Switched reluctance motor anti-polarity step-up power converter and control method thereof

Abstract

The application discloses a power converter and a control method thereof for a switched reluctance motor reverse polarity step-up voltage conversion, wherein the power converter is composed of a reverse polarity main circuit and a step-up auxiliary circuit, and the input and output of the two are connected in a head-to-tail mode; the reverse polarity main circuit is composed of five switching tubes, three-phase windings, two capacitors, two diodes and an inductor; the step-up auxiliary circuit is composed of an isolation converter, two switching tubes, four capacitors, six diodes and two inductors; the output end of the reverse polarity main circuit is opposite in polarity to the input end; when the switched reluctance motor operates as a generator, the voltage output power can be directly raised; the step-up effect of the step-up auxiliary circuit is obviously greater than that of a conventional BOOST circuit; the variable voltage output to the reverse polarity main circuit can be obtained by adjusting the related duty cycle, and the variable excitation power source of the switched reluctance generator or the adjustable power supply of the switched reluctance motor can be obtained; and the application is suitable for the field of high-speed switched reluctance motor systems with small and medium power levels.

Description

Technical Field

[0001] This invention relates to the field of motor systems, and more specifically to a four-quadrant switched reluctance motor power converter system with direct boost reverse polarity and variable voltage control, and its control method. Background Technology

[0002] Switched reluctance motors (SRMs) are a type of motor with promising applications. The rotor has no windings, while the stator has several phase windings. When operating as a motor or generator, not all windings are energized simultaneously. Instead, the energization of specific windings is determined by the relative positions of the rotor and stator. As a motor, energizing occurs in the region that generates positive electrical torque; as a generator, energizing occurs primarily in the region that generates negative torque, i.e., the region that converts negative mechanical energy into stored energy. Furthermore, when operating as a generator, each phase winding operates in at least two phases: an excitation phase and a generation phase, which occur sequentially. During the excitation phase, the phase winding absorbs electrical energy; during the generation phase, it generates electrical energy. Additionally, due to the storage of excess energy in the negative torque region... The converted mechanical energy, excluding the inductive characteristics, results in an output electrical energy greater than the electrical energy absorbed during the excitation phase, achieving an overall positive power output. When used as a motor, it generates power in the positive torque region, but after power is switched off and on, a certain time is generally required to allow the remaining energy stored in the phase windings to be released. In other words, the operation of a motor is actually divided into two stages. In short, apart from the different stator and rotor positions and energy comparison relationships, any switched reluctance motor can achieve motoring or generating operation. However, all of this depends on the support of its dedicated power converter, i.e., the converter in the field of motor systems. For switched reluctance motors, the power converter is even more important. Without a power converter, a switched reluctance motor cannot operate at all.

[0003] The most widely used power converter for switched reluctance motors is the traditional asymmetric half-bridge power converter. However, with the increasing demands for system performance and the complexity of applications in this field, the asymmetric half-bridge power converter has shown more and more drawbacks, and some new power converter structures have emerged.

[0004] The voltage of electrical energy directly generated by a conventional generator often cannot meet the needs of the power grid or load, requiring the installation of a special step-up device. In recent years, power converters that utilize excitation voltage as a new variable have received some attention, especially when switched reluctance motor power converters are used as generators, which can effectively increase the options in system performance control. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a four-quadrant switching reluctance motor power converter and its control method that directly increases voltage and outputs electrical energy in reverse polarity, features variable excitation power generation, variable voltage speed regulation control, and high voltage boost enhancement.

[0006] Technical solution: A reverse polarity boost converter for switched reluctance motors, consisting of a reverse polarity main circuit and a boost auxiliary circuit. The output terminals of the reverse polarity main circuit are connected to the input terminals of the boost auxiliary circuit, and the output terminals of the boost auxiliary circuit are connected to the input terminals of the reverse polarity main circuit.

[0007] The reverse polarity main circuit consists of a first switch, a second switch, a third switch, a fourth switch, a fifth switch, a first phase winding, a second phase winding, a third phase winding, a first capacitor, a second capacitor, a first diode, a second diode, and a first inductor. The anode of the first switch is connected to the anodes of the second and third switches, serving as the positive input terminal of the reverse polarity main circuit. The cathode of the first switch is connected to one end of the first phase winding, the cathode of the second switch is connected to one end of the second phase winding, the cathode of the third switch is connected to one end of the third phase winding, and the other end of the first phase winding is connected to the second... The third phase winding has the other end of the first phase winding, the anode of the fourth switch, the anode of the fifth switch, and one end of the first capacitor. The cathode of the fifth switch is connected to the cathode of the second diode and one end of the first inductor. The other end of the first inductor is connected to the other end of the first capacitor and the anode of the first diode. The anode of the second diode is connected to one end of the second capacitor and serves as the negative terminal of the reverse polarity main circuit output. The other end of the second capacitor is connected to the cathode of the fourth switch and the cathode of the first diode and serves as the positive terminal of the reverse polarity main circuit output and the negative terminal of the input. All switches are three-terminal fully controlled power electronic switching devices.

