A multi-modal flexible switched motor driver and method of switching thereof

Abstract

The application provides a multi-mode flexible switching motor driver and a switching method thereof, which comprises a first bridge arm, a second bridge arm, a third bridge arm, a fourth bridge arm and a first bidirectional thyristor and a second bidirectional thyristor. By controlling the conduction and turn-off of the two bidirectional thyristors in the switching circuit, the motor driver topology can be switched among three modes, i.e. a three-phase series winding topology, a single-phase reverse connection three-phase half-bridge topology and a single-phase reverse connection three-phase four-bridge arm topology, so that the motor driver can adopt different topological structures according to different motor operating conditions, thereby improving the constant torque speed regulation range, the control degree of freedom and the fault tolerance of the motor driver. The topological structure switching method provided by the application has no transient transition process during the switching of the topological structure, can improve the driving performance of the motor in the full speed range, has fewer bidirectional thyristors, has low hardware cost and high reliability.

Description

Technical Field

[0001] This invention relates to the field of AC motor and drive control technology, and in particular to a multi-modal flexible switching motor driver and its switching method. Background Technology

[0002] Motor drive systems are crucial components in applications such as electric vehicles, drones, and industrial robots. The topology of the power electronic converter directly affects the performance of the motor drive system. Currently, the most commonly used AC motor drive topologies include the three-phase half-bridge topology with a conventional three-phase inverter connected to a Y-type motor, and the dual-inverter open-winding motor topology. [1-2] Three-phase four-arm topology [3] The three-phase half-bridge topology, with a single inverter connecting a Y-type motor load, includes three bridge arms. Its topology is simple but lacks fault-tolerant operation. The dual-inverter open-winding motor topology opens the neutral point of the Y-connected motor stator winding, with each end of the winding powered by two inverters. It boasts high inverter utilization, multi-level output, and redundancy, providing fault-tolerant operation. However, it involves a large number of switches, higher cost, and more complex control. The three-phase four-bridge-arm topology provides a zero-sequence current path for the motor, enabling fault tolerance in case of open circuits, but other performance aspects remain unchanged. In recent years, a three-phase series winding topology has emerged... [4] The proposed structure opens the neutral point of the three-phase stator windings of the motor, connects the three-phase windings in series, and drives the motor with a four-bridge converter. The three-phase series winding topology has high DC bus voltage utilization, wide constant torque speed regulation range, and fewer switching devices required. However, this topology leads to increased current stress in some bridge arms, greater power loss, and limits the motor's torque output capability at low speeds. It is difficult to simultaneously guarantee torque output capability and speed output range, and cannot maximize the utilization of the motor's operating range.

[0003] It can be seen that the various motor drive topologies currently in use all have performance defects that are difficult to overcome. In order to overcome the above defects, reference [5] proposed an inverter and its switching method for switching a three-phase half-bridge-series winding topology. Four bidirectional thyristors are added to the three-phase series winding topology, so that the inverter is converted to a three-phase half-bridge topology and the motor stator winding is connected in a star configuration at low speed, and the inverter is converted to a three-phase series winding topology and the motor stator winding is connected in a series configuration at high speed, thereby ensuring the torque output capability and speed output range of the motor in the full speed range. However, this topology uses a lot of bidirectional thyristor devices, and there is a transient process during switching, which will inevitably affect the motor drive performance. Reference [6] proposed a multi-mode flexible switching motor drive and topology switching control method, which realizes the switching of multiple topologies without affecting the operation of the motor, ensuring the torque output capability at low speed and the speed output capability at high speed, maximizing the motor working range, and improving the control freedom and fault tolerance of the motor drive system. However, this topology uses a lot of bidirectional thyristor devices, which increases the loss.

