High-speed switch reluctance wind power generator power converter

Abstract

A high-speed switched reluctance wind power generator power converter is composed of a main circuit and a variable excitation circuit. The number of switching tubes of the main circuit is obviously less than that of a traditional asymmetric half-bridge structure. The variable excitation circuit only needs one switching tube, which is one of the structures with the least number of switching tubes in the current variable excitation type power converter structure. The voltage stress of the main switching tube is low. The main circuit can directly high-multiple boost output in the excitation and power generation work. The whole power converter is common ground without isolation link. In the power generation stage of the working phase of each phase winding, the excitation power supply, the phase winding and the power generation output end are in the same loop, so that the control of the phase current can be realized directly in the power generation stage through the variable excitation voltage. It is suitable for the application of high-speed small-power switched reluctance generator system in the field of variable speed wind power working condition direct current grid.

Description

Technical Field

[0001] This invention relates to the field of DC power grids containing switched reluctance wind turbine generator systems, and specifically to a switched reluctance wind turbine generator power converter with a minimum number of switching transistors, DC boost, and variable excitation, and its control method. Background Technology

[0002] Over the years, with the acceleration of the utilization of new energy sources, DC power grids have made continuous progress and development, absorbing small and medium power wind and photovoltaic power generation systems into DC power grids. However, most traditional wind power generation systems are AC, requiring the addition of a rectifier stage.

[0003] Switched reluctance generators are driven by wind turbines and directly generate direct current, eliminating the need for a rectifier stage.

[0004] The power converter is the heart of a switched reluctance wind turbine generator. Essentially, it is a power electronic device. In the field of modern power electronics engineering, due to the extensive use of power electronic switching transistors, especially high-frequency switching operations, the loss of switching transistors has become an increasingly important issue restricting the development of new power electronics technologies. Therefore, the design of the power converter for a switched reluctance generator should aim to minimize the number of switching transistors while achieving the required functions.

[0005] In addition to switching losses, the voltage stress of switching transistors is also a major concern in the power conversion industry. High voltage stress leads to larger size and weight of the switching transistor, difficulty in heat dissipation, higher cost, and a greater susceptibility to failure.

[0006] As a small wind power system, when connected to the DC grid, it often requires the addition of a dedicated voltage boosting device, which further reduces the power efficiency. Currently, for switched reluctance generator power converters, some have emerged where the power converter directly boosts the voltage when the switched reluctance generator is working, but most of them have the disadvantage of using a large number of switching transistors.

[0007] In variable-speed wind power operation, the excitation voltage can be used as a new variable to optimize performance in the operation control of switched reluctance generators, especially in maximum power point tracking (MPPT) control and maximum efficiency control. Some innovative examples have emerged in this regard. However, in most cases, similar to traditional switching angle or current chopping, it can only be indirectly controlled during the excitation stage. During the power generation stage, it cannot be directly controlled by adjusting the excitation voltage.

[0008] In addition, switched reluctance generator power converters with variable excitation circuits inevitably require additional isolation components due to the increased complexity of the circuitry, which also increases the size, weight, and losses of the power converter. Summary of the Invention

[0009] Based on the above background technology, the present invention proposes a high-speed, low-power switched reluctance generator power converter system and its control method, which features a small number of switching transistors, low voltage stress on the main switching transistor, high-multiplication DC boost, a common ground without isolation links in the entire power converter, and a variable excitation voltage in the same circuit for the excitation power supply, phase windings, and generator output terminals. It is suitable for application in the field of DC microgrids containing switched reluctance wind turbine generator systems.

