bridge three-phase bidirectional AC / DC converter. Background Art

[0002] In recent years, the number of renewable energy systems used to solve environmental problems has continued to increase. The power generation of renewable energy systems such as solar power generation and wind power generation fluctuates greatly, which often causes instability in the power grid. In order to avoid this effect, a battery energy storage system is used to adjust the power and compensate for the fluctuations in the power grid. The connection between the battery energy storage system and the power grid requires a bidirectional AC / DC converter, which needs to achieve high efficiency and high power density while ensuring the quality of power. The dual-active full-bridge three-phase bidirectional AC / DC converter uses a high-frequency transformer to achieve energy transmission. Compared with the two-stage structure, it has fewer DC bus capacitors and energy storage inductors, which greatly reduces the volume and weight.

[0003] Most scholars have studied the circuit structure and control strategy of dual-active full-bridge three-phase bidirectional AC / DC converters. Although certain results have been achieved, the interaction and mutual influence between the main circuit parameters and the control parameters are often not taken into account when analyzing the circuit performance indicators. If only a single performance indicator in the circuit is optimized and analyzed, the designed parameters will be locally optimal to a certain extent, and the stability of the entire system cannot be guaranteed. Therefore, it is of great significance to conduct multi-objective analysis on the converter and study the optimization methods of the main circuit parameters and control parameters. Summary of the invention

[0004] The object of the present invention is to provide a multi-objective parameter optimization design method based on a dual active full-bridge three-phase bidirectional AC / DC converter to improve the efficiency and power density of the converter.

[0005] The technical solution to achieve the purpose of the present invention is: a multi-objective parameter optimization design method based on a dual active full-bridge three-phase bidirectional AC / DC converter, wherein the dual active full-bridge three-phase bidirectional AC / DC converter includes an AC side filter inductor 1, an AC side filter capacitor 2, an AC side three-phase bridge arm 3, an energy transmission inductor L, and a high-frequency transformer T r , DC side full bridge circuit 4, DC side filter capacitor C dc , DC side filter inductor L dc The AC side filter inductor 1 includes a phase A inductor L a 、B phase inductance L b 、C phase inductance L c The AC side filter capacitor 2 includes a phase A capacitor C a 、B phase capacitor C b 、C phase capacitance C cThe three-phase bridge arm 3 on the AC side includes three bridge arms, each bridge arm is composed of four switch tubes in series, wherein the first bridge arm is composed of the first switch tube S a1 , the second switch tube S a2 , the third switch tube S a3 , the fourth switch tube S a4 The second bridge arm is composed of the fifth switch tube S b1 , the sixth switch tube S b2 , the seventh switch tube S b3 , the eighth switch tube S b4 The third bridge arm consists of the ninth switch tube S c1 , the tenth switch tube S c2 , Eleventh switch tube S c3 , the twelfth switch tube S c4 The DC side full bridge circuit 4 comprises two bridge arms, each bridge arm is composed of two switch tubes in series, wherein the fourth bridge arm is composed of the thirteenth switch tube S 1 , the fourteenth switch tube S 2 The fifth bridge arm is composed of the fifteenth switch tube S 3 , the sixteenth switch tube S 4 composition;

[0006] A phase capacitor C a 、B phase capacitor C b 、C phase capacitance C c One end of the first switch tube S a1 The emitter of the second switch tube S a2 The emitter of the third switch tube S a3 The emitter of the fourth switch tube S a4 The emitter of the second switch tube S a2 The collector of the third switch tube S a3 The collector of is connected to the A phase inductor L a One end is connected to the A phase capacitor C a The other end of the fifth switch tube S b1 The emitter of the sixth switch tube S b2 The emitter of the seventh switch tube S b3 The emitter of the eighth switch tube S b4 The emitter of the sixth switch tube S b2 The collector of the seventh switch tube S b3 The collector of the connection point is connected to the B phase inductor L b One end is connected to the B phase capacitor C b The other end of the ninth switch tube S c1 The emitter of the tenth switch tube S c2 The emitter of the eleventh switch tube Sc3 The emitter of the twelfth switch tube S c4 The emitter of the tenth switch tube S c2 The collector of the eleventh switch tube S c3 The collector of is connected to the C phase inductor L c One end is connected to the C phase capacitor C c The other end of the A phase inductor L a 、B phase inductance L b 、C phase inductance L c The other end of each of the first switch tube S is connected to the AC power supply; a1 The collector of the fifth switch tube S b1 The collector of the ninth switch tube S c1 The collector of the fourth switch tube S is connected, and the connection point serves as the first common terminal; a4 The collector of the eighth switch tube S b4 The collector of the twelfth switch tube S c4 The collector of is connected to the connection point as the second common terminal;

[0007] Thirteenth switch tube S 1 The emitter of the fourteenth switch tube S 2 The collector of the fifteenth switch tube S is connected to the third common port; 3 The emitter of the sixteenth switch tube S 4 The collector of the thirteenth switch tube S is connected to the collector of the thirteenth switch tube S, and the connection point is used as the fourth common port; 1 The collector of the fifteenth switch tube S 3 The collector of the DC side filter capacitor C dc The positive end of the fourteenth switch tube S 2 The emitter of the sixteenth switch tube S 4 The emitter of the capacitor is connected to the DC side filter capacitor C dc The negative end is connected to the DC side filter capacitor C dc The positive terminal and the DC side filter inductor L dc One end of the DC side filter inductor L dc The other end is connected to the DC power supply;

[0008] One end of the energy transfer inductor L is connected to the first common port, and the high frequency transformer T r The primary winding is respectively connected to the other end of the energy transfer inductor L and the second common port, and the secondary winding is respectively connected to the third common port and the fourth common port;

[0009] The multi-objective parameter optimization design method based on dual active full-bridge three-phase bidirectional AC / DC converter has the following steps:

[0010] Step 1, analyzing the dual-line voltage modulation process of the dual-active full-bridge three-phase bidirectional AC / DC converter, selecting the energy transfer inductance L, the high-frequency transformer turns ratio n and the phase shift ratio x as the three parameters to be optimized, and determining them as the optimization objects;

[0011] Step 2, analyzing the performance indicators related to the power conversion efficiency, selecting the ratio of reactive power to active power of the high-frequency transformer, the effective value of the energy transmission inductor current and the peak-to-peak value of the current as the optimization targets, and calculating the expressions of each optimization target and the optimization object;

[0012] Step 3, determining the constraints between the energy transfer inductance L, the high-frequency transformer turns ratio n and the phase shift ratio x;

[0013] Step 4, synthesizing the expressions of various optimization objectives into a single-objective optimization function according to the weight coefficients;

[0014] Step 5, change the weight coefficient according to a certain step size, and use a method combining genetic algorithm and chaotic search to iteratively optimize the energy transmission inductance L, the high-frequency transformer turns ratio n and the phase shift ratio x to obtain several groups of optimal solutions, and then perform loss analysis based on the actual hardware circuit to select the energy transmission inductance L, the high-frequency transformer turns ratio n and the phase shift ratio x when the circuit loss is minimized.

