DAB converter control method based on global minimum backflow power, and device

Abstract

Disclosed in the present application are a DAB converter control method based on global minimum backflow power, a device, and a storage medium. The method comprises: acquiring the current consumed power inside a DAB converter, and determining whether the current consumed power is equal to a preset power threshold; if the current consumed power is not equal to the preset power threshold, acquiring the current input voltage and the current output voltage of the DAB converter, and then, with the objective of minimizing the deviation of the average transmitted power of the DAB converter and the output backflow power of the DAB converter, using a particle swarm optimization algorithm to optimize the current phase shift ratio combination applied by the DAB converter during triple phase shift control, so as to obtain an optimal phase shift ratio combination; and on the basis of a preset voltage reference value and the current output voltage of the DAB converter, determining an outer phase shift angle correction value, and then controlling the DAB converter by combining the outer phase shift angle correction value with the optimal phase shift ratio combination. The present application introduces the particle swarm optimization algorithm for solving a multi-objective optimization problem, such that the DAB converter can maintain a relatively high energy transmission efficiency and reduce the effect of the output backflow power after operation adjustment.

Description

DAB converter control method and device based on global minimum backflow power TECHNICAL FIELD

[0001] The present application relates to the technical field of power electronics, in particular to a DAB converter control method and device based on global minimum backflow power, and a storage medium. BACKGROUND

[0002] A DAB (Dual Active Bridge) converter is an isolated bidirectional DC-DC converter, which is widely used in electrochemical energy storage systems to realize power conversion due to its high efficiency and good power density. Electrochemical energy storage systems are usually applied in direct current microgrids, distributed power generation and electric vehicles, and the DAB converter can improve the power quality of the electrochemical energy storage system during charging or discharging. However, the DAB converter will generate backflow power during operation, which not only reduces the efficiency of the electrochemical energy storage system, but also may adversely affect the stability and life of the DAB converter. How to effectively reduce the backflow power of the DAB converter is a problem to be solved.

[0003] SUMMARY

[0004] The present application provides a DAB converter control method and device based on global minimum backflow power, and a storage medium, to solve one or more technical problems existing in the prior art and provide at least one beneficial option or create conditions.

[0005] In a first aspect, a DAB converter control method based on global minimum backflow power is provided. The DAB converter applies a phase-shifted ratio combination when performing triple phase-shift control. The method comprises:

[0006] Obtaining the current consumption power inside the DAB converter and determining whether it is equal to a preset power threshold;

[0007] If not, obtaining the current input voltage and the current output voltage of the DAB converter, and then minimizing the deviation of the average transmission power and the output backflow power of the DAB converter as the target, using a particle swarm algorithm to optimize the current phase-shifted ratio combination of the DAB converter to obtain an optimal phase-shifted ratio combination;

[0008] Determining an external phase-shift angle correction value according to a preset voltage reference value and the current output voltage;

[0009] Controlling the DAB converter according to the optimal phase-shifted ratio combination and the external phase-shift angle correction value.

[0010] Further, the DAB converter comprises a transformer, an inductor, and input and output bridges which are mutually symmetrical, and the phase-shift ratio combination comprises an inner phase-shift ratio d1 of the input bridge, an inner phase-shift ratio d2 of the output bridge, and an outer phase-shift ratio d between the input bridge and the output bridge.

[0011] Further, when it is determined that the current consumption power is equal to the preset power threshold, the current phase-shift ratio combination of the DAB converter is taken as an optimal phase-shift ratio combination.

[0012] Further, the obtaining of the current consumption power inside the DAB converter comprises:

[0013] obtaining a current input power and a current output power of the DAB converter;

[0014] calculating a first difference between the current input power and the current output power, and taking the first difference as the current consumption power.

[0015] Further, the average transmission power of the DAB converter is calculated by the following expression:

[0016] when the DAB converter works in a d≥d2 mode:

[0017] when the DAB converter works in a d

[0018] wherein P is the average transmission power of the DAB converter, V i is an input voltage of the DAB converter, V o is an output voltage of the DAB converter, f S is a switching frequency, and L is an inductance of the inductor.

[0019] Further, the output backflow power of the DAB converter is calculated by the following expression:

[0020] when the DAB converter works in a d≥d2 mode:

[0021] when the DAB converter works in a d

[0022] wherein P b is the output backflow power of the DAB converter, n is a transformation ratio of the transformer, and k is a voltage conversion ratio.