[0010] The technical solution of this invention is as follows:

[0011] A high-speed switched reluctance wind turbine power converter consists of a main circuit and a variable excitation circuit. The positive input terminal of the main circuit is connected to the positive output terminal of the variable excitation circuit, and the positive output terminal of the main circuit is connected to the positive input terminal of the variable excitation circuit. The negative input terminal of the main circuit is connected to the negative output terminal of the main circuit, the negative output terminal of the variable excitation circuit, and the negative input terminal of the variable excitation circuit. The voltage across the positive and negative input terminals of the main circuit is the excitation voltage, which is also the voltage across the positive and negative output terminals of the variable excitation circuit. The voltage across the positive and negative output terminals of the main circuit is the generation voltage, which is also connected to an external DC grid. The electrical energy output by the variable excitation circuit is used as the excitation power supply to excite the main circuit.

[0012] The main circuit consists of a first switching transistor, a second switching transistor, a third switching transistor, a fourth switching transistor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a first diode, a second diode, a third diode, a first inductor, a second inductor, and a third inductor. The anode of the first switching transistor is connected to the anodes of the second and third switching transistors and serves as the positive input terminal of the main circuit. The cathode of the first switching transistor is connected to one end of the first phase winding, the cathode of the second switching transistor is connected to one end of the second phase winding, the cathode of the third switching transistor is connected to one end of the third phase winding, and the other end of the first phase winding is connected to the other end of the second and third phase windings, the anode of the fourth switching transistor, and one end of the first capacitor. The first diode anode, the other end of the first capacitor is connected to one end of the second inductor, the other end of the second inductor is connected to one end of the first inductor and one end of the third inductor, the first diode cathode is connected to one end of the second capacitor, the second diode anode, and the other end of the first inductor, the other end of the third inductor is connected to one end of the third capacitor, the other end of the third capacitor is connected to the second diode cathode and the third diode anode, the third diode cathode is connected to one end of the fourth capacitor and serves as the positive output terminal of the main circuit, the fourth switch cathode is connected to the other end of the second capacitor and the other end of the fourth capacitor and serves as the input and output negative terminals of the main circuit, and the first inductor, the second inductor, and the third inductor are magnetically coupled to each other.

[0013] The variable excitation circuit consists of a fifth switching transistor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, a fourth diode, a fifth diode, a sixth diode, a fourth inductor, a fifth inductor, a sixth inductor, and a buck non-isolated converter. The positive input terminal of the buck non-isolated converter serves as the positive input terminal of the variable excitation circuit. The positive output terminal of the buck non-isolated converter is connected to one end of the fourth inductor. The other end of the fourth inductor is connected to one end of the fifth capacitor and one end of the fifth inductor. The other end of the fifth capacitor is connected to the cathode of the fifth diode, the anode of the sixth diode, and one end of the sixth inductor. The other end of the sixth inductor is connected to one end of the sixth capacitor. The other end of the sixth capacitor is connected to... Connect one end of the seventh capacitor, the cathode of the fourth diode, and the anode of the fifth diode. The anode of the fourth diode is connected to the anode of the fifth switch and the other end of the fifth inductor. The cathode of the sixth diode is connected to one end of the eighth capacitor and serves as the positive output terminal of the variable excitation circuit. The other end of the eighth capacitor is connected to the cathode of the fifth switch, the other end of the seventh capacitor, and the negative output terminal of the buck non-isolated converter. The negative input terminal of the buck non-isolated converter serves as the negative input terminal of the variable excitation circuit and shares a common ground with the negative output terminal of the buck non-isolated converter. The fifth and sixth inductors are magnetically coupled to each other. The output voltage of the buck non-isolated converter is lower than the input voltage, i.e., lower than the DC grid voltage.

[0014] All five switching transistors in the power converter are fully controlled three-terminal power electronic switching devices.