[0004] To compensate for the shortcomings of motor drive methods such as three-phase half-bridge topology, dual-inverter open-winding motor topology, three-phase four-bridge-arm topology, and three-phase series winding topology, existing topology switching methods based on four-bridge-arm converters can ensure the motor's torque output capability and speed output range across the entire speed range. However, the topology uses a large number of bidirectional thyristor devices, and the switching process involves a transient transition, which inevitably affects the motor drive performance.

[0005] References

[0006] [1] Takahashi I, Ohmori Y. High—performance direct torque control of an induction motor[J]. Industry Applications, IEEE Transactions on, 1989, 25(2): 257-264.

[0007] [2] Stemmler H, Guggenbach P. Configurations of high-power voltagesource inverter drives: Power Electronics and Applications, 1993. , Fifth European Conference on, Brighton, 1993[C].

[0008] [3] Ca ricci, F.Cres cimb ini, TALipo.Converter Topology with Load-Neutral Modulation for Trapezoidal-EMF PM Motor Drives[J]. IEEE Trans.onPower Electronics, 1994, 9(2): 232-239.

[0009] [4] Jiang Dong, Li An, Qu Ronghai. A topology for an open-winding motor driver and its modulation method [P]. Chinese Patent: CN108258976A, 2018.07.06

[0010] [5] Inverter with three-phase half-bridge-series winding topology switching and its switching method [P], CN201910866276.0, 2021.

[0011] [6] Jiang Dong, Li An, Liu Zicheng, et al. A multimodal flexible switching motor driver and topology switching control method [P]. CN112532144B, 2021-12-17. Summary of the Invention

[0012] This invention proposes a multi-modal flexible switching motor driver and its switching method, which can ensure that the motor driver topology can be switched to three modes according to the operation needs: three-phase half-bridge topology, three-phase four-bridge arm topology, and three-phase series winding topology. The switching uses fewer bidirectional thyristors and there is no transient transition process during switching, which can improve the driving performance of the motor in the full speed range.

[0013] The present invention adopts the following technical solution.

[0014] A multi-modal flexible switching motor driver, the motor driver topology including a first bridge arm, a second bridge arm, a third bridge arm, a fourth bridge arm, a first bidirectional thyristor S1, and a second bidirectional thyristor S2; each bridge arm includes an upper bridge arm power switch device and a lower bridge arm power switch device; the upper node of the upper bridge arm power switch device of each bridge arm is connected to the DC bus voltage, the lower node of the lower bridge arm power switch device is connected to the power supply ground, and the lower node of the upper bridge arm power switch device is connected to the upper node of the lower bridge arm power switch device, serving as the output node of the bridge arm;

[0015] In the motor driver topology, the left node of phase A winding is connected to the output node of the first bridge arm, and the right node of phase A winding is connected to the output node of the second bridge arm.

[0016] The left node of phase B winding is connected to the output node of the second bridge arm, and the right node of phase B winding is connected to the output node of the third bridge arm.

[0017] The left node of the C-phase winding is connected to the right node of the first bidirectional thyristor S1 and the right node of the second bidirectional thyristor S2, and the right node of the C-phase winding is connected to the output node of the fourth bridge arm.

[0018] The left node of the first bidirectional thyristor S1 is connected to the output node of the third bridge arm, and the left node of the second bidirectional thyristor S2 is connected to the output node of the second bridge arm.

[0019] The motor stator winding polarity and phase sequence of the motor driver topology are variable, and the first bidirectional thyristor S1 and the second bidirectional thyristor S2 are used to switch the topology of the motor driver.

[0020] The topologies of motor drives include single-phase reverse-connected three-phase half-bridge topology, single-phase reverse-connected three-phase four-bridge-arm topology switching, and three-phase series winding topology.

[0021] In the motor driver topology, the first bridge arm includes an upper bridge arm power switch device T1 and a lower bridge arm power switch device T2, the second bridge arm includes an upper bridge arm power switch device T3 and a lower bridge arm power switch device T4, the third bridge arm includes an upper bridge arm power switch device T5 and a lower bridge arm power switch device T6, and the fourth bridge arm includes an upper bridge arm power switch device T7 and a lower bridge arm power switch device T8.

