A three winding coupled inductor high gain dc-dc converter and method

Abstract

This invention discloses a high-gain DC-DC converter and method with a three-winding coupled inductor. The DC-DC converter includes: a DC power supply V1, an energy storage inductor L1, a switching transistor S1, an output capacitor Co, a first diode D1, a second diode D2, a third diode D3, a fourth diode Do1, a fifth diode Do2, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C11, and a three-winding coupled inductor unit. The circuit structure is simple, reducing system size and cost, increasing the converter's power density, and allowing flexible adjustment of the output voltage by changing the switching transistor's duty cycle and the number of turns of the coupled inductor. It is also suitable for the output characteristics of low-voltage DC power supplies, thereby significantly improving the converter's voltage gain.

Description

Technical Field

[0001] This invention relates to the field of DC-DC converter technology, and in particular to a three-winding coupled inductor high-gain DC-DC converter and method. Background Technology

[0002] With the widespread application of DC microgrid technology, its advantages, such as the absence of synchronization problems and minimal harmonic and reactive power impact, have made it an important research direction in the field of power electronics. Bipolar DC microgrids, as an extension of this technology, can provide symmetrical positive and negative voltages, improving system reliability, flexibility, and efficiency, and are suitable for the integration of renewable energy and emerging loads. Renewable energy sources (such as photovoltaics and energy storage batteries) have low and fluctuating output voltages, requiring high-efficiency, high-gain DC-DC converters to boost the voltage. However, these converters need to operate near their maximum duty cycle, which can easily lead to excessive stress on switching devices, significant current ripple, and a substantial decrease in energy conversion efficiency.

[0003] The prior art proposes a high-gain DC-DC converter based on the fusion of an actively switched inductor and a passively switched capacitor network. It achieves efficient voltage boosting through a non-isolated structure, and its topology is as follows: Figure 1 As shown, this topology utilizes an active switching inductor network to achieve parallel charging / series discharging of inductors and a passive switching capacitor network to achieve parallel charging / series discharging of capacitors, working together in continuous conduction mode. However, it only regulates the output voltage by simultaneously turning on and off the switching transistors S1 and S2, resulting in a limited output voltage regulation range. Furthermore, its input current is discontinuous, causing significant current ripple, which not only increases the power stress on the front-end photovoltaic modules or energy storage units but also requires a larger input filter, increasing system cost and size. Structurally, this topology relies on three independent inductors, which directly increases the overall size, weight, and cost of the magnetic core components. The increased number of magnetic components also leads to increased winding and core losses, limiting the power density and efficiency improvement of the converter. In addition, the discontinuous input current exacerbates the current stress on the switching devices, and the single control degree of freedom, under high voltage gain requirements, easily causes the switching transistors to operate at their limit duty cycle, further causing voltage spikes and electromagnetic interference problems. These factors collectively limit the applicability of this converter in modern photovoltaic-energy storage systems with strict requirements for size, efficiency, and dynamic response.

[0004] Existing technology also proposes a high-gain DC-DC converter based on a dual-switch structure and a three-winding coupled inductor, the topology of which is as follows: Figure 2As shown, high-efficiency voltage boosting is achieved through the synchronous drive of dual switches (S1, S2) and the coordinated operation of a three-winding coupled inductor. While high gain can be achieved through a high turns ratio, a high turns ratio subjects the output diode to a higher reverse voltage, requiring the selection of devices with higher voltage ratings. These devices typically have larger forward voltage drops and poorer reverse recovery characteristics, which in turn increases conduction losses and may induce turn-off oscillations. The core design and winding process of high-turn-ratio coupled inductors are also more complex, increasing cost and implementation difficulty, and reducing the efficiency and lifespan of the converter. Another drawback is the higher voltage stress on the components, which affects the equivalent series resistance of the windings, the on-resistance of the diodes, and the reverse recovery characteristics.

[0005] In addition, Chinese patents CN120200481A and CN118282202A both provide design concepts for adjusting bipolar output voltage by using the turns ratio of coupling inductors and the duty cycle of switching transistors. However, they are respectively based on a three-level boost circuit and two boost circuits connected in anti-parallel, which involve more components and have a more complex structure.