[0015] A control method for a high-speed switched reluctance wind turbine power converter, based on the working principle of a switched reluctance generator, uses a variable excitation circuit as the excitation power supply. According to rotor position information, when the first phase winding needs to be engaged, the first and fourth switching transistors are turned on, entering the excitation stage. The excitation power supply excites the first phase winding through the first and fourth switching transistors. Simultaneously, a second capacitor, a second diode, a third capacitor, a third inductor, a second inductor, and the first capacitor are connected in series through the fourth switching transistor to form a circuit, as well as a circuit consisting of the second capacitor, the first inductor, the second inductor, and the first capacitor connected in series through the fourth switching transistor. When the container discharges, the first and third capacitors are charged. According to the rotor position information, when the excitation stage of the first phase winding needs to end, the fourth switch is turned off, and the generation stage begins. The excitation power supply is connected in series with the first phase winding, the first capacitor, the second inductor, the third inductor, and the third capacitor, and outputs electrical energy to the main circuit output terminal through the first switch and the third diode. At the same time, the second capacitor is charged through the first switch. In the initial stage of the fourth switch being turned off, the first diode is turned on, and the voltage of the fourth switch is equal to the terminal voltage of the second capacitor. When the generation stage needs to end according to the rotor position information, the first switch is turned off, and the operation of the first phase winding ends.

[0016] According to the rotor position information, when the second phase winding needs to be put into operation, the second and fourth switches are turned on, entering the excitation stage. The excitation power supply excites the second phase winding through the second and fourth switches. At the same time, the second capacitor, the second diode, the third capacitor, the third inductor, the second inductor, and the first capacitor are connected in series and form a circuit through the fourth switch. The second capacitor discharges, and the first and third capacitors are charged. According to the rotor position information, when the excitation stage of the second phase winding needs to end, the fourth switch is turned off, entering the power generation stage. The excitation power supply, the second phase winding, the first capacitor, the second inductor, the third inductor, and the third capacitor are connected in series and output electrical energy to the main circuit output terminal through the second switch and the third diode. At the same time, the second capacitor is charged through the second switch. When the fourth switch is turned off, the first diode is turned on. The voltage of the fourth switch is equal to the terminal voltage of the second capacitor. According to the rotor position information, when the power generation stage needs to end, the second switch is turned off, and the operation of the second phase winding ends.

[0017] According to the rotor position information, when the third phase winding needs to be put into operation, the third and fourth switches are turned on, entering the excitation stage. The excitation power supply excites the third phase winding through the third and fourth switches. At the same time, the second capacitor, the second diode, the third capacitor, the third inductor, the second inductor, and the first capacitor are connected in series and form a circuit through the fourth switch. The second capacitor discharges, and the first and third capacitors are charged. According to the rotor position information, when the excitation stage of the third phase winding needs to end, the fourth switch is turned off, entering the power generation stage. The excitation power supply, the third phase winding, the first capacitor, the second inductor, the third inductor, and the third capacitor are connected in series and output electrical energy to the main circuit output terminal through the third switch and the third diode. At the same time, the second capacitor is charged through the third switch. When the fourth switch is turned off, the first diode is turned on. The voltage of the fourth switch is equal to the terminal voltage of the second capacitor. According to the rotor position information, when the power generation stage needs to end, the third switch is turned off, and the operation of the third phase winding ends.

[0018] As can be seen from the working process of each phase winding above, the voltage stress of the fourth switch is the terminal voltage of the second capacitor.

[0019] The variable excitation circuit serves as the excitation power supply. The fifth switching transistor operates in PWM mode. When the fifth switching transistor is turned on, the fifth capacitor is charged, and the sixth and seventh capacitors are discharged. When the fifth switching transistor is turned off, the fifth capacitor discharges, and the sixth and seventh capacitors are charged. Under the coupling effect of the fifth and sixth inductors, when the PWM duty cycle of the fifth switching transistor is changed, the average value of the excitation voltage at the output of the variable excitation circuit changes, thereby adapting to the excitation voltage requirements of the maximum power point tracking control of the switched reluctance generator system when the speed changes due to wind speed changes.

[0020] When the fifth switch is turned off, the voltage stress is the terminal voltage of the seventh capacitor.

