Fast and flexible switching method for winding reconstruction circuit of permanent magnet synchronous motor

Abstract

The invention provides a rapid flexible switching method for a permanent magnet synchronous motor winding reconstruction circuit, and belongs to the technical field of permanent magnet synchronous motor winding reconstruction. In order to solve the problems of surge voltage, impact current, torque drop and even torque interruption generated in a motor winding reconstruction transient state and relatively long transient state reconstruction time in an existing permanent magnet synchronous motor winding reconstruction method, the method comprises the following steps: step 1, in a zero vector interval of space vector pulse width modulation, carrying out space vector pulse width modulation; the permanent magnet synchronous motor winding reconstruction circuit enters a reconstruction transient state; 2, forming three different natural follow current loops of a mode 1, a mode 2 and a mode 3 by utilizing the combination of the switching states of the motor winding, the inverter, the series reconfiguration switch and the parallel reconfiguration switch, and adjusting the length of a zero vector interval required by winding reconfiguration according to the operation condition; and step 3, completing all reconstruction transient states in a zero vector interval of space vector pulse width modulation, and realizing switching of motor winding connection modes.

Description

Technical Field

[0001] This invention relates to a fast and flexible switching method for the winding reconfiguration circuit of a permanent magnet synchronous motor, belonging to the field of permanent magnet synchronous motor winding reconfiguration technology. Background Technology

[0002] New energy vehicles, as a crucial direction for global energy transition and automotive industry upgrading, have experienced rapid development worldwide. As a core component of the "three major electric systems" (battery, motor, and electronic control) in new energy vehicles, the high efficiency and high power density of the electric drive system are of great significance for improving the competitiveness of new energy vehicle products. In the electric drive system of new energy vehicles, permanent magnet synchronous motors (PMSMs) have become the mainstream drive motor due to their advantages such as small size, light weight, high power density, and maintenance-free operation. However, traditional PMSMs struggle to simultaneously meet the requirements of zero-speed, low-speed, high-torque output characteristics under extreme conditions such as hill starts and high-speed, high-power output characteristics under intercity traffic conditions in new energy vehicle electric drive applications.

[0003] To balance the requirements of low-speed high torque and high-speed high power output characteristics of electric drive systems in new energy vehicles, the commonly used solution is a variable-speed drive system using a permanent magnet synchronous motor and a transmission. However, the use of a transmission introduces additional volume and losses, affecting the power density and efficiency of the electric drive system, and also impacting the system's reliability and lifespan. Therefore, winding reconfiguration technology for permanent magnet synchronous motors is receiving increasing attention and research as a promising new solution.

[0004] Winding reconfiguration technology, also known as winding switching technology or variable winding technology, refers to the technique of changing the connection form of motor windings using external circuits, thereby altering the torque-speed output characteristics of the motor. It was initially used to expand the speed range of AC induction motors, later extended to permanent magnet synchronous motors, and has been gradually applied in the home appliance industry, electric scooters, industrial lathe processing, and electrified rail transportation since the 1990s. Today, with the vigorous development of new energy vehicles such as pure electric and hybrid vehicles, it is demonstrating even greater research and application value.

[0005] The winding reconfiguration technology of permanent magnet synchronous motors is mainly divided into star-delta reconfiguration, variable turns reconfiguration, and series-parallel reconfiguration, depending on the winding connection method. Series-parallel reconfiguration refers to using a reconfiguration circuit to switch between series and parallel winding configurations. The torque / speed characteristics of the motor change exponentially between series and parallel modes, resulting in high winding utilization and low harmonic current content, making it a good solution for new energy vehicle applications. Based on the torque-speed output characteristics of the series-parallel reconfigured permanent magnet synchronous motor, using the series winding mode in the low-speed range doubles the maximum output torque, equivalent to a low gear in a traditional mechanical transmission; while using the parallel winding mode in the high-speed range doubles the maximum constant power speed, equivalent to a high gear in a traditional mechanical transmission. Thus, by changing the series and parallel connection method of the motor windings, the electric drive system of new energy vehicles achieves power output characteristics similar to a traditional mechanical transmission.

