Trapezoidal wave control method of double-active-bridge direct-current transformer and related equipment

Abstract

The invention discloses a trapezoidal wave control method of a double-active-bridge direct-current transformer and related equipment, and relates to the technical field of direct-current transformers. In the double-active-bridge direct-current transformer, the first side of a first active bridge is electrically connected with a first direct-current port, the first end of the second side of the first active bridge is electrically connected with the first end of an auxiliary inductor, and the second end of the auxiliary inductor is electrically connected with the first end of a primary winding of an isolation transformer. The second side of the first active bridge is electrically connected with the second end of the primary winding of the isolation transformer; a secondary winding of the isolation transformer is electrically connected with a first side of a second active bridge, and a second side of the second active bridge is electrically connected with a second direct current port; the method comprises the following steps: controlling an inner phase shift angle of a first active bridge to be a first main phase shift angle, and controlling an inner phase shift angle of a second active bridge to be a second main phase shift angle; the difference value between the second main phase shift angle and the first main phase shift angle is a preset auxiliary phase shift angle. According to the embodiment of the invention, the operation reliability and efficiency of the double-active-bridge direct-current transformer can be improved.

Description

Technical Field

[0001] This application belongs to the field of DC transformer technology, and particularly relates to a trapezoidal wave control method and related equipment for a dual active bridge DC transformer. Background Technology

[0002] With the rapid development of medium-voltage direct current (MVDC) power distribution systems, the demand for efficient and reliable energy conversion between different voltage levels in these systems is becoming increasingly prominent. DC transformers (DCTs), as key power electronic equipment connecting different voltage levels and enabling bidirectional energy transfer, have become an important component in building flexible and efficient power distribution systems. Existing dual active bridge (DAB) DC transformers are widely used due to their advantages such as strong electrical isolation, symmetrical topology, and ease of high-frequency transformation. However, in medium-voltage, high-power scenarios, to increase the system voltage level and reduce device current pressure, multiple power devices need to be connected in series to construct the medium-voltage side bridge arm. At this point, how to achieve high-efficiency soft-switching control while ensuring voltage balance among the series-connected devices becomes a key challenge in engineering practice.

[0003] However, existing technologies often employ active voltage equalization control, precision drive, or passive RC / RCD absorption circuits to address voltage distribution issues in series-connected devices. The former is highly complex, while the latter suffers from high losses, making it difficult to balance efficiency and reliability. Furthermore, achieving zero-voltage switching typically relies on appropriate load current or the introduction of a resonant branch, making stable operation under extreme conditions such as light load or no-load. In addition, while traditional single-phase shift (SPS) or three-phase shift (TPS) control strategies have been extensively studied in low-voltage scenarios, they still face challenges in medium-voltage applications with series-connected devices and buffer capacitors, including insufficient control freedom and poor zero-voltage switching (ZVS) stability. Summary of the Invention

[0004] This application provides a trapezoidal wave control method and related equipment for a dual active bridge DC transformer, which can improve the reliability and efficiency of the dual active bridge DC transformer operation.

[0005] In a first aspect, embodiments of this application provide a trapezoidal wave control method for a dual active bridge DC transformer, wherein the dual active bridge DC transformer includes a first active bridge, a second active bridge, an isolation transformer, and an auxiliary inductor; The first side of the first active bridge is electrically connected to the first DC port, the first end of the second side of the first active bridge is electrically connected to the first end of the auxiliary inductor, the second end of the auxiliary inductor is electrically connected to the first end of the primary winding of the isolation transformer, and the second side of the first active bridge is electrically connected to the second end of the primary winding of the isolation transformer; the secondary winding of the isolation transformer is electrically connected to the first side of the second active bridge, and the second side of the second active bridge is electrically connected to the second DC port; the trapezoidal wave control method of this dual active bridge DC transformer includes: The inner phase shift angle of the first active bridge is controlled as the first main phase shift angle, and the inner phase shift angle of the second active bridge is controlled as the second main phase shift angle; wherein, the difference between the second main phase shift angle and the first main phase shift angle is a preset auxiliary phase shift angle.

[0006] In some possible implementations, the first active bridge includes a first arm and a second arm, and the second active bridge includes a third arm and a fourth arm; controlling the inner phase angle of the first active bridge to be a first major phase angle, and controlling the inner phase angle of the second active bridge to be a second major phase angle, includes: During the first time period within the target switching cycle, the upper half of the first bridge arm and the upper half of the third bridge arm are controlled to be turned on. During the time period outside the first time period within the target switching cycle, the upper half of the first bridge arm and the upper half of the third bridge arm are controlled to be turned off. The first time period is the period from the start time of the target switching cycle to the half-switching cycle time. During the second time period within the target switching cycle, the lower half of the second bridge arm is controlled to be turned on. During the time period outside the second time period within the target switching cycle, the lower half of the second bridge arm is controlled to be turned off. The second time period is the period from the first target time to the second target time within the target switching cycle. The first target time is separated from the start time by the first main phase shift angle, and the second target time is separated from the first target time by half a switching cycle. During the third time period within the target switching cycle, the lower half of the fourth bridge arm is controlled to be turned on. During the non-third time period within the target switching cycle, the lower half of the fourth bridge arm is controlled to be turned off. The second time period is the period from the third target time to the fourth target time within the target switching cycle. The third target time is separated from the starting time by the second main phase shift angle, and the fourth target time is separated from the third target time by half a switching cycle. Among them, the upper and lower halves of any one of the first, second, third, and fourth bridge arms are complementary and conductive.

[0007] In some possible implementations, the auxiliary phase shift angle is determined based on the switching frequency of the dual active bridge DC transformer, the inductance value of the auxiliary inductor, and the target buffer capacitor value. The target buffer capacitance value is the total equivalent buffer capacitance value on any half of the bridge arm in the first active bridge.

[0008] In some possible implementations, the auxiliary phase shift angle is determined by a first relationship based on the switching frequency of the dual active bridge DC transformer, the inductance value of the auxiliary inductor, and the target buffer capacitor value. The first relation includes:

[0009] in, To assist in phase shift angle, For switching frequency, The target buffer capacitance value, The inductance value is for the auxiliary inductor.

[0010] In some possible implementations, the trapezoidal wave control method for the dual active bridge DC transformer further includes: The active power of the dual-active-bridge DC transformer is adjusted by adjusting the values ​​of the first and second main phase shift angles, wherein the auxiliary phase shift angle between the first and second main phase shift angles is fixed.

[0011] Based on the same inventive concept, in a second aspect, embodiments of this application provide a dual active bridge DC transformer, which includes a first active bridge, a second active bridge, an isolation transformer, and an auxiliary inductor; The first side of the first active bridge is electrically connected to the first DC port, the first end of the second side of the first active bridge is electrically connected to the first end of the auxiliary inductor, the second end of the auxiliary inductor is electrically connected to the first end of the primary winding of the isolation transformer, and the second side of the first active bridge is electrically connected to the second end of the primary winding of the isolation transformer; the secondary winding of the isolation transformer is electrically connected to the first side of the second active bridge, and the second side of the second active bridge is electrically connected to the second DC port. The inner phase angle of the first active bridge is the first main phase angle, the inner phase angle of the second active bridge is the second main phase angle, and the difference between the second main phase angle and the first main phase angle is a preset auxiliary phase angle.

[0012] In some possible implementations, the first active bridge includes a first arm and a second arm, and the second active bridge includes a third arm and a fourth arm; During the first time period within the target switching cycle, the upper half of the first bridge arm and the upper half of the third bridge arm are turned on. During the time period outside the first time period within the target switching cycle, the upper half of the first bridge arm and the upper half of the third bridge arm are turned off. The first time period is the period from the start time of the target switching cycle to the half-switching cycle time. During the second time period within the target switching cycle, the lower half of the second bridge arm is turned on; during the time period outside the second time period within the target switching cycle, the lower half of the second bridge arm is turned off. The second time period is the time period from the first target time to the second target time within the target switching cycle. The first target time is separated from the start time by the first main phase shift angle, and the second target time is separated from the first target time by half a switching cycle. During the third time period within the target switching cycle, the lower half of the fourth bridge arm is turned on; during the time period outside the third time period within the target switching cycle, the lower half of the fourth bridge arm is turned off. The second time period is the time period from the third target time to the fourth target time within the target switching cycle. The third target time is separated from the starting time by the second main phase shift angle, and the fourth target time is separated from the third target time by half a switching cycle. Among them, the upper and lower halves of any one of the first, second, third, and fourth bridge arms are complementary and conductive.

[0013] In some possible implementations, the first active bridge includes a first bridge arm and a second bridge arm; The upper half of the first bridge arm includes at least one first switching unit, the lower half of the first bridge arm includes at least one second switching unit, the upper half of the second bridge arm includes at least one third switching unit, and the lower half of the second bridge arm includes at least one fourth switching unit. The first end of the upper half of the first bridge arm is electrically connected to the first end of the first DC port, the second end of the upper half of the first bridge arm is electrically connected to the first end of the lower half of the first bridge arm at the first node, and the second end of the lower half of the first bridge arm is electrically connected to the second end of the first DC port. The first end of the upper half of the second bridge arm is electrically connected to the first end of the first DC port, the second end of the upper half of the second bridge arm is electrically connected to the first end of the lower half of the second bridge arm at the second node, and the second end of the lower half of the second bridge arm is electrically connected to the second end of the first DC port. The first node is the first end of the second side of the first active bridge, and the second node is the second end of the second side of the first active bridge.