[0021] The main technical effects of this invention are:

[0022] In the main circuit of this invention, for X-phase windings, there are X+1 switching transistors, which is significantly fewer than the main circuit of a traditional asymmetrical half-bridge power converter. The switching frequency of the fourth switching transistor is X times that of the other switching transistors. The variable excitation circuit has only one switching transistor. Although its switching frequency is generally greater than that of the fourth switching transistor, it is already the variable excitation circuit with the fewest switching transistors in the industry. Therefore, for the variable excitation switched reluctance generator power converter, the number of switching transistors in this invention is one of the fewest, the overall switching loss is also low, and the control is simple. In addition, the voltage stress of the fourth switching transistor is the voltage of the second capacitor terminal, and the voltage stress of the fifth switching transistor is the voltage of the seventh capacitor terminal. From the perspective of circuit structure and operation, these are relatively low stresses, significantly lower than the DC grid-side generated voltage.

[0023] As can be seen from the operation of the main circuit, during the power generation stage, the output voltage is the sum of the excitation voltage, the phase winding voltage, the voltage of the first capacitor, the second inductor, the third inductor, and the voltage of the third capacitor. Thus, the output voltage is significantly greater than the phase winding voltage or the excitation voltage. Furthermore, by adjusting the number of inductance turns among the first, second, and third inductors, a more ideal boost ratio can be obtained, saving the boost stage before grid connection.

[0024] The entire power converter has only one ground terminal and no isolation components, which reduces cost and lightens size and weight.

[0025] In the generation stage of each phase winding of a switched reluctance generator, the excitation power supply, the phase winding, and the generation output terminal are in the same series circuit. According to the mathematical model of the switched reluctance generator, if the excitation voltage is adjusted at this time, the trend of the phase winding current during the generation stage can be directly controlled. In other words, the generation output capacity is directly controlled, which is of great significance to the generation efficiency. Especially for the maximum power point tracking control required under variable speed wind power conditions, it can be achieved by changing the excitation voltage, overcoming the disadvantage of the traditional method that can only be indirectly controlled through the excitation stage. In addition, a more ideal excitation voltage output range can be obtained by changing the turns ratio between the fifth and sixth inductors. Attached Figure Description

[0026] Figure 1 The diagram shown is a circuit structure diagram of a high-speed switched reluctance wind turbine power converter according to the present invention.

[0027] Figure 1 In the diagram, 1: Main circuit; 2: Variable excitation circuit. Detailed Implementation

[0028] This embodiment describes a high-speed switched reluctance wind turbine power converter, the circuit structure of which is shown in the attached figure. Figure 1 As shown, the switched reluctance generator has a three-phase winding and a 6 / 4 pole structure. The power converter consists of a main circuit 1 and a variable excitation circuit 2. The positive input terminal of the main circuit 1 is connected to the positive output terminal of the variable excitation circuit 2, and the positive output terminal of the main circuit 1 is connected to the positive input terminal of the variable excitation circuit 2. The negative input terminal of the main circuit 1 is connected to the negative output terminal of the main circuit 1, the negative output terminal of the variable excitation circuit 2, and the negative input terminal of the variable excitation circuit 2. That is, the main circuit 1 and the variable excitation circuit 2 share a common ground. The voltage across the positive and negative input terminals of the main circuit 1 is the excitation voltage, which is also the voltage across the positive and negative output terminals of the variable excitation circuit 2. The voltage across the positive and negative output terminals of the main circuit 1 is the generating voltage. It is also connected to an external DC grid, or connected to a DC grid after passing through a certain intermediate device. The electrical energy output by the variable excitation circuit 2 is used as the excitation power supply to excite the main circuit 1.

