Dual-active bridge DC-DC converter hybrid half-frequency modulation method, system, device and medium

Abstract

The invention discloses a hybrid half-frequency modulation method, system and device for a dual-active bridge DC-DC converter and a medium. The method comprises the following steps: judging a working mode of a current working point of the dual-active bridge DC-DC converter according to the transmission power p, the input voltage Vin and the output voltage Vo of the dual-active bridge DC-DC converter; the modulation type is determined according to the working mode of the current working point of the dual-active bridge DC-DC converter, and the modulation type comprises three-phase shift (TPS) modulation, secondary side half-frequency modulation, primary side half-frequency modulation and double-side half-frequency modulation; according to the method, the system, the equipment and the medium, the problems of large inductive current stress and low efficiency of the DAB converter in a wide voltage range and a full power section can be effectively solved.

Description

Technical Field

[0001] The invention belongs to the field of power electronic technology DC / DC converters, and relates to a hybrid half-frequency modulation method, system, equipment and medium for a dual active bridge DC-DC converter. Background Art

[0002] In response to the strategic goals of carbon peak and carbon neutrality, DC microgrid and electric vehicle technologies have developed rapidly. In this context, bidirectional DC / DC converters, as important devices connecting DC buses of different voltage levels with various energy storage units, play a key role. In particular, the performance of the converter is crucial in the management and optimization of energy flow. Among them, the dual active bridge (DAB) converter has gradually become the focus of widespread attention due to its high power density, bidirectional power flow capability, and wide soft switching (Zero Voltage Switching, ZVS) operating range. However, the difference between full load and light load efficiency of DAB converters may exceed 10% under the same operating voltage; in addition, under different operating voltage conditions, even if the transmission power is the same, the efficiency of the converter is significantly different. These problems have seriously restricted the promotion and industrialization of DAB converters in industrial applications.

[0003] The most commonly used modulation strategy for DAB converters is single phase shift modulation (SPS), which only provides one control variable and therefore cannot provide optimization space under more complex operating conditions. When the input and output voltages do not match, the inductor current stress will increase significantly, causing some switches to be unable to maintain ZVS conditions, which in turn significantly reduces the operating efficiency at light loads. In order to expand the ZVS operating range, reduce reactive power, and improve efficiency at light loads, the industry has successively proposed modulation strategies such as extended phase shift (EPS), dual phase shift (DPS), and triple phase shift (TPS) and their optimization solutions. These strategies have improved system performance to a certain extent, but when the DAB converter operates in a wide voltage range, if these modulation strategies continue to be used, the current stress will increase significantly at the same power level, which will have a negative impact on the overall efficiency of the system. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a dual active bridge DC-DC converter hybrid half-frequency modulation method, system, device and medium, which can effectively solve the problems of large inductor current stress and low efficiency of DAB converter in a wide voltage range and full power range.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme:

[0006] In one aspect, the present invention provides a dual active bridge DC-DC converter hybrid half-frequency modulation method, comprising:

[0007] According to the transmission power p and input voltage V of the dual active bridge DC-DC converter in And the output voltage V o Determine the working mode of the current working point of the dual active bridge DC-DC converter;

[0008] The type of modulation is determined according to the working mode of the current working point of the dual active bridge DC-DC converter, and the modulation types include three-phase shift (TPS) modulation, secondary half-frequency modulation, primary half-frequency modulation and bilateral half-frequency modulation.

[0009] The hybrid half-frequency modulation method of the dual active bridge DC-DC converter of the present invention is further improved in that:

[0010] Furthermore, the per-unit values ​​of transmission power and current stress of the secondary half-frequency modulation, the primary half-frequency modulation and the bilateral half-frequency modulation are shown in Table 1:

[0011] Table 1

[0012]

[0013]

[0014] Among them, in the secondary half-frequency modulation, the inward shift ratio of the primary H bridge is D1, and the outward shift ratio between the primary and secondary sides is D2; in the primary half-frequency modulation, the inward shift ratio of the secondary H bridge is D1, and the outward shift ratio between the primary and secondary sides is D2; in the double-side half-frequency modulation, the outward shift ratio between the primary and secondary sides is D2. s is the voltage conversion ratio.