[0022] In the motor driver, the power switching device is a fully controlled power switching device, including MOSFET or IGBT; alternative devices for the first bidirectional thyristor S1 and the second bidirectional thyristor S2 in the motor driver include switching devices with arc extinguishing capability, or a switch with the ability to conduct and turn off current composed of a rectifier circuit and an IGBT.

[0023] A switching method for a multimodal flexible switching motor driver topology, used in the motor driver described above, the switching method comprising:

[0024] Method A1: The first bidirectional thyristor S1 is turned off and the second bidirectional thyristor S2 is turned on; the power switching device of the second bridge arm is turned off; the first bridge arm, the third bridge arm, and the fourth bridge arm form a single-phase reverse-connected three-phase half-bridge topology; the motor windings are star-connected; the motor driver switches to the low-voltage mode for low-speed operation of the motor.

[0025] Method A2: The first bidirectional thyristor S1 is turned on and the second bidirectional thyristor S2 is turned off. The first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm form a three-phase series winding topology, and the motor windings are connected in series. The motor driver switches to the high-voltage mode of the motor phase voltage for the motor to operate at high speed.

[0026] In method A3, the first bidirectional thyristor S1 is turned off and the second bidirectional thyristor S2 is turned on. The first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm form a single-phase, opposite-connected three-phase, four-bridge-arm topology. The motor windings are star-connected, and the motor driver provides a zero-sequence current path for fault-tolerant motor operation.

[0027] The switching method for smooth switching between single-phase reverse-connected three-phase half-bridge topology, single-phase reverse-connected three-phase four-bridge arm topology, and three-phase series winding topology includes:

[0028] Method B1, a control method for switching from a single-phase reverse-connected three-phase half-bridge topology to a single-phase reverse-connected three-phase four-bridge-arm topology, specifically: keeping the drive signals of the first bidirectional thyristor S1 and the second bidirectional thyristor S2 unchanged, switching the original drive scheme consisting of the first bridge arm, the third bridge arm, and the fourth bridge arm to a drive scheme consisting of the first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm, and switching the topology to a single-phase reverse-connected three-phase four-bridge-arm topology;

[0029] Method B2, a control method for switching from a single-phase reverse-connected three-phase four-bridge topology to a single-phase reverse-connected three-phase half-bridge topology, specifically: keeping the drive signals of the first bidirectional thyristor S1 and the second bidirectional thyristor S2 unchanged, switching the original drive scheme consisting of the first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm to a drive scheme consisting of the first bridge arm, the third bridge arm, and the fourth bridge arm, and switching the topology to a single-phase reverse-connected three-phase half-bridge topology;

[0030] Method B3, a control method for switching from a single-phase reverse-connected three-phase half-bridge topology to a three-phase series winding topology, specifically: remove the drive signal of the second bidirectional thyristor S2, wait for the C-phase current to naturally cross zero, turn off the second bidirectional thyristor S2, drive the first bidirectional thyristor S1 to conduct, and at the same time switch the original drive scheme consisting of the first bridge arm, the third bridge arm, and the fourth bridge arm to a drive scheme consisting of the first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm, and switch the topology to a three-phase series winding topology;

[0031] Method B4, the control method for switching from a three-phase series winding topology to a single-phase reverse-connected three-phase half-bridge topology, specifically: remove the drive signal of the first bidirectional thyristor S1, wait for the C-phase current to naturally cross zero, turn off the first bidirectional thyristor S1, drive the second bidirectional thyristor S2 to conduct, and at the same time switch the original drive scheme consisting of the first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm to a drive scheme consisting of the first bridge arm, the third bridge arm, and the fourth bridge arm, and switch the topology to a three-phase half-bridge topology;

[0032] Method B5, the control method for switching from a single-phase reverse-connected three-phase four-bridge-arm topology to a three-phase series winding topology, specifically: remove the drive signal of the second bidirectional thyristor S2, wait for the C-phase current to naturally cross zero, turn off the second bidirectional thyristor S2, drive the first bidirectional thyristor S1 to conduct, and switch the topology to a three-phase series winding topology.