[0029] The main circuit 1 consists of a first switch V1, a second switch V2, a third switch V3, a fourth switch V4, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a first diode D1, a second diode D2, a third diode D3, a first inductor L1, a second inductor L2, and a third inductor L3. The anode of the first switch V1 is connected to the anodes of the second switch V2 and the third switch V3, serving as the positive input terminal of the main circuit 1. The cathode of the first switch V1 is connected to one end of the first phase winding M, the cathode of the second switch V2 is connected to one end of the second phase winding N, and the cathode of the third switch V3 is connected to one end of the third phase winding P. The other end of the first phase winding M is connected to the other end of the second phase winding N, the other end of the third phase winding P, the anode of the fourth switch V4, and the first capacitor C1. The first inductor L1 is connected to the anode of the first diode D1, and the other end of the first capacitor C1 is connected to one end of the second inductor L2. The other end of the second inductor L2 is connected to one end of the first inductor L1 and one end of the third inductor L3. The cathode of the first diode D1 is connected to one end of the second capacitor C2, the anode of the second diode D2, and the other end of the first inductor L1. The other end of the third inductor L3 is connected to one end of the third capacitor C3. The other end of the third capacitor C3 is connected to the cathode of the second diode D2 and the anode of the third diode D3. The cathode of the third diode D3 is connected to one end of the fourth capacitor C4 and serves as the positive output terminal of the main circuit 1. The cathode of the fourth switch V4 is connected to the other end of the second capacitor C2 and the other end of the fourth capacitor C4 and serves as the negative input and output terminals of the main circuit 1. The first inductor L1, the second inductor L2, and the third inductor L3 are magnetically coupled to each other.

[0030] The variable excitation circuit 2 consists of a fifth switch V5, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8, a fourth diode D4, a fifth diode D5, a sixth diode D6, a fourth inductor L4, a fifth inductor L5, a sixth inductor L6, and a buck non-isolated converter. The positive input terminal of the buck non-isolated converter serves as the positive input terminal of the variable excitation circuit 2. The positive output terminal of the buck non-isolated converter is connected to one end of the fourth inductor L4. The other end of the fourth inductor L4 is connected to one end of the fifth capacitor C5 and one end of the fifth inductor L5. The other end of the fifth capacitor C5 is connected to the cathode of the fifth diode D5, the anode of the sixth diode D6, and one end of the sixth inductor L6. The other end of the sixth inductor L6 is connected to one end of the sixth capacitor C6. The other end of the sixth capacitor C6 is connected to the fifth diode D5, the anode of the sixth diode D6, and one end of the sixth inductor L6. One end of capacitor C7, the cathode of diode D4, and the anode of diode D5 are connected. The anode of diode D4 is connected to the anode of switch V5 and the other end of inductor L5. The cathode of diode D6 is connected to one end of capacitor C8 and serves as the positive output terminal of excitation circuit 2. The other end of capacitor C8 is connected to the cathode of switch V5, the other end of capacitor C7, and the negative output terminal of buck non-isolated converter. The negative input terminal of buck non-isolated converter serves as the negative input terminal of excitation circuit 2 and shares a common ground with the negative output terminal of buck non-isolated converter. Inductor L5 and inductor L6 are magnetically coupled to each other. The output voltage of buck non-isolated converter is lower than the input voltage, i.e., lower than the DC grid voltage, to facilitate matching the excitation power supply with the DC grid generation voltage.

[0031] All five switching transistors in the power converter are fully controlled three-terminal power electronic switching devices.

[0032] This embodiment describes a control method for a high-speed switched reluctance wind turbine power converter. Based on the working principle of a switched reluctance generator, the excitation circuit 2 serves as the excitation power supply. According to the rotor position information, when the first phase winding M needs to be engaged, the first switch V1 and the fourth switch V4 are turned on, entering the excitation stage. The excitation power supply excites the first phase winding M through the first switch V1 and the fourth switch V4. Simultaneously, there exists a circuit consisting of a second capacitor C2, a second diode D2, a third capacitor C3, a third inductor L3, a second inductor L2, and a first capacitor C1 connected in series through the fourth switch V4, and a circuit consisting of a second capacitor C2, a first inductor L1, a second inductor L2, and a first capacitor C1 connected in series through the fourth switch V4. The first capacitor C1 and the third capacitor C3 are charged while the second capacitor C2 discharges. According to the rotor position information, when the excitation stage of the first phase winding M needs to end, the fourth switch V4 is turned off, and the power generation stage begins. The excitation power supply is connected in series with the first phase winding M, the first capacitor C1, the second inductor L2, the third inductor L3, and the third capacitor C3, and outputs electrical energy to the output terminal of the main circuit 1 through the first switch V1 and the third diode D3. At the same time, the second capacitor C2 is charged through the first switch V1. In the initial stage of the fourth switch V4 being turned off, the first diode D1 is turned on, and the voltage of the fourth switch V4 is the terminal voltage of the second capacitor C2. When the power generation stage needs to end according to the rotor position information, the first switch V1 is turned off, and the first phase winding M ends its operation.