[0014] In some possible implementations, any one of the first, second, third, and fourth switching units includes: a power switch, and an anti-parallel diode and a buffer capacitor connected in parallel with the power switch, respectively.

[0015] In some possible implementations, the second active bridge includes a third arm and a fourth arm; The upper half of the third bridge arm includes at least one fifth switch unit, the lower half of the third bridge arm includes at least one sixth switch unit, the upper half of the fourth bridge arm includes at least one seventh switch unit, and the lower half of the fourth bridge arm includes at least one eighth switch unit. The first end of the upper half of the third bridge arm is electrically connected to the first end of the second DC port, the second end of the upper half of the third bridge arm is electrically connected to the first end of the lower half of the third bridge arm at the third node, and the second end of the lower half of the third bridge arm is electrically connected to the second end of the second DC port. The first end of the upper half of the fourth bridge arm is electrically connected to the first end of the second DC port, the second end of the upper half of the fourth bridge arm is electrically connected to the first end of the lower half of the fourth bridge arm at the fourth node, and the second end of the lower half of the fourth bridge arm is electrically connected to the second end of the second DC port. The third node is the first end of the first side of the second active bridge, and the fourth node is the second end of the first side of the second active bridge.

[0016] In some possible implementations, any one of the fifth, sixth, seventh, and eighth switching units includes: a power switch and anti-parallel diodes connected in parallel with the power switch. The fifth and sixth switching units also include buffer capacitors connected in parallel with the corresponding power switches; Alternatively, the seventh and eighth switching units may also include buffer capacitors connected in parallel with the corresponding power switches.

[0017] In some possible implementations, the auxiliary phase shift angle is determined based on the switching frequency of the dual active bridge DC transformer, the inductance value of the auxiliary inductor, and the target buffer capacitor value. The target buffer capacitance value is the total equivalent buffer capacitance value on any half of the bridge arm in the first active bridge.

[0018] In some possible implementations, the auxiliary phase shift angle is determined by a first relationship based on the switching frequency of the dual active bridge DC transformer, the inductance value of the auxiliary inductor, and the target buffer capacitor value. The first relation includes:

[0019] in, To assist in phase shift angle, For switching frequency, The target buffer capacitance value, The inductance value is for the auxiliary inductor.

[0020] In some possible implementations, the active power of the dual active bridge DC transformer is adjusted by adjusting the values ​​of the first main phase shift angle and the second main phase shift angle, wherein the auxiliary phase shift angle between the first main phase shift angle and the second main phase shift angle is fixed.

[0021] In some possible implementations, the first DC port is a medium-voltage DC port and the second DC port is a low-voltage DC port; the dual active bridge DC transformer also includes a clamping circuit; The clamping circuit includes a clamping diode, a clamping inductor, a clamping resistor, and a clamping capacitor; The first terminal of the clamping inductor and the anode of the clamping diode are electrically connected to the first terminal of the second active bridge, respectively. The cathode of the clamping diode and the first terminal of the clamping capacitor are electrically connected to the first terminal of the clamping resistor, respectively. The second terminal of the clamping inductor and the second terminal of the clamping resistor are electrically connected to the first terminal of the second DC port, respectively. The second terminal of the clamping capacitor is electrically connected to the second terminal of the second DC port.

[0022] Based on the same inventive concept, in a third aspect, embodiments of this application provide a dual active bridge DC transformer system, which includes a dual active bridge DC transformer and a controller; The controller is configured to perform the trapezoidal wave control method for a dual active bridge DC transformer according to any embodiment of the first aspect of this application; And / or, the dual active bridge DC transformer is the dual active bridge DC transformer of any embodiment of the second aspect of this application.

[0023] Based on the same inventive concept, in a fourth aspect, embodiments of this application provide a trapezoidal wave control device for a dual active bridge DC transformer, wherein the dual active bridge DC transformer includes a first active bridge, a second active bridge, an isolation transformer, and an auxiliary inductor. The first side of the first active bridge is electrically connected to the first DC port, the first end of the second side of the first active bridge is electrically connected to the first end of the auxiliary inductor, the second end of the auxiliary inductor is electrically connected to the first end of the primary winding of the isolation transformer, and the second side of the first active bridge is electrically connected to the second end of the primary winding of the isolation transformer; the secondary winding of the isolation transformer is electrically connected to the first side of the second active bridge, and the second side of the second active bridge is electrically connected to the second DC port; the trapezoidal wave control device of the dual active bridge DC transformer includes: The control module is used to control the inner phase angle of the first active bridge to be the first main phase angle, and to control the inner phase angle of the second active bridge to be the second main phase angle; wherein the difference between the second main phase angle and the first main phase angle is a preset auxiliary phase angle.

[0024] Fifthly, embodiments of this application provide a trapezoidal wave control device for a dual-active-bridge DC transformer, the trapezoidal wave control device for the dual-active-bridge DC transformer comprising: Processor and memory storing computer program instructions; When the processor executes the computer program instructions, it implements the trapezoidal wave control method for a dual active bridge DC transformer as provided in any of the embodiments of this application above.

[0025] Sixthly, embodiments of this application provide a computer storage medium storing computer program instructions, which, when executed by a processor, implement the trapezoidal wave control method for a dual active bridge DC transformer as provided in any of the above embodiments of this application.

[0026] In a seventh aspect, embodiments of this application provide a computer program product in which instructions, when executed by a processor of an electronic device, cause the electronic device to perform a trapezoidal wave control method for a dual active bridge DC transformer as provided in any of the embodiments of this application described above.

[0027] This application provides a trapezoidal wave control method and related equipment for a dual-active-bridge DC transformer. The dual-active-bridge DC transformer includes a first active bridge, a second active bridge, an isolation transformer, and an auxiliary inductor. A first side of the first active bridge is electrically connected to a first DC port. A first end of the second side of the first active bridge is electrically connected to a first end of the auxiliary inductor. A second end of the auxiliary inductor is electrically connected to a first end of the primary winding of the isolation transformer. The second side of the first active bridge is electrically connected to a second end of the primary winding of the isolation transformer. The secondary winding of the isolation transformer is electrically connected to a first side of the second active bridge, and the second side of the second active bridge is electrically connected to a second DC port. The inner phase shift angle of the first active bridge is controlled as a first main phase shift angle, and the inner phase shift angle of the second active bridge is controlled as a second main phase shift angle. The difference between the second main phase shift angle and the first main phase shift angle is a preset auxiliary phase shift angle.

[0028] As described above, the trapezoidal wave control method and related equipment for a dual-active-bridge DC transformer according to embodiments of this application can determine the active power transmission of the entire dual-active-bridge DC transformer system by using the first main phase shift angle of the first active bridge and the second main phase shift angle of the second active bridge. The difference between the second main phase shift angle and the first main phase shift angle is a preset auxiliary phase shift angle, which is equivalent to introducing an auxiliary phase shift angle between the control signals of the first and second active bridges. This auxiliary phase shift angle can be used to form active reactive power injection. By introducing the above-mentioned auxiliary phase shift angle, the inductor current can be adjusted to form a trapezoidal waveform consisting of a linear rising segment, a plateau segment, and a falling segment within one and a half switching cycles. Through the construction of the trapezoidal wave of the inductor current, sufficient capacitor discharge current is provided at the moment of switching device turn-on in at least some bridge arms, enabling zero-voltage turn-on across the entire power range. The charge released by the auxiliary inductor meets the capacitor discharge requirements of devices requiring soft-start, ensuring that the trapezoidal wave current meets the conditions required for some bridge arms to achieve ZVS, thereby improving the reliability and efficiency of the dual-active-bridge DC transformer operation. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic flowchart of a trapezoidal wave control method for a dual active bridge DC transformer provided in an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a dual active bridge DC transformer provided in one embodiment of this application; Figure 3 This is a schematic diagram of the modulation principle of the trapezoidal wave control method for a dual active bridge DC transformer provided in an embodiment of this application; Figure 4 This is a schematic diagram of the structure of a dual active bridge DC transformer system provided in one embodiment of this application; Figure 5 This is a schematic diagram of the trapezoidal wave control device for a dual active bridge DC transformer provided in an embodiment of this application; Figure 6 This is a schematic diagram of the trapezoidal wave control device for a dual active bridge DC transformer provided in one embodiment of this application. Detailed Implementation

[0031] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0032] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0033] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0034] In the embodiments of this application, the term "electrical connection" can refer to a direct electrical connection between two components, or it can refer to an electrical connection between two components via one or more other components.

[0035] In the embodiments of this application, the first node, the second node, and the third node are defined only for the convenience of describing the circuit structure, and the first node, the second node, and the third node are not actual circuit units.

[0036] Various modifications and variations can be made to this application without departing from its spirit or scope, which will be apparent to those skilled in the art. Therefore, this application is intended to cover modifications and variations falling within the scope of the corresponding claims (the claimed technical solutions) and their equivalents. It should be noted that the implementation methods provided in the embodiments of this application can be combined with each other without contradiction.