[0006] In view of the above, this application is hereby submitted. Summary of the Invention

[0007] This application provides a three-winding coupled inductor high-gain DC-DC converter and method, which solves the technical problem of complex structure in existing high-gain DC-DC converters and achieves the technical effect of optimizing the design structure of high-gain DC-DC converters.

[0008] In a first aspect, this application provides a three-winding coupled inductor high-gain DC-DC converter, comprising:

[0009] DC power supply V1, energy storage inductor L1, switching transistor S1, output capacitor Co, first diode D1, second diode D2, third diode D3, fourth diode Do1, fifth diode Do2, first capacitor C1, second capacitor C2, third capacitor C3, fourth capacitor C11, and a three-winding coupled inductor unit; the three-winding coupled inductor unit includes a first winding N1, a second winding N2, and a third winding N3 that are coupled to each other;

[0010] In this configuration, one end of the energy storage inductor L1 is connected to the positive terminal of the DC power supply V1, and the other end of the energy storage inductor L1 is connected to the positive terminal of the first diode D1. The negative terminal of the second diode D1 is connected to the same-name terminal of the second winding N2, and the opposite-name terminal of the second winding N2 is connected to the negative terminal of the second capacitor C2. The positive terminal of the second capacitor C2 is connected to the positive terminal of the fourth diode Do1, and the negative terminal of the fourth diode Do1 is connected to the positive terminal of the output capacitor Co. The negative terminal of the output capacitor Co is connected to the positive terminal of the fifth diode Do2, and the negative terminal of the fifth diode Do2 is connected to the negative terminal of the third capacitor C3. The positive terminal of the third capacitor C3 is connected to the same-name terminal of the third winding N3, and the opposite-name terminal of the third winding N3 is connected to the negative terminal of the DC power supply V1.

[0011] The drain of the switching transistor S1 is connected to the first node between the energy storage inductor L1 and the first diode D1, and the source of the switching transistor S1 is connected to the negative terminal of the DC power supply V1.

[0012] The positive terminal of the fourth capacitor C11 is connected to the second node between the first diode D1 and the second winding N2, and the negative terminal of the fourth capacitor C11 is connected to the negative terminal of the DC power supply V1.

[0013] The same-name terminal of the first winding N1 is connected to the first node, the opposite-name terminal of the first winding N1 is connected to the negative terminal of the first capacitor C1, and the positive terminal of the first capacitor C2 is connected to the third node between the second capacitor C2 and the fourth diode Do1.

[0014] The positive terminal of the second diode D2 is connected to the second node, and the negative terminal of the second diode is connected to the third node; the positive terminal of the third diode D3 is connected to the fourth node between the fifth diode Do2 and the third capacitor C3, and the negative terminal of the third diode D3 is connected to the negative terminal of the DC power supply V1.

[0015] In some embodiments of this application, based on the aforementioned scheme, the DC-DC converter uses a unipolar PWM control method to control the switching transistor S1 to turn on or off, thereby switching different operating modes of the DC-DC converter.

[0016] In some embodiments of this application, based on the aforementioned scheme, when the switching transistor S1 is turned on, the DC-DC converter switches to the first operating mode: the second diode D2 and the third diode D3 are forward-biased, the first diode D1, the fourth diode Do1, and the fifth diode Do2 are reverse-biased and cut off, the DC power supply V1 transfers electrical energy to the energy storage inductor L1, the current of the energy storage inductor L1 increases linearly, the first capacitor C1 releases electrical energy to the first winding N1, and the output capacitor Co releases electrical energy to the parallel load.

[0017] In some embodiments of this application, based on the aforementioned scheme, when the switching transistor S1 is turned off, the DC-DC converter switches to the second operating mode: the first diode D1, the fourth diode Do1, and the fifth diode Do2 are forward-biased, the second diode D2 and the third diode D3 are reverse-biased and cut off, the energy storage inductor L1 transfers electrical energy to the fourth capacitor C11 through the first diode D1, the current of the energy storage inductor L1 decreases linearly, and the first winding N1, the second winding N2, and the third winding N3 transfer electrical energy to the output capacitor Co.