[0033] Method B6, the control method for switching from a three-phase series winding topology to a single-phase reverse-connected three-phase four-arm bridge topology, specifically: remove the drive signal of the first bidirectional thyristor S1, wait for the C-phase current to naturally cross zero, turn off the first bidirectional thyristor S1, drive the second bidirectional thyristor S2 to conduct, and switch the topology to a three-phase series winding topology.

[0034] Methods B1, B2, B3, B4, B5, and B6 are flexible switching methods without transient transition processes, and their impact on the output dynamic performance of the motor drive system is negligible.

[0035] In method A1, the motor driver is switched to a single-phase reverse-connected three-phase half-bridge topology for low-speed operation of the motor. Under the same DC bus voltage, the stator winding phase current provided by the three-phase half-bridge topology is 1 / √3 of that of the three-phase series winding topology, so as to reduce the operating loss of the motor driver when running at low speed.

[0036] In method A2, the motor driver is switched to a three-phase series winding topology for the motor to operate at high speed. Under the same DC bus voltage, the maximum value of the motor stator winding phase voltage provided by the three-phase series winding topology is √3 times that of the three-phase half-bridge topology, and the constant torque speed regulation range is correspondingly expanded by √3 times.

[0037] In method A3, the motor driver is switched to a single-phase reverse-connected three-phase four-arm topology. When an arm or phase winding is open-circuited due to a fault, the system switches to a single-phase reverse-connected three-phase four-arm topology to improve the fault-tolerant operation capability of the motor drive system.

[0038] Compared with the prior art, the above technical solutions of the present invention have the following beneficial effects:

[0039] 1. The multi-modal flexible switching motor driver proposed in this invention can switch between three topologies, adapting to different operating conditions to allow the driver to operate in different topologies and leverage their respective advantages. At low speeds, it switches to a single-phase reverse-connected three-phase half-bridge topology. Under the same DC bus voltage, the stator winding phase current provided by the three-phase half-bridge topology is 1 / √3 that of the three-phase series winding topology, reducing operating losses at low speeds. At high speeds, it switches to a three-phase series winding topology. Under the same DC bus voltage, the maximum stator winding phase voltage provided by the three-phase series winding topology is √3 times that of the three-phase half-bridge topology, correspondingly expanding the constant torque speed regulation range by √3 times. When a bridge arm or phase winding fault occurs, it switches to a single-phase reverse-connected three-phase four-bridge arm topology, improving fault-tolerant operation.

[0040] 2. The multi-mode flexible switching motor driver proposed in this invention adds only two bidirectional thyristors and their driving circuits as switching circuits on the basis of a three-phase series winding topology. This can significantly improve the voltage and current control freedom, constant torque speed regulation range and fault-tolerant operation capability of the motor drive system. At the same time, it can significantly reduce the cost and size of the controller, reduce power loss during operation, and improve the reliability of system operation.

[0041] 3. When switching topologies, only two bidirectional thyristors need to be changed and the modulation mode of the four-arm converter appropriately adjusted. The switching process has no intermediate transition circuit or intermediate transition state, and the switching time is close to zero, achieving seamless switching. The switching process does not affect the motor's speed or torque. For example, when switching between the DC voltage utilization of a unidirectional reverse-connected three-phase four-arm topology and a three-phase half-bridge topology, only the drive state of the second arm needs to be changed. The switching process can always be smooth, without voltage distortion or torque fluctuations. When switching with a three-phase series winding topology, only the left node connection of the C-phase winding needs to be changed each time. The drive signal of the bidirectional thyristor can be removed at any time, and the switching can be performed while waiting for the C-phase current to naturally cross zero. There is no transient transition process, and the switching process does not affect the motor's speed or torque. Attached Figure Description