[0006] To date, scholars both domestically and internationally have proposed various reconfiguration circuit topologies for the series-parallel reconfiguration of permanent magnet synchronous motor (PMSM) windings in the electric drive field. These are mainly categorized into single-inverter eight-switch topologies, single-inverter nine-switch topologies, dual-inverter three-switch topologies, and dual-inverter five-switch topologies. The reconfiguration switches in these PSM winding reconfiguration circuit topologies can be classified as mechanical or semiconductor. Mechanical switches, including relays and contactors, are characterized by low cost, low loss, and no need for cooling, but have a limited number of reliable switching cycles and a long response time, typically ranging from a few milliseconds to hundreds of milliseconds. Semiconductor reconfiguration switches, including bidirectional thyristors, solid-state relays, IGBTs, and MOSFETs, offer a high number of reliable switching cycles and a fast response speed, reaching the microsecond to nanosecond level, making them more suitable for high-speed winding reconfiguration applications in the electric drive field of new energy vehicles.

[0007] For electric drive systems of new energy vehicles with winding reconfiguration capabilities, transient control of winding topology reconfiguration is crucial for the stable and reliable operation of the electric drive system. Inappropriate reconfiguration transients can cause fluctuations in motor current, torque, and speed, and may even generate surge voltages due to sudden changes in winding current, damaging the inverter, power electronic switches in the reconfiguration circuit, and motor insulation, leading to irreversible damage to the electric drive system. To avoid surge voltages during motor winding reconfiguration, some researchers have designed hardware buffer circuits. However, adding buffer circuits increases the system's size, weight, and cost, reducing system reliability. Furthermore, while hardware buffer circuits can suppress or eliminate surge voltages, they are ineffective against fluctuations in motor current, torque, and speed caused by winding reconfiguration. Currently, commonly used reconfiguration transient control methods include three-phase synchronous current interruption reconfiguration and phase-by-phase zero-crossing reconfiguration.

[0008] Three-phase synchronous current interruption reconfiguration refers to the motor initially operating stably in a series or parallel mode. Upon receiving a winding reconfiguration signal, the inverter output is controlled to zero the three-phase current. After detecting the zero-current state, the reconfiguration switch is simultaneously switched on / off, switching the motor winding connection to another mode. Subsequently, the three-phase current begins to rebuild, and the motor eventually stabilizes in the new mode. This method avoids surge voltage and current spikes during winding reconfiguration transients. However, the reconfiguration time is long, and during the reconfiguration transient period, the motor current is zero, and the output torque completely disappears, leading to power interruption, output jerking, and a poor driving experience in the electric drive system. Phase-by-phase zero-crossing reconfiguration refers to reconfiguring each phase of the motor when the phase current is zero, theoretically eliminating surge voltage and current spikes. However, this reconfiguration method is affected by the motor current frequency, so the winding reconfiguration time is still long when the motor speed is low. During winding reconfiguration, the motor operates in an asymmetrical state, requiring more complex transient control, and the output torque inevitably decreases. Furthermore, this method relies on the accuracy of the detection of the zero-crossing point of the motor phase current. If the detection of the zero-crossing point of the phase current is inaccurate, i.e., reconfiguration at a non-zero-crossing point, surge voltage and inrush current will still be generated. Therefore, this method is more suitable for designs that use semi-controlled thyristors as reconfiguration switches.

[0009] The above analysis shows that permanent magnet synchronous motor winding reconfiguration technology is a good solution for new energy vehicle electric drive systems that can simultaneously achieve both low-speed high torque and high-speed high power output characteristics. Meanwhile, excellent winding reconfiguration transient control strategies are of great significance for the implementation of winding reconfiguration technology in the field of new energy vehicle electric drives. How to solve the surge voltage, inrush current, torque drop, and even torque interruption generated during motor winding reconfiguration transients, and to minimize the reconfiguration transient time, are key issues that urgently need to be addressed. Summary of the Invention

[0010] To address the problems of surge voltage, inrush current, torque drop, and even torque interruption, as well as the long reconfiguration transient time, in existing permanent magnet synchronous motor winding reconfiguration methods, this invention proposes a fast and flexible switching method for permanent magnet synchronous motor winding reconfiguration circuits.

[0011] The technical solution adopted by this invention to solve the above problems is: a fast and flexible switching method for the winding reconfiguration circuit of a permanent magnet synchronous motor, comprising: Step 1: Establish the permanent magnet synchronous motor winding reconstruction circuit. In the zero vector interval of space vector pulse width modulation, the permanent magnet synchronous motor winding reconstruction circuit enters the reconstruction transient state. Step 2: By combining the switching states of the motor windings, inverter, series reconfiguration switch and parallel reconfiguration switch, three different natural freewheeling circuits, namely mode 1, mode 2 and mode 3, are formed. The length of the zero vector interval required for winding reconfiguration is adjusted according to the operating conditions. Step 3: Complete all reconstruction transients within the zero vector interval of space vector pulse width modulation to achieve the switching of motor winding connection mode.