[0015] Further, in step 2, the performance indicators related to the power conversion efficiency are analyzed, the ratio of reactive power to active power of the high-frequency transformer, the effective value of the energy transmission inductor current and the peak-to-peak value of the current are selected as optimization targets, and the expressions of each optimization target and the optimization object are calculated, which are specifically:

[0016] 4)i Lrms The effective value expression of the energy transfer inductor current is as follows:

[0017]

[0018] Among them, T is the power frequency period, x is the phase shift ratio, d 1 is the first duty cycle, d 2 is the second duty cycle, e M is the line voltage with the largest amplitude among the three-phase line voltages, e m is the line voltage with the second largest amplitude among the three-phase line voltages, n is the turns ratio of the high-frequency transformer, V dc is the DC power supply voltage, f s is the switching frequency, L is the energy transfer inductance;

[0019] 5) Q / P is the ratio of reactive power to active power of high-frequency transformer, as shown in formula (2):

[0020]

[0021] Among them, S is the apparent power transmitted by the high-frequency transformer, P is the active power transmitted by the high-frequency transformer, Q is the reactive power transmitted by the high-frequency transformer, and u prms is the effective value of the output voltage on the AC side;

[0022] 6)i Lmax The peak-to-peak value of the energy transfer inductor current is expressed as follows:

[0023]

[0024] Among them, T s is the switching cycle.

[0025] Further, in step 3, the constraints between the energy transmission inductance L, the high-frequency transformer turns ratio n and the phase shift ratio x are determined as follows:

[0026] The first constraint is the limit range of the modulation coefficient M, as shown in the following formula (4):

[0027]

[0028] Among them, L is the energy transmission inductance, P is the active power transmitted by the high-frequency transformer, T s is the switching period, n is the high-frequency transformer turns ratio, V dc is the DC power supply voltage, x is the phase shift ratio, d 1 is the first duty cycle, d 2 is the second duty cycle, e M is the line voltage with the largest amplitude among the three-phase line voltages, e m It is the line voltage with the second largest amplitude among the three-phase line voltages;

[0029] The second constraint condition is the range of the phase shift ratio x: in rectification mode, the value range of the phase shift ratio x is 0≤x≤1; in inverter mode, the value range of the phase shift ratio x is -1≤x<0.

[0030] Furthermore, in step 4, the expressions of the various optimization objectives are synthesized into a single objective optimization function F according to the weight coefficients, as shown in formula (5):

[0031]

[0032] Among them, λ 1 , 2 and λ 3 is the weight coefficient, λ 1 +λ 2 +λ 3 =1,i Lrms_maxis the maximum effective value of the energy transfer inductor current within the constraints, Q / P is the ratio of the reactive power to the active power of the high-frequency transformer, (Q / P) max is the maximum value of the ratio of reactive power to active power of the high-frequency transformer within the constraints, i Lmax_max is the maximum value of the peak-to-peak value of the energy transfer inductor current within the constraints.

[0033] Further, in step 5, the weight coefficient is changed according to a certain step length, and a method combining genetic algorithm and chaotic search is used to iteratively optimize the energy transmission inductance value L, the high-frequency transformer turn ratio n and the phase shift proportion x to obtain several groups of optimal solutions, and then a loss analysis is performed according to the actual hardware circuit to select the energy transmission inductance value L, the high-frequency transformer turn ratio n and the phase shift proportion x when the circuit loss is minimized. The specific process of iterative optimization by combining genetic algorithm and chaotic search is as follows:

[0034] S1: Initialize the population and parameters: The population is initialized using real number coding, the parent individual y i,j It is obtained by the following formula:

[0035]

[0036] Wherein, j is 1 to 3, representing the energy transmission inductance L, high-frequency transformer turns ratio n and phase shift ratio x of the three optimization objects, pop is the population size of each optimization object, i is the parent individual number of each optimization object, rand is a random number in the range of [0, 1], y jmax and jmin are the upper and lower bounds of the value range of each optimization object, respectively. The value range of the optimization object is determined by the voltage stress and current stress of the switch tube, energy transfer inductor and high-frequency transformer; the parameters include algorithm parameters: maximum number of iterations of genetic algorithm, maximum number of iterations of chaos search, population size, crossover probability and mutation probability; specification parameters of dual active full-bridge three-phase bidirectional AC / DC converter: three-phase sinusoidal voltage e of AC side power supply a 、e b 、e c , DC side power supply voltage V dc , transmission power P and switching frequency f s ;

[0037] S2: Calculate individual fitness: Take the inverse of the single-objective optimization function F as the fitness function fitness, and under the constraints of the three optimization objects, convert y i,j Substitute into the calculation;

[0038] S3: After selection, crossover and mutation, a new generation is obtained: several y with large fitness values ​​are selected i,jThe combination of y is directly copied to the next generation, and the remaining y is randomly sampled. i,j Perform selection operation;

[0039] Select a certain crossover probability to select individuals from the new population for crossover, and use the following linear combination crossover method to obtain individual y′ i,j :

[0040]

[0041] The individuals that need to be mutated are randomly determined among the individuals after selection and crossover, and the positions that need to be mutated are randomly determined, and a certain mutation probability is selected for mutation, as shown in the following formula (8):

[0042]

[0043] Among them, rand' is a random number in the range of [0, 1], MutShrink is the range of compressed mutation, g is the number of iterations of the current genetic algorithm, G max is the maximum number of iterations of the genetic algorithm, Y i,j The offspring individuals produced after selection and crossover;