[0023] Further, the determining of the outer phase-shift angle correction value according to the preset voltage reference value and the current output voltage comprises:

[0024] a second difference between the preset voltage reference value and the current output voltage is calculated, and the second difference is processed by a PI controller to obtain the outer phase shift angle correction value.

[0025] Further, the controlling the DAB converter according to the optimal phase shift ratio combination and the outer phase shift angle correction value comprises:

[0026] determining an optimal inner phase shift angle of the input bridge according to the optimal inner phase shift ratio of the input bridge;

[0027] determining an optimal inner phase shift angle of the output bridge according to the optimal inner phase shift ratio of the output bridge;

[0028] determining an optimal outer phase shift angle between the input bridge and the output bridge according to the outer phase shift angle correction value and the optimal outer phase shift ratio between the input bridge and the output bridge;

[0029] generating all gate pulse signals of the DAB converter by using a phase accumulator and a timer according to the optimal inner phase shift angle of the input bridge, the optimal inner phase shift angle of the output bridge and the optimal outer phase shift angle between the input bridge and the output bridge, so as to control the DAB converter.

[0030] In the second aspect, a computer device is provided, comprising a memory and a processor, the memory stores a computer program, and the processor executes the computer program to realize the DAB converter control method based on the global minimum backflow power as described in the first aspect.

[0031] In the third aspect, a computer readable storage medium is provided, which stores a computer program, and the computer program is executed by a processor to realize the DAB converter control method based on the global minimum backflow power as described in the first aspect.

[0032] The present application has at least the following beneficial effects: in the case that the DAB converter does not reach the expected power output level, the particle swarm algorithm is used to find the optimal phase shift ratio combination of the DAB converter by minimizing the deviation of the average transmission power of the DAB converter and the output backflow power, and it is proposed that the outer phase shift angle of the DAB converter needs to be corrected when the optimal phase shift ratio combination is put into application, so that the DAB converter can maintain a relatively high energy transmission efficiency and reduce the influence of the output backflow power after adjustment, thereby enhancing the stability of the DAB converter. BRIEF DESCRIPTION OF DRAWINGS

[0033] The accompanying drawings are included to provide a further understanding of the technical scheme of the present application, and constitute a part of the specification, and are used together with the embodiments of the present application to explain the technical scheme of the present application, and do not constitute a limitation on the technical scheme of the present application.

[0034] Fig. 1 is a schematic diagram of a DAB converter according to an embodiment of the present application;

[0035] Fig. 2 is a flowchart of a DAB converter control method based on global minimum backflow power according to an embodiment of the present application;

[0036] Fig. 3 is a schematic diagram of a hardware structure of a computer device according to an embodiment of the present application. DETAILED DESCRIPTION

[0037] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0038] It should be noted that although the logical order is shown in the flowchart, in some cases, the steps shown or described can be performed in an order different from that in the flowchart. The terms "first", "second", and the like in the specification and claims and the above-described drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence, it should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used herein are only for the purpose of describing the embodiments of the present application and are not intended to limit the present application.

[0040] In addition, the described features, structures or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, many specific details are provided to give a sufficient understanding of the embodiments of the present application. However, one skilled in the art will realize that the technical solutions of the present application can be practiced without one or more of the specific details, or other methods, components, devices, steps, etc. can be used. In other cases, well-known methods, devices, implementations or operations are not shown or described in detail to avoid obscuring the aspects of the present application.

[0041] The flowchart shown in the accompanying drawings is only an exemplary description and does not necessarily include all contents and operations / steps, nor does it necessarily execute in the order described. For example, some operations / steps can be further divided, and some operations / steps can be combined or partially combined, so the actual execution order may be changed according to the actual situation.

[0042] Please refer to Fig. 1, which is a schematic diagram of a DAB converter provided in the embodiments of the present application. The DAB converter comprises an input bridge, an inductor L, a transformer HFT and an output bridge. The input bridge and the output bridge are in a symmetrical relationship with each other. The input bridge is a power supply side, and the output bridge is a load side.