[0008] The boost converter auxiliary circuit consists of an isolation converter, a sixth and seventh switching transistor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a third diode, a fourth diode, a fifth diode, a sixth diode, a seventh diode, an eighth diode, a second inductor, and a third inductor. The positive input terminal of the isolation converter serves as the positive input terminal of the boost converter auxiliary circuit and is connected to the positive output terminal of the reverse polarity main circuit. The negative input terminal of the isolation converter serves as the negative input terminal of the boost converter auxiliary circuit and is connected to the negative output terminal of the reverse polarity main circuit. The positive output terminal of the isolation converter is connected to one end of the second inductor and one end of the third inductor. The other end of the second inductor is connected to the anode of the sixth switching transistor, one end of the third capacitor, and the anode of the third diode. The other end of the third inductor is connected to the anode of the seventh switching transistor, one end of the fourth capacitor, and the anode of the fourth diode. The other end of the third capacitor is connected to the cathode of the fifth diode and the anode of the sixth diode. The other end of the four capacitors is connected to the cathode of the seventh diode and the anode of the eighth diode. The cathode of the third diode is connected to the cathode of the fourth diode, the anode of the fifth diode, the anode of the seventh diode, one end of the fifth capacitor, and one end of the sixth capacitor. The cathode of the sixth diode is connected to the cathode of the eighth diode and the other end of the fifth capacitor, and serves as the positive output terminal of the boost auxiliary circuit connected to the positive input terminal of the reverse polarity main circuit. The other end of the sixth capacitor is connected to the negative output terminal of the isolation converter, the cathode of the sixth switch, and the cathode of the seventh switch, and serves as the negative output terminal of the boost auxiliary circuit connected to the negative input terminal of the reverse polarity main circuit. All switches are three-terminal fully controlled power electronic switching devices. The third capacitor is the same as the fourth capacitor, the fifth capacitor is the same as the sixth capacitor, and the second inductor is the same as the third inductor. In addition to isolation function, the isolation converter also has a suitable input-output voltage ratio set according to the needs of the power converter.

[0009] The control method of the switched reluctance motor reverse polarity step-up power converter involves the following steps: When the switched reluctance motor operates as a generator, and the step-up auxiliary circuit operates as the excitation power supply for each phase winding of the switched reluctance generator, based on the rotor position information, when the first phase winding needs to be engaged, the first, fourth, and fifth switches are first closed to enter the excitation stage of the first phase winding. The excitation power supply is supplied to the first phase winding via the first and fourth switches, while the first capacitor discharges to the first inductor via the fifth switch. The output power of the reverse polarity main circuit is maintained by the second capacitor. Based on the rotor position information, when the excitation stage needs to end, the fourth and fifth switches are disconnected to enter the generation stage of the first phase winding. The excitation power supply and the first phase winding together charge the first capacitor via the first switch and the first diode. Simultaneously, the energy stored in the first inductor is output to the output terminal of the reverse polarity main circuit via the first and second diodes and charges the second capacitor. Based on the rotor position information, when the generation stage needs to end, the first switch is disconnected, and the operation of the first phase winding ends.

[0010] Based on the rotor position information, when the second phase winding needs to be put into operation, the second, fourth, and fifth switches are first closed to initiate the excitation phase of the second phase winding. The excitation power supply is supplied to the second phase winding via the second and fourth switches, while the first capacitor discharges to the first inductor via the fifth switch. The output power of the reverse polarity main circuit is maintained by the second capacitor. Based on the rotor position information, when the excitation phase needs to end, the fourth and fifth switches are disconnected to initiate the power generation phase of the second phase winding. The excitation power supply and the second phase winding together charge the first capacitor via the second switch and the first diode. Simultaneously, the energy stored in the first inductor is output to the output terminal of the reverse polarity main circuit via the first and second diodes and charges the second capacitor. Based on the rotor position information, when the power generation phase needs to end, the second switch is disconnected, and the operation of the second phase winding ends.

[0011] Based on the rotor position information, when the third phase winding needs to be put into operation, the third, fourth, and fifth switches are first closed to enter the excitation stage of the third phase winding. The excitation power supply supplies power to the third phase winding through the third and fourth switches, and at the same time, the first capacitor discharges to the first inductor through the fifth switch. The output power of the reverse polarity main circuit is maintained by the second capacitor. Based on the rotor position information, when the excitation stage needs to end, the fourth and fifth switches are disconnected to enter the power generation stage of the third phase winding. The excitation power supply and the third phase winding together charge the first capacitor through the third switch and the first diode. At the same time, the energy stored in the first inductor is output to the output terminal of the reverse polarity main circuit through the first and second diodes and charges the second capacitor. Based on the rotor position information, when the power generation stage needs to end, the third switch is disconnected, and the operation of the third phase winding ends.

[0012] When the switched reluctance motor is running as an electric motor, the boost auxiliary circuit serves as the power supply for each phase winding. Based on the rotor position information, when the first phase winding needs to be engaged, the first, fourth, and fifth switches are closed to initiate the first operating stage of the first phase winding. The power supply, via the first and fourth switches, supplies power to the first phase winding, generating electric torque. Simultaneously, the energy stored in the first capacitor discharges to the first inductor via the fifth switch. Based on the rotor position information, when the first operating stage needs to end, the fourth and fifth switches are disconnected, initiating the second operating stage of the first phase winding. The remaining energy stored in the first phase winding, along with the power supply, is released to the first capacitor via the first switch and the first diode. Simultaneously, the energy stored in the first inductor is released to the output terminal of the reverse polarity main circuit via the first and second diodes and charges the second capacitor. When the next phase winding needs to be engaged, the first switch is disconnected, and the operation of the first phase winding ends.