[0033] Based on the rotor position information, when the second phase winding N needs to be put into operation, the second switch V2 and the fourth switch V4 are turned on, entering the excitation stage. The excitation power supply excites the second phase winding N through the second switch V2 and the fourth switch V4. At the same time, there is a circuit consisting of the second capacitor C2, the second diode D2, the third capacitor C3, the third inductor L3, the second inductor L2, and the first capacitor C1 connected in series through the fourth switch V4, and a circuit consisting of the second capacitor C2, the first inductor L1, the second inductor L2, and the first capacitor C1 connected in series through the fourth switch V4. The second capacitor C2 discharges, while the first capacitor C1 and the third capacitor C3 are charged. According to the rotor position information, when the excitation stage of the second phase winding N needs to end, the fourth switch V4 is disconnected, and the power generation stage begins. The excitation power supply is connected in series with the second phase winding N, the first capacitor C1, the second inductor L2, the third inductor L3, and the third capacitor C3, and outputs electrical energy to the output terminal of the main circuit 1 through the second switch V2 and the third diode D3. At the same time, the second capacitor C2 is charged through the second switch V2. When the fourth switch V4 is turned off, the first diode D1 is initially turned on, and the voltage of the fourth switch V4 is the terminal voltage of the second capacitor C2. When the power generation stage needs to end according to the rotor position information, the second switch V2 is disconnected, and the operation of the second phase winding N ends.

[0034] Based on the rotor position information, when the third phase winding P needs to be put into operation, the third switch V3 and the fourth switch V4 are turned on, entering the excitation stage. The excitation power supply excites the third phase winding P through the third switch V3 and the fourth switch V4. At the same time, there is a circuit consisting of the second capacitor C2, the second diode D2, the third capacitor C3, the third inductor L3, the second inductor L2, and the first capacitor C1 connected in series through the fourth switch V4, and a circuit consisting of the second capacitor C2, the first inductor L1, the second inductor L2, and the first capacitor C1 connected in series through the fourth switch V4. The second capacitor C2 discharges, and the first capacitor C1 and the third capacitor C3 are charged. According to the rotor position information, when the excitation stage of the third phase winding P needs to end, the fourth switch V4 is disconnected, and the power generation stage begins. The excitation power supply is connected in series with the third phase winding P, the first capacitor C1, the second inductor L2, the third inductor L3, and the third capacitor C3, and outputs electrical energy to the output terminal of the main circuit 1 through the third switch V3 and the third diode D3. At the same time, the second capacitor C2 is charged through the third switch V3. When the fourth switch V4 is turned off, the first diode D1 is initially turned on, and the voltage of the fourth switch V4 is the terminal voltage of the second capacitor C2. When the power generation stage needs to end according to the rotor position information, the third switch V3 is disconnected, and the operation of the third phase winding P ends.

[0035] As can be seen from the working process of each phase winding above, the voltage stress of the fourth switch V4 is the terminal voltage of the second capacitor C2.