[0043] More specifically, the input bridge comprises a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, a first diode T1 in anti-parallel connection with the first switch S1, a second diode T2 in anti-parallel connection with the second switch S2, a third diode T3 in anti-parallel connection with the third switch S3, a fourth diode T4 in anti-parallel connection with the fourth switch S4, and a first filter capacitor C1. The first switch S1 and the second switch S2 form a first bridge arm. The third switch S3 and the fourth switch S4 form a second bridge arm. The first filter capacitor C1 is in parallel connection with the first bridge arm. The first bridge arm is in parallel connection with the second bridge arm. The middle node of the first bridge arm is connected to a first primary end point of the transformer HFT through the inductor L. The middle node of the second bridge arm is connected to a second primary end point of the transformer HFT.

[0044] More specifically, the output bridge comprises a fifth switch S5, a sixth switch S6, a seventh switch S7, an eighth switch S8, a fifth diode T5 in anti-parallel connection with the fifth switch S5, a sixth diode T6 in anti-parallel connection with the sixth switch S6, a seventh diode T7 in anti-parallel connection with the seventh switch S7, an eighth diode T8 in anti-parallel connection with the eighth switch S8, and a second filter capacitor C2. The fifth switch S5 and the sixth switch S6 form a third bridge arm. The seventh switch S7 and the eighth switch S8 form a fourth bridge arm. The third bridge arm is in parallel connection with the fourth bridge arm. The fourth bridge arm is in parallel connection with the second filter capacitor C2. The middle node of the third bridge arm is connected to a first secondary end point of the transformer HFT. The middle node of the fourth bridge arm is connected to a second secondary end point of the transformer HFT.

[0045] In the embodiments of the present application, triple phase-shift control is provided for the DAB converter. At this time, the phase-shift ratio combination applied by the DAB converter comprises the following:

[0046] (1) The outer phase-shift ratio d between the input bridge and the output bridge refers to the outer phase-shift ratio between the first switch S1 and the fifth switch S5.

[0047] (2) The inner phase-shift ratio d1 of the input bridge refers to the inner phase-shift ratio between the first switch S1 and the fourth switch S4, or the inner phase-shift ratio between the second switch S2 and the third switch S3.

[0048] (3) The inner phase-shift ratio d2 of the output bridge refers to the inner phase-shift ratio between the fifth switch S5 and the eighth switch S8, or the inner phase-shift ratio between the sixth switch S6 and the seventh switch S7.

[0049] Based on the above, FIG. 2 is a flowchart of a DAB converter control method based on global minimum backflow power provided by an embodiment of the present application, which comprises the following steps:

[0050] In step S110, the current consumption power inside the DAB converter is obtained and it is determined whether it is equal to the preset power threshold value; if yes, step S120 is executed; if no, step S130 is executed.

[0051] In step S120, the current phase shift ratio combination of the DAB converter is taken as the optimal phase shift ratio combination.

[0052] In step S130, the current input voltage and the current output voltage of the DAB converter are obtained, and the current phase shift ratio combination of the DAB converter is optimized by using a particle swarm algorithm to minimize the deviation of the average transmission power and the output backflow power of the DAB converter, so as to obtain the optimal phase shift ratio combination.

[0053] In step S140, the external phase shift angle correction value is determined according to the preset voltage reference value and the current output voltage.

[0054] In step S150, the DAB converter is controlled according to the optimal phase shift ratio combination and the external phase shift angle correction value.

[0055] In some embodiments, the current consumption power inside the DAB converter mentioned in step S110 is obtained by the following method: the current input power of the DAB converter is obtained by placing the detection end of the power table on the input end of the DAB converter (i.e. the power supply side of the DAB converter); the current output power of the DAB converter is obtained by placing the detection end of the power table on the output end of the DAB converter (i.e. the load side of the DAB converter); the first difference between the current input power and the current output power of the DAB converter is calculated and defined as the current consumption power output inside the DAB converter.

[0056] In step S110, by comparing the current consumption power inside the DAB converter with the preset power threshold value, it can be determined whether the DAB converter currently reaches the expected power output level, so as to determine whether the current phase shift ratio combination of the DAB converter needs to be further optimized, thereby avoiding wasting computing resources.

[0057] In some embodiments, the implementation process of step S130 comprises but is not limited to the following:

[0058] Step S131, the current input voltage of the DAB converter is obtained, which can be obtained by placing the detection end of the voltage meter on the input end of the DAB converter (i.e. the power supply side of the DAB converter).