[0044] S4: Determine whether the genetic algorithm is terminated: If the maximum number of iterations of the genetic algorithm is reached, stop the genetic algorithm, and select three sets of energy transmission inductance values ​​L, high-frequency transformer turns ratio n, and phase shift ratio x with large fitness values ​​for chaotic search; otherwise, return to S2;

[0045] S5: Perform chaotic search on the three groups of parameters with large fitness values: The better individuals Y after genetic algorithm i,j Mapped to the Logistic equation domain [0, 1], the chaotic variable Z is obtained by the following formula i,j :

[0046]

[0047] S6: Generate chaotic variables: Use Logistic mapping to generate chaotic variables, as shown in the following formula (10):

[0048]

[0049] Among them, μ is the control parameter of Logistic, and size is the population size of each optimization object participating in chaotic search;

[0050] S7: Map the changing range of the chaotic variable to the value range of the optimization object, as shown in formula (11):

[0051] Y′ i,j =y j min +z i,j(y j max -y j min ) (11)

[0052] S8: Update the value range of the optimization object: i,j As the approximate value of the global optimum, the value range of each optimization object is narrowed with this value as the center, as shown in the following formula (12):

[0053]

[0054] Where k is the number of iterations of the current chaos search. If y' j min <y j min , then y' j min =y j min ; if y' j max >y j max , then y' j max =y j max . y' j max ,y' j min They are the upper and lower bounds of the value range of each optimization object after update;

[0055] S9: Iterative search using chaotic variables: Let Y′ i,j (k) = Y′ i,j , calculate the fitness value fitness(k). fitness * =fitnesss(Y′ i,j (0)), if fitnesss * <fitnesss(Y′ i,j (k)), then fitness * =fitnesss(y i,j (k)); otherwise, fitnesss * is the maximum fitness value, The parameter value that maximizes the fitness value;

[0056] S10: Determine whether the chaotic search is terminated: if the maximum number of chaotic search iterations has not been reached, return to S5; otherwise, end and obtain a set of energy transfer inductance L, high-frequency transformer turns ratio n and phase shift ratio x values ​​that enable the dual-active full-bridge three-phase bidirectional AC / DC converter to operate best under a certain weight coefficient.

[0057] A multi-objective parameter optimization design system based on a dual active full-bridge three-phase bidirectional AC / DC converter implements a multi-objective parameter optimization design based on a dual active full-bridge three-phase bidirectional AC / DC converter based on the multi-objective parameter optimization design method based on a dual active full-bridge three-phase bidirectional AC / DC converter.

[0058] A computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, based on the multi-objective parameter optimization design method based on a dual-active full-bridge three-phase bidirectional AC / DC converter, a multi-objective parameter optimization design based on a dual-active full-bridge three-phase bidirectional AC / DC converter is realized.

[0059] A computer-readable storage medium stores a computer program. When the computer program is executed by a processor, based on the multi-objective parameter optimization design method based on a dual-active full-bridge three-phase bidirectional AC / DC converter, a multi-objective parameter optimization design based on a dual-active full-bridge three-phase bidirectional AC / DC converter is implemented.

[0060] Compared with the prior art, the present invention has the following significant advantages: it comprehensively considers the relationship between the three optimization objects, namely, the energy transmission inductance L, the high-frequency transformer turns ratio n, and the phase shift ratio x, and adopts a method combining genetic algorithm and chaotic search to achieve the optimization of the three optimization objects, which has the characteristics of simple optimization algorithm and good optimization effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 It is a flow chart of a multi-objective parameter optimization design method based on a dual active full-bridge three-phase bidirectional AC / DC converter.

[0062] Figure 2 It is the topology diagram of a dual active full-bridge three-phase bidirectional AC / DC converter.

[0063] Figure 3 is u in rectification mode p 、u s and the energy transfer inductor current i L Schematic diagram of .

[0064] Figure 4 It is the three-phase current waveform of sector 1 in rectification mode.

[0065] Figure 5 is u in inverter mode p 、u s and the energy transfer inductor current i L Schematic diagram of .

[0066] Figure 6 It is a flow chart of hybrid control of genetic algorithm and chaos search. DETAILED DESCRIPTION

[0067] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application 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 application and are not used to limit the present application.

[0068] like Figure 1 As shown, based on the multi-objective parameter optimization design method of the above dual active full-bridge three-phase bidirectional AC / DC converter, the steps are as follows:

[0069] Step 1, analyzing the dual-line voltage modulation process of the dual-active full-bridge three-phase bidirectional AC / DC converter, selecting the energy transfer inductance L, the high-frequency transformer turns ratio n and the phase shift ratio x as the three parameters to be optimized, and determining them as the optimization objects;

[0070] like Figure 2 As shown, the dual active full-bridge three-phase bidirectional AC / DC converter includes an AC side filter inductor 1, an AC side filter capacitor 2, an AC side three-phase bridge arm 3, an energy transmission inductor L, and a high-frequency transformer T r , DC side full bridge circuit 4, DC side filter capacitor C dc , DC side filter inductor L dc .

[0071] The AC side filter inductor 1 includes an A phase inductor L a 、B phase inductance L b 、C phase inductance L c The AC side filter capacitor 2 includes a phase A capacitor C a 、B phase capacitor C b 、C phase capacitance C c The three-phase bridge arm 3 on the AC side includes three bridge arms, each bridge arm is composed of four switch tubes in series, wherein the first bridge arm is composed of the first switch tube S a1 , the second switch tube S a2 , the third switch tube S a3 , the fourth switch tube S a4 The second bridge arm is composed of the fifth switch tube S b1 , the sixth switch tube S b2 , the seventh switch tube S b3 , the eighth switch tube S b4 The third bridge arm consists of the ninth switch tube S c1 , the tenth switch tube S c2 , Eleventh switch tube S c3 , the twelfth switch tube S c4 The DC side full bridge circuit 4 comprises two bridge arms, each bridge arm is composed of two switch tubes in series, wherein the fourth bridge arm is composed of the thirteenth switch tube S1 , the fourteenth switch tube S 2 The fifth bridge arm is composed of the fifteenth switch tube S 3 , the sixteenth switch tube S 4 composition.