[0042] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0043] Appendix Figure 1 This is a topology diagram of the multimodal seamless switching motor driver of the present invention;

[0044] Appendix Figure 2 This is a schematic diagram of the three-phase series winding topology of the motor driver of the present invention;

[0045] Appendix Figure 3This is a schematic diagram of a single-phase reverse-connected three-phase half-bridge topology of the motor driver of the present invention;

[0046] Appendix Figure 4 This is a schematic diagram of a single-phase, reverse-connected, three-phase, four-arm bridge topology of the motor driver of the present invention;

[0047] The grayscale element in the above figure indicates that the element is currently in an inactive state. Detailed Implementation

[0048] As shown in the figure, a multi-mode flexible switching motor driver is disclosed. The motor driver topology includes a first bridge arm, a second bridge arm, a third bridge arm, a fourth bridge arm, a first bidirectional thyristor S1, and a second bidirectional thyristor S2. Each bridge arm includes an upper bridge arm power switch device and a lower bridge arm power switch device. The upper node of the upper bridge arm power switch device in each bridge arm is connected to the DC bus voltage, and the lower node of the lower bridge arm power switch device is connected to the power supply ground. The lower node of the upper bridge arm power switch device is connected to the upper node of the lower bridge arm power switch device, serving as the output node of the bridge arm.

[0049] In the motor driver topology, the left node of phase A winding is connected to the output node of the first bridge arm, and the right node of phase A winding is connected to the output node of the second bridge arm.

[0050] The left node of phase B winding is connected to the output node of the second bridge arm, and the right node of phase B winding is connected to the output node of the third bridge arm.

[0051] The left node of the C-phase winding is connected to the right node of the first bidirectional thyristor S1 and the right node of the second bidirectional thyristor S2, and the right node of the C-phase winding is connected to the output node of the fourth bridge arm.

[0052] The left node of the first bidirectional thyristor S1 is connected to the output node of the third bridge arm, and the left node of the second bidirectional thyristor S2 is connected to the output node of the second bridge arm.

[0053] The motor stator winding polarity and phase sequence of the motor driver topology are variable, and the first bidirectional thyristor S1 and the second bidirectional thyristor S2 are used to switch the topology of the motor driver.

[0054] The topologies of motor drives include single-phase reverse-connected three-phase half-bridge topology, single-phase reverse-connected three-phase four-bridge-arm topology switching, and three-phase series winding topology.

[0055] In the motor driver topology, the first bridge arm includes an upper bridge arm power switch device T1 and a lower bridge arm power switch device T2, the second bridge arm includes an upper bridge arm power switch device T3 and a lower bridge arm power switch device T4, the third bridge arm includes an upper bridge arm power switch device T5 and a lower bridge arm power switch device T6, and the fourth bridge arm includes an upper bridge arm power switch device T7 and a lower bridge arm power switch device T8.

[0056] In the motor driver, the power switching device is a fully controlled power switching device, including MOSFET or IGBT; alternative devices for the first bidirectional thyristor S1 and the second bidirectional thyristor S2 in the motor driver include switching devices with arc extinguishing capability, or a switch with the ability to conduct and turn off current composed of a rectifier circuit and an IGBT.

[0057] A switching method for a multimodal flexible switching motor driver topology, used in the motor driver described above, the switching method comprising:

[0058] Method A1: The first bidirectional thyristor S1 is turned off and the second bidirectional thyristor S2 is turned on; the power switching device of the second bridge arm is turned off; the first bridge arm, the third bridge arm, and the fourth bridge arm form a single-phase reverse-connected three-phase half-bridge topology; the motor windings are star-connected; the motor driver switches to the low-voltage mode for low-speed operation of the motor.

[0059] Method A2: The first bidirectional thyristor S1 is turned on and the second bidirectional thyristor S2 is turned off. The first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm form a three-phase series winding topology, and the motor windings are connected in series. The motor driver switches to the high-voltage mode of the motor phase voltage for the motor to operate at high speed.