[0015] Furthermore, the phase shift combination and the corresponding current stress I in a wide voltage range and full power range under TPS modulation are p As shown in Table 2:

[0016] Table 2

[0017]

[0018] Furthermore, the phase shift combination and current stress of the secondary side half-frequency modulation are shown in Table 3:

[0019] Table 3

[0020]

[0021]

[0022] Furthermore, the shift ratio combination and current stress of primary half-frequency modulation and bilateral half-frequency modulation are shown in Table 4:

[0023] Table 4

[0024]

[0025] Furthermore, the boundary conditions of TPS modulation, secondary half-frequency modulation and primary half-frequency modulation are shown in Table 5:

[0026] Table 5

[0027]

[0028] In a second aspect of the present invention, the present invention provides a dual active bridge DC-DC converter hybrid half-frequency modulation system, comprising:

[0029] The judgment module is used to determine the transmission power p and input voltage V of the dual active bridge DC-DC converter. in And the output voltage V o Determine the working mode of the current working point of the dual active bridge DC-DC converter;

[0030] A modulation module is used to determine the type of modulation according to the working mode of the current working point of the dual active bridge DC-DC converter, and the modulation types include three-phase shift (TPS) modulation, secondary half-frequency modulation, primary half-frequency modulation and bilateral half-frequency modulation.

[0031] The dual active bridge DC-DC converter hybrid half-frequency modulation system of the present invention is further improved in that:

[0032] Furthermore, the boundary conditions of TPS modulation, secondary half-frequency modulation and primary half-frequency modulation are shown in Table 5:

[0033] Table 5

[0034]

[0035] In a third aspect of the present invention, the present invention provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the dual active bridge DC-DC converter hybrid half-frequency modulation method when executing the computer program.

[0036] In a fourth aspect of the present invention, the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of implementing the hybrid half-frequency modulation method of the dual active bridge DC-DC converter are implemented.

[0037] The present invention has the following beneficial effects:

[0038] When the hybrid half-frequency modulation method, system, device and medium of the dual-active-bridge DC-DC converter are specifically operated, the type of modulation is determined according to the working mode in which the current working point of the dual-active-bridge DC-DC converter is located. The types of modulation include three-phase-shift (TPS) modulation, secondary-side half-frequency modulation, primary-side half-frequency modulation, and bilateral half-frequency modulation. The current stress between TPS and hybrid half-frequency modulation is compared. By determining the boundaries between the four modes, the hybrid half-frequency modulation of the DAB converter based on the minimum current stress not only reduces the conduction loss, but also further improves the efficiency of the converter, solving the problems of large inductance current stress and low efficiency of the DAB converter in a wide voltage range and the full power range. Description of the Drawings

[0039] The specification drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0040] Figure 1 is the topology diagram of the DAB converter with a DC-blocking capacitor;

[0041] Figure 2 is the typical waveform diagram of secondary-side half-frequency modulation, where a represents the waveform diagram when D1 < D2; b is the waveform diagram when D1 > D2;

[0042] Figure 3 is the typical waveform diagram of primary-side half-frequency modulation, where a represents the waveform diagram when 0 < D1 + D2 < 1; b is the waveform diagram when D1 + D2 > 1;

[0043] Figure 4 is the typical waveform diagram of bilateral half-frequency modulation, where a represents the waveform diagram when 0 < D2 < 1; b is the waveform diagram when D2 > 1;

[0044] Figure 5 is the three-dimensional relationship diagram of current stress under four modes;

[0045] Figure 6 is the image of the four-mode region division;

[0046] Figure 7 is the mode switching control block diagram;

[0047] Figure 8 is the experimental waveform diagram under the working condition of point 1 selection, where a is the experimental waveform diagram of TPS modulation under the working condition of point 1 selection, and b is the experimental waveform diagram of secondary-side half-frequency modulation under the working condition of point 1 selection;

[0048] Fig. 9is the experimental waveform diagram under the working condition of point 2, where a is the TPS modulation experimental waveform diagram under the working condition of point 2, and b is the primary side half-frequency modulation experimental waveform diagram under the working condition of point 2;

[0049] Fig.10 : is the experimental waveform diagram under the working condition of point 3, where a is the TPS modulation experimental waveform diagram under the working condition of point 3, b is the secondary side half-frequency modulation experimental waveform diagram under the working condition of point 3, and c is the primary side half-frequency modulation experimental waveform diagram under the working condition of point 3;

[0050] Fig.11 is a line graph of current stress and efficiency varying with power when k=2, a is a line graph of current stress varying with power when k=2, and b is a line graph of efficiency varying with power when k=2. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] In the description of the present invention, it should be understood that the terms “include” and “comprises” indicate the presence of described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0053] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0054] It should be further understood that the term "and / or" used in the present specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects are in an "or" relationship.