[0012] Furthermore, the permanent magnet synchronous motor winding reconfiguration circuit in step 1 includes a DC power supply U. dc and inverter; DC power supply U dc The positive terminal is connected to the common collector of the inverter, and the DC power supply U dc The negative terminal is connected to the common emitter of the inverter. The inverter consists of an upper bridge arm and a lower bridge arm. The upper bridge arm includes switching devices V1, V3 and V5, and the lower bridge arm includes switching devices V2, V4 and V6.

[0013] The collectors of switching devices V1, V3, and V5 and the DC power supply U dc The positive terminals of switching devices V2, V4, and V6 are connected to the DC power supply U. dc The negative terminal of the switch is connected. The emitter of the switch device V1 is connected to the collector of the switch device V2 to form the A-phase bridge arm. The A-phase bridge arm is connected to the A-phase reconfiguration circuit. The emitter of the switch device V3 is connected to the collector of the switch device V4 to form the B-phase bridge arm. The B-phase bridge arm is connected to the B-phase reconfiguration circuit. The emitter of the switch device V5 is connected to the collector of the switch device V6 to form the C-phase bridge arm. The C-phase bridge arm is connected to the C-phase reconfiguration circuit.

[0014] Furthermore, the A-phase reconfiguration circuit includes motor winding A1, motor winding A2, series reconfiguration switch S1, parallel reconfiguration switch P1, and parallel reconfiguration switch P2; the B-phase reconfiguration circuit includes motor winding B1, motor winding B2, series reconfiguration switch S2, parallel reconfiguration switch P3, and parallel reconfiguration switch P4; and the C-phase reconfiguration circuit includes motor winding C1, motor winding C2, series reconfiguration switch S3, parallel reconfiguration switch P5, and parallel reconfiguration switch P6. Series reconfiguration switch S1 is connected in series with motor windings A1 and A2; series reconfiguration switch S2 is connected in series with motor windings B1 and B2; series reconfiguration switch S3 is connected in series with motor windings C1 and C2; parallel reconfiguration switches P1 and P2 are connected in parallel with motor windings A1 and A2; parallel reconfiguration switches P3 and P4 are connected in parallel with motor windings B1 and B2; parallel reconfiguration switches P5 and P6 are connected in parallel with motor windings C1 and C2. When the series reconfiguration switches S1-S3 are closed and the parallel reconfiguration switches P1-P6 are closed, the motor windings A1 and A2 are connected in series, the motor windings B1 and B2 are connected in series, and the motor windings C1 and C2 are connected in series, and the motor is in the winding series mode. When the parallel reconfiguration switches P1-P6 are closed and the series reconfiguration switches S1-S3 are closed, motor windings A1 and A2 are connected in parallel, motor windings B1 and B2 are connected in parallel, and motor windings C1 and C2 are connected in parallel, and the motor is in the winding parallel mode.

[0015] Furthermore, in steps 1-3, the option to apply... u 7. Switch the motor winding connection method in the zero vector range.

[0016] Furthermore, step 2 involves switching the motor winding connection method, specifically including: Before and after the motor windings switch, three operating modes are formed, including mode 1, mode 2, and mode 3. Mode 1 includes the motor windings being in series connection mode and the inverter output voltage vector being zero. u 7. An on signal is applied to the upper arm of the inverter, and an off signal is applied to the lower arm. The series reconfiguration switches S1-S3 are turned on, and the parallel reconfiguration switches P1-P6 are turned off. The current forms a freewheeling circuit through the upper arm of the inverter, the motor winding, and the series reconfiguration switches. Mode 2 includes: the motor winding is in transition mode, and the inverter output voltage vector is zero. u 7. An on signal is applied to the upper arm of the inverter, and an off signal is applied to the lower arm. Series reconfiguration switches S1-S3 and parallel reconfiguration switches P1-P6 are all turned on. Current flows through the upper arm of the inverter, the motor windings, the series reconfiguration switches, and the parallel reconfiguration switches to form a freewheeling circuit. Mode 3 includes: the motor windings are in parallel connection mode, and the inverter output voltage vector is zero. u 7. When the upper arm of the inverter is given an on signal and the lower arm is given an off signal, the series reconfiguration switches S1-S3 are turned off and the parallel reconfiguration switches P1-P6 are turned on. The current flows through the upper arm of the inverter, the motor windings, and the parallel reconfiguration switches to form a freewheeling circuit. During the process of the motor windings switching from series mode reconfiguration to parallel mode, the system sequentially experiences mode 1, mode 2, and mode 3, which occurs within one SVPWM cycle. u Within the zero vector interval, the switching from winding series mode to winding parallel mode is completed; during the process of the motor windings switching from parallel mode reconfiguration to series mode, the system sequentially experiences mode 3, mode 2, and mode 1, that is, within one SVPWM cycle. u Within the zero vector range, the switching from the parallel winding mode to the series winding mode is completed.