[0036] The variable excitation circuit 2 serves as the excitation power supply. The fifth switch V5 operates in PWM mode with a switching frequency of over 10kHz. When the fifth switch V5 is turned on, the fifth capacitor C5 is charged, while the sixth capacitor C6 and the seventh capacitor C7 are discharged. When the fifth switch V5 is turned off, the fifth capacitor C5 is discharged, while the sixth capacitor C6 and the seventh capacitor C7 are charged. Furthermore, due to the coupling effect of the fifth inductor L5 and the sixth inductor L6, the average value of the excitation voltage at the output of the variable excitation circuit 2 changes when the PWM duty cycle of the fifth switch V5 is changed. This adapts to the maximum power point tracking control requirements of the switched reluctance generator system when the rotational speed changes due to wind speed variations.

[0037] When the fifth switch V5 is turned off, the voltage stress is the voltage across the seventh capacitor C7.

Claims

1. A high-speed switched reluctance wind turbine power converter, comprising a main circuit and a variable excitation circuit, characterized by the following technical features: The positive input terminal of the main circuit is connected to the positive output terminal of the variable excitation circuit, the positive output terminal of the main circuit is connected to the positive input terminal of the variable excitation circuit, the negative input terminal of the main circuit is connected to the negative output terminal of the main circuit, the negative output terminal of the variable excitation circuit, and the negative input terminal of the variable excitation circuit. The positive and negative output terminals of the main circuit are also connected to the external DC power grid. The electrical energy output by the variable excitation circuit is used as the excitation power supply to excite the main circuit. The main circuit consists of a first switching transistor, a second switching transistor, a third switching transistor, a fourth switching transistor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a first diode, a second diode, a third diode, a first inductor, a second inductor, and a third inductor. The anode of the first switching transistor is connected to the anodes of the second and third switching transistors and serves as the positive input terminal of the main circuit. The cathode of the first switching transistor is connected to one end of the first phase winding, the cathode of the second switching transistor is connected to one end of the second phase winding, and the cathode of the third switching transistor is connected to one end of the third phase winding. The other end of the first phase winding is connected to the other end of the second and third phase windings, the anode of the fourth switching transistor, one end of the first capacitor, and the third inductor. The anode of the first diode is connected to one end of the second inductor, the other end of the second inductor is connected to one end of the first inductor and one end of the third inductor, the cathode of the first diode is connected to one end of the second capacitor, the anode of the second diode, and the other end of the first inductor, the other end of the third inductor is connected to one end of the third capacitor, the other end of the third capacitor is connected to the cathode of the second diode and the anode of the third diode, the cathode of the third diode is connected to one end of the fourth capacitor and serves as the positive output terminal of the main circuit, the cathode of the fourth switch is connected to the other end of the second capacitor and the other end of the fourth capacitor and serves as the input and output negative terminals of the main circuit, and the first inductor, the second inductor, and the third inductor are magnetically coupled to each other; The variable excitation circuit consists of a fifth switching transistor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, a fourth diode, a fifth diode, a sixth diode, a fourth inductor, a fifth inductor, a sixth inductor, and a buck non-isolated converter. The positive input terminal of the buck non-isolated converter serves as the positive input terminal of the variable excitation circuit. The positive output terminal of the buck non-isolated converter is connected to one end of the fourth inductor. The other end of the fourth inductor is connected to one end of the fifth capacitor and one end of the fifth inductor. The other end of the fifth capacitor is connected to the cathode of the fifth diode, the anode of the sixth diode, and one end of the sixth inductor. The other end of the sixth inductor is connected to one end of the sixth capacitor. The other end of the sixth capacitor is connected to one end of the seventh capacitor, the cathode of the fourth diode, and the anode of the fifth diode. The anode of the fourth diode is connected to the anode of the fifth switch and the other end of the fifth inductor. The cathode of the sixth diode is connected to one end of the eighth capacitor and serves as the positive output terminal of the variable excitation circuit. The other end of the eighth capacitor is connected to the cathode of the fifth switch, the other end of the seventh capacitor, and the negative output terminal of the buck non-isolated converter. The negative input terminal of the buck non-isolated converter serves as the negative input terminal of the variable excitation circuit and shares a common ground with the negative output terminal of the buck non-isolated converter. The fifth inductor and the sixth inductor are magnetically coupled to each other. The output voltage of the buck non-isolated converter is lower than the input voltage.