[0055] It should be understood that, although the terms first, second, third, etc. may be used to describe preset ranges, etc. in the embodiments of the present invention, these preset ranges should not be limited to these terms. These terms are only used to distinguish preset ranges from each other. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0056] The word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0057] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings here can usually be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0058] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0059] Embodiment 1

[0060] refer to Figure 1 The dual active bridge DC-DC converter hybrid half-frequency modulation method of the present invention comprises the following steps:

[0061] According to the transmission power p and input voltage V of the dual active bridge DC-DC converter in And the output voltage V oDetermine the operating mode of the current operating point of the dual-active-bridge DC-DC converter, and determine the type of modulation according to the operating mode of the current operating point of the dual-active-bridge DC-DC converter. The types of modulation include three-phase-shift (TPS) modulation, secondary-side half-frequency modulation, primary-side half-frequency modulation, and bilateral half-frequency modulation.

[0062] Figure 1 Fig. is the topological structure diagram of the DAB converter. The DAB converter consists of a primary-side support capacitor C1, a secondary-side support capacitor C2, a primary-side full-bridge circuit, a secondary-side full-bridge circuit, a high-frequency transformer T, an auxiliary inductor L, and a primary-secondary side DC-blocking capacitor C b The primary-side full-bridge output voltage and the secondary-side full-bridge output voltage are V p and V s .

[0063] Reference Figures 2 to 4 , in the secondary-side half-frequency modulation, the internal phase shift ratio of the primary-side H-bridge is D1, and the external phase shift ratio between the primary and secondary sides is D2; in the primary-side half-frequency modulation, the internal phase shift ratio of the secondary-side H-bridge is D1, and the external phase shift ratio between the primary and secondary sides is D2; in the bilateral half-frequency modulation, the external phase shift ratio between the primary and secondary sides is D2. According to the analysis of the typical waveforms, the transmission characteristics of the three modes are calculated respectively, including the normalized transmission power P * and the normalized current stress, the mode domain, and the necessary conditions for realizing soft switching. Among them, the expressions of each characteristic take their normalized values, and a new voltage conversion ratio k s =2k = 2V1 / V2 is introduced in the secondary-side half-frequency modulation; a new voltage conversion ratio k s =k / 2 = V1 / 2V2 is introduced in the primary-side half-frequency modulation.

[0064] Taking one case of the secondary-side half-frequency modulation as an example, that is, when D1 < D2, the expression of the inductor current at each moment is:

[0065]

[0066] The expression of the transmission power is calculated by combining the inductor current expressions at each moment with the inductor current expressions in each time period:

[0067]

[0068] For the convenience of calculation, the transmission power is normalized to obtain:

[0069]

[0070] Since the moment when the maximum inductor current appears is different according to k s , the current stress will be divided into two cases according to k s , which are 0 < ks <1 and k s > 1, and the expressions of the per-unit values of the current stress are respectively:

[0071]

[0072] And so on, using the same analysis and calculation method to calculate the three modulation modes respectively, and the per-unit values of the transmission power and the per-unit values of the current stress of the three modulation modes are calculated as shown in Table 1.

[0073] Table 1

[0074]

[0075] The phase shift ratio combinations and the corresponding current stress under TPS modulation in the wide voltage range and the full power range are shown in Table 2.

[0076] Table 2

[0077]

[0078] Taking the low power section operation under the secondary side half-frequency modulation as an example, at this time, the relationship of the phase shift ratio is 0 ≤ D2 < D1 < 1. According to the expressions of the per-unit values of its transmission power and current stress, the Lagrangian function is established as:

[0079]

[0080] It can be calculated that the phase shift ratio combination with the minimum current stress in this case is:

[0081]

[0082] And so on to the high power section, the phase shift ratio combination and the current stress of the secondary side half-frequency modulation are calculated as shown in Table 3.

[0083] Table 3

[0084]

[0085] Similar methods can be used to summarize the phase shift ratio combinations and the current stress of the primary side half-frequency modulation and the bilateral half-frequency modulation as shown in Table 4.