[0037] To address the problems of existing technologies, this application provides a trapezoidal wave control method and related equipment for a dual active bridge DC transformer, thereby solving the problem of buffer capacitor failure due to surge current in existing series devices and improving system reliability and efficiency. It should be noted that the embodiments provided in this application are not intended to limit the scope of this application.

[0038] The trapezoidal wave control method for a dual active bridge DC transformer provided in this application embodiment will be introduced below.

[0039] Figure 1 A schematic flowchart of a trapezoidal wave control method for a dual-active-bridge DC transformer according to an embodiment of this application is shown. The dual-active-bridge DC transformer includes a first active bridge, a second active bridge, an isolation transformer, and an auxiliary inductor; a first side of the first active bridge is electrically connected to a first DC port, a first end of the second side of the first active bridge is electrically connected to a first end of the auxiliary inductor, a second end of the auxiliary inductor is electrically connected to a first end of the primary winding of the isolation transformer, and a second side of the first active bridge is electrically connected to a second end of the primary winding of the isolation transformer; the secondary winding of the isolation transformer is electrically connected to a first side of the second active bridge, and a second side of the second active bridge is electrically connected to a second DC port.

[0040] like Figure 1 As shown, the trapezoidal wave control method for the dual active bridge DC transformer includes the following steps: S110, control the inner phase shift angle of the first active bridge to be the first main phase shift angle, and control the inner phase shift angle of the second active bridge to be the second main phase shift angle; wherein, the difference between the second main phase shift angle and the first main phase shift angle is a preset auxiliary phase shift angle.

[0041] To facilitate understanding of the trapezoidal wave control method for the dual active bridge DC transformer provided in this application, the dual active bridge DC transformer in the embodiments of this application will be briefly introduced below. Figure 2 This is a schematic diagram of the structure of a dual-active-bridge DC transformer provided in one embodiment of this application. Figure 2 As shown, the dual active bridge DC transformer 100 includes a first active bridge 10, a second active bridge 20, an isolation transformer T, and an auxiliary inductor L.

[0042] The first side of the first active bridge 10 is electrically connected to the first DC port, the first end of the second side of the first active bridge 10 is electrically connected to the first end of the auxiliary inductor L, the second end of the auxiliary inductor L is electrically connected to the first end of the primary winding of the isolation transformer T, and the second side of the first active bridge 10 is electrically connected to the second end of the primary winding of the isolation transformer T; the secondary winding of the isolation transformer T is electrically connected to the first side of the second active bridge 20, and the second side of the second active bridge 20 is electrically connected to the second DC port.

[0043] The first DC port is, for example, a medium-voltage side DC port, and the second DC port is, for example, a low-voltage side DC port.

[0044] The first active bridge 10 includes a first bridge arm Arm1 and a second bridge arm Arm2, and the second active bridge 20 includes a third bridge arm Arm3 and a fourth bridge arm Arm4. Each of the first bridge arm Arm1, the second bridge arm Arm2, the third bridge arm Arm3, and the fourth bridge arm Arm4 includes an upper bridge arm and a lower bridge arm.

[0045] The first end of the first bridge arm Arm1 is electrically connected to the first end of the first DC port, and the second end of the first bridge arm Arm1 is electrically connected to the second end of the first DC port. The first end of the second bridge arm Arm2 is electrically connected to the first end of the first DC port, and the second end of the second bridge arm Arm2 is electrically connected to the second end of the first DC port.

[0046] The first end of the third bridge arm Arm3 is electrically connected to the first end of the second DC port, and the second end of the third bridge arm Arm3 is electrically connected to the second end of the second DC port. The first end of the fourth bridge arm Arm4 is electrically connected to the first end of the second DC port, and the second end of the fourth bridge arm Arm4 is electrically connected to the second end of the second DC port.

[0047] The upper half of the first bridge arm Arm1 includes at least one first switching unit 11, the lower half of the first bridge arm Arm1 includes at least one second switching unit 12, the upper half of the second bridge arm Arm2 includes at least one third switching unit 13, and the lower half of the second bridge arm Arm2 includes at least one fourth switching unit 14.

[0048] The upper half of the third bridge arm Arm3 includes at least one fifth switch unit 21, the lower half of the third bridge arm Arm3 includes at least one sixth switch unit 22, the upper half of the fourth bridge arm Arm4 includes at least one seventh switch unit 23, and the lower half of the fourth bridge arm Arm4 includes at least one eighth switch unit 24.

[0049] Any of the following switching units—first switching unit 11, second switching unit 12, third switching unit 13, and fourth switching unit 14—includes a power switch and an anti-parallel diode and a buffer capacitor connected in parallel with the power switch, respectively.

[0050] Any of the fifth switching unit 21, the sixth switching unit 22, the seventh switching unit 23, and the eighth switching unit 24 includes: a power switch and anti-parallel diodes connected in parallel with the power switch. Figure 2 In the second active bridge 20 shown, the fifth switch unit 21 and the sixth switch unit 22 in the third bridge arm Arm3 do not include buffer capacitors, while the seventh switch unit 23 and the eighth switch unit 24 in the fourth bridge arm Arm4 do include buffer capacitors.

[0051] Combination Figure 2 The dual active bridge DC transformer 100 shown below will be described in detail below in terms of the specific implementation of step 110.

[0052] In S110, specifically, this application modulates the first active bridge 10 and the second active bridge 20. The inner phase shift angle of the first active bridge 10 is set as the first main phase shift angle, and the inner phase shift angle of the second active bridge 20 is set as the second main phase shift angle. The difference between the second main phase shift angle and the first main phase shift angle is a preset auxiliary phase shift angle. The first and second main phase shift angles can be used to determine the active power transmission of the entire dual-active-bridge DC voltage converter system.

[0053] In this embodiment, the difference between the second main phase shift angle and the first main phase shift angle is a preset auxiliary phase shift angle, which is equivalent to introducing an auxiliary phase shift angle between the control signals of the first active bridge 10 and the second active bridge 20. This auxiliary phase shift angle can be used to actively inject a reactive circulating current for soft switching into the dual active bridge DC transformer 100, forming active reactive power injection.

[0054] In this way, by introducing the aforementioned auxiliary phase shift angle, the inductor current can be adjusted to form a trapezoidal waveform consisting of a linear rising segment, a plateau segment, and a falling segment within one and a half switching cycles. For example, combined with... Figure 2 As shown, through the aforementioned inductor current construction, sufficient capacitor discharge current is provided at the moment of device turn-on in the first bridge arm Arm1 and the second bridge arm Arm2 of the first active bridge 10, and the fourth bridge arm Arm4 of the second active bridge 20, enabling them to achieve zero-voltage turn-on across the entire power range. The amount of charge released by the auxiliary inductor L satisfies the capacitor discharge requirements of devices requiring soft turn-on, thereby ensuring that the trapezoidal current meets the conditions required for some bridge arms to achieve ZVS.

[0055] Therefore, this embodiment achieves this by actively activating a preset bridge arm (such as...) Figure 2 The third bridge arm (Arm3) shown operates in hard switching (HS) mode, and at the cost of ensuring that the other bridge arms (such as Arm3) are powered on. Figure 2 The first bridge arm Arm1, the second bridge arm Arm2, and the fourth bridge arm Arm4 shown can stably achieve zero-voltage turn-on across the entire power range, thereby effectively solving the surge problem of the buffer capacitor, avoiding damage caused by surge current on the lossless buffer capacitor used for voltage balancing of series devices, and thus improving the reliability of the system.

[0056] It should be added that in some other embodiments, the fourth bridge arm Arm4 can also be adjusted to work in hard switching mode, while the other bridge arms achieve zero-voltage switching, which is not strictly limited here.

[0057] Optionally, according to some embodiments of this application, the first active bridge 10 includes a first bridge arm Arm1 and a second bridge arm Arm2, and the second active bridge 20 includes a third bridge arm Arm3 and a fourth bridge arm Arm4; controlling the inner phase angle of the first active bridge 10 to be a first major phase angle and controlling the inner phase angle of the second active bridge 20 to be a second major phase angle includes: During the first time period within the target switching cycle, the upper half of the first bridge arm Arm1 and the upper half of the third bridge arm Arm3 are controlled to be turned on. During the time period outside the first time period within the target switching cycle, the upper half of the first bridge arm Arm1 and the upper half of the third bridge arm Arm3 are controlled to be turned off. The first time period is the period from the start time of the target switching cycle to the half-switching cycle time. During the second time period within the target switching cycle, the lower half of the second bridge arm Arm2 is controlled to be turned on. During the time period outside the second time period within the target switching cycle, the lower half of the second bridge arm Arm2 is controlled to be turned off. The second time period is the time period from the first target time to the second target time within the target switching cycle. The first target time is separated from the start time by the first main phase shift angle, and the second target time is separated from the first target time by half a switching cycle. During the third time period within the target switching cycle, the lower half of the fourth bridge arm Arm4 is controlled to be turned on. During the non-third time period within the target switching cycle, the lower half of the fourth bridge arm Arm4 is controlled to be turned off. The second time period is the period from the third target time to the fourth target time within the target switching cycle. The third target time is separated from the starting time by the second main phase shift angle, and the fourth target time is separated from the third target time by half a switching cycle. Among them, the upper and lower halves of any one of the first arm Arm1, the second arm Arm2, the third arm Arm3, and the fourth arm Arm4 are complementary and conductive.