[0072] A phase capacitor C a 、B phase capacitor C b 、C phase capacitance C c One end of the first switch tube S a1 The emitter of the second switch tube S a2 The emitter of the third switch tube S a3 The emitter of the fourth switch tube S a4 The emitter of the second switch tube S a2 The collector of the third switch tube S a3 The collector of is connected to the A phase inductor L a One end is connected to the A phase capacitor C a The other end of the fifth switch tube S b1 The emitter of the sixth switch tube S b2 The emitter of the seventh switch tube S b3 The emitter of the eighth switch tube S b4 The emitter of the sixth switch tube S b2 The collector of the seventh switch tube S b3 The collector of the connection point is connected to the B phase inductor L b One end is connected to the B phase capacitor C b The other end of the ninth switch tube S c1 The emitter of the tenth switch tube S c2 The emitter of the eleventh switch tube S c3 The emitter of the twelfth switch tube S c4 The emitter of the tenth switch tube S c2 The collector of the eleventh switch tube S c3 The collector of is connected to the C phase inductor L c One end is connected to the C phase capacitor C c The other end of the A phase inductor L a 、B phase inductance L b 、C phase inductance L c The other end of each of the first switch tube S is connected to the AC power supply; a1 The collector of the fifth switch tube S b1 The collector of the ninth switch tube S c1 The collector of the fourth switch tube S is connected, and the connection point serves as the first common terminal; a4 The collector of the eighth switch tube S b4The collector of the twelfth switch tube S c4 The connection point serves as the second common terminal.

[0073] Thirteenth switch tube S 1 The emitter of the fourteenth switch tube S 2 The collector of the fifteenth switch tube S is connected to the third common port; 3 The emitter of the sixteenth switch tube S 4 The collector of the thirteenth switch tube S is connected to the collector of the thirteenth switch tube S, and the connection point is used as the fourth common port; 1 The collector of the fifteenth switch tube S 3 The collector of the DC side filter capacitor C dc The positive end of the fourteenth switch tube S 2 The emitter of the sixteenth switch tube S 4 The emitter of the capacitor is connected to the DC side filter capacitor C dc The negative end is connected to the DC side filter capacitor C dc The positive terminal and the DC side filter inductor L dc One end of the DC side filter inductor L dc The other end is connected to the DC power supply.

[0074] One end of the energy transfer inductor L is connected to the first common port, and the high frequency transformer T r The primary winding is respectively connected to the other end of the energy transfer inductor L and the second common port, and the secondary winding is respectively connected to the third common port and the fourth common port.

[0075] The dual-line voltage modulation process of the dual active full-bridge three-phase bidirectional AC / DC converter is as follows:

[0076] (1) Basic Definition

[0077] According to the direction of energy flow of the converter, the power flow from the AC side to the DC side is defined as rectification, and the power flow from the DC side to the AC side is defined as inversion. The voltage difference between the collector of the ninth switch tube and the collector of the twelfth switch tube is defined as u p , that is, the voltage on the left side of the energy transfer inductor L, the terminal voltage of the primary winding of the high-frequency transformer is defined as u s , that is, the voltage on the right side of the energy transfer inductor L.

[0078] (2) Sector division

[0079] The AC power supply provides three-phase sinusoidal voltage a 、e b 、e c , a power frequency cycle T is divided into 12 sectors. When the phase voltage e a >e b>e c And e b <0, it is defined as sector 1; when the phase voltage e a >e b >e c And e b >0, it is defined as sector 2; when the phase voltage e b >e a >e c And e a >0, it is defined as sector 3; when the phase voltage e b >e a >e c And e a <0, it is defined as sector 4; when the phase voltage e b >e c >e a And e c <0, it is defined as sector 5; when the phase voltage e b >e c >e a And e c >0, it is defined as sector 6; when the phase voltage e c >e b >e a And e b >0, it is defined as sector 7; when the phase voltage e c >e b >e a And e b <0, it is defined as sector 8; when the phase voltage e c >e a >e b And e a <0, it is defined as sector 9; when the phase voltage e c >e a >e b And e a >0, it is defined as sector 10; when the phase voltage e a >e c >e b And e c >0, it is defined as sector 11; when the phase voltage e a >e c >e b And e c <0, it is defined as sector 12. The line voltage with the largest amplitude among the three-phase line voltages is defined as e M , the second largest line voltage is defined as e m .

[0080] (3) Establish u p and u s Voltage distribution during the switching cycle

[0081] Each switching cycle T s Divided into 9 sections, t 0 ~t 9 is the switch action time point. Define t 0 ~t 4 is the first duty cycle action time d 1 T s , t 4 ~t 8 is the second duty cycle action time d 2 T s , t 8 ~t 9 is the zero voltage action time d 0 T s , t 1 ~t 2 and t 3 ~t 4 The first phase shift time t 5 ~t 6 and t 7 ~t 8 The second phase shift time Among them, x is the phase shift ratio, which is the phase shift angle is the ratio of π / 2, and Therefore, the phase shift ratio x ranges from 0≤x≤1. p and u s The distribution within the switching cycle is shown in the table:

[0082] Table 1 u in each sector under rectification and inversion mode p and u s Distribution in the switching cycle

[0083]

[0084] Where n is the turns ratio of the high-frequency transformer, which refers to the ratio of the primary winding to the secondary winding of the high-frequency transformer, V dc is the DC side power supply voltage.

[0085] (4) Determine the switch status

[0086] S k (k=a, b, c...i, j) is defined as the switching state of the switch tube: when the first switch tube and the second switch tube are turned on, S is defined a is 1, and S is defined when it is turned off. a is 0; when the third switch tube and the fourth switch tube are turned on, S is defined b is 1, and S is defined when it is turned off. b is 0; when the fifth switch tube and the sixth switch tube are turned on, S is defined cis 1, and S is defined when it is turned off. c is 0; when the seventh switch tube and the eighth switch tube are turned on, S is defined d is 1, and S is defined when it is turned off. d is 0; when the ninth switch tube and the tenth switch tube are turned on, S e is 1, and S is defined when it is turned off. e is 0; when the eleventh switch tube and the twelfth switch tube are turned on, S is defined f is 1, and S is defined when it is turned off. f is 0; when the thirteenth switch is turned on, S g is 1, and S is defined when it is turned off. g is 0; when the fourteenth switch is turned on, S h is 1, and S is defined when it is turned off. h is 0; when the fifteenth switch is turned on, S i is 1, and S is defined when it is turned off. i is 0; when the sixteenth switch is turned on, S j is 1, and S is defined when it is turned off. j is 0. Taking sector 1 as an example, each switching cycle T in sector 1 in rectification and inversion mode s The internal switch status is shown in the table:

[0087] Table 2 Each switching cycle T in sector 1 in rectification mode s Internal switch status

[0088]

[0089] Table 3 Each switching cycle T in sector 1 in inverter mode s Internal switch status

[0090]

[0091]

[0092] Similarly, the switching states of the remaining 11 sectors in the two modes can be obtained.