[0086] Table 4

[0087]

[0088] Aiming at reducing the current stress, on the basis of ensuring the transmission power, the four modes are compared and analyzed to optimize the current stress of the DAB converter in the wide voltage range and the full power range. First, draw the three-dimensional relationship diagram of the current stress of the four modes with the voltage conversion ratio and the per-unit value of the transmission power, as Figure 5In order to divide the boundary conditions for switching between the four modes and obtain the working ranges corresponding to the four modes, the three-dimensional image is flipped to obtain its bottom view, as shown in Figure 6 As shown. Figure 6 The analysis shows that the entire operating range is divided into three regions, representing TPS modulation (region 1), secondary half-frequency modulation (region 2) and primary half-frequency modulation (region 3). By sampling points at the boundaries between modes and fitting the boundaries of the three regions, the boundary conditions between modes can be obtained and the operating range corresponding to each mode can be determined, as shown in Table 5.

[0089] Table 5

[0090]

[0091] Figure 7 The mode switching block diagram shows that the transmission power p can be controlled by the output voltage V o And the output current I o The mode switching part is obtained by transmitting power p, input voltage V in and output voltage V o Determine the working mode of the current working point and adopt appropriate modulation strategy to control the PWM wave output according to the corresponding mode.

[0092] Under the condition of point 1, the system parameters are k = 0.5, P * =0.25. According to the experiment Figure 8 The results show that the current stress in TPS control mode is 1.59A, while in primary half-frequency modulation mode, the current stress is significantly reduced to 0.633A. In contrast, the secondary half-frequency modulation mode reduces the current stress by 60.18%. This result shows that under this working condition, primary half-frequency modulation has a significant advantage in reducing current stress; for the working condition of point 2, the system parameters are adjusted to k=2, P * =0.25, the experimental results are as follows Fig. 9 As shown in the figure, the current stress in TPS control mode reaches 3.06A, while the current stress in primary half-frequency modulation mode is reduced to 1.30A. By comparison, it can be seen that primary half-frequency modulation can effectively reduce the current stress by more than 50%, which further verifies the superiority of this modulation method in reducing current stress. Under the working condition of point 3, the parameter is k=1.2, P * =0.25, the experimental waveform is as follows Fig.10As shown. By comparing the current stress, it can be concluded that the current stress in the TPS control mode is lower than that in the secondary half-frequency modulation, with a difference of 1.30A. At the same time, compared with the primary half-frequency modulation, the current stress in the TPS control mode is lower, reducing by 3.45A. This result is consistent with the theoretical analysis results based on regional division, further proving that different modulation methods have significant differences in the impact of current stress under various working conditions.

[0093] The above measured data show that the proposed hybrid half-frequency modulation effectively reduces the current stress of the DAB converter, and the mode division within the operating area is reasonable. To further verify the improvement of efficiency by modulation, sampling experiments on current stress and efficiency were carried out for the full power range under a fixed voltage conversion ratio. Fig.11 The measured data under the condition of k = 2 are shown. The hybrid half-frequency modulation significantly reduces the current stress and improves the converter efficiency.

[0094] Embodiment 2

[0095] The dual active bridge DC-DC converter hybrid half-frequency modulation system of the present invention comprises:

[0096] The judgment module is used to determine the transmission power p and input voltage V of the dual active bridge DC-DC converter. in And the output voltage V o Determine the working mode of the current working point of the dual active bridge DC-DC converter;

[0097] A modulation module is used to determine the type of modulation according to the working mode of the current working point of the dual active bridge DC-DC converter, and the modulation types include three-phase shift (TPS) modulation, secondary half-frequency modulation, primary half-frequency modulation and bilateral half-frequency modulation.

[0098] The division of modules in the embodiments of the present application is schematic and is only a logical function division. There may be other division methods in actual implementation. In addition, each functional module in each embodiment of the present application may be integrated into a processor, or may exist physically separately, or two or more modules may be integrated into one module. The above-mentioned integrated modules may be implemented in the form of hardware or in the form of software functional modules.

[0099] Embodiment 3

[0100] 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 steps of implementing the hybrid half-frequency modulation method of the dual active bridge DC-DC converter are implemented, for example, including: according to the transmission power p of the dual active bridge DC-DC converter, the input voltage V inAnd the output voltage V o Determine the working mode of the current working point of the dual active bridge DC-DC converter; determine the type of modulation according to the working mode of the current working point of the dual active bridge DC-DC converter, and the modulation type includes three-phase shift (TPS) modulation, secondary half-frequency modulation, primary half-frequency modulation and bilateral half-frequency modulation. Wherein, the memory may include a memory, such as a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk memory, etc.; the processor, the network interface, and the memory are interconnected through an internal bus, and the internal bus can be an industrial standard architecture bus, a peripheral component interconnection standard bus, an extended industrial standard architecture bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. The memory is used to store programs, and specifically, the program can include a program code, and the program code includes computer operation instructions. The memory can include a memory and a non-volatile memory, and provides instructions and data to the processor.