[0060] In method A3, the first bidirectional thyristor S1 is turned off and the second bidirectional thyristor S2 is turned on. The first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm form a single-phase, opposite-connected three-phase, four-bridge-arm topology. The motor windings are star-connected, and the motor driver provides a zero-sequence current path for fault-tolerant motor operation.

[0061] The switching method for smooth switching between single-phase reverse-connected three-phase half-bridge topology, single-phase reverse-connected three-phase four-bridge arm topology, and three-phase series winding topology includes:

[0062] Method B1, a control method for switching from a single-phase reverse-connected three-phase half-bridge topology to a single-phase reverse-connected three-phase four-bridge-arm topology, specifically: keeping the drive signals of the first bidirectional thyristor S1 and the second bidirectional thyristor S2 unchanged, switching the original drive scheme consisting of the first bridge arm, the third bridge arm, and the fourth bridge arm to a drive scheme consisting of the first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm, and switching the topology to a single-phase reverse-connected three-phase four-bridge-arm topology;

[0063] Method B2, a control method for switching from a single-phase reverse-connected three-phase four-bridge topology to a single-phase reverse-connected three-phase half-bridge topology, specifically: keeping the drive signals of the first bidirectional thyristor S1 and the second bidirectional thyristor S2 unchanged, switching the original drive scheme consisting of the first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm to a drive scheme consisting of the first bridge arm, the third bridge arm, and the fourth bridge arm, and switching the topology to a single-phase reverse-connected three-phase half-bridge topology;

[0064] Method B3, a control method for switching from a single-phase reverse-connected three-phase half-bridge topology to a three-phase series winding topology, specifically: remove the drive signal of the second bidirectional thyristor S2, wait for the C-phase current to naturally cross zero, turn off the second bidirectional thyristor S2, drive the first bidirectional thyristor S1 to conduct, and at the same time switch the original drive scheme consisting of the first bridge arm, the third bridge arm, and the fourth bridge arm to a drive scheme consisting of the first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm, and switch the topology to a three-phase series winding topology;

[0065] Method B4, the control method for switching from a three-phase series winding topology to a single-phase reverse-connected three-phase half-bridge topology, specifically: remove the drive signal of the first bidirectional thyristor S1, wait for the C-phase current to naturally cross zero, turn off the first bidirectional thyristor S1, drive the second bidirectional thyristor S2 to conduct, and at the same time switch the original drive scheme consisting of the first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm to a drive scheme consisting of the first bridge arm, the third bridge arm, and the fourth bridge arm, and switch the topology to a three-phase half-bridge topology;

[0066] Method B5, the control method for switching from a single-phase reverse-connected three-phase four-bridge-arm topology to a three-phase series winding topology, specifically: remove the drive signal of the second bidirectional thyristor S2, wait for the C-phase current to naturally cross zero, turn off the second bidirectional thyristor S2, drive the first bidirectional thyristor S1 to conduct, and switch the topology to a three-phase series winding topology.

[0067] Method B6, the control method for switching from a three-phase series winding topology to a single-phase reverse-connected three-phase four-arm bridge topology, specifically: remove the drive signal of the first bidirectional thyristor S1, wait for the C-phase current to naturally cross zero, turn off the first bidirectional thyristor S1, drive the second bidirectional thyristor S2 to conduct, and switch the topology to a three-phase series winding topology.

[0068] Methods B1, B2, B3, B4, B5, and B6 are flexible switching methods without transient transition processes, and their impact on the output dynamic performance of the motor drive system is negligible.

[0069] In method A1, the motor driver is switched to a single-phase reverse-connected three-phase half-bridge topology for low-speed operation of the motor. Under the same DC bus voltage, the stator winding phase current provided by the three-phase half-bridge topology is 1 / √3 of that of the three-phase series winding topology, so as to reduce the operating loss of the motor driver when running at low speed.