[0059] Step S132, the current output voltage of the DAB converter is obtained, which can be obtained by placing the detection end of the voltage meter on the output end of the DAB converter (i.e. the load side of the DAB converter).

[0060] Step S133, the decision variable required to be applied in the particle swarm algorithm is set as X = {d, d1, d2}, and the constraint condition of the decision variable X is set as: 0 < d < 1, 0 < d1 < 1, 0 < d2 < 1 and 0 < d + d1 + d2 < 1. The decision variable X is usually encoded as the position of a particle, and each particle represents a solution in the problem space.

[0061] Step S134, two cost functions required to be applied in the particle swarm algorithm are set, the first cost function is used to solve the deviation between the average transmission power of the DAB converter and the preset average transmission power reference value, and the second cost function is used to solve the output backflow power of the DAB converter. In the particle swarm algorithm, the optimization problem of the decision variable X is realized by minimizing the two cost functions;

[0062] Wherein, the solving formula of the average transmission power of the DAB converter is:

[0063] The solving formula of the output backflow power of the DAB converter is:

[0064] Wherein, d ≥ d2 and d < d2 represent that the DAB converter works in different modes, P is the average transmission power of the DAB converter, V i is the input voltage of the DAB converter (also known as the power supply side voltage), V o is the output voltage of the DAB converter (also known as the load side voltage), f S is the switching frequency, considering that the average current of the inductor L in one switching period 2π is zero, f S = 1 / (2π), L is the inductance of the inductor L, P b is the output backflow power of the DAB converter, n is the transformation ratio of the transformer HFT, k is the voltage conversion ratio and k = V i / (nV o ).

[0065] Step S135, the basic parameters required to be applied in the particle swarm algorithm are set, specifically including the size of the particle swarm (i.e. the number of particles participating in the search), the maximum iteration number T maxThe system includes an inertia weight w, a cognitive coefficient c1, a social coefficient c2, and an empty repository, which is mainly used to store all non-dominated solutions found by the particle swarm during the iterative search process.

[0066] Step S136: Randomly initialize the particle swarm according to the constraints of the decision variable X.

[0067] Step S137: In the t-th iteration, calculate the two cost function values ​​corresponding to each particle based on the current input voltage and current output voltage of the DAB converter and the two cost functions;

[0068] More specifically, by substituting the shift ratio combination represented by each particle, along with the current input voltage and current output voltage of the DAB converter, into the two cost functions for calculation, the two cost function values ​​corresponding to that particle can be obtained.

[0069] Step S138: Update the repository using a non-dominant solution based on the two cost function values ​​corresponding to each particle;

[0070] More specifically, for each particle in the particle swarm, based on the two cost function values ​​corresponding to the particle, the particle is treated as a new solution and compared with each non-dominated solution currently stored in the repository, and the following four cases are considered: (1) When the new solution can dominate one or more non-dominated solutions currently stored in the repository, the dominated non-dominated solutions are removed from the repository and the new solution is added to the repository; (2) When the new solution has no dominance relationship with any of the non-dominated solutions currently stored in the repository and the repository is not full, the new solution is directly added to the repository; (3) When the new solution has no dominance relationship with any of the non-dominated solutions currently stored in the repository, but the repository is full, the non-dominated solution with the smallest crowding distance (or density estimate) is deleted from all the non-dominated solutions currently stored in the repository and the new solution is added to the repository; (4) When the new solution can be dominated by all the non-dominated solutions currently stored in the repository, the solution is discarded, that is, the solution is not added to the repository.

[0071] Step S139: Update the position and velocity of each particle using the following mathematical expression:

[0072] In the formula, V i (t) represents the updated velocity of the i-th particle, V i (t-1) represents the velocity of the i-th particle before the update, pbest i (t-1) represents the optimal position of the i-th particle before the update, gbest(t-1) represents the global optimal position of the particle swarm before the update, and X i (t) represents the updated position of the i-th particle, Xi (t-1) is the position of the i-th particle before updating.

[0073] Step S1310, judging whether t < T max is established; if so, assigning t+1 to t, and returning to execute the above step S137; if not, selecting a suitable non-dominated solution from the current storage of the Pareto optimal solution set in the storage, and outputting the non-dominated solution as the optimal phase-shift ratio combination;

[0074] Optionally, the non-dominated solution corresponding to the minimum output backflow power of the DAB converter is selected from the Pareto optimal solution set, or the non-dominated solution corresponding to the minimum deviation between the average transmission power of the DAB converter and the preset average transmission power reference value is selected from the Pareto optimal solution set.