[0013] Based on the rotor position information, when the second phase winding needs to be put into operation, the second, fourth, and fifth switches are first closed to enter the first operating stage of the second phase winding. The power supply supplies power to the second phase winding through the second and fourth switches to generate electric torque. At the same time, the energy stored in the first capacitor is discharged to the first inductor through the fifth switch. Based on the rotor position information, when the first operating stage needs to be ended, the fourth and fifth switches are opened to enter the second operating stage of the second phase winding. The remaining energy stored in the second phase winding and the power supply are released to the first capacitor through the second switch and the first diode. At the same time, the energy stored in the first inductor is released to the output terminal of the reverse polarity main circuit through the first and second diodes and charges the second capacitor. Based on the rotor position information, when the next phase winding needs to be put into operation, the second switch is opened, and the operation of the second phase winding ends.

[0014] Based on the rotor position information, when the third phase winding needs to be put into operation, the third, fourth, and fifth switches are first closed to enter the first operating stage of the third phase winding. The power supply supplies power to the third phase winding through the third and fourth switches to generate electric torque. At the same time, the energy stored in the first capacitor is discharged to the first inductor through the fifth switch. Based on the rotor position information, when the first operating stage needs to be ended, the fourth and fifth switches are disconnected to enter the second operating stage of the third phase winding. The remaining energy stored in the third phase winding and the power supply are released to the first capacitor through the third switch and the first diode. At the same time, the energy stored in the first inductor is released to the output terminal of the reverse polarity main circuit through the first and second diodes and charges the second capacitor. Based on the rotor position information, when the next phase winding needs to be put into operation, the third switch is disconnected, and the operation of the third phase winding ends.

[0015] The control method of the boost auxiliary circuit is that the sixth and seventh switching transistors operate in PWM mode. They have the same operating frequency and duty cycle, and their phases differ by 180 degrees when they are turned on, i.e., they are turned on alternately.

[0016] When the PWM duty cycle of the sixth and seventh switches of the boost auxiliary circuit is greater than 0.5, it is the first operating mode of the boost auxiliary circuit.

[0017] When the PWM duty cycle of the sixth and seventh switches of the boost auxiliary circuit is less than 0.5, it is the second operating mode of the boost auxiliary circuit.

[0018] Based on the principle of energy storage element balance during the operation of the boost auxiliary circuit, the input-output voltage relationship of the boost auxiliary circuit can be obtained as follows:

[0019]

[0020] In equation (1), U LU is the output voltage of the boost auxiliary circuit; d is the PWM duty cycle of the sixth and seventh switches; U F This is the output voltage of the isolation converter.

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

[0022] The power converter of the present invention can realize the reverse polarity output of electrical energy from a switched reluctance generator; at the same time, it can be seen from the working process of the excitation and generation stages of each phase winding that the voltage at the output terminal of the reverse polarity main circuit is significantly greater than the input excitation power supply voltage and the phase winding voltage, thus realizing direct voltage boosting output.

[0023] When the boost auxiliary circuit is working, it can adjust the output voltage by adjusting the PWM duty cycle of the sixth and seventh switching transistors, thereby realizing the variable excitation voltage control of the switched reluctance generator and the variable speed control of the switched reluctance motor. Its output voltage is generally in boost mode (relative to the output voltage of the isolation converter), and the boost amplitude is higher than that of the traditional BOOST circuit. Attached Figure Description

[0024] Figure 1 The diagram shown is a structural diagram of the reverse polarity boost converter for switched reluctance motors according to the present invention.

[0025] Figure 2 The diagram shows the first operating stage of the first phase winding of the reverse polarity main circuit of the present invention.

[0026] Figure 3 The diagram shows the second operating stage of the first phase winding of the reverse polarity main circuit of the present invention.

[0027] Figure 4 The diagram shown is a switching timing diagram of the first mode of the boost auxiliary circuit of the present invention.

[0028] Figure 5 The diagram shows the first and third operating stages of the first mode of the boost auxiliary circuit of the present invention.

[0029] Figure 6 The diagram shows the second working stage of the first mode and the first working stage of the second mode of the boost auxiliary circuit of the present invention.

[0030] Figure 7 The diagram shows the fourth working stage of the first mode and the third working stage of the second mode of the boost auxiliary circuit of the present invention.

[0031] Figure 8 The diagram shown is a timing diagram of the second mode switching of the boost auxiliary circuit of the present invention.

[0032] Figure 9 The diagram shows the second and fourth operating stages of the second mode of the boost auxiliary circuit of the present invention.

[0033] Figure 1 In the diagram: 1 is the main circuit with reverse polarity; 2 is the boost auxiliary circuit. Detailed Implementation

[0034] A reverse polarity boost converter for a switched reluctance motor and its control method are disclosed. The power converter consists of a reverse polarity main circuit 1 and a boost auxiliary circuit 2, as shown in the attached diagram. Figure 1 As shown, the output terminals of the reverse polarity main circuit 1 are connected to the input terminals of the boost auxiliary circuit 2, and the output terminals of the boost auxiliary circuit 2 are connected to the input terminals of the reverse polarity main circuit 1. The three-phase windings of the switched reluctance motor are connected in the reverse polarity main circuit 1.