[0093] like Figure 3 As shown, taking sector 1 in rectification mode as an example, the voltage across the energy transfer inductor is u p and u s The difference between , can establish the following energy transfer inductor current expression:

[0094]

[0095] Among them, i L0 is the initial value of the inductor current, and L is the energy transfer inductor value.

[0096] like Figure 4The three-phase current waveform in sector 1 under the rectification mode is shown in FIG. According to formula (1), the current of each switching cycle T in sector 1 is calculated. s The mean value expression of each phase current is as follows:

[0097]

[0098] Simplified, we get the following formula (3):

[0099]

[0100] Among them, f s is the switching frequency.

[0101] In order to ensure that the three-phase current is sinusoidal and has the same phase as the three-phase voltage, it is assumed that the ideal three-phase current expression is as follows:

[0102]

[0103] Among them, I i is the amplitude of the phase current, and ωt is the phase angle.

[0104] Combining equations (3) and (4), we can calculate the control parameter d in sector 1: 1 d 2 and d 0 The expression is as follows:

[0105]

[0106] Among them, θ is the sector angle, and its relationship with the phase angle ωt is N is the sector number, and the value range of the sector angle θ is

[0107] Similarly, the control parameters d in the remaining 11 sectors can be derived 1 d 2 and d 0 The expression is as follows:

[0108]

[0109] Figure 5 u in inverter mode shown p 、u s and the energy transfer inductor current i L According to the above method, the control parameter d obtained in the inverter mode 1 d 2 and d 0 The expression is the same as that in the rectification mode. Due to the different power flow directions, the value range of the phase shift ratio x is -1≤x<0.

[0110] In summary, there are only three variable parameters in the two-wire voltage modulation process, namely, the energy transmission inductance L, the high-frequency transformer turns ratio n, and the phase shift ratio x. These three parameters will affect the power conversion efficiency, so the design of these three parameters is particularly important.

[0111] Step 2, analyzing the performance indicators related to the power conversion efficiency, selecting the ratio of reactive power to active power of the high-frequency transformer, the effective value of the energy transmission inductor current and the peak-to-peak value of the current as the optimization targets, and calculating the expressions of each optimization target and the optimization object;

[0112] 1)i Lrms The effective value expression of the energy transfer inductor current is as follows:

[0113]

[0114] 2) Q / P is the ratio of reactive power to active power of the high-frequency transformer, as shown in formula (8):

[0115]

[0116] Among them, S is the apparent power transmitted by the high-frequency transformer, P is the active power transmitted by the high-frequency transformer, Q is the reactive power transmitted by the high-frequency transformer, and u prms is the effective value of the output voltage on the AC side.

[0117] 3)i Lmaxs The peak-to-peak value of the energy transfer inductor current is expressed as follows:

[0118]

[0119] Step 3, determining the constraints between the energy transfer inductance L, the high-frequency transformer turns ratio n and the phase shift ratio x;

[0120] In order to avoid overmodulation of the dual-active full-bridge three-phase bidirectional AC / DC converter based on dual-line voltage modulation and realize bidirectional energy flow, two constraints between the energy transfer inductance L, the high-frequency transformer turns ratio n and the phase shift ratio x are determined:

[0121] The first constraint condition is the limit range of the modulation coefficient M, as shown in the following formula (10):

[0122]

[0123] The second constraint condition is the range of the phase shift ratio x: in rectification mode, the value range of the phase shift ratio x is 0≤x≤1; in inverter mode, the value range of the phase shift ratio x is -1≤x<0.

[0124] Step 4, synthesizing the expressions of various optimization objectives into a single-objective optimization function according to the weight coefficients;

[0125] The single objective optimization function F is as follows:

[0126]

[0127] Among them, λ 1 , 2 and λ 3 is the weight coefficient, λ 1 +λ 2 +λ 3 =1. i Lrms_max is the maximum effective value of the energy transfer inductor current within the constraints, (Q / P) max is the maximum value of the ratio of reactive power to active power of the high-frequency transformer within the constraints, i Lmax_max is the maximum value of the peak-to-peak value of the energy transfer inductor current within the constraints.

[0128] Step 5, adopt a method combining genetic algorithm and chaotic search to iteratively optimize the energy transmission inductance L, high-frequency transformer turns ratio n and phase shift ratio x, obtain several groups of optimal solutions, and then perform loss analysis based on the actual hardware circuit to select the energy transmission inductance L, high-frequency transformer turns ratio n and phase shift ratio x when the circuit loss is minimized.

[0129] like Figure 6 As shown in the figure, a method combining genetic algorithm and chaos search is used for iterative optimization. The process is divided into two stages: in the first stage, genetic algorithm is used to solve nonlinear optimization problems; in the second stage, local search in chaos theory is introduced to improve the quality of the solution and find the optimal solution. The specific process is as follows:

[0130] S1: Initialize the population and parameters: The population is initialized using real number coding, the parent individual y i,j It is obtained by the following formula:

[0131]

[0132] Wherein, j is 1 to 3, representing the energy transmission inductance L, high-frequency transformer turns ratio n and phase shift ratio x of the three optimization objects, pop is the population size of each optimization object, i is the parent individual number of each optimization object, rand is a random number in the range of [0, 1], y jmax and jmin They are respectively the upper and lower bounds of the value range of each optimization object. The value range of the optimization object is determined by the voltage stress and current stress of the switching tube, energy transfer inductor and high-frequency transformer.