[0018] In some embodiments of this application, based on the aforementioned scheme, the turns ratio between the first winding N1, the second winding N2, and the third winding N3 is 1:n1:n2;

[0019] When the circuit elements in the DC-DC converter operate under ideal conditions, the leakage inductance of the three-winding coupled inductor unit is ignored in steady-state analysis, and the coupled inductor is an ideal transformer, n1=N2:N1, n2=N3:N1, n1=n2=n;

[0020] In the first operating mode, the voltage relationship in the DC-DC converter is shown in equation (1):

[0021] (1)

[0022] In the second operating mode, the voltage relationship in the DC-DC converter is shown in equation (2):

[0023] (2)

[0024] Where V1 is the voltage of DC power supply V1, The voltage across the energy storage inductor L1, The voltage of the first winding N1, The voltage of the second winding N2, The voltage of the third winding N3, The voltage across the first capacitor C1. The voltage across the second capacitor C2. The voltage across the third capacitor C3. The voltage across the output capacitor Co. The output voltage of the DC-DC converter;

[0025] According to the volt-second balance theory of inductive elements:

[0026] (3)

[0027] in, This represents the duty cycle of the switching transistor S1.

[0028] According to formulas (1), (2), and (3), we get:

[0029] (4)

[0030] The output voltage gain of the DC-DC converter is:

[0031] ;(5)

[0032] In some embodiments of this application, based on the foregoing scheme, the DC power supply V1 is either a photovoltaic cell or a fuel cell.

[0033] Secondly, this application provides a three-winding coupled inductor high-gain DC-DC conversion method, applicable to the DC-DC converter provided in the first aspect, the method comprising:

[0034] By adjusting the duty cycle of the switching transistor S1 and / or adjusting the turns ratio of the three-winding coupled inductor unit, the output voltage of the DC-DC converter can reach the target voltage.

[0035] Thirdly, this application provides a bipolar DC microgrid system, including: a three-winding coupled inductor high-gain DC-DC converter as provided in the first aspect.

[0036] In some embodiments of this application, based on the aforementioned scheme, two DC-DC converters are provided, wherein the positive output terminal of one DC-DC converter is connected to the positive terminal of the DC bus of the bipolar DC microgrid, and the negative output terminal is connected to the neutral point of the DC bus of the bipolar DC microgrid.

[0037] The positive output terminal of another DC-DC converter is connected to the neutral point of the DC bus of the bipolar DC microgrid, and the negative output terminal is connected to the negative terminal of the DC bus of the bipolar DC microgrid.

[0038] Fourthly, this application provides an electronic device, comprising:

[0039] processor;

[0040] Memory used to store processor-executable instructions;

[0041] The processor is configured to execute a three-winding coupled inductor high-gain DC-DC conversion method as provided in the second aspect.

[0042] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0043] 1. By using a single switching transistor and a three-winding coupled inductor unit in a collaborative design, the circuit control logic is simplified, while the input current is made continuous, effectively reducing the input current ripple, improving the compatibility with photovoltaic modules and energy storage units, greatly simplifying the circuit control architecture and debugging process, and reducing the number of switching devices, thereby reducing the system hardware cost and failure rate.

[0044] 2. By combining the degree of freedom in adjusting the duty cycle of the switching transistor and the number of turns of the coupling inductor, a wide range of flexible adjustment of the output voltage is achieved, avoiding the situation where traditional converters need to operate at the extreme duty cycle to achieve high gain, thus improving the flexibility of voltage regulation and the range of applicable operating conditions.

[0045] 3. No need to configure voltage divider capacitors or dual-output structure, it is precisely adapted to application scenarios in photovoltaic energy storage systems that only require a single high-voltage output. It avoids the adaptation limitations of bipolar topologies to specific loads. The number of magnetic core components is reduced through magnetic integration design. Combined with input-side interleaved parallel topology and switched capacitor technology, it simplifies the circuit structure, reduces system size and cost, and improves the power density of the converter while achieving high gain.

[0046] 4. By adopting a single-switch transistor combined with unipolar PWM control, the converter achieves energy conversion through only two main operating modes, reducing the impact of transition modes, improving dynamic response speed, greatly simplifying the circuit control architecture and debugging process, and reducing the number of switching devices, thereby reducing system hardware costs and failure rate.

[0047] 5. Adapts to the output characteristics of low-voltage DC power supplies such as photovoltaic cells and energy storage batteries, and achieves voltage boosting through high-efficiency and high-gain conversion, meeting the stringent requirements of emerging power loads such as electric vehicle charging piles and photovoltaic emergency lighting systems for power supply quality, efficiency and reliability, thus expanding the application scenarios of the converter. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This is a schematic diagram of the topology of a novel high-gain DC-DC converter in the prior art.