[0075] In the multi-objective particle swarm algorithm, considering that excessive dependence on the dominant solution may lead to the algorithm falling into a local optimal solution, using the non-dominant solution can include some non-dominant solutions in the storage to increase the diversity and global exploration ability of the search, so that the optimal phase-shift ratio combination obtained finally can meet the requirements of reaching the required power transmission level and reducing the output backflow power as much as possible to make it as close to zero as possible.

[0076] In some embodiments, the optional implementation of the above step S140 is to calculate a second difference value between the preset voltage reference value and the current output voltage of the DAB converter and process it through a PI controller, and the PI controller finally realizes stable output of the voltage by adjusting the outer phase-shift angle between the corresponding switch tubes of the two bridge pairs, that is, adjusting the current output voltage of the DAB converter to equal the preset voltage reference value through the PI controller can obtain the outer phase-shift angle correction value D 2T .

[0077] In the DAB converter, the outer phase-shift angle is one of the key factors affecting the energy transmission efficiency. By dynamically adjusting the size of the outer phase-shift angle according to the actual operating conditions of the DAB converter and combining the PI controller, the DAB converter can realize efficient and stable energy transmission.

[0078] In some embodiments, the optimal phase-shift ratio combination includes the optimal outer phase-shift ratio d b between the input bridge and the output bridge, the optimal inner phase-shift ratio d 1b of the input bridge, and the optimal inner phase-shift ratio d 2b of the output bridge. The implementation process of the above step S150 includes but is not limited to the following:

[0079] Step S151, based on the optimal inner phase-shift ratio d 1b of the input bridge, calculating the optimal inner phase-shift angle of the input bridge as D1b = d 1b π;

[0080] Step S152, based on the optimal internal phase shift d 2b of the output bridge, the optimal internal phase angle D 2b = d 2b π;

[0081] Step S153, based on the optimal external phase shift d b between the input bridge and the output bridge and the external phase angle correction value D 2T , the optimal external phase angle D b = d b π + D 2T between the input bridge and the output bridge is calculated.

[0082] Step S154, based on the optimal internal phase angle D 1b of the input bridge, the optimal internal phase angle D 2b of the output bridge and the optimal external phase angle D b between the input bridge and the output bridge, the all gate pulse signals (i.e. the PWM signals of each switch tube) of the DAB converter are generated by combining the timer and the phase accumulator to control the DAB converter, that is, each gate pulse signal is used to control the corresponding switch tube contained in the DAB converter.

[0083] More specifically, the formation of the PWM (Pulse-Width Modulation) signals in the DAB converter actually determines the efficiency of power conversion and the waveform quality of the output voltage, and the optional implementation of the above step S154 is: the phase accumulator is initialized to have a value of zero or a preset initial phase value, and the accumulation step of the phase accumulator is set according to the preset PWM frequency requirement, which is in a proportional relationship with the switching frequency f S ; the timer is initialized to have a period matching the period of the PWM signal; the timer is controlled to generate an interrupt event at the end of each period, so that the value of the phase accumulator is increased by the accumulation step, when the value of the phase accumulator reaches the optimal internal phase angle D 1b of the input bridge, four PWM signals corresponding to the four switch tubes (S1-S4) contained in the input bridge are generated, and when the value of the phase accumulator reaches the optimal internal phase angle D b of the output bridge after adding the optimal external phase angle D 2b between the input bridge and the output bridge, the four PWM signals corresponding to the four switch tubes (S1-S4) contained in the output bridge are generated.When the output bridge is generated, four PWM signals corresponding to four switch tubes (S5-S8) contained in the output bridge are generated, and a dead time needs to be set between two PWM signals corresponding to two switch tubes on the same bridge arm to avoid the short circuit phenomenon caused by the simultaneous conduction of the two switch tubes.

[0084] In the embodiment of the present application, in the case that the DAB converter does not reach the expected power output level, the particle swarm algorithm is used to find the optimal phase shift ratio combination of the DAB converter by minimizing the deviation of the average transmission power of the DAB converter and the output backflow power, and it is proposed that the outer phase shift angle of the DAB converter needs to be corrected when the optimal phase shift ratio combination is put into application, so that the DAB converter can maintain as high energy transmission efficiency as possible and reduce the influence of the output backflow power after adjustment, thereby enhancing the stability of the DAB converter.