[0035] The reverse polarity main circuit 1 consists of a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, a fifth switch S5, a first phase winding M, a second phase winding N, a third phase winding P, a first capacitor C1, a second capacitor C2, a first diode D1, a second diode D2, and a first inductor L1, as shown in the attached diagram. Figure 1 As shown, the anode of the first switch S1 is connected to the anodes of the second switch S2 and the third switch S3, and serves as the positive input terminal of the reverse polarity main circuit 1. The cathode of the first switch S1 is connected to one end of the first phase winding M. The cathode of the second switch S2 is connected to one end of the second phase winding N. The cathode of the third switch S3 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 S4, the anode of the fifth switch S5, and one end of the first capacitor C1. The cathode of the fifth switch S5 is connected to the cathode of the second diode D2 and one end of the first inductor L1. The other end of the first inductor L1 is connected to the other end of the first capacitor C1 and the anode of the first diode D1. The anode of the second diode D2 is connected to one end of the second capacitor C2, and serves as the negative output terminal of the reverse polarity main circuit 1. The other end of the second capacitor C2 is connected to the cathode of the fourth switch S4 and the cathode of the first diode D1, and serves as the positive output terminal and negative input terminal of the reverse polarity main circuit 1. All switches are three-terminal fully controlled power electronic switching devices.

[0036] The boost converter auxiliary circuit 2 consists of an isolation converter, a sixth switch S6, a seventh switch S7, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a third diode D3, a fourth diode D4, a fifth diode D5, a sixth diode D6, a seventh diode D7, an eighth diode D8, a second inductor L2, and a third inductor L3, as shown in the attached diagram. Figure 1As shown, the positive input terminal of the isolation converter serves as the positive input terminal of the boost auxiliary circuit 2, connected to the positive output terminal of the reverse polarity main circuit 1. The negative input terminal of the isolation converter serves as the negative input terminal of the boost auxiliary circuit 2, connected to the negative output terminal of the reverse polarity main circuit 1. The positive output terminal of the isolation converter is connected to one end of the second inductor L2 and one end of the third inductor L3. The other end of the second inductor L2 is connected to the anode of the sixth switch S6, one end of the third capacitor C3, and the anode of the third diode D3. The other end of the third inductor L3 is connected to the anode of the seventh switch S7, one end of the fourth capacitor C4, and the anode of the fourth diode D4. The other end of the third capacitor C3 is connected to the cathode of the fifth diode D5 and the anode of the sixth diode D6. The other end of the fourth capacitor C4 is connected to the cathode of the seventh diode D7 and the anode of the eighth diode D8. The cathode of the third diode D3 is connected to the cathode of the fourth diode D4 and the cathode of the fifth diode D6. The anode of diode D5, the anode of the seventh diode D7, one end of the fifth capacitor C5, and one end of the sixth capacitor C6 are connected. The cathode of the sixth diode D6 is connected to the cathode of the eighth diode D8 and the other end of the fifth capacitor C5, and serves as the positive output terminal of the boost auxiliary circuit 2, which is connected to the positive input terminal of the reverse polarity main circuit 1. The other end of the sixth capacitor C6 is connected to the negative output terminal of the isolation converter, the cathode of the sixth switch S6, and the cathode of the seventh switch S7, and serves as the negative output terminal of the boost auxiliary circuit 2, which is connected to the negative input terminal of the reverse polarity main circuit 1. All switches are three-terminal fully controlled power electronic switching devices. The third capacitor C3 is the same as the fourth capacitor C4, the fifth capacitor C5 is the same as the sixth capacitor C6, and the second inductor L2 is the same as the third inductor L3. In addition to isolation function, the isolation converter also sets an appropriate input-output voltage ratio according to the needs of the power converter.

[0037] The control method of the reverse polarity step-up power converter for switched reluctance motors is based on the operating principle of the switched reluctance motor. When the switched reluctance motor operates as a generator, the reverse polarity main circuit 1 outputs electrical energy to the DC grid or the electrical load, and supplies power to the input terminals of the step-up auxiliary circuit 2. The step-up auxiliary circuit 2 acts as the excitation power supply for each phase winding when the switched reluctance generator is running. Its initial input electrical energy comes from the DC grid or other power sources. According to the rotor position information, when the first phase winding M needs to be put into operation, the first switch S1, the fourth switch S4, and the fifth switch S5 are closed first, as shown in the attached diagram. Figure 2 As shown, during the excitation stage of the first phase winding M, i.e., the first operating stage, the excitation power supply supplies excitation power to the first phase winding M through the first switch S1 and the fourth switch S4. Simultaneously, the first capacitor C1 discharges to the first inductor L1 through the fifth switch S5. The output power of the reverse polarity main circuit 1 is maintained by the second capacitor C2. Based on the rotor position information, when the excitation stage needs to end, the fourth switch S4 and the fifth switch S5 are disconnected, as shown in the attached diagram. Figure 3As shown, the first phase winding M enters the power generation stage, i.e., the second working stage. The excitation power supply and the first phase winding M together charge the first capacitor C1 through the first switch S1 and the first diode D1. At the same time, the energy stored in the first inductor L1 is output to the output terminal of the reverse polarity main circuit 1 through the first diode D1 and the second diode D2, and charges the second capacitor C2. According to the rotor position information, when the power generation stage needs to end, the first switch S1 is disconnected, and the first phase winding M ends its operation.