[0070] In method A2, the motor driver is switched to a three-phase series winding topology for the motor to operate at high speed. Under the same DC bus voltage, the maximum value of the motor stator winding phase voltage provided by the three-phase series winding topology is √3 times that of the three-phase half-bridge topology, and the constant torque speed regulation range is correspondingly expanded by √3 times.

[0071] In method A3, the motor driver is switched to a single-phase reverse-connected three-phase four-arm topology. When an arm or phase winding is open-circuited due to a fault, the system switches to a single-phase reverse-connected three-phase four-arm topology to improve the fault-tolerant operation capability of the motor drive system.

Claims

1. A multi-modal flexible switching motor driver, characterized in that: The motor driver topology includes a first bridge arm, a second bridge arm, a third bridge arm, a fourth bridge arm, a first bidirectional thyristor S1, and a second bidirectional thyristor S2; each bridge arm includes an upper bridge arm power switch device and a lower bridge arm power switch device; the upper node of the upper bridge arm power switch device of each bridge arm is connected to the DC bus voltage, the lower node of the lower bridge arm power switch device is connected to the power supply ground, and the lower node of the upper bridge arm power switch device is connected to the upper node of the lower bridge arm power switch device, serving as the output node of the bridge arm; In the motor driver topology, the left node of phase A winding is connected to the output node of the first bridge arm, and the right node of phase A winding is connected to the output node of the second bridge arm. The left node of phase B winding is connected to the output node of the second bridge arm, and the right node of phase B winding is connected to the output node of the third bridge arm. The left node of the C-phase winding is connected to the right node of the first bidirectional thyristor S1 and the right node of the second bidirectional thyristor S2, and the right node of the C-phase winding is connected to the output node of the fourth bridge arm. The left node of the first bidirectional thyristor S1 is connected to the output node of the third bridge arm, and the left node of the second bidirectional thyristor S2 is connected to the output node of the second bridge arm. The polarity and phase sequence of the motor stator windings in the motor driver topology can be changed, and the first bidirectional thyristor S1 and the second bidirectional thyristor S2 are used to switch the topology of the motor driver. The topologies of motor drives include single-phase reverse-connected three-phase half-bridge topology, single-phase reverse-connected three-phase four-bridge-arm topology switching, and three-phase series winding topology.

2. The multi-modal flexible switching motor driver according to claim 1, characterized in that: In the motor driver, the power switching device is a fully controlled power switching device, including MOSFET or IGBT; the replacement devices for the first bidirectional thyristor S1 and the second bidirectional thyristor S2 in the motor driver include switching devices with arc extinguishing capability, or a switch with the ability to conduct and turn off current composed of a rectifier circuit and an IGBT.

3. A method for switching the topology of a multimodal flexible switching motor driver, used in the motor driver of claim 1, characterized in that: The switching method includes: Method A1: The first bidirectional thyristor S1 is turned off and the second bidirectional thyristor S2 is turned on; the power switching device of the second bridge arm is turned off; the first bridge arm, the third bridge arm, and the fourth bridge arm form a single-phase reverse-connected three-phase half-bridge topology; the motor windings are star-connected; the motor driver switches to the low-voltage mode for low-speed operation of the motor. Method A2: The first bidirectional thyristor S1 is turned on and the second bidirectional thyristor S2 is turned off. The first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm form a three-phase series winding topology, and the motor windings are connected in series. The motor driver switches to the high-voltage mode of the motor phase voltage for the motor to operate at high speed. In method A3, the first bidirectional thyristor S1 is turned off and the second bidirectional thyristor S2 is turned on. The first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm form a single-phase, opposite-connected three-phase, four-bridge-arm topology. The motor windings are star-connected, and the motor driver provides a zero-sequence current path for fault-tolerant motor operation.