[0058] To facilitate understanding of the trapezoidal wave control method for the dual active bridge DC transformer 100 provided in the above embodiments, please refer to the following: Figure 3 . Figure 3 This is a schematic diagram of the modulation principle of the trapezoidal wave control method of the dual active bridge DC transformer 100 provided in an embodiment of this application.

[0059] exist Figure 3 In this diagram, T1 is the trigger signal for all devices in the upper half of the first bridge arm Arm1, T4 is the trigger signal for all devices in the lower half of the second bridge arm Arm2, T5 is the trigger signal for the devices in the upper half of the third bridge arm Arm3, and T8 is the trigger signal for the devices in the lower half of the fourth bridge arm Arm4. Ths represents half a switching cycle, t0 is the start time of the target switching cycle, t1 corresponds to the first target time in the above embodiment, t3 corresponds to the third target time in the above embodiment, and t4 corresponds to the half-switching cycle time in the above embodiment. t0 to t4 constitute a complete half-switching cycle, ensuring the formation of the trapezoidal wave and the maintenance of the soft-switching conditions.

[0060] The following is combined with Figure 3 The following explanations are provided for stages t0 to t4 in the timing diagram shown: (1) Preparation phase (t0-t1 phase): At time t0, the upper half of the first bridge arm Arm1 and the upper half of the third bridge arm Arm3 are turned on, and the first switching unit 11 in the first active bridge 10 and the fifth switching unit 21 in the second active bridge 20 are turned on simultaneously.

[0061] At this time, the first switching unit 11 in the first active bridge 10 and the fifth switching unit 21 in the second active bridge 20 are not yet turned on, and both Vab and Vcd are at zero level. The inductor current iL remains at a low level (or starts from zero).

[0062] (2) Linear rise phase of inductor current (t1-t2): At time t1, the lower half of the second bridge arm Arm2 in the first active bridge 10 is turned on, and the fourth switching unit 14 in the first active bridge 10 is turned on. At this time, both the first switching unit 11 and the fourth switching unit 14 in the second bridge arm Arm2 are turned on, causing the AC output voltage Vab of the first active bridge 10 to jump to a positive level.

[0063] During this period, the lower half of the fourth arm Arm4 of the second active bridge 20 is not conducting, the eighth switching unit 24 is not conducting, and Vcd remains zero. Therefore, a large positive voltage (Vab-Vcd>0) is applied to the auxiliary inductor L, causing the inductor current iL to rise linearly and rapidly.

[0064] exist Figure 3 In the first main phase shift angle D1, the phase shift inside the bridge arm of the first active bridge 10 is defined, namely the conduction delay of the lower half of the second bridge arm Arm2 relative to the upper half of the first bridge arm Arm1, and the conduction delay of the fourth switching unit 14 relative to the first switching unit 11.

[0065] (3) Power transmission platform stage (t2-t4): The top of the trapezoidal wave is formed in this stage. At time t2, the lower half of the fourth bridge arm Arm4 in the second active bridge 20 is turned on, and the eighth switching unit 24 is turned on. At this time, the upper half of the third bridge arm Arm3 and the lower half of the fourth bridge arm Arm4 are both turned on, and the fifth switching unit 21 and the eighth switching unit 24 are both turned on, so that the AC output voltage Vcd of the second active bridge 20 also jumps to a positive level.

[0066] Within this range, both Vab and Vcd are positive. With voltage matching, the voltage difference applied across the auxiliary inductor L is approximately zero. Therefore, the inductor current iL stops rising and remains on a peak plateau, forming the flat top of the trapezoidal wave. This is the primary active power transfer phase.

[0067] exist Figure 3 In the diagram, the second primary phase shift angle D2 defines the phase shift within the bridge arm of the second active bridge 20, specifically the conduction delay of the lower half of the fourth bridge arm Arm4 relative to the upper half of the third bridge arm Arm3, and the conduction delay of the eighth switching unit 24 relative to the fifth switching unit 21. The auxiliary phase shift angle Dz defines the external phase shift between the rising edges of Vab and Vcd.

[0068] (4) Core Modulation Action and Commutation Stage (t4): At time t4, it is important to note that when T1 and T5 are turned off simultaneously, the upper half of the first bridge arm Arm1 and the upper half of the third bridge arm Arm3 are also turned off at the same time. This action forces Vab and Vcd to be clamped to zero level simultaneously, ending the trapezoidal wave. At this instant t4, the inductor current iL is still at its peak. In this case, the energy stored in the auxiliary inductor L does not disappear immediately, but begins to play a role in the subsequent commutation stage. It will force the flow through other freewheeling diodes and charge and discharge the buffer capacitors of other bridge arms (such as the second bridge arm Arm2 and the fourth bridge arm Arm4).

[0069] By utilizing the peak freewheeling current after time t4, the buffer capacitor voltage of the next switch (such as T2, T3, T7) to be turned on in the first bridge arm Arm1, the second bridge arm Arm2, and the fourth bridge arm Arm4 is completely discharged to zero, thus creating the conditions for them to achieve zero-voltage turn-on (ZVS). In this way, through the above timing control, it can be effectively ensured that the first bridge arm Arm1, the second bridge arm Arm2, and the fourth bridge arm Arm4 all achieve zero-voltage turn-on, and no inrush current is generated on the buffer capacitor.

[0070] In this embodiment, a trapezoidal inductor current waveform is actively constructed by precisely controlling the conduction timing of T1 / T4 and T5 / T8. By simultaneously turning off the upper half of the first bridge arm Arm1 and the upper half of the third bridge arm Arm3 at time t4, the current enters the freewheeling phase at the current peak. This utilizes the energy stored in the auxiliary inductor L to provide reliable zero-voltage turn-on conditions for the first bridge arm Arm1, the second bridge arm Arm2, and the fourth bridge arm Arm4, effectively solving the surge problem of the buffer capacitor.

[0071] Optionally, according to some embodiments of this application, the auxiliary phase shift angle is determined based on the switching frequency of the dual active bridge DC transformer 100, the inductance value of the auxiliary inductor L, and the target buffer capacitor value; The target buffer capacitance value is the total equivalent buffer capacitance value on any half of the bridge arm in the first active bridge 10.

[0072] More specifically, the auxiliary phase shift angle is determined by the first relationship based on the switching frequency of the dual active bridge DC transformer 100, the inductance value of the auxiliary inductor L, and the target buffer capacitor value. The first relation includes: (1) In equation (1), To assist in phase shift angle, For switching frequency, The target buffer capacitance value, The inductance value of the auxiliary inductor L.

[0073] Thus, by determining the value of the auxiliary phase shift angle through the above first relationship, it can be effectively ensured that the reactive current generated by the auxiliary phase shift angle is sufficient to drive the buffer capacitors in the first bridge arm Arm1, the second bridge arm Arm2, and the fourth bridge arm Arm4 to be fully discharged before being turned on.

[0074] Optionally, according to some embodiments of this application, the trapezoidal wave control method for the dual active bridge DC transformer 100 further includes: The active power of the dual active bridge DC transformer 100 is adjusted by adjusting the values ​​of the first and second main phase shift angles, wherein the auxiliary phase shift angle between the first and second main phase shift angles is fixed.

[0075] Thus, by keeping the auxiliary phase shift angle constant throughout the power regulation process, the change in system power is achieved only by adjusting the first and second main phase shift angles, thereby ensuring that the ZVS conditions of the first bridge arm Arm1, the second bridge arm Arm2, and the fourth bridge arm Arm4 do not fail with changes in load or voltage.

[0076] For example, when power needs to be increased, the system power can be adjusted by simultaneously reducing the first main phase shift angle D1 of the first active bridge 10 and the second inner phase shift angle D2 of the second active bridge 20. At this time, the auxiliary phase shift angle Dz remains unchanged, and the switching states of the first bridge arm Arm1, the second bridge arm Arm2 and the fourth bridge arm Arm4 remain at zero voltage.

[0077] It is worth noting that the above control strategy is demonstrated using voltage matching as an example. When the voltage is mismatched, for example, when the low-voltage DC voltage of the second DC port is not equal to the medium-voltage DC voltage of the first DC port after being converted to the medium-voltage side by the isolation transformer T ratio, i.e., nV2 is not equal to V1, the same function can be achieved by changing the phase shift angle.

[0078] In summary, the above embodiments of this application propose an improved trapezoidal wave control method, which effectively realizes the zero-voltage turn-on state of the devices in the first bridge arm Arm1, the second bridge arm Arm2, and the fourth bridge arm Arm4 of the series dual active bridge DC transformer 100 with devices in series across the full power range. This avoids the damage caused by surge current on the lossless buffer capacitor used for voltage balancing of series devices, solves the problems of voltage balancing of series devices and surge current of buffer capacitor, and improves the reliability of the system.