[0133] The parameters include algorithm parameters: maximum number of iterations of genetic algorithm, maximum number of iterations of chaos search, population size, crossover probability and mutation probability; specification parameters of dual active full-bridge three-phase bidirectional AC / DC converter: three-phase sinusoidal voltage e of AC side power supply a 、e b 、e c , DC side power supply voltage V dc , transmission power P and switching frequency f s .

[0134] S2: Calculate individual fitness: The present invention takes the inverse of the single-objective optimization function F as the fitness function fitness, and calculates y under the constraints of the three optimization objects. i,j Substitute into the calculation.

[0135] S3: A new generation is obtained after selection, crossover and mutation:

[0136] Select several y with large fitness values i,j The combination of y is directly copied to the next generation, and the remaining y is randomly sampled. i,j Make a selection.

[0137] Select a certain crossover probability to select individuals from the new population for crossover, and use the following linear combination crossover method to obtain individual y′ i,j :

[0138]

[0139] The individuals that need to be mutated are randomly determined among the individuals after selection and crossover, and the positions that need to be mutated are randomly determined, and a certain mutation probability is selected for mutation, as shown in the following formula (14):

[0140]

[0141] Among them, rand' is a random number in the range of [0, 1], MutShrink is the range of compressed mutation, g is the number of iterations of the current genetic algorithm, G max is the maximum number of iterations of the genetic algorithm, Y i,j The offspring individuals produced after selection and crossover.

[0142] S4: Determine whether the genetic algorithm is terminated: If the maximum number of iterations of the genetic algorithm is reached, stop the genetic algorithm, and select three sets of energy transfer inductance values ​​L, high-frequency transformer turns ratio n and phase shift ratio x with large fitness values ​​for chaotic search; otherwise, return to S2.

[0143] S5: Perform chaotic search on the three groups of parameters with large fitness values: The better individuals Y after genetic algorithm i,jMapped to the Logistic equation domain [0, 1], the chaotic variable Z is obtained by the following formula i,j :

[0144]

[0145] S6: Generate chaotic variables: Use Logistic mapping to generate chaotic variables, as shown in formula (16):

[0146]

[0147] Among them, μ is the control parameter of Logistic, and size is the population size of each optimization object participating in chaotic search.

[0148] S7: Map the changing range of the chaotic variable to the value range of the optimization object, as shown in formula (17):

[0149] Y′ i,j =y j min +z i,j (y j max -y j min ) (17)

[0150] S8: Update the value range of the optimization object: i,j As the approximate value of the global optimum, the value range of each optimization object is narrowed with this value as the center, as shown in the following formula (18):

[0151]

[0152] Where k is the number of iterations of the current chaos search. If y' j min <y j min , then y' j min =y j min ; if y' j max >y j max , then y' j max =y j max . y' j max ,y' j min They are respectively the upper and lower bounds of the value range of each optimization object after update.

[0153] S9: Iterative search using chaotic variables: Let Y′ i,j (k) = Y′ i,j , calculate the fitness value fitness(k). fitness * =fitnesss(Y′ i,j (0)), if fitnesss * <fitnesss(Y′ i,j(k)), then fitness * =fitnesss(y i,j (k)); otherwise give up. Among them, fitnesss * is the maximum fitness value, is the parameter value that maximizes the fitness value.

[0154] S10: Determine whether the chaotic search is terminated: if the maximum number of chaotic search iterations has not been reached, return to S5; otherwise, end and obtain a set of energy transfer inductance L, high-frequency transformer turns ratio n and phase shift ratio x that enable the dual-active full-bridge three-phase bidirectional AC / DC converter to operate best under a certain weight coefficient.

[0155] As a specific implementation method, taking the three-phase AC voltage effective value of 220V, DC voltage 400V, transmission power size 1500W, switching frequency 40kHz as an example, the weight coefficient λ is finally obtained. 1 , 2 and λ 3 When the inductances are 0.4, 0.3, and 0.3 respectively, the energy transfer inductance L is 72.7 mH, the high-frequency transformer turns ratio n is 1, and in the power flow mode from the AC side to the DC side, the phase shift ratio x is 0.4; otherwise, it is -0.4.

[0156] The present invention also proposes a multi-objective parameter optimization design system based on a dual active full-bridge three-phase bidirectional AC / DC converter. Based on the multi-objective parameter optimization design method based on a dual active full-bridge three-phase bidirectional AC / DC converter, a multi-objective parameter optimization design based on a dual active full-bridge three-phase bidirectional AC / DC converter is realized.

[0157] A computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, based on the multi-objective parameter optimization design method based on a dual-active full-bridge three-phase bidirectional AC / DC converter, a multi-objective parameter optimization design based on a dual-active full-bridge three-phase bidirectional AC / DC converter is realized.

[0158] A computer-readable storage medium stores a computer program. When the computer program is executed by a processor, based on the multi-objective parameter optimization design method based on a dual-active full-bridge three-phase bidirectional AC / DC converter, a multi-objective parameter optimization design based on a dual-active full-bridge three-phase bidirectional AC / DC converter is implemented.