4. The switching method for a multimodal flexible switching motor driver topology according to claim 3, characterized in that: The switching method for smooth switching between the single-phase reverse-connected three-phase half-bridge topology, the single-phase reverse-connected three-phase four-bridge arm topology, and the three-phase series winding topology includes: Method B1, a control method for switching from a single-phase reverse-connected three-phase half-bridge topology to a single-phase reverse-connected three-phase four-bridge-arm topology, specifically: keeping the drive signals of the first bidirectional thyristor S1 and the second bidirectional thyristor S2 unchanged, switching the original drive scheme consisting of the first bridge arm, the third bridge arm, and the fourth bridge arm to a drive scheme consisting of the first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm, and switching the topology to a single-phase reverse-connected three-phase four-bridge-arm topology; Method B2, a control method for switching from a single-phase reverse-connected three-phase four-bridge topology to a single-phase reverse-connected three-phase half-bridge topology, specifically: keeping the drive signals of the first bidirectional thyristor S1 and the second bidirectional thyristor S2 unchanged, switching the original drive scheme consisting of the first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm to a drive scheme consisting of the first bridge arm, the third bridge arm, and the fourth bridge arm, and switching the topology to a single-phase reverse-connected three-phase half-bridge topology; Method B3, a control method for switching from a single-phase reverse-connected three-phase half-bridge topology to a three-phase series winding topology, specifically: remove the drive signal of the second bidirectional thyristor S2, wait for the C-phase current to naturally cross zero, turn off the second bidirectional thyristor S2, drive the first bidirectional thyristor S1 to conduct, and at the same time switch the original drive scheme consisting of the first bridge arm, the third bridge arm, and the fourth bridge arm to a drive scheme consisting of the first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm, and switch the topology to a three-phase series winding topology; Method B4, the control method for switching from a three-phase series winding topology to a single-phase reverse-connected three-phase half-bridge topology, specifically: remove the drive signal of the first bidirectional thyristor S1, wait for the C-phase current to naturally cross zero, turn off the first bidirectional thyristor S1, drive the second bidirectional thyristor S2 to conduct, and at the same time switch the original drive scheme consisting of the first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm to a drive scheme consisting of the first bridge arm, the third bridge arm, and the fourth bridge arm, and switch the topology to a three-phase half-bridge topology; Method B5, the control method for switching from a single-phase reverse-connected three-phase four-bridge-arm topology to a three-phase series winding topology, specifically: remove the drive signal of the second bidirectional thyristor S2, wait for the C-phase current to naturally cross zero, turn off the second bidirectional thyristor S2, drive the first bidirectional thyristor S1 to conduct, and switch the topology to a three-phase series winding topology. Method B6, the control method for switching from a three-phase series winding topology to a single-phase reverse-connected three-phase four-arm topology, specifically: remove the drive signal of the first bidirectional thyristor S1, wait for the C-phase current to naturally cross zero, turn off the first bidirectional thyristor S1, drive the second bidirectional thyristor S2 to conduct, and switch the topology to a three-phase four-arm topology.

5. The switching method for a multimodal flexible switching motor driver topology according to claim 4, characterized in that: In method A1, the motor driver is switched to a single-phase reverse-connected three-phase half-bridge topology for low-speed motor operation. Under the same DC bus voltage, the stator winding phase current provided by the three-phase half-bridge topology is 1 / 3 the value of that provided by the three-phase series winding topology. To reduce the operating losses of the motor driver when it is running at low speed; In method A2, the motor driver is switched to a three-phase series winding topology for high-speed motor operation. Under the same DC bus voltage, the maximum value of the motor stator winding phase voltage provided by the three-phase series winding topology is higher than that of the three-phase half-bridge topology. The constant torque speed regulation range is correspondingly expanded by a factor of two. times; In method A3, the motor driver is switched to a single-phase reverse-connected three-phase four-arm topology. When an arm or phase winding is open-circuited due to a fault, the system switches to a single-phase reverse-connected three-phase four-arm topology to improve the fault-tolerant operation capability of the motor drive system.

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