[0038] Based on the rotor position information, when the second phase winding N needs to be put into operation, the second switch S2, the fourth switch S4, and the fifth switch S5 are first closed and turned on, entering the excitation stage of the second phase winding N, i.e., the first working stage. The excitation power supply supplies power to the second phase winding N through the second switch S2 and the fourth switch S4 for excitation. At the same time, the first capacitor C1 discharges to the first inductor L1 through the fifth switch S5. The output power of the reverse polarity main circuit 1 is maintained by the second capacitor C2. Based on the rotor position information, when the excitation stage needs to be ended... When the fourth switch S4 and the fifth switch S5 are disconnected, the second phase winding N enters the power generation stage, i.e., the second working stage. The excitation power supply and the second phase winding N together charge the first capacitor C1 through the second switch S2 and the first diode D1. At the same time, the energy stored in the first inductor L1 is output to the output terminal of the reverse polarity main circuit 1 through the first diode D1 and the second diode D2, and charges the second capacitor C2. According to the rotor position information, when the power generation stage needs to end, the second switch S2 is disconnected, and the second phase winding N ends its operation.

[0039] Based on the rotor position information, when the third phase winding P needs to be put into operation, the third switch S3, the fourth switch S4, and the fifth switch S5 are first closed and turned on, entering the excitation stage of the third phase winding P, i.e., the first working stage. The excitation power supply supplies power to the third phase winding P through the third switch S3 and the fourth switch S4 for excitation. At the same time, the first capacitor C1 discharges to the first inductor L1 through the fifth switch S5. The output power of the reverse polarity main circuit 1 is maintained by the second capacitor C2. Based on the rotor position information, when the excitation stage needs to be ended... When the fourth switch S4 and the fifth switch S5 are disconnected, the third phase winding P enters the power generation stage, i.e., the second working stage. The excitation power supply and the third phase winding P together charge the first capacitor C1 through the third switch S3 and the first diode D1. At the same time, the energy stored in the first inductor L1 is output to the output terminal of the reverse polarity main circuit 1 through the first diode D1 and the second diode D2, and charges the second capacitor C2. According to the rotor position information, when the power generation stage needs to end, the third switch S3 is disconnected, and the third phase winding P ends its operation.

[0040] The control method of the reverse polarity step-up power converter for switched reluctance motors is based on the operating principle of the switched reluctance motor. When the switched reluctance motor is running as a motor, the step-up auxiliary circuit 2 serves as the power supply for each phase winding of the switched reluctance motor. Its input energy mainly comes from the power grid or other power sources. According to the rotor position information, when the first phase winding M needs to be put into operation, the first switch S1, the fourth switch S4, and the fifth switch S5 are closed and turned on first, as shown in the attached diagram. Figure 2 As shown, the first operating stage of the first phase winding M, which is also the main stage and the stage of generating electric torque, is initiated by the power supply through the first switch S1 and the fourth switch S4 to generate electric torque. Simultaneously, the energy stored in the first capacitor C1 is discharged to the first inductor L1 through the fifth switch S5. Based on the rotor position information, when the first operating stage needs to end, the fourth switch S4 and the fifth switch S5 are disconnected, as shown in the attached diagram. Figure 3 As shown, when entering the second working stage of the first phase winding M, the remaining stored energy of the first phase winding M and the power supply are released together to the first capacitor C1 through the first switch S1 and the first diode D1. At the same time, the stored energy of the first inductor L1 is released to the output terminal of the reverse polarity main circuit 1 through the first diode D1 and the second diode D2, and charges the second capacitor C2. When the next phase winding needs to be put into operation, the first switch S1 is turned off, and the operation of the first phase winding M ends.

[0041] According to the rotor position information, when the second phase winding N needs to be put into operation, the second switch S2, the fourth switch S4, and the fifth switch S5 are first closed and turned on, entering the first working stage of the second phase winding N, which is also the main stage and the stage of generating electric torque. The power supply supplies power to the second phase winding N through the second switch S2 and the fourth switch S4 to generate electric torque. At the same time, the energy stored in the first capacitor C1 is discharged to the first inductor L1 through the fifth switch S5. According to the rotor position information, when the first working stage needs to be ended, the fourth switch S4 and the fifth switch S5 are turned off, entering the second working stage of the second phase winding N. The remaining energy stored in the second phase winding N and the power supply are released to the first capacitor C1 through the second switch S2 and the first diode D1. At the same time, the energy stored in the first inductor L1 is released to the output terminal of the reverse polarity main circuit 1 through the first diode D1 and the second diode D2, and charges the second capacitor C2. According to the rotor position information, when the next phase winding needs to be put into operation, the second switch S2 is turned off, and the operation of the second phase winding N ends.