[0079] For example, by simultaneously adjusting the phase relationship between the first main phase shift angle, the second main phase shift angle and the third main phase shift angle, the amplitude of the trapezoidal wave current is rematched with the platform position, thereby maintaining the ZVS of the first bridge arm Arm1, the second bridge arm Arm2 and the fourth bridge arm Arm4 even under voltage mismatch conditions.

[0080] Based on the trapezoidal wave control method of the dual active bridge DC transformer 100 provided in the above embodiments, and for the same inventive concept, this application also provides a corresponding dual active bridge DC transformer 100, which will be described below. Figure 2 A detailed introduction to the dual active bridge DC transformer 100 is provided.

[0081] like Figure 2 As shown, this application embodiment provides a dual-active-bridge DC transformer 100. This dual-active-bridge DC transformer 100 is suitable for medium-voltage DC (MVDC) power distribution systems, especially in applications with high power density and high voltage levels. The dual-active-bridge DC transformer 100 includes a first active bridge 10, a second active bridge 20, an isolation transformer T, and an auxiliary inductor L; The first side of the first active bridge 10 is electrically connected to the first DC port, the first end of the second side of the first active bridge 10 is electrically connected to the first end of the auxiliary inductor L, the second end of the auxiliary inductor L is electrically connected to the first end of the primary winding of the isolation transformer T, and the second side of the first active bridge 10 is electrically connected to the second end of the primary winding of the isolation transformer T; the secondary winding of the isolation transformer T is electrically connected to the first side of the second active bridge 20, and the second side of the second active bridge 20 is electrically connected to the second DC port. The inner phase shift angle of the first active bridge 10 is the first main phase shift angle, the inner phase shift angle of the second active bridge 20 is the second main phase shift angle, and the difference between the second main phase shift angle and the first main phase shift angle is a preset auxiliary phase shift angle.

[0082] In some examples, the first DC port is a medium-voltage DC port, which can be used to directly connect to a medium-voltage DC power grid. The second DC port is, for example, a low-voltage DC port. The isolation transformer T serves as an electrical isolation and voltage transformation unit, with a turns ratio of, for example, n:1. The auxiliary inductor L can be integrated into the isolation transformer T or externally supplied. The auxiliary inductor L works in conjunction with the isolation transformer T to adjust the current waveform and ensure stable system operation. The first active bridge 10 is connected to the first DC port (high-voltage side or medium-voltage side) and is responsible for converting DC voltage to high-frequency AC voltage. The second active bridge 20 is connected to the second DC port (low-voltage side) and is responsible for converting high-frequency AC voltage back to DC voltage.

[0083] In this application, the first main phase shift angle of the first active bridge 10 and the second main phase shift angle of the second active bridge 20 can be used to determine the active power transmission of the overall dual-active-bridge DC voltage converter system. The difference between the second main phase shift angle and the first main phase shift angle is a preset auxiliary phase shift angle, which is equivalent to introducing an auxiliary phase shift angle between the control signals of the first active bridge 10 and the second active bridge 20. This auxiliary phase shift angle can be used to form active reactive power injection.

[0084] Therefore, by introducing the aforementioned auxiliary phase shift angle, the inductor current can be adjusted to form a trapezoidal waveform consisting of a linear rising segment, a plateau segment, and a falling segment within one and a half switching cycles. For example, by constructing the aforementioned inductor current, sufficient capacitor discharge current is provided at the moment of device turn-on for the first arm Arm1 and the second arm Arm2 of the first active bridge 10, and the fourth arm Arm4 of the second active bridge 20, enabling them to achieve zero-voltage turn-on across the entire power range.

[0085] This embodiment achieves this by actively activating a preset bridge arm (such as...). Figure 2 The third bridge arm (Arm3) shown operates in hard-on mode, and at the cost of ensuring that the other bridge arms (such as Arm3) are powered on. Figure 2 The first bridge arm Arm1, the second bridge arm Arm2, and the fourth bridge arm Arm4 shown can all stably achieve zero-voltage turn-on across the entire power range.

[0086] It should be added that in some other embodiments, the fourth bridge arm Arm4 can also be adjusted to work in hard switching mode, while the other bridge arms achieve zero-voltage switching, which is not strictly limited here.

[0087] Optionally, according to some embodiments of this application, the first active bridge 10 includes a first bridge arm Arm1 and a second bridge arm Arm2, and the second active bridge 20 includes a third bridge arm Arm3 and a fourth bridge arm Arm4. During the first time period within the target switching cycle, the upper half of the first bridge arm Arm1 and the upper half of the third bridge arm Arm3 are turned on. During the time periods outside the first time period within the target switching cycle, the upper half of the first bridge arm Arm1 and the upper half of the third bridge arm Arm3 are turned off. The first time period is the period from the start time of the target switching cycle to the half-switching cycle time. During the second time period within the target switching cycle, the lower half of the second bridge arm Arm2 is turned on; during the time period outside the second time period within the target switching cycle, the lower half of the second bridge arm Arm2 is turned off. The second time period is the time period from the first target time to the second target time within the target switching cycle. The first target time is separated from the start time by the first main phase shift angle, and the second target time is separated from the first target time by half a switching cycle. During the third time period within the target switching cycle, the lower half of the fourth bridge arm Arm4 is turned on; during the time period outside the third time period within the target switching cycle, the lower half of the fourth bridge arm Arm4 is turned off. The second time period is the time period from the third target time to the fourth target time within the target switching cycle. The third target time is separated from the starting time by the second main phase shift angle, and the fourth target time is separated from the third target time by half a switching cycle. Among them, the upper and lower halves of any one of the first arm Arm1, the second arm Arm2, the third arm Arm3, and the fourth arm Arm4 are complementary and conductive.

[0088] In this embodiment, a trapezoidal inductor current waveform is actively constructed by precisely controlling the conduction timing of different upper and lower half-arms. By simultaneously turning off the upper half-arm of the first arm Arm1 and the upper half-arm of the third arm Arm3 at the aforementioned half-switching cycle, the freewheeling phase is entered at the current peak. This allows the auxiliary inductor L to store energy and provide reliable zero-voltage turn-on conditions for the first arm Arm1, the second arm Arm2, and the fourth arm Arm4, effectively solving the surge problem of the buffer capacitor.

[0089] Optionally, according to some embodiments of this application, the first active bridge 10 includes a first bridge arm Arm1 and a second bridge arm Arm2; the upper half of the first bridge arm Arm1 includes at least one first switching unit 11, the lower half of the first bridge arm Arm1 includes at least one second switching unit 12, the upper half of the second bridge arm Arm2 includes at least one third switching unit 13, and the lower half of the second bridge arm Arm2 includes at least one fourth switching unit 14; the first end of the upper half of the first bridge arm Arm1 is electrically connected to the first end of the first DC port, and the second end of the upper half of the first bridge arm Arm1 is electrically connected to the first end of the first DC port. The first end of the lower half of the first bridge arm Arm1 is connected to the first node a, and the second end of the lower half of the first bridge arm Arm1 is electrically connected to the second end of the first DC port; the first end of the upper half of the second bridge arm Arm2 is electrically connected to the first end of the first DC port, and the second end of the upper half of the second bridge arm Arm2 is electrically connected to the first end of the lower half of the second bridge arm Arm2 at the second node b, and the second end of the lower half of the second bridge arm Arm2 is electrically connected to the second end of the first DC port; wherein, the first node a is the first end of the second side of the first active bridge 10, and the second node b is the second end of the second side of the first active bridge 10.

[0090] In this embodiment, each arm of the first active bridge 10 achieves a high-voltage withstand structure through multiple switching units connected in series. Combined with... Figure 2 As shown, the upper half of the first bridge arm Arm1 includes i first switching units 11, and the lower half of the first bridge arm Arm1 includes i second switching units 12. The upper half of the second bridge arm Arm2 includes i third switching units 13, and the lower half of the second bridge arm Arm2 includes i fourth switching units 14.

[0091] Optionally, according to some embodiments of this application, any one of the first switching unit 11, the second switching unit 12, the third switching unit 13, and the fourth switching unit 14 includes: a power switch, and an anti-parallel diode and a buffer capacitor respectively connected in parallel with the power switch.

[0092] The power switches mentioned above may be fully controlled power switches, for example. Fully controlled power switches include gate turn-off thyristors, high-power transistors, power MOSFETs, or insulated-gate bipolar transistors (IGBTs), and others are not strictly limited here. The aforementioned anti-parallel diodes can be used to provide a freewheeling path.

[0093] Each of the aforementioned switching units is equipped with a buffer capacitor to achieve voltage equalization, ensuring voltage balance among the series-connected devices. By introducing an auxiliary phase shift angle to limit the discharge rate of the buffer capacitor, inrush current at the moment of turn-on can be avoided, preventing device overvoltage failure.

[0094] Combination Figure 2 As shown, the upper half of the first bridge arm Arm1 includes i first switching units 11, and the power switches in the i first switching units 11 are as follows: Figure 2 The power switches T11~T1i shown, the anti-parallel diodes in the i first switching units 11 are as follows Figure 2 The diodes D11~D1i shown, and the buffer capacitors in the i first switching units 11 are as follows: Figure 2 The buffer capacitors shown are Cs11~Cs1i.