[0050] Figure 2 This is a schematic diagram of the topology of a high-gain DC-DC converter with a dual-switch structure and a three-winding coupled inductor in the prior art.

[0051] Figure 3This is a schematic diagram of the topology of a three-winding coupled inductor high-gain DC-DC converter provided in an embodiment of this application;

[0052] Figure 4 A schematic diagram illustrating the topology of a three-winding coupled inductor high-gain DC-DC converter provided in this application embodiment;

[0053] Figure 5 Key waveform diagrams of the main components of a three-winding coupled inductor high-gain DC-DC converter provided in this application embodiment;

[0054] Figure 6a An equivalent circuit diagram of a three-winding coupled inductor high-gain DC-DC converter in the first operating mode is provided for an embodiment of this application.

[0055] Figure 6b An equivalent circuit diagram of a three-winding coupled inductor high-gain DC-DC converter in the second operating mode is provided for embodiments of this application.

[0056] Figure 7 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0057] This application provides a three-winding coupled inductor high-gain DC-DC converter and method, which solves the technical problem of complex structure in existing high-gain DC-DC converters.

[0058] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0059] Example 1

[0060] This application provides a high-gain DC-DC converter with a three-winding coupled inductor. By introducing a three-winding coupled inductor and switched capacitor technology into a conventional boost converter, the output voltage of the load can be flexibly adjusted by the duty cycle and the turns ratio of the coupled inductor. The topology derivation process is as follows: Figure 3 As shown, voltage multiplier units 1, 2, and 3 achieve voltage multiplication through the unidirectional conductivity of the corresponding diodes and the charging and discharging characteristics of the capacitors, respectively. Structurally, the input side of the converter employs an interleaved parallel connection technique, which not only significantly reduces input current ripple and improves compatibility with low-voltage energy sources such as photovoltaic modules, but also helps reduce the number of magnetic core components used, promoting increased power density and structural simplification of the converter. This converter has the advantages of low voltage stress on switching devices and high voltage gain, and the output voltage of the load can be flexibly adjusted by the duty cycle and the turns ratio of the coupling inductor.

[0061] Continue to refer to Figure 4 This is a schematic diagram of the topology of a three-winding coupled inductor high-gain DC-DC converter provided in an embodiment of this application. The three-winding coupled inductor high-gain DC-DC converter includes: a DC power supply V1, an energy storage inductor L1, a switching transistor S1, an output capacitor Co, a first diode D1, a second diode D2, a third diode D3, a fourth diode Do1, a fifth diode Do2, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C11, and a three-winding coupled inductor unit. The DC power supply V1 can be any type of photovoltaic cell or fuel cell.

[0062] The three-winding coupled inductor unit includes a first winding N1, a second winding N2, and a third winding N3 that are coupled to each other. The first winding N1 is the primary winding, while the second winding N2 and the third winding N3 are the secondary windings. The magnetizing inductance Lm is connected in parallel across the first winding N1, and the leakage inductance L1k is connected in series with the corresponding terminals of the first winding N1. The leakage inductance L1k can be ignored in the subsequent steady-state analysis. The turns ratio of the first winding N1, the second winding N2, and the third winding N3 is 1:n1:n2.

[0063] One end of the energy storage inductor L1 is connected to the positive terminal of the DC power supply V1, and the other end of the energy storage inductor L1 is connected to the positive terminal of the first diode D1. The negative terminal of the second diode D1 is connected to the same-name terminal of the second winding N2, and the opposite-name terminal of the second winding N2 is connected to the negative terminal of the second capacitor C2. The positive terminal of the second capacitor C2 is connected to the positive terminal of the fourth diode Do1, and the negative terminal of the fourth diode Do1 is connected to the positive terminal of the output capacitor Co. The negative terminal of the output capacitor Co is connected to the positive terminal of the fifth diode Do2, and the negative terminal of the fifth diode Do2 is connected to the negative terminal of the third capacitor C3. The positive terminal of the third capacitor C3 is connected to the same-name terminal of the third winding N3, and the opposite-name terminal of the third winding N3 is connected to the negative terminal of the DC power supply V1.