[0085] In addition, the embodiment of the present application also provides a computer readable storage medium, and the computer readable storage medium stores a computer program. The computer program is executed by a processor to realize the DAB converter control method based on the global minimum backflow power in the above embodiment. The computer readable storage medium includes but is not limited to any type of disk (including a floppy disk, a hard disk, an optical disk, a CD-ROM and a magneto-optical disk), a ROM (Read-Only Memory), a RAM (Random Access Memory), an EPROM (Erasable Programmable Read-Only Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), a flash memory, a magnetic card or an optical card. That is, the storage device includes any medium that stores or transmits information in a readable form by a device (for example, a computer, a mobile phone and the like), and can be a read-only memory, a magnetic disk or an optical disk and the like.

[0086] In addition, FIG. 3 is a schematic diagram of a hardware structure of a computer device according to an embodiment of the present application. The computer device includes a processor 220, a memory 230, an input unit 240, a display unit 250, and the like. Those skilled in the art can understand that the device structure shown in FIG. 3 does not constitute a limitation on all devices, and some components can be combined or more or fewer components can be included. The memory 230 can be used to store a computer program 210 and various function modules. The processor 220 runs the computer program 210 stored in the memory 230, thereby performing various function applications and data processing of the device. The memory can be an internal memory or an external memory, or include an internal memory and an external memory. The internal memory can include a read-only memory (ROM), a programmable ROM (PROM), an electrically programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a flash memory, or a random memory. The external memory can include a hard disk, a floppy disk, a USB memory, a magnetic tape, and the like. The memory 230 disclosed in the embodiments of the present application includes but is not limited to the above-mentioned types of memory. The memory 230 disclosed in the embodiments of the present application is only an example and not a limitation.

[0087] The input unit 240 is used to receive the input of signals and receive the keyword input by the user. The input unit 240 can include a touch panel and other input devices. The touch panel can collect the touch operation of the user thereon or nearby (such as the operation of the user on or near the touch panel by using a finger, a stylus, or any suitable object or accessory), and drive the corresponding connection device according to the pre-set program; the other input devices can include but are not limited to one or more of a physical keyboard, a function key (such as a play control button, an on-off button, and the like), a trackball, a mouse, a joystick, and the like. The display unit 250 can be used to display the information input by the user or the information provided to the user and various menus of the terminal device. The display unit 250 can adopt the form of a liquid crystal display, an organic light-emitting diode, and the like. The processor 220 is the control center of the terminal device, connects all parts of the device through various interfaces and lines, executes the software program and / or module stored in the memory 230, and calls the data stored in the memory 230, thereby performing various functions and processing data.

[0088] As an embodiment, the computer device includes a processor 220, a memory 230, and a computer program 210, wherein the computer program 210 is stored in the memory 230 and configured to be executed by the processor 220, and the computer program 210 is configured to perform the DAB converter control method based on the global minimum backflow power in one of the above-mentioned embodiments.

[0089] The terms "including", "containing", "having" and their conjugates, as used throughout the present application and the preceding description of the related drawings, are meant to encompass the presence of stated features, steps or elements, but not the exclusion of others thereof. The use of the indefinite article "a" or "an" preceding an element, installation, fabrication or step is not meant to restrict the number of those elements but to represent an example of at least one. The use of the definite article "the" preceding an element, installation, fabrication or step is not meant in a limiting sense, but to refer to that element, installation, fabrication or step in combination with at least one of the previous or following occurrences of such an element, installation, fabrication or step. The use of the term "comprising" or "comprises" used in the context of describing constructional elements of a whole or part of a process, method, system, product or apparatus is not meant to be construed as implying any servitudes with regard to the described elements, but to indicate that the elements so described are included in the process, method, system, product or apparatus, but not excluding other elements or additional or other steps which can be inherent to such a process, method, system, product or apparatus.