[0095] The lower half of the first bridge arm Arm1 includes i second switching units 12, and the power switches in the i second switching units 12 are as follows: Figure 2 The power switches T21~T2i shown, and the anti-parallel diodes in the i second switching units 12 are as follows: Figure 2 The diodes D21~D2i shown, and the buffer capacitors in the i second switching units 12 are as follows: Figure 2 The buffer capacitors shown are Cs21~Cs2i.

[0096] The upper half of the second bridge arm Arm2 includes i third switching units 13, and the power switches in the i third switching units 13 are as follows: Figure 2 The power switches T31~T3i shown, i of the third switch units 13, have anti-parallel diodes as follows: Figure 2 The diodes D31~D3i shown, and the buffer capacitors in the i third switching units 13 are as follows: Figure 2 The buffer capacitors shown are Cs31~Cs3i.

[0097] The lower half of the second bridge arm Arm2 includes i fourth switching units 14, and the power switches in the i fourth switching units 14 are as follows: Figure 2 The power switches T41~T4i shown, i of the fourth switch units 14, have anti-parallel diodes as follows: Figure 2 The diodes D41~D4i shown, and the buffer capacitors in the i fourth switching units 14 are as follows: Figure 2 The buffer capacitors shown are Cs41~Cs4i.

[0098] Optionally, according to some embodiments of this application, the second active bridge 20 includes a third bridge arm Arm 3 and a fourth bridge arm Arm 4; the upper half of the third bridge arm Arm 3 includes at least one fifth switching unit 21, the lower half of the third bridge arm Arm 3 includes at least one sixth switching unit 22, the upper half of the fourth bridge arm Arm 4 includes at least one seventh switching unit 23, and the lower half of the fourth bridge arm Arm 4 includes at least one eighth switching unit 24; the first end of the upper half of the third bridge arm Arm 3 is electrically connected to the first end of the second DC port, and the second end of the upper half of the third bridge arm Arm 3 is electrically connected to the first end of the second DC port. The first end of the lower half of the three-bridge arm Arm3 is connected to the third node c, and the second end of the lower half of the third bridge arm Arm3 is electrically connected to the second end of the second DC port; the first end of the upper half of the fourth bridge arm Arm4 is electrically connected to the first end of the second DC port, and the second end of the upper half of the fourth bridge arm Arm4 is electrically connected to the first end of the lower half of the fourth bridge arm Arm4 at the fourth node d, and the second end of the lower half of the fourth bridge arm Arm4 is electrically connected to the second end of the second DC port; wherein, the third node c is the first end of the first side of the second active bridge 20, and the fourth node d is the second end of the first side of the second active bridge 20.

[0099] Optionally, according to some embodiments of this application, any one of the fifth switching unit 21, the sixth switching unit 22, the seventh switching unit 23, and the eighth switching unit 24 includes: a power switch and anti-parallel diodes connected in parallel with the power switch; wherein the fifth switching unit 21 and the sixth switching unit 22 further include buffer capacitors connected in parallel with the corresponding power switches; or, the seventh switching unit 23 and the eighth switching unit 24 further include buffer capacitors connected in parallel with the corresponding power switches.

[0100] Power switches, for example, may be fully controlled power switches. Fully controlled power switches include gate turn-off thyristors, high-power transistors, power MOSFETs, or insulated-gate bipolar transistors (IGBTs), and others are not strictly limited here. The aforementioned anti-parallel diodes can be used to provide a freewheeling path. The aforementioned buffer capacitors are used to ensure voltage balance among the series-connected devices.

[0101] For example, such as Figure 2 As shown, the fifth switching unit 21 includes a power switch T5 and an anti-parallel diode D5 connected in parallel with the power switch T5. The sixth switching unit 22 includes a power switch T6 and an anti-parallel diode D6 connected in parallel with the power switch T6. The seventh switching unit 23 includes a power switch T7, an anti-parallel diode D7 connected in parallel with the power switch T7, and a buffer capacitor C7. The eighth switching unit 24 includes a power switch T8, an anti-parallel diode D8 connected in parallel with the power switch T8, and a buffer capacitor C8.

[0102] In this embodiment, by selecting one of the third bridge arm (Arm3) or the fourth bridge arm (Arm4) to include a buffer capacitor, while omitting a buffer capacitor in the other bridge arm, switching losses are reduced and zero-voltage turn-on is achieved. This solves the problems of voltage balancing in series devices and inrush current from the buffer capacitor, thus improving system reliability. Furthermore, this design reduces system complexity and cost by decreasing the number of buffer capacitors.

[0103] Optionally, according to some embodiments of this application, the auxiliary phase shift angle is determined based on the switching frequency of the dual active bridge DC transformer 100, the inductance value of the auxiliary inductor L, and the target buffer capacitor value; The target buffer capacitance value is the total equivalent buffer capacitance value on any half of the bridge arm in the first active bridge 10.

[0104] Optionally, according to some embodiments of this application, the auxiliary phase shift angle is determined by a first relationship based on the switching frequency of the dual active bridge DC transformer 100, the inductance value of the auxiliary inductor L, and the target buffer capacitor value. The first relation includes:

[0105] in, To assist in phase shift angle, For switching frequency, The target buffer capacitance value, The inductance value of the auxiliary inductor L.

[0106] Thus, by determining the value of the auxiliary phase shift angle through the above first relationship, it can be effectively ensured that the reactive current generated by the auxiliary phase shift angle is sufficient to drive the buffer capacitors in the first bridge arm Arm1, the second bridge arm Arm2, and the fourth bridge arm Arm4 to be fully discharged before being turned on.

[0107] Optionally, according to some embodiments of this application, the active power of the dual active bridge DC transformer 100 is adjusted by adjusting the values ​​of the first main phase shift angle and the second main phase shift angle, wherein the auxiliary phase shift angle between the first main phase shift angle and the second main phase shift angle is fixed.

[0108] Thus, by keeping the auxiliary phase shift angle constant throughout the power regulation process, the change in system power is achieved only by adjusting the first and second main phase shift angles, thereby ensuring that the ZVS conditions of the first bridge arm Arm1, the second bridge arm Arm2, and the fourth bridge arm Arm4 do not fail with changes in load or voltage.

[0109] Optionally, according to some embodiments of this application, the first DC port is a medium-voltage DC port, and the second DC port is a low-voltage DC port; the dual active bridge DC transformer 100 further includes a clamping circuit 30; the clamping circuit 30 includes a clamping diode Ds, a clamping inductor Ls, a clamping resistor Rs, and a clamping capacitor Cs; the first end of the clamping inductor Ls and the anode of the clamping diode Ds are respectively electrically connected to the first end of the second active bridge 20, the cathode of the clamping diode Ds and the first end of the clamping capacitor Cs are respectively electrically connected to the first end of the clamping resistor Rs, the second end of the clamping inductor Ls and the second end of the clamping resistor Rs are respectively electrically connected to the first end of the second DC port, and the second end of the clamping capacitor Cs is electrically connected to the second end of the second DC port.

[0110] Specifically, the clamping circuit 30 described above can effectively limit the rate of current rise during the turn-on process, ensuring the current plateau shaping effect while avoiding overshoot caused by the reverse recovery of the switching transistor, thus improving ZVS stability. It should be noted that in actual circuit topologies, the inclusion or exclusion of the clamping circuit 30 can be flexibly selected based on actual needs; this embodiment does not impose strict limitations on this.

[0111] It should be added that, optionally, in combination Figure 2 As shown, the dual active bridge DC transformer 100 may also include a first support capacitor Cdc1 disposed between the first DC ports and a second support capacitor Cdc2 disposed between the second DC ports.

[0112] In this way, by setting the first supporting capacitor Cdc1 between the positive and negative terminals of the first DC port, high-frequency noise and ripple in the input voltage can be filtered out. The first supporting capacitor Cdc1 stabilizes the DC voltage of the first DC port by filtering, storing energy and reducing voltage spikes, thereby reducing the impact of transient voltage changes on the circuit.

[0113] By connecting the second supporting capacitor Cdc2 in parallel between the positive and negative terminals of the second DC port, the DC voltage at the second DC port can be further smoothed, ripple reduced, and the overall circuit performance and reliability improved. The second supporting capacitor Cdc2 stabilizes the DC voltage at the second DC port by smoothing the voltage, storing energy, and reducing voltage spikes.

[0114] Based on the trapezoidal wave control method for the dual active bridge DC transformer provided in the above embodiments, or the dual active bridge DC transformer provided in the above embodiments, and for the same inventive concept, this application also provides a corresponding dual active bridge DC transformer system 1000, which will be described below. Figure 4 The System 1000 with dual active bridge DC transformers is described in detail.

[0115] Figure 4This is a schematic diagram of the structure of a dual active bridge DC transformer system 1000 provided in one embodiment of this application. Figure 4 As shown, this application provides a dual active bridge DC transformer system 1000, which includes a dual active bridge DC transformer 100 and a controller 200. The controller 200 is configured to execute the trapezoidal wave control method of the dual active bridge DC transformer 100 according to any of the foregoing embodiments of this application; And / or, the dual active bridge DC transformer 100 is the dual active bridge DC transformer 100 of any of the foregoing embodiments of this application.