[0042] According to the rotor position information, when the third phase winding P needs to be put into operation, the third switch S3, the fourth switch S4, and the fifth switch S5 are first closed and turned on, entering the first working stage of the third phase winding P, which is also the main stage and the stage of generating electric torque. The power supply supplies power to the third phase winding P through the third switch S3 and the fourth switch S4 to generate electric torque. At the same time, the energy stored in the first capacitor C1 is discharged to the first inductor L1 through the fifth switch S5. According to the rotor position information, when the first working stage needs to be ended, the fourth switch S4 and the fifth switch S5 are turned off, entering the second working stage of the third phase winding P. The remaining energy stored in the third phase winding P and the power supply are released together to the first capacitor C1 through the third switch S3 and the first diode D1. At the same time, the energy stored in the first inductor L1 is released to the output terminal of the reverse polarity main circuit 1 through the first diode D1 and the second diode D2, and charges the second capacitor C2. According to the rotor position information, when the next phase winding needs to be put into operation, the third switch S3 is turned off, and the operation of the third phase winding P ends.

[0043] According to the theory of switched reluctance motors, the switching angle regions of a switched reluctance motor are completely different when it is used as a generator and when it is used as a motor. When the switched reluctance motor is used as a motor, the energy released by each phase winding is much less than when it is used as a generator. Therefore, the electrical energy output by the reverse polarity main circuit 1 is insufficient to support the input requirements of the boost auxiliary circuit 2. An external power grid or power supply must be used as one of the input power sources for the boost auxiliary circuit 2.

[0044] The control method of boost auxiliary circuit 2 is that the sixth switch S6 and the seventh switch S7 operate in PWM mode. They have the same operating frequency and the same duty cycle, and their phases differ by 180 degrees when they are turned on, that is, they are turned on alternately.

[0045] Under the control method of the two switching transistors in the boost auxiliary circuit 2, the operating state of the boost auxiliary circuit 2 differs when their duty cycles are greater than 0.5 and less than 0.5. These differences need to be analyzed separately as two modes. First, when the duty cycle is greater than 0.5, which is the first operating mode of the boost auxiliary circuit 2, its switching sequence is shown in the attached figure. Figure 4 As shown in the figure, GS6 and GS7 represent the switching signals of the sixth switch S6 and the seventh switch S7, respectively. In the T0-T1 interval and the T2-T3 interval, both switches are in a closed conducting state, i.e., the first and third operating stages of the first mode. The operation process of the boost auxiliary circuit 2 is the same in both operating stages, as shown in the attached diagram. Figure 5 As shown, the second inductor L2, the third inductor L3, the third capacitor C3, and the fourth capacitor C4 are all in a charging state; (See attached image) Figure 6The diagram shows the T1-T2 interval, i.e., the second operating stage. The sixth switch S6 is off, and the seventh switch S7 is on. At this time, the second inductor L2 and the third capacitor C3 discharge and, together with the isolation converter, output to the output terminal. (See attached diagram.) Figure 7 As shown in the T3-T4 interval, which is the fourth operating stage, the sixth switch S6 is turned on and the seventh switch S7 is turned off. At this time, the third inductor L3 and the fourth capacitor C4 discharge and are output to the output terminal together with the isolation converter.

[0046] When the duty cycle of the sixth switch S6 and the seventh switch S7 of the boost auxiliary circuit 2 is less than 0.5, it is the second mode of the boost auxiliary circuit 2, and its switching sequence is as follows: Figure 8 As shown, in the T0-T1 interval, i.e., its first working stage, it is the same as the second working stage of the first mode, as shown in the attached figure. Figure 6 As shown; in the T1-T2 interval and the T3-T4 interval, both switching transistors are in the off state, that is, the second and fourth operating stages of the second mode. The operation process of the boost auxiliary circuit 2 is the same in both operating stages, as shown in the attached figure. Figure 9 As shown, the second inductor L2, the third inductor L3, the third capacitor C3, and the fourth capacitor C4 are all in the state of discharging to the output terminal; in the T2-T3 interval, i.e., the third operating stage, it is the same as the fourth operating stage of the first mode, as shown in the attached diagram. Figure 7 As shown.

[0047] Based on the principle of energy storage element balance during the operation of the boost auxiliary circuit 2, the input-output voltage relationship of the boost auxiliary circuit 2 can be obtained as follows:

[0048]

[0049] In equation (1), U L U is the output voltage of the boost auxiliary circuit 2; d is the PWM duty cycle of the sixth switch S6 and the seventh switch S7; U F The voltage at the output terminal of the isolation converter is shown. It can be seen that: (1) the output voltage of the boost auxiliary circuit 2 can be adjusted by adjusting the duty cycle d; (2) compared with the traditional BOOST circuit, the boost effect of the boost auxiliary circuit 2 of the present invention is about twice that of the traditional BOOST.

[0050] Although the switched reluctance motor described in this invention has three-phase windings, according to the appendix... Figure 1 Based on the structure and control method shown, for non-three-phase winding switched reluctance motors, it is simply a matter of increasing or decreasing the number of series branches of each phase winding and switching transistor. The control method for each phase winding is based on the rotor position information and there is no difference. Therefore, this invention necessarily has the right to protect non-three-phase winding switched reluctance motors.