2. The control method for a high-speed switched reluctance wind turbine power converter according to claim 1, characterized in that: Based on the working principle of the switched reluctance generator, according to the rotor position information, when the first phase winding needs to be put into operation, the first and fourth switching transistors are turned on, entering the excitation stage. The excitation power supply excites the first phase winding through the first and fourth switching transistors. At the same time, the second capacitor, the second diode, the third capacitor, the third inductor, the second inductor, and the first capacitor are connected in series to form a circuit through the fourth switching transistor. There is also a circuit of the second capacitor, the first inductor, the second inductor, and the first capacitor connected in series through the fourth switching transistor. The second capacitor discharges, and the first and third capacitors are charged. According to the rotor position information, when the excitation stage of the first phase winding needs to end, the fourth switching transistor is turned off, entering the generation stage. The excitation power supply, the first phase winding, the first capacitor, the second inductor, the third inductor, and the third capacitor are connected in series and output electrical energy to the main circuit output terminal through the first switching transistor and the third diode. At the same time, the second capacitor is charged through the first switching transistor. According to the rotor position information, when the generation stage needs to end, the first switching transistor is turned off, and the operation of the first phase winding ends. According to the rotor position information, when the second phase winding needs to be put into operation, the second and fourth switches are turned on, entering the excitation stage. The excitation power supply excites the second phase winding through the second and fourth switches. At the same time, the second capacitor, the second diode, the third capacitor, the third inductor, the second inductor, and the first capacitor are connected in series to form a circuit through the fourth switch. There is also a circuit of the second capacitor, the first inductor, the second inductor, and the first capacitor connected in series through the fourth switch. The second capacitor discharges, and the first and third capacitors are charged. According to the rotor position information, when the excitation stage of the second phase winding needs to end, the fourth switch is turned off, entering the power generation stage. The excitation power supply, the second phase winding, the first capacitor, the second inductor, the third inductor, and the third capacitor are connected in series and output electrical energy to the main circuit output terminal through the second switch and the third diode. At the same time, the second capacitor is charged through the second switch. According to the rotor position information, when the power generation stage needs to end, the second switch is turned off, and the operation of the second phase winding ends. According to the rotor position information, when the third phase winding needs to be put into operation, the third and fourth switches are turned on, entering the excitation stage. The excitation power supply excites the third phase winding through the third and fourth switches. At the same time, the second capacitor, the second diode, the third capacitor, the third inductor, the second inductor, and the first capacitor are connected in series to form a circuit through the fourth switch. There is also a circuit of the second capacitor, the first inductor, the second inductor, and the first capacitor connected in series through the fourth switch. The second capacitor discharges, and the first and third capacitors are charged. According to the rotor position information, when the excitation stage of the third phase winding needs to end, the fourth switch is turned off, entering the power generation stage. The excitation power supply, the third phase winding, the first capacitor, the second inductor, the third inductor, and the third capacitor are connected in series and output electrical energy to the main circuit output terminal through the third switch and the third diode. At the same time, the second capacitor is charged through the third switch. According to the rotor position information, when the power generation stage needs to end, the third switch is turned off, and the operation of the third phase winding ends. The variable excitation circuit acts as the excitation power supply. The fifth switch operates in PWM mode. When the fifth switch is turned on, the fifth capacitor is charged, and the sixth and seventh capacitors are discharged. When the fifth switch is turned off, the fifth capacitor is discharged, and the sixth and seventh capacitors are charged. Under the coupling effect of the fifth and sixth inductors, when the PWM duty cycle of the fifth switch is changed, the average value of the excitation voltage at the output of the variable excitation circuit changes.

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