[0116] It should be understood that the specific functions and technical effects of the dual active bridge DC transformer system 1000 provided in the above embodiments of this application can be found in the relevant descriptions of the foregoing embodiments. For the sake of brevity, they will not be elaborated further here.

[0117] Based on the trapezoidal wave control method for a dual-active-bridge DC transformer provided in the above embodiments, and for the same inventive concept, this application also provides a trapezoidal wave control device for a dual-active-bridge DC transformer corresponding to the above-described trapezoidal wave control method. The following describes... Figure 5 A detailed introduction is given to the trapezoidal wave control device for a dual active bridge DC transformer.

[0118] Figure 5 This illustration shows a schematic diagram of a trapezoidal wave control device for a dual-active-bridge DC transformer according to an embodiment of this application. The dual-active-bridge DC transformer includes a first active bridge, a second active bridge, an isolation transformer, and an auxiliary inductor. The first side of the first active bridge is electrically connected to the first DC port, the first end of the second side of the first active bridge is electrically connected to the first end of the auxiliary inductor, the second end of the auxiliary inductor is electrically connected to the first end of the primary winding of the isolation transformer, and the second side of the first active bridge is electrically connected to the second end of the primary winding of the isolation transformer; the secondary winding of the isolation transformer is electrically connected to the first side of the second active bridge, and the second side of the second active bridge is electrically connected to the second DC port. Figure 5 The trapezoidal wave control device 500 for the dual active bridge DC transformer shown includes: The control module 510 is used to control the inner phase angle of the first active bridge to be the first main phase angle, and to control the inner phase angle of the second active bridge to be the second main phase angle; wherein the difference between the second main phase angle and the first main phase angle is a preset auxiliary phase angle.

[0119] It should be understood that the specific functions and technical effects of the trapezoidal wave control device for the dual active bridge DC transformer provided in the above embodiments of this application can be found in the relevant descriptions of the foregoing embodiments. For the sake of brevity, they will not be elaborated further here.

[0120] Based on the trapezoidal wave control method for a dual-active-bridge DC transformer provided in the above embodiments, and with the same inventive concept, this application also provides a trapezoidal wave control device for a dual-active-bridge DC transformer corresponding to the above-described trapezoidal wave control method. The following describes... Figure 6 This paper provides a detailed introduction to the trapezoidal wave control equipment for dual active bridge DC transformers.

[0121] Please see below. Figure 6 , Figure 6 This is a schematic diagram of the trapezoidal wave control device for a dual active bridge DC transformer provided in one embodiment of this application.

[0122] The trapezoidal wave control device for a dual active bridge DC transformer may include a processor 601 and a memory 602 storing computer program instructions.

[0123] Specifically, the processor 601 may include a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits that can be configured to implement the embodiments of this application.

[0124] Memory 602 may include mass storage for data or instructions. For example, and not limitingly, memory 602 may include a hard disk drive (HDD), floppy disk drive, flash memory, optical disk, magneto-optical disk, magnetic tape, or Universal Serial Bus (USB) drive, or a combination of two or more of these. Where appropriate, memory 602 may include removable or non-removable (or fixed) media. Where appropriate, memory 602 may be internal or external to the integrated gateway disaster recovery device. In a particular embodiment, memory 602 is non-volatile solid-state memory.

[0125] Memory may include read-only memory (ROM), random access memory (RAM), disk storage media devices, optical storage media devices, flash memory devices, and electrical, optical, or other physical / tangible memory storage devices. Therefore, typically, memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the methods according to one aspect of this disclosure.

[0126] The processor 601 reads and executes computer program instructions stored in the memory 602 to implement any of the trapezoidal wave control methods for dual active bridge DC transformers in the above embodiments.

[0127] In one example, the trapezoidal wave control device for the dual active bridge DC transformer may also include a communication interface 603 and a bus 610. For example, Figure 6 As shown, the processor 601, memory 602, and communication interface 603 are connected through bus 610 and complete communication with each other.

[0128] The communication interface 603 is mainly used to realize communication between various modules, devices, units and / or equipment in the embodiments of this application.

[0129] Bus 610 includes hardware, software, or both, that couples components of a trapezoidal wave control device with a dual active bridge DC transformer together. For example, and not limitingly, the bus may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), HyperTransport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an Infinite Bandwidth Interconnect, a Low Pin Count (LPC) bus, a memory bus, a Microchannel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local (VLB) bus, or other suitable buses, or combinations of two or more of these. Where appropriate, bus 610 may include one or more buses. Although specific buses are described and illustrated in embodiments of this application, any suitable bus or interconnect is contemplated herein.

[0130] The trapezoidal wave control device of the dual active bridge DC transformer executes the trapezoidal wave control method of the dual active bridge DC transformer in the embodiments of this application, thereby realizing the trapezoidal wave control method of the dual active bridge DC transformer described in the embodiments of this application.

[0131] Furthermore, in conjunction with the trapezoidal wave control method for the dual active bridge DC transformer in the above embodiments, this application embodiment can provide a computer storage medium for implementation. This computer storage medium stores computer program instructions; when these computer program instructions are executed by a processor, they implement any one of the trapezoidal wave control methods for the dual active bridge DC transformer in the above embodiments.

[0132] Based on the trapezoidal wave control method for dual active bridge DC transformers in the above embodiments, this application provides a computer program product. When the instructions in the computer program product are executed by the processor of an electronic device, the electronic device executes the trapezoidal wave control method for dual active bridge DC transformers provided in any of the above embodiments of this application.

[0133] It should be clarified that this application is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of this application is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of this application.

[0134] The functional blocks shown in the above-described structural diagram can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this application are programs or code segments used to perform the required tasks. Programs or code segments can be stored on a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried on a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, etc. Code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0135] It should also be noted that the exemplary embodiments mentioned in this application describe methods or systems based on a series of steps or apparatus. However, this application is not limited to the order of the above steps; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0136] The aspects of this disclosure have been described above with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It should be understood that each block in the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, 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, or other programmable data processing apparatus to produce a machine such that these instructions, executable via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions / actions specified in one or more blocks of the flowchart illustrations and / or block diagrams. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field-programmable logic circuit. It is also understood that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can also be implemented by special-purpose hardware performing the specified functions or actions, or can be implemented by a combination of special-purpose hardware and computer instructions.

[0137] The above description is merely a specific implementation of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A trapezoidal wave control method for a dual-active-bridge DC transformer, characterized in that, The dual active bridge DC transformer includes a first active bridge, a second active bridge, an isolation transformer, and an auxiliary inductor; The first side of the first active bridge is electrically connected to the first DC port, the first end of the second side of the first active bridge is electrically connected to the first end of the auxiliary inductor, the second end of the auxiliary inductor is electrically connected to the first end of the primary winding of the isolation transformer, and the second side of the first active bridge is electrically connected to the second end of the primary winding of the isolation transformer. The secondary winding of the isolation transformer is electrically connected to the first side of the second active bridge, and the second side of the second active bridge is electrically connected to the second DC port; the method includes: The inner phase shift angle of the first active bridge is controlled as the first main phase shift angle, and the inner phase shift angle of the second active bridge is controlled as the second main phase shift angle; wherein, the difference between the second main phase shift angle and the first main phase shift angle is a preset auxiliary phase shift angle.

2. The method according to claim 1, characterized in that, The first active bridge includes a first bridge arm and a second bridge arm, and the second active bridge includes a third bridge arm and a fourth bridge arm; controlling the inner phase angle of the first active bridge to be a first major phase angle and controlling the inner phase angle of the second active bridge to be a second major phase angle includes: During the first time period within the target switching cycle, the upper half of the first bridge arm and the upper half of the third bridge arm are controlled to be turned on. During the time period outside the first time period within the target switching cycle, the upper half of the first bridge arm and the upper half of the third bridge arm are controlled to be turned off. The first time period is the period from the start time of the target switching cycle to the half-switching cycle time. During the second time period within the target switching cycle, the lower half of the second bridge arm is controlled to be turned on; during the time period outside the second time period within the target switching cycle, the lower half of the second bridge arm is controlled to be turned off; the second time period is the period from the first target time to the second target time within the target switching cycle, the first target time is separated from the start time by the first main phase shift angle, and the second target time is separated from the first target time by half a switching cycle; During the third time period within the target switching cycle, the lower half of the fourth bridge arm is controlled to be turned on; during the time period outside the third time period within the target switching cycle, the lower half of the fourth bridge arm is controlled to be turned off; the second time period is the time period from the third target time to the fourth target time within the target switching cycle, the third target time is separated from the starting time by the second main phase shift angle, and the fourth target time is separated from the third target time by half a switching cycle; In this configuration, the upper and lower halves of any one of the first, second, third, and fourth bridge arms are complementaryly connected.

3. The method according to claim 1, characterized in that, The auxiliary phase shift angle is determined based on the switching frequency of the dual active bridge DC transformer, the inductance value of the auxiliary inductor, and the target buffer capacitor value. The target buffer capacitance value is the total equivalent buffer capacitance value on any half of the bridge arm in the first active bridge.