Claims

1. A reverse polarity boost converter for switched reluctance motors, comprising a reverse polarity main circuit and a boost auxiliary circuit, characterized in that the output terminals of the reverse polarity main circuit are connected to the input terminals of the boost auxiliary circuit, and the output terminals of the boost auxiliary circuit are connected to the input terminals of the reverse polarity main circuit.

2. The switched reluctance motor reverse polarity boost converter according to claim 1, wherein the reverse polarity main circuit comprises a first switch, a second switch, a third switch, a fourth switch, a fifth switch, a first phase winding, a second phase winding, a third phase winding, a first capacitor, a second capacitor, a first diode, a second diode, and a first inductor, characterized in that... The anode of the first switch is connected to the anodes of the second and third switches and serves as the positive input terminal of the reverse polarity main circuit. The cathode of the first switch is connected to one end of the first phase winding, the cathode of the second switch is connected to one end of the second phase winding, the cathode of the third switch 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 phase winding, the other end of the third phase winding, the anode of the fourth switch, the anode of the fifth switch, and one end of the first capacitor. The cathode of the fifth switch is connected to the cathode of the second diode and one end of the first inductor. The other end of the first inductor is connected to the other end of the first capacitor and the anode of the first diode. The anode of the second diode is connected to one end of the second capacitor and serves as the negative output terminal of the reverse polarity main circuit. The other end of the second capacitor is connected to the cathode of the fourth switch and the cathode of the first diode and serves as the positive output terminal and the negative input terminal of the reverse polarity main circuit. All switching transistors are three-terminal fully controlled power electronic switching devices.

3. The switched reluctance motor reverse polarity boost converter according to claim 1, wherein the boost auxiliary circuit comprises an isolation converter, a sixth switch, a seventh switch, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a third diode, a fourth diode, a fifth diode, a sixth diode, a seventh diode, an eighth diode, a second inductor, and a third inductor, characterized in that the positive input terminal of the isolation converter is connected to the positive output terminal of the reverse polarity main circuit as the positive input terminal of the boost auxiliary circuit, the negative input terminal of the isolation converter is connected to the negative output terminal of the reverse polarity main circuit as the negative input terminal of the boost auxiliary circuit, the positive output terminal of the isolation converter is connected to one end of the second inductor and one end of the third inductor, the other end of the second inductor is connected to the anode of the sixth switch, one end of the third capacitor, and the anode of the third diode, the other end of the third inductor is connected to the anode of the seventh switch, one end of the fourth capacitor, and the anode of the fourth diode, and the third capacitor... The other end of the capacitor is connected to the cathode of the fifth diode and the anode of the sixth diode. The other end of the fourth capacitor is connected to the cathode of the seventh diode and the anode of the eighth diode. The cathode of the third diode is connected to the cathode of the fourth diode, the anode of the fifth diode, the anode of the seventh diode, one end of the fifth capacitor, and one end of the sixth capacitor. The cathode of the sixth diode is connected to the cathode of the eighth diode and the other end of the fifth capacitor, and serves as the positive output terminal of the boost auxiliary circuit connected to the positive input terminal of the reverse polarity main circuit. The other end of the sixth capacitor is connected to the negative output terminal of the isolation converter, the cathode of the sixth switch, and the cathode of the seventh switch, and serves as the negative output terminal of the boost auxiliary circuit connected to the negative input terminal of the reverse polarity main circuit. All switches are three-terminal fully controlled power electronic switching devices. The third capacitor is the same as the fourth capacitor, the fifth capacitor is the same as the sixth capacitor, and the second inductor is the same as the third inductor. In addition to isolation function, the isolation converter also has a suitable input-output voltage ratio set according to the power converter requirements.

4. The control method for the reverse polarity boost converter of the switched reluctance motor according to claims 1-3, wherein when the switched reluctance motor operates as a generator, the boost auxiliary circuit serves as the excitation power supply for each phase winding of the switched reluctance generator, its technical feature is that... According to the rotor position information, when the first phase winding needs to be put into operation, the first switch, the fourth switch, and the fifth switch are closed first to enter the excitation stage of the first phase winding. The excitation power supply supplies power to the first phase winding through the first switch and the fourth switch. At the same time, the first capacitor discharges to the first inductor through the fifth switch. The output power of the reverse polarity main circuit is maintained by the second capacitor. According to the rotor position information, when the excitation stage needs to end, the fourth and fifth switching transistors are disconnected, and the first phase winding enters the power generation stage. The excitation power supply and the first phase winding together charge the first capacitor through the first switching transistor and the first diode. At the same time, the energy stored in the first inductor is output to the reverse polarity main circuit output terminal through the first and second diodes, and charges the second capacitor. According to the rotor position information, when the power generation stage needs to end, the first switching transistor is disconnected, and the first phase winding ends its operation. According to the rotor position information, when the second phase winding needs to be put into operation, the second, fourth and fifth switches are closed first to enter the excitation stage of the second phase winding. The excitation power supply supplies power to the second phase winding through the second and fourth switches for excitation. At the same time, the first capacitor discharges to the first inductor through the fifth switch. The output power of the reverse polarity main circuit is maintained by the second capacitor. According to the rotor position information, when the excitation stage needs to end, the fourth and fifth switching transistors are disconnected, and the second phase winding enters the power generation stage. The excitation power supply and the second phase winding together charge the first capacitor through the second switching transistor and the first diode. At the same time, the energy stored in the first inductor is output to the reverse polarity main circuit output terminal through the first and second diodes, and also charges the second capacitor. According to the rotor position information, when the power generation stage needs to end, the second switching transistor is disconnected, and the second phase winding operation ends. According to the rotor position information, when the third phase winding needs to be put into operation, the third, fourth and fifth switches are closed first to enter the excitation stage of the third phase winding. The excitation power supply supplies power to the third phase winding through the third and fourth switches for excitation. At the same time, the first capacitor discharges to the first inductor through the fifth switch. The output power of the reverse polarity main circuit is maintained by the second capacitor. According to the rotor position information, when the excitation stage needs to end, the fourth and fifth switches are disconnected, and the third phase winding enters the power generation stage. The excitation power supply and the third phase winding together charge the first capacitor through the third switch and the first diode. At the same time, the energy stored in the first inductor is output to the reverse polarity main circuit output terminal through the first and second diodes, and charges the second capacitor. According to the rotor position information, when the power generation stage needs to end, the third switch is disconnected, and the third phase winding operation ends.