[0064] The drain of the switching transistor S1 is connected to the first node between the energy storage inductor L1 and the first diode D1, and the source of the switching transistor S1 is connected to the negative terminal of the DC power supply V1.

[0065] The positive terminal of the fourth capacitor C11 is connected to the second node between the first diode D1 and the second winding N2, and the negative terminal of the fourth capacitor C11 is connected to the negative terminal of the DC power supply V1.

[0066] The same-name terminal of the first winding N1 is connected to the first node, the opposite-name terminal of the first winding N1 is connected to the negative terminal of the first capacitor C1, and the positive terminal of the first capacitor C2 is connected to the third node between the second capacitor C2 and the fourth diode Do1.

[0067] The anode of the second diode D2 is connected to the second node, and the cathode of the second diode is connected to the third node. The anode of the third diode D3 is connected to the fourth node between the fifth diode Do2 and the third capacitor C3, and the cathode of the third diode D3 is connected to the cathode of the DC power supply V1.

[0068] Furthermore, the DC-DC converter uses unipolar PWM control to control the switching transistor S1 to turn it on or off, thereby switching between different operating modes of the DC-DC converter.

[0069] For simplified circuit analysis, the circuit components in the DC-DC converter operate under ideal conditions, the leakage inductance of the three-winding coupled inductor unit is ignored in steady-state analysis, and the coupled inductor is an ideal transformer. Therefore, n1 = N2:N1, n2 = N3:N1, and n1 = n2 = n. The key waveforms of the main components in the DC-DC converter are shown below. Figure 5 As shown, the left side represents the corresponding component, the red line represents the voltage, the blue line represents the current, Ts is the switching period of the switching transistor S1, and d1 is the duty cycle of the switching transistor S1.

[0070] The operating modes of a three-winding coupled inductor high-gain DC-DC converter provided in this application embodiment include a first operating mode and a second operating mode.

[0071] refer to Figure 6a , Figure 6a The blue dashed line indicates the direction of current, and the gray lines and gray components indicate no conduction. When the switching transistor S1 is on, that is... Figure 5 At t=t0, the DC-DC converter switches to the first operating mode: the second diode D2 and the third diode D3 are forward-biased, while the first diode D1, the fourth diode Do1, and the fifth diode Do2 are reverse-biased and cut off. The DC power supply V1 transfers electrical energy to the energy storage inductor L1, and the current in the energy storage inductor L1 increases linearly. The first capacitor C1 releases electrical energy to the first winding N1, the second capacitor C2 releases electrical energy to the second winding N2, and the output capacitor Co releases electrical energy to the parallel load.

[0072] In the first operating mode, the voltage relationship in the DC-DC converter is shown in equation (1):

[0073] (1)

[0074] Where V1 is the voltage of DC power supply V1, The voltage across the energy storage inductor L1, The voltage of the first winding N1, The voltage of the second winding N2, The voltage of the third winding N3, The voltage across the first capacitor C1. The voltage across the second capacitor C2. The voltage across the third capacitor C3. The voltage across the output capacitor Co. This is the output voltage of the DC-DC converter.

[0075] refer to Figure 6b , Figure 6b The blue dashed line indicates the direction of current, and the gray lines and gray components indicate no conduction. This occurs when the switch S1 is turned off, that is... Figure 5 At t=t1, the DC-DC converter switches to the second operating mode: the first diode D1, the fourth diode Do1, and the fifth diode Do2 are forward-biased, while the second diode D2 and the third diode D3 are reverse-biased and cut off. The energy storage inductor L1 transfers electrical energy to the fourth capacitor C11 through the first diode D1. The current of the energy storage inductor L1 decreases linearly, and the first winding N1, the second winding N2, and the third winding N3 transfer electrical energy to the output capacitor Co.

[0076] In the second operating mode, the voltage relationship in the DC-DC converter is shown in equation (2):

[0077] (2)

[0078] Where V1 is the voltage of DC power supply V1, The voltage across the energy storage inductor L1, The voltage of the first winding N1, The voltage of the second winding N2, The voltage of the third winding N3, The voltage across the first capacitor C1. The voltage across the second capacitor C2. The voltage across the third capacitor C3. The voltage across the output capacitor Co. This is the output voltage of the DC-DC converter.