4. The method according to claim 3, characterized in that, The auxiliary phase shift angle is determined by the first formula based on the switching frequency of the dual active bridge DC transformer, the inductance value of the auxiliary inductor, and the target buffer capacitor value. The first relation includes: in, The auxiliary phase shift angle, The switching frequency, The target buffer capacitance value is... The inductance value of the auxiliary inductor.

5. The method according to claim 1, characterized in that, The method further includes: The active power of the dual active bridge DC transformer is adjusted by adjusting the values ​​of the first main phase shift angle and the second main phase shift angle, wherein the auxiliary phase shift angle between the first main phase shift angle and the second main phase shift angle is fixed.

6. A dual-active-bridge DC transformer, characterized in that, The dual active bridge DC transformer includes a first active bridge, a second active bridge, an isolation transformer, and an auxiliary inductor; The first side of the first active bridge is electrically connected to the first DC port, the first end of the second side of the first active bridge is electrically connected to the first end of the auxiliary inductor, the second end of the auxiliary inductor is electrically connected to the first end of the primary winding of the isolation transformer, and the second side of the first active bridge is electrically connected to the second end of the primary winding of the isolation transformer; the secondary winding of the isolation transformer is electrically connected to the first side of the second active bridge, and the second side of the second active bridge is electrically connected to the second DC port. Wherein, the inner phase shift angle of the first active bridge is the first main phase shift angle, the inner phase shift angle of the second active bridge is the second main phase shift angle, and the difference between the second main phase shift angle and the first main phase shift angle is a preset auxiliary phase shift angle.

7. The dual active bridge DC transformer according to claim 6, characterized in that, The first active bridge includes a first bridge arm and a second bridge arm, and the second active bridge includes a third bridge arm and a fourth bridge arm; During the first time period within the target switching cycle, the upper half of the first bridge arm and the upper half of the third bridge arm are turned on; during the time period outside the first time period within the target switching cycle, the upper half of the first bridge arm and the upper half of the third bridge arm are turned off. The first time period is the period from the start time of the target switching cycle to the half-switching cycle time; During the second time period within the target switching cycle, the lower half of the second bridge arm is turned on; during periods outside the second time period within the target switching cycle, the lower half of the second bridge arm is turned off. The second time period is the period from the first target time to the second target time within the target switching cycle. The first target time is separated from the start time by the first main phase shift angle, and the second target time is separated from the first target time by half a switching cycle. During the third time period within the target switching cycle, the lower half of the fourth bridge arm is turned on, and during periods other than the third time period within the target switching cycle, the lower half of the fourth bridge arm is turned off. The second time period is the period from the third target time to the fourth target time within the target switching cycle. The third target time is separated from the starting time by the second main phase shift angle, and the fourth target time is separated from the third target time by half a switching cycle. In this configuration, the upper and lower halves of any one of the first, second, third, and fourth bridge arms are complementaryly connected.

8. The dual active bridge DC transformer according to claim 6, characterized in that, The first active bridge includes a first bridge arm and a second bridge arm; The upper half of the first bridge arm includes at least one first switching unit, the lower half of the first bridge arm includes at least one second switching unit, the upper half of the second bridge arm includes at least one third switching unit, and the lower half of the second bridge arm includes at least one fourth switching unit. The first end of the upper half of the first bridge arm is electrically connected to the first end of the first DC port, the second end of the upper half of the first bridge arm is electrically connected to the first end of the lower half of the first bridge arm at the first node, and the second end of the lower half of the first bridge arm is electrically connected to the second end of the first DC port. The first end of the upper half of the second bridge arm is electrically connected to the first end of the first DC port, the second end of the upper half of the second bridge arm is electrically connected to the first end of the lower half of the second bridge arm at the second node, and the second end of the lower half of the second bridge arm is electrically connected to the second end of the first DC port. Wherein, the first node is the first end of the second side of the first active bridge, and the second node is the second end of the second side of the first active bridge.

9. The dual active bridge DC transformer according to claim 8, characterized in that, Each of the first switching unit, the second switching unit, the third switching unit, and the fourth switching unit includes: a power switch, and an anti-parallel diode and a buffer capacitor connected in parallel with the power switch.

10. The dual active bridge DC transformer according to claim 6, characterized in that, The second active bridge includes a third arm and a fourth arm; The upper half of the third bridge arm includes at least one fifth switch unit, the lower half of the third bridge arm includes at least one sixth switch unit, the upper half of the fourth bridge arm includes at least one seventh switch unit, and the lower half of the fourth bridge arm includes at least one eighth switch unit. The first end of the upper half of the third bridge arm is electrically connected to the first end of the second DC port, the second end of the upper half of the third bridge arm is electrically connected to the first end of the lower half of the third bridge arm at the third node, and the second end of the lower half of the third bridge arm is electrically connected to the second end of the second DC port. The first end of the upper half of the fourth bridge arm is electrically connected to the first end of the second DC port, the second end of the upper half of the fourth bridge arm is electrically connected to the first end of the lower half of the fourth bridge arm at the fourth node, and the second end of the lower half of the fourth bridge arm is electrically connected to the second end of the second DC port. The third node is the first end of the first side of the second active bridge, and the fourth node is the second end of the first side of the second active bridge.

11. The dual active bridge DC transformer according to claim 10, characterized in that, Any one of the fifth, sixth, seventh, and eighth switching units includes: a power switch and anti-parallel diodes connected in parallel with the power switch; The fifth and sixth switching units also include buffer capacitors connected in parallel with the corresponding power switches. Alternatively, the seventh and eighth switching units may further include a buffer capacitor connected in parallel with the corresponding power switch.

12. The dual active bridge DC transformer according to claim 10, characterized in that, The auxiliary phase shift angle is determined based on the switching frequency of the dual active bridge DC transformer, the inductance value of the auxiliary inductor, and the target buffer capacitor value. The target buffer capacitance value is the total equivalent buffer capacitance value on any half of the bridge arm in the first active bridge.

13. The dual active bridge DC transformer according to claim 12, characterized in that, The auxiliary phase shift angle is determined by the first formula based on the switching frequency of the dual active bridge DC transformer, the inductance value of the auxiliary inductor, and the target buffer capacitor value. The first relation includes: in, The auxiliary phase shift angle, The switching frequency, The target buffer capacitance value is... The inductance value of the auxiliary inductor.

14. The dual active bridge DC transformer according to claim 10, characterized in that, The active power of the dual active bridge DC transformer is adjusted by adjusting the values ​​of the first main phase shift angle and the second main phase shift angle, wherein the auxiliary phase shift angle between the first main phase shift angle and the second main phase shift angle is fixed.

15. The dual active bridge DC transformer according to claim 10, characterized in that, The first DC port is a medium-voltage DC port, and the second DC port is a low-voltage DC port; the dual active bridge DC transformer also includes a clamping circuit; The clamping circuit includes a clamping diode, a clamping inductor, a clamping resistor, and a clamping capacitor; The first end of the clamping inductor and the anode of the clamping diode are respectively electrically connected to the first end of the second active bridge. The cathode of the clamping diode and the first end of the clamping capacitor are respectively electrically connected to the first end of the clamping resistor. The second end of the clamping inductor and the second end of the clamping resistor are respectively electrically connected to the first end of the second DC port. The second end of the clamping capacitor is electrically connected to the second end of the second DC port.

16. A dual-active-bridge DC transformer system, characterized in that, The dual active bridge DC transformer system includes a dual active bridge DC transformer and a controller; The controller is configured to perform the trapezoidal wave control method for the dual active bridge DC transformer as described in any one of claims 1-5; And / or, the dual active bridge DC transformer is a dual active bridge DC transformer as described in any one of claims 6-15.

17. A trapezoidal wave control device for a dual-active-bridge DC transformer, characterized in that, The dual active bridge DC transformer includes a first active bridge, a second active bridge, an isolation transformer, and an auxiliary inductor; The first side of the first active bridge is electrically connected to the first DC port, the first end of the second side of the first active bridge is electrically connected to the first end of the auxiliary inductor, the second end of the auxiliary inductor is electrically connected to the first end of the primary winding of the isolation transformer, and the second side of the first active bridge is electrically connected to the second end of the primary winding of the isolation transformer. The secondary winding of the isolation transformer is electrically connected to the first side of the second active bridge, and the second side of the second active bridge is electrically connected to the second DC port; the device includes: The control module is used to control the inner phase angle of the first active bridge to be the first main phase angle, and to control the inner phase angle of the second active bridge to be the second main phase angle; wherein the difference between the second main phase angle and the first main phase angle is a preset auxiliary phase angle.

18. A trapezoidal wave control device for a dual active bridge DC transformer, characterized in that, The device includes: a processor and a memory storing computer program instructions; When the processor executes the computer program instructions, it implements the trapezoidal wave control method for a dual active bridge DC transformer as described in any one of claims 1-5.

19. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer program instructions, which, when executed by a processor, implement the trapezoidal wave control method for a dual active bridge DC transformer as described in any one of claims 1-5.

20. A computer program product, characterized in that, When the instructions in the computer program product are executed by the processor of the electronic device, the electronic device performs the trapezoidal wave control method for the dual active bridge DC transformer as described in any one of claims 1-5.

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