[0159] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0160] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A multi-objective parameter optimization design method for a dual active full-bridge three-phase bidirectional AC / DC converter, characterized in that: The dual active full-bridge three-phase bidirectional AC / DC converter includes an AC side filter inductor 1, an AC side filter capacitor 2, an AC side three-phase bridge arm 3, an energy transmission inductor L, a high frequency transformer T r , DC side full bridge circuit 4, DC side filter capacitor C dc , DC side filter inductor L dc The AC side filter inductor 1 includes a phase A inductor L a 、B phase inductance L b 、C phase inductance L c The AC side filter capacitor 2 includes a phase A capacitor C a 、B phase capacitor C b 、C phase capacitance C c The three-phase bridge arm 3 on the AC side includes three bridge arms, each bridge arm is composed of four switch tubes in series, wherein the first bridge arm is composed of the first switch tube S a1 , the second switch tube S a2 , the third switch tube S a3 , the fourth switch tube S a4 The second bridge arm is composed of the fifth switch tube S b1 , the sixth switch tube S b2 , the seventh switch tube S b3 , the eighth switch tube S b4 The third bridge arm consists of the ninth switch tube S c1 , the tenth switch tube S c2 , Eleventh switch tube S c3 , the twelfth switch tube S c4 The DC side full-bridge circuit 4 comprises two bridge arms, each of which is composed of two switch tubes connected in series, wherein the fourth bridge arm is composed of a thirteenth switch tube S1 and a fourteenth switch tube S2, and the fifth bridge arm is composed of a fifteenth switch tube S3 and a sixteenth switch tube S4; A phase capacitor C a 、B phase capacitor C b 、C phase capacitance C c One end of the first switch tube S a1 The emitter of the second switch tube S a2 The emitter of the third switch tube S a3 The emitter of the fourth switch tube S a4 The emitter of the second switch tube S a2 The collector of the third switch tube S a3 The collector of is connected to the A phase inductor L a One end is connected to the A phase capacitor C a The other end of the fifth switch tube S b1 The emitter of the sixth switch tube S b2 The emitter of the seventh switch tube S b3 The emitter of the eighth switch tube S b4 The emitter of the sixth switch tube S b2 The collector of the seventh switch tube S b3 The collector of is connected to the B phase inductor L b One end is connected to the B phase capacitor C b The other end of the ninth switch tube S c1 The emitter of the tenth switch tube S c2 The emitter of the eleventh switch tube S c3 The emitter of the twelfth switch tube S c4 The emitter of the tenth switch tube S c2 The collector of the eleventh switch tube S c3 The collector of is connected to the C phase inductor L c One end is connected to the C phase capacitor C c The other end of the A phase inductor L a 、B phase inductance L b 、C phase inductance L c The other end of each of the first switch tube S is connected to the AC power supply; a1 The collector of the fifth switch tube S b1 The collector of the ninth switch tube S c1 The collector of is connected to the connection point as the first common terminal; The fourth switch tube S a4 The collector of the eighth switch tube S b4 The collector of the twelfth switch tube S c4 The collector of is connected to the connection point as the second common terminal; The emitter of the thirteenth switch tube S1 is connected to the collector of the fourteenth switch tube S2, and the connection point is used as the third common port; the emitter of the fifteenth switch tube S3 is connected to the collector of the sixteenth switch tube S4, and the connection point is used as the fourth common port; the collector of the thirteenth switch tube S1 is connected to the collector of the fifteenth switch tube S3, and the connection point is connected to the DC side filter capacitor C dc The emitter of the fourteenth switch tube S2 is connected to the emitter of the sixteenth switch tube S4, and the connection point is connected to the DC side filter capacitor C dc The negative end is connected to the DC side filter capacitor C dc The positive terminal and the DC side filter inductor L dc One end of the DC side filter inductor L dc The other end is connected to the DC power supply; One end of the energy transfer inductor L is connected to the first common port, and the high frequency transformer T r The primary winding is respectively connected to the other end of the energy transfer inductor L and the second common port, and the secondary winding is respectively connected to the third common port and the fourth common port; The multi-objective parameter optimization design method based on dual active full-bridge three-phase bidirectional AC / DC converter has the following steps: Step 1, analyzing the dual-line voltage modulation process of the dual-active full-bridge three-phase bidirectional AC / DC converter, selecting the energy transfer inductance L, the high-frequency transformer turns ratio n and the phase shift ratio x as the three parameters to be optimized, and determining them as the optimization objects; Step 2, analyzing the performance indicators related to the power conversion efficiency, selecting the ratio of reactive power to active power of the high-frequency transformer, the effective value of the energy transmission inductor current and the peak-to-peak value of the current as the optimization targets, and calculating the expressions of each optimization target and the optimization object; Step 3, determining the constraints between the energy transfer inductance L, the high-frequency transformer turns ratio n and the phase shift ratio x; Step 4, synthesizing the expressions of various optimization objectives into a single-objective optimization function according to the weight coefficients; Step 5, change the weight coefficient according to a certain step size, and use a method combining genetic algorithm and chaotic search to iteratively optimize the energy transmission inductance L, the high-frequency transformer turns ratio n and the phase shift ratio x to obtain several groups of optimal solutions, and then perform loss analysis based on the actual hardware circuit to select the energy transmission inductance L, the high-frequency transformer turns ratio n and the phase shift ratio x when the circuit loss is minimized.

2. The multi-objective parameter optimization design method based on dual active full-bridge three-phase bidirectional AC / DC converter according to claim 1 is characterized in that: Step 2: Analyze the performance indicators related to power conversion efficiency, select the ratio of reactive power to active power of the high-frequency transformer, the effective value of the energy transmission inductor current and the peak-to-peak current as the optimization targets, and calculate the expressions of each optimization target and the optimization object, which are as follows: 1)i Lrms The effective value expression of the energy transfer inductor current is as follows: Where T is the power frequency period, x is the phase shift ratio, d1 is the first duty cycle, d2 is the second duty cycle, e M is the line voltage with the largest amplitude among the three-phase line voltages, e m is the line voltage with the second largest amplitude among the three-phase line voltages, n is the turns ratio of the high-frequency transformer, V dc is the DC power supply voltage, f s is the switching frequency, L is the energy transfer inductance; 2) Q / P is the ratio of reactive power to active power of high-frequency transformer, as shown in formula (2): Among them, S is the apparent power transmitted by the high-frequency transformer, P is the active power transmitted by the high-frequency transformer, Q is the reactive power transmitted by the high-frequency transformer, and u prms is the effective value of the output voltage on the AC side; 3)i Lmax The peak-to-peak value of the energy transfer inductor current is expressed as follows: Among them, T s is the switching cycle.

3. The multi-objective parameter optimization design method based on dual active full-bridge three-phase bidirectional AC / DC converter according to claim 1 is characterized in that: Step 3, determine the constraints between the energy transfer inductance L, the high-frequency transformer turns ratio n and the phase shift ratio x, as follows: The first constraint is the limit range of the modulation coefficient M, as shown in the following formula (4): Among them, L is the energy transmission inductance, P is the active power transmitted by the high-frequency transformer, T s is the switching period, n is the high-frequency transformer turns ratio, V dc is the DC side power supply voltage, x is the phase shift ratio, d1 is the first duty cycle, d2 is the second duty cycle, e M is the line voltage with the largest amplitude among the three-phase line voltages, e m It is the line voltage with the second largest amplitude among the three-phase line voltages; The second constraint condition is the range of the phase shift ratio x: in rectification mode, the value range of the phase shift ratio x is 0≤x≤1; in inverter mode, the value range of the phase shift ratio x is -1≤x<0.