[0090] In the present application, it should be understood that "at least one" means one or more, "multiple" means two or more. "And / or" is used to describe the relationship between associated objects, which means that there can be three relationships, for example, "A and / or B" can mean: only A, only B, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects. "At least one of the following" or similar expressions means any combination of these items, including any combination of single or multiple items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0091] Although the description of the present application has been quite detailed and particularly described with respect to several embodiments, it is not intended to be limited to any of these details or embodiments or any particular embodiment, but should be considered to effectively encompass the intended scope of the present application by reference to the appended claims, taking into account the prior art, providing a broad interpretation of these claims. In addition, the present application is described above in embodiments that the inventors can foresee, the purpose of which is to provide a useful description, and non-essential modifications to the present application that have not yet been foreseen can still represent equivalent modifications of the present application.

Claims

1. A DAB converter control method based on global minimum circulating power, the DAB converter applying to phase-shift ratio combination when performing triple phase-shift control, the method comprising: obtaining a current consumption power inside the DAB converter and determining whether it is equal to a preset power threshold; if not, obtaining a current input voltage and a current output voltage of the DAB converter, and then optimizing a current phase-shift ratio combination of the DAB converter by using a particle swarm algorithm to minimize a deviation of an average transmission power and an output circulating power of the DAB converter, to obtain an optimal phase-shift ratio combination; determining an outer phase-shift angle correction value according to a preset voltage reference value and the current output voltage; and controlling the DAB converter according to the optimal phase-shift ratio combination and the outer phase-shift angle correction value. The DAB converter comprises a transformer, an inductor, and input and output bridges which are mutually symmetrical, and the phase-shift ratio combination comprises an inner phase-shift ratio d1 of the input bridge, an inner phase-shift ratio d2 of the output bridge, and an outer phase-shift ratio d between the input and output bridges. When it is determined that the current consumption power is equal to the preset power threshold, the current phase-shift ratio combination of the DAB converter is taken as the optimal phase-shift ratio combination. The obtaining of the current consumption power inside the DAB converter comprises: obtaining a current input power and a current output power of the DAB converter; and calculating a first difference value between the current input power and the current output power, and taking the first difference value as the current consumption power. The average transmission power of the DAB converter is calculated by the following expression:

2. The DAB converter control method based on global minimum- backflow power according to claim 1, wherein, The output circulating power of the DAB converter is calculated by the following expression:

3. The DAB converter control method based on global minimum- backflow power according to claim 1, wherein, The determination of the outer phase-shift angle correction value according to the preset voltage reference value and the current output voltage comprises: calculating a second difference value between the preset voltage reference value and the current output voltage, and then processing the second difference value by using a PI controller to obtain the outer phase-shift angle correction value.

4. The DAB converter control method based on global minimum- backflow power according to claim 1, wherein, The control of the DAB converter according to the optimal phase-shift ratio combination and the outer phase-shift angle correction value comprises: determining an optimal inner phase-shift angle of the input bridge according to the optimal inner phase-shift ratio of the input bridge; determining an optimal inner phase-shift angle of the output bridge according to the optimal inner phase-shift ratio of the output bridge; determining an optimal outer phase-shift angle between the input and output bridges according to the outer phase-shift angle correction value and the optimal outer phase-shift ratio between the input and output bridges; and generating all gate pulse signals of the DAB converter by using a phase accumulator and a timer according to the optimal inner phase-shift angle of the input bridge, the optimal inner phase-shift angle of the output bridge, and the optimal outer phase-shift angle between the input and output bridges, to control the DAB converter. 9.A computer device comprising a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement the DAB converter control method based on global minimum circulating power according to any one of claims 1 to 8. ​ 5. The DAB converter control method based on global minimum- backflow power of claim 2, wherein, ​ When the DAB converter operates in a mode where d > d2: When the DAB converter operates in the d < d2 mode: where P is the average transmitted power of the DAB converter, V i the input voltage of the DAB converter V o Voutis the output voltage of the DAB converter, f S is the switching frequency and L is the inductance value of the inductor.

6. The DAB converter control method based on global minimum- backflow power of claim 5, wherein, ​ When the DAB converter operates in a mode where d > d2: When the DAB converter operates in the d < d2 mode: where P b is the output backflow power of the DAB converter, n is the transformation ratio of the transformer, and k is the voltage conversion ratio.

7. The DAB converter control method based on global minimum- reflux power of claim 1, wherein, ​ ​ 8. The DAB converter control method based on global minimum- backflow power of claim 2, wherein, ​ ​ ​ ​ ​ ​ 10. A computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements the global minimum backhaul power based DAB inverter control method of any one of claims 1 to 8.

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