5. The control method for the reverse polarity boost converter of the switched reluctance motor according to claims 1-3, wherein when the switched reluctance motor operates as a motor, the boost auxiliary circuit serves as the power supply for each phase winding of the switched reluctance motor, its technical feature is that... Based on the rotor position information, when the first phase winding needs to be put into operation, the first, fourth, and fifth switching transistors are first closed to enter the first working stage of the first phase winding. The power supply supplies power to the first phase winding through the first and fourth switching transistors to generate electric torque. At the same time, the energy stored in the first capacitor is discharged to the first inductor through the fifth switching transistor. Based on the rotor position information, when the first working stage needs to be ended, the fourth and fifth switching transistors are disconnected to enter the second working stage of the first phase winding. The remaining energy stored in the first phase winding and the power supply are released to the first capacitor through the first switching transistor and the first diode. At the same time, the energy stored in the first inductor is released to the output terminal of the reverse polarity main circuit through the first and second diodes and charges the second capacitor. When the next phase winding needs to be put into operation, the first switching transistor is disconnected, and the operation of the first phase winding ends. Based on the rotor position information, when the second phase winding needs to be put into operation, the second, fourth, and fifth switches are first closed to enter the first operating stage of the second phase winding. The power supply supplies power to the second phase winding through the second and fourth switches to generate electric torque. At the same time, the energy stored in the first capacitor is discharged to the first inductor through the fifth switch. Based on the rotor position information, when the first operating stage needs to be ended, the fourth and fifth switches are opened to enter the second operating stage of the second phase winding. The remaining energy stored in the second phase winding and the power supply are released to the first capacitor through the second switch and the first diode. At the same time, the energy stored in the first inductor is released to the output terminal of the reverse polarity main circuit through the first and second diodes and charges the second capacitor. Based on the rotor position information, when the next phase winding needs to be put into operation, the second switch is opened, and the operation of the second phase winding ends. Based on the rotor position information, when the third phase winding needs to be put into operation, the third, fourth, and fifth switches are first closed to enter the first operating stage of the third phase winding. The power supply supplies power to the third phase winding through the third and fourth switches to generate electric torque. At the same time, the energy stored in the first capacitor is discharged to the first inductor through the fifth switch. Based on the rotor position information, when the first operating stage needs to be ended, the fourth and fifth switches are disconnected to enter the second operating stage of the third phase winding. The remaining energy stored in the third phase winding and the power supply are released to the first capacitor through the third switch and the first diode. At the same time, the energy stored in the first inductor is released to the output terminal of the reverse polarity main circuit through the first and second diodes and charges the second capacitor. Based on the rotor position information, when the next phase winding needs to be put into operation, the third switch is disconnected, and the operation of the third phase winding ends.

6. The control method for the reverse polarity boost converter of the switched reluctance motor according to claims 1-3, and the control method for the boost auxiliary circuit, are characterized in that the sixth and seventh switching transistors operate in PWM mode, with the same operating frequency and duty cycle, and their phases differ by 180 degrees when turned on, i.e., they are interleaved.

7. The control method for the reverse polarity boost converter of the switched reluctance motor according to claims 1-3 and 6 is characterized in that when the PWM duty cycle of the sixth and seventh switching transistors of the boost auxiliary circuit is greater than 0.5, it is the first mode of operation of the boost auxiliary circuit.

8. The control method for the reverse polarity boost converter of the switched reluctance motor according to claims 1-3 and 6 is characterized in that when the PWM duty cycle of the sixth and seventh switching transistors of the boost auxiliary circuit is less than 0.5, it is the second mode of operation of the boost auxiliary circuit.

9. The control method for the switched reluctance motor reverse polarity boost converter according to claims 1-3 and 6-8 is characterized in that, based on the energy storage element balance principle in each working mode of the boost auxiliary circuit, the input-output voltage relationship of the boost auxiliary circuit is as follows: In equation (1), U L U is the output voltage of the boost auxiliary circuit; d is the PWM duty cycle of the sixth and seventh switches; U F This is the output voltage of the isolation converter.

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