[0079] According to the volt-second balance theory of inductive elements:

[0080] (3)

[0081] in, This represents the duty cycle of the switching transistor S1.

[0082] According to formulas (1), (2), and (3), we get:

[0083] (4)

[0084] The output voltage gain of the DC-DC converter is:

[0085] ;(5)

[0086] Example 2

[0087] Based on the same inventive concept, this application also provides a three-winding coupled inductor high-gain DC-DC conversion method, applicable to the aforementioned DC-DC converter. The method includes: adjusting the duty cycle of the switching transistor S1 and / or adjusting the turns ratio of the three-winding coupled inductor unit to make the output voltage of the DC-DC converter reach the target voltage.

[0088] Example 3

[0089] Based on the same inventive concept, this application also provides a bipolar DC microgrid system, including: a three-winding coupled inductor high-gain DC-DC converter as described above.

[0090] Furthermore, two DC-DC converters are provided, with the positive output terminal of one DC-DC converter connected to the positive terminal of the DC bus of the bipolar DC microgrid and the negative output terminal connected to the neutral point of the DC bus of the bipolar DC microgrid.

[0091] The positive output terminal of another DC-DC converter is connected to the neutral point of the DC bus of the bipolar DC microgrid, and the negative output terminal is connected to the negative terminal of the DC bus of the bipolar DC microgrid.

[0092] Example 4

[0093] Based on the same inventive concept, embodiments of this application also provide an electronic device, including:

[0094] Processor 71;

[0095] Memory 72 is used to store executable instructions of processor 71;

[0096] The processor 71 is configured to execute a three-winding coupled inductor high-gain DC-DC conversion method as described above.

[0097] Since the electronic device described in this embodiment is an electronic device used to implement the information processing method in the embodiments of this application, those skilled in the art can understand the specific implementation methods and various variations of the electronic device in this embodiment based on the information processing method described in the embodiments of this application. Therefore, how the electronic device implements the method in the embodiments of this application will not be described in detail here. Any electronic device used by those skilled in the art to implement the information processing method in the embodiments of this application falls within the scope of protection of this application.

[0098] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0099] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A three-winding coupled inductor high-gain DC-DC converter, characterized in that, include: DC power supply V1, energy storage inductor L1, switching transistor S1, output capacitor Co, first diode D1, second diode D2, third diode D3, fourth diode Do1, fifth diode Do2, first capacitor C1, second capacitor C2, third capacitor C3, fourth capacitor C11, and a three-winding coupled inductor unit; the three-winding coupled inductor unit includes a first winding N1, a second winding N2, and a third winding N3 that are coupled to each other; One end of the energy storage inductor L1 is connected to the positive terminal of the DC power supply V1, and the other end of the energy storage inductor L1 is connected to the positive terminal of the first diode D1. The negative terminal of the first diode D1 is connected to the same-name terminal of the second winding N2, and the opposite-name terminal of the second winding N2 is connected to the negative terminal of the second capacitor C2. The positive terminal of the second capacitor C2 is connected to the positive terminal of the fourth diode Do1, and the negative terminal of the fourth diode Do1 is connected to the positive terminal of the output capacitor Co. The negative terminal of the output capacitor Co is connected to the positive terminal of the fifth diode Do2, and the negative terminal of the fifth diode Do2 is connected to the negative terminal of the third capacitor C3. The positive terminal of the third capacitor C3 is connected to the same-name terminal of the third winding N3, and the opposite-name terminal of the third winding N3 is connected to the negative terminal of the DC power supply V1. The drain of the switching transistor S1 is connected to the first node between the energy storage inductor L1 and the first diode D1, and the source of the switching transistor S1 is connected to the negative terminal of the DC power supply V1. The positive terminal of the fourth capacitor C11 is connected to the second node between the first diode D1 and the second winding N2, and the negative terminal of the fourth capacitor C11 is connected to the negative terminal of the DC power supply V1. The same-name terminal of the first winding N1 is connected to the first node, the opposite-name terminal of the first winding N1 is connected to the negative terminal of the first capacitor C1, and the positive terminal of the first capacitor C1 is connected to the third node between the second capacitor C2 and the fourth diode Do1. The positive terminal of the second diode D2 is connected to the second node, and the negative terminal of the second diode D2 is connected to the third node; the positive terminal of the third diode D3 is connected to the fourth node between the fifth diode Do2 and the third capacitor C3, and the negative terminal of the third diode D3 is connected to the negative terminal of the DC power supply V1.