4. The multi-objective parameter optimization design method based on dual active full-bridge three-phase bidirectional AC / DC converter according to claim 1 is characterized in that: Step 4: The expressions of each optimization objective are synthesized into a single objective optimization function F according to the weight coefficient, as shown in formula (5): Among them, λ1, λ2 and λ3 are weight coefficients, λ1+λ2+λ3=1, i Lrms_max is the maximum effective value of the energy transfer inductor current within the constraints, Q / P is the ratio of the reactive power to the active power of the high-frequency transformer, (Q / P) max is the maximum value of the ratio of reactive power to active power of the high-frequency transformer within the constraints, i Lmax_max is the maximum value of the peak-to-peak value of the energy transfer inductor current within the constraints.

5. The multi-objective parameter optimization design method based on dual active full-bridge three-phase bidirectional AC / DC converter according to claim 1 is characterized in that: Step 5, changing the weight coefficient according to a certain step length, using a method combining genetic algorithm and chaotic search to iteratively optimize the energy transmission inductance L, high-frequency transformer turns ratio n and phase shift proportion x, to obtain several groups of optimal solutions, and then performing loss analysis based on the actual hardware circuit to select the energy transmission inductance L, high-frequency transformer turns ratio n and phase shift proportion x when the circuit loss is minimized. The specific process of iterative optimization using the method combining genetic algorithm and chaotic search is as follows: S1: Initialize the population and parameters: The population is initialized using real number coding, the parent individual y i,j It is obtained by the following formula: Wherein, j is 1 to 3, representing the energy transmission inductance L, high-frequency transformer turns ratio n, and phase shift ratio x of the three optimization objects, pop is the population size of each optimization object, i is the parent individual number of each optimization object, rand is a random number in the range of [0, 1], y jmax and jmin are the upper and lower bounds of the value range of each optimization object, respectively. The value range of the optimization object is determined by the voltage stress and current stress of the switch tube, energy transfer inductor and high-frequency transformer; the parameters include algorithm parameters: maximum number of iterations of genetic algorithm, maximum number of iterations of chaos search, population size, crossover probability and mutation probability; specification parameters of dual active full-bridge three-phase bidirectional AC / DC converter: three-phase sinusoidal voltage e of AC side power supply a 、e b 、e c , DC side power supply voltage V dc , transmission power P and switching frequency f s ; S2: Calculate individual fitness: Take the inverse of the single-objective optimization function F as the fitness function fitness, and under the constraints of the three optimization objects, convert y i,j Substitute into the calculation; S3: After selection, crossover and mutation, a new generation is obtained: several y with large fitness values ​​are selected i,j The combination of y is directly copied to the next generation, and the remaining y is randomly sampled. i,j Perform selection operation; Select a certain crossover probability to select individuals from the new population for crossover, and use the following linear combination crossover method to obtain individual y i ' ,j : The individuals that need to be mutated are randomly determined among the individuals after selection and crossover, and the positions that need to be mutated are randomly determined, and a certain mutation probability is selected for mutation, as shown in the following formula (8): Among them, rand' is a random number in the range of [0, 1], MutShrink is the range of compressed mutation, g is the number of iterations of the current genetic algorithm, G max is the maximum number of iterations of the genetic algorithm, Y i,j The offspring individuals produced after selection and crossover; S4: Determine whether the genetic algorithm is terminated: If the maximum number of iterations of the genetic algorithm is reached, stop the genetic algorithm, and select three sets of energy transmission inductance values ​​L, high-frequency transformer turns ratio n, and phase shift ratio x with large fitness values ​​for chaotic search; otherwise, return to S2; S5: Perform chaotic search on the three groups of parameters with large fitness values: The better individuals Y after genetic algorithm i,j Mapped to the Logistic equation domain [0, 1], the chaotic variable Z is obtained by the following formula i,j : S6: Generate chaotic variables: Use Logistic mapping to generate chaotic variables, as shown in the following formula (10): Among them, μ is the control parameter of Logistic, and size is the population size of each optimization object participating in chaotic search; S7: Map the changing range of the chaotic variable to the value range of the optimization object, as shown in formula (11): AND i ' ,j =and jmin +z i,j (and jmax -and jmin )(11) S8: Update the value range of the optimization object: i, ' j As the approximate value of the global optimum, the value range of each optimization object is narrowed with this value as the center, as shown in the following formula (12): Among them, k is the number of iterations of the current chaos search. If y' jmin <y jmin , then y' jmin =y jmin ; if y' jmax >y jmax , then y' jmax =y jmax , y' jmax ,y' jmin They are the upper and lower bounds of the value range of each optimization object after update; S9: Iterative search using chaotic variables: Let Y i, ' j (k) = Y i, ' j , calculate the fitness value fitness(k), let fitness * =fitnesss(Y i, ' j (0)), if fitnesss * <fitnesss(Y i, ' j (k)), then fitness * =fitnesss(y i,j (k)); otherwise, fitnesss * is the maximum fitness value, The parameter value that maximizes the fitness value; S10: Determine whether the chaotic search is terminated: if the maximum number of chaotic search iterations has not been reached, return to S5; otherwise, end and obtain a set of energy transfer inductance L, high-frequency transformer turns ratio n and phase shift ratio x values ​​that enable the dual-active full-bridge three-phase bidirectional AC / DC converter to operate best under a certain weight coefficient.

6. A multi-objective parameter optimization design system based on a dual active full-bridge three-phase bidirectional AC / DC converter, characterized in that: Based on the multi-objective parameter optimization design method based on a dual active full-bridge three-phase bidirectional AC / DC converter as described in any one of claims 1 to 5, a multi-objective parameter optimization design based on a dual active full-bridge three-phase bidirectional AC / DC converter is implemented.

7. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the multi-objective parameter optimization design method based on a dual-active full-bridge three-phase bidirectional AC / DC converter according to any one of claims 1 to 5 is used to implement a multi-objective parameter optimization design based on a dual-active full-bridge three-phase bidirectional AC / DC converter.

8. A computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the multi-objective parameter optimization design method based on a dual-active full-bridge three-phase bidirectional AC / DC converter according to any one of claims 1 to 5 is used to implement a multi-objective parameter optimization design based on a dual-active full-bridge three-phase bidirectional AC / DC converter.

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