[0101] Embodiment 4

[0102] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of implementing the hybrid half-frequency modulation method of the dual active bridge DC-DC converter are implemented, for example, including: according to the transmission power p of the dual active bridge DC-DC converter, the input voltage V in And the output voltage V o Determine the working mode of the current working point of the dual active bridge DC-DC converter; determine the type of modulation according to the working mode of the current working point of the dual active bridge DC-DC converter, and the type of modulation includes three-phase shift (TPS) modulation, secondary half-frequency modulation, primary half-frequency modulation and bilateral half-frequency modulation. Specifically, the computer-readable storage medium includes, but is not limited to, for example, volatile memory and / or non-volatile memory. The volatile memory may include random access memory (RAM) and / or cache memory (cache), etc. The non-volatile memory may include read-only memory (ROM), hard disk, flash memory, optical disk, magnetic disk, etc.

[0103] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0104] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0105] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0106] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0107] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and disclosure of the invention. This application is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed by the present invention. The specification and examples are to be considered exemplary only, and the true scope and spirit of the present invention are indicated by the following claims.

[0108] It should be understood that the present invention is not limited to the exact construction that has been described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

[0109] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A dual active bridge DC-DC converter hybrid half-frequency modulation method, characterized in that: include: According to the transmission power p and input voltage V of the dual active bridge DC-DC converter in And the output voltage V o Determine the working mode of the current working point of the dual active bridge DC-DC converter; The type of modulation is determined according to the working mode of the current working point of the dual active bridge DC-DC converter, and the modulation types include three-phase shift (TPS) modulation, secondary half-frequency modulation, primary half-frequency modulation and bilateral half-frequency modulation.

2. The hybrid half-frequency modulation method of the dual active bridge DC-DC converter according to claim 1, characterized in that: The per-unit values ​​of transmission power and current stress of secondary half-frequency modulation, primary half-frequency modulation and bilateral half-frequency modulation are shown in Table 1: Table 1 Among them, in the secondary half-frequency modulation, the inward shift ratio of the primary H bridge is D1, and the outward shift ratio between the primary and secondary sides is D2; in the primary half-frequency modulation, the inward shift ratio of the secondary H bridge is D1, and the outward shift ratio between the primary and secondary sides is D2; in the double-side half-frequency modulation, the outward shift ratio between the primary and secondary sides is D2, k s is the voltage conversion ratio.

3. The hybrid half-frequency modulation method of the dual active bridge DC-DC converter according to claim 1, characterized in that: Phase shift combinations and corresponding current stress I in a wide voltage range and full power range under TPS modulation p As shown in Table 2: Table 2 4. The hybrid half-frequency modulation method of the dual active bridge DC-DC converter according to claim 1, characterized in that: The phase shift combination and current stress of the secondary half-frequency modulation are shown in Table 3: Table 3 5. The hybrid half-frequency modulation method of the dual active bridge DC-DC converter according to claim 1, characterized in that: The shift ratio combination and current stress of primary half-frequency modulation and bilateral half-frequency modulation are shown in Table 4: Table 4 6. The hybrid half-frequency modulation method of the dual active bridge DC-DC converter according to claim 1, characterized in that: The boundary conditions of TPS modulation, secondary half-frequency modulation and primary half-frequency modulation are shown in Table 5: Table 5 7. A dual active bridge DC-DC converter hybrid half-frequency modulation system, characterized in that: include: The judgment module is used to determine the transmission power p and input voltage V of the dual active bridge DC-DC converter. in And the output voltage V o Determine the working mode of the current working point of the dual active bridge DC-DC converter; A modulation module is used to determine the type of modulation according to the working mode of the current working point of the dual active bridge DC-DC converter, and the modulation types include three-phase shift (TPS) modulation, secondary half-frequency modulation, primary half-frequency modulation and bilateral half-frequency modulation.

8. The dual active bridge DC-DC converter hybrid half-frequency modulation system according to claim 7, characterized in that: The boundary conditions of TPS modulation, secondary half-frequency modulation and primary half-frequency modulation are shown in Table 5: Table 5 9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the hybrid half-frequency modulation method of the dual active bridge DC-DC converter as described in any one of claims 1 to 6 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the hybrid half-frequency modulation method of the dual active bridge DC-DC converter as described in any one of claims 1 to 6 are implemented.

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