2. The three-winding coupled inductor high-gain DC-DC converter as described in claim 1, characterized in that, The DC-DC converter uses unipolar PWM control to control the switching transistor S1 to turn it on or off, thereby switching between different operating modes of the DC-DC converter.

3. The three-winding coupled inductor high-gain DC-DC converter as described in claim 1, characterized in that, When the switching transistor S1 is turned on, the DC-DC converter switches to the first operating mode: the second diode D2 and the third diode D3 are forward-biased, the first diode D1, the fourth diode Do1, and the fifth diode Do2 are reverse-biased and cut off. The DC power supply V1 transfers electrical energy to the energy storage inductor L1, the current of the energy storage inductor L1 increases linearly, the first capacitor C1 releases electrical energy to the first winding N1, and the output capacitor Co releases electrical energy to the parallel load.

4. The three-winding coupled inductor high-gain DC-DC converter as described in claim 1, characterized in that, When the switching transistor S1 is turned off, the DC-DC converter switches to the second operating mode: the first diode D1, the fourth diode Do1, and the fifth diode Do2 are forward-biased, the second diode D2 and the third diode D3 are reverse-biased and cut off, the energy storage inductor L1 transfers electrical energy to the fourth capacitor C11 through the first diode D1, the current of the energy storage inductor L1 decreases linearly, and the first winding N1, the second winding N2, and the third winding N3 transfer electrical energy to the output capacitor Co.

5. The three-winding coupled inductor high-gain DC-DC converter as described in claim 1, characterized in that, The turns ratio between the first winding N1, the second winding N2, and the third winding N3 is 1:n1:n2; When the circuit elements in the DC-DC converter operate under ideal conditions, the leakage inductance of the three-winding coupled inductor unit is ignored in steady-state analysis, and the coupled inductor is an ideal transformer, n1=N2:N1, n2=N3:N1, n1=n2=n; In the first operating mode, the voltage relationship in the DC-DC converter is shown in equation (1): ；（1） In the second operating mode, the voltage relationship in the DC-DC converter is shown in equation (2): ；（2） in, The voltage of DC power supply V1, The voltage across the energy storage inductor L1, The voltage of the first winding N1, The voltage of the second winding N2, The voltage of the third winding N3, The voltage across the first capacitor C1. The voltage across the second capacitor C2. The voltage across the third capacitor C3. The voltage across the fourth capacitor C11. The voltage across the output capacitor Co. This refers to the output voltage of the DC-DC converter. According to the volt-second balance theory of inductive elements: ；（3） in, This represents the duty cycle of the switching transistor S1. According to formulas (1), (2), and (3), we get: ；（4） The output voltage gain of the DC-DC converter is then: ；（5）。 6. The three-winding coupled inductor high-gain DC-DC converter as described in claim 1, characterized in that, The DC power supply V1 can be either a photovoltaic cell or a fuel cell.

7. A high-gain DC-DC converter method with three-winding coupled inductors, characterized in that, The method, applicable to any one of claims 1-6, comprises: By adjusting the duty cycle of the switching transistor S1 and / or adjusting the turns ratio of the three-winding coupled inductor unit, the output voltage of the DC-DC converter can reach the target voltage.

8. A bipolar DC microgrid system, characterized in that, include: The three-winding coupled inductor high-gain DC-DC converter as described in any one of claims 1-6.

9. The bipolar DC microgrid system as described in claim 8, characterized in that, The DC-DC converter is provided in two parts, one of which has its positive output terminal connected to the positive terminal of the DC bus of the bipolar DC microgrid and its negative output terminal connected to the neutral point of the DC bus of the bipolar DC microgrid. The positive output terminal of the other DC-DC converter is connected to the neutral point of the DC bus of the bipolar DC microgrid, and the negative output terminal is connected to the negative terminal of the DC bus of the bipolar DC microgrid.

10. An electronic device, characterized in that, include: processor; Memory used to store the processor's executable instructions; The processor is configured to execute a three-winding coupled inductor high-gain DC-DC conversion method as described in claim 7.

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