[0017] Furthermore, during the zero-vector interval of space vector pulse width modulation, all reconstruction transient processes are completed, and the six effective voltage vectors of the inverter are obtained based on the closed / open states of switching devices V1-V6. u 1- u 6 and two zero-voltage vectors u 0 and u 7, of which six effective voltage vectors u 1- u The six effective voltage vectors of the inverter are uniformly distributed on the α-β vector plane, with the angle between adjacent effective voltage vectors being 60°. u 1- u 6 and two zero-voltage vectors u 0 and u The vector space containing 7 is divided into 6 sectors, where sector I is the composite voltage vector. U ref Located at the effective voltage vector u 4 and voltage vector u The region enclosed by 6 sectors, sector II is the composite voltage vector. U ref Located at the effective voltage vector u 6 and voltage vector u The region enclosed by 2, sector III is the composite voltage vector. U ref Located at the effective voltage vector u 3 and voltage vector u The region enclosed by 2, sector IV is the composite voltage vector. U ref Located at the effective voltage vector u 1 and voltage vector u The region enclosed by 3 sectors, where sector V is the resultant voltage vector. U ref Located at the effective voltage vector u 1 and voltage vector u Within the area enclosed by 5, sector VI represents the composite voltage vector. U ref Located at the effective voltage vector u 4 and voltage vector u The area enclosed by 5.

[0018] Furthermore, the total time required for the transient reconfiguration of the motor windings is calculated based on the different winding reconfiguration methods and the sector where the reference voltage vector is located. During the reconfiguration process of the motor windings from series connection to parallel connection, when the resultant voltage vector is in sector I or sector II... t x1 This indicates the turn-on time of the switching device V5 in the upper arm of phase C. t x2Indicates the turn-on time of parallel reconfiguration switches P1-P6. t y This indicates the total turn-off time of the series reconfiguration switches S1-S3; when the synthesized voltage vector is in sector III or sector IV, t x1 This indicates the turn-on time of the switching device V1 in the upper arm of phase A. t x2 Indicates the turn-on time of parallel reconfiguration switches P1-P6. t y This indicates the turn-off time of the series reconfiguration switches S1-S3; when the synthesized voltage vector is in sector V or sector VI, t x1 This indicates the turn-on time of the switching device V3 in the upper arm of phase B. t x2 Indicates the turn-on time of parallel reconfiguration switches P1-P6. t y This indicates the turn-off time of the series reconfiguration switches S1-S3; During the reconfiguration process of the motor windings from parallel connection to series connection, when the resultant voltage vector is in sector I or sector II... t x1 This indicates the turn-on time of the switching device V5 in the upper arm of phase C. t x2 This indicates the on-time of the series reconfiguration switches S1-S3. t y This indicates the turn-off time of the parallel reconfiguration switches P1-P6; when the synthesized voltage vector is in sector III or sector IV, t x1 This indicates the turn-on time of the switching device V1 in the upper arm of phase A. t x2 This indicates the on-time of the series reconfiguration switches S1-S3. t y This indicates the turn-off time of the parallel reconfiguration switches P1-P6; when the synthesized voltage vector is in sector V or sector VI, t x1 This indicates the turn-on time of the switching device V3 in the upper arm of phase B. t x2 This indicates the on-time of the series reconfiguration switches S1-S3. t y Indicates the turn-off time of the parallel reconfiguration switches P1-P6; The expression for the total time required for the motor winding reconfiguration transient is: (1); In formula (1), t dz This indicates the dead time of SVPWM. tx1 , t x2 , t y Based on the winding reconstruction method and the synthesized voltage vector U ref The different sectors they occupy determine, and t dz , t x1 , t x2 , t y All can be determined based on the datasheet of the power components used.

[0019] Furthermore, step 2 involves adjusting the length of the corresponding zero vector interval based on the operating conditions, specifically including: If the motor windings operate in a light-load or low-speed region, the zero-vector action time is relatively long, t sw If t ≤ T0 / 2, then no adjustment to the zero vector interval is needed; if the motor windings are operating in the heavy load or high speed range, t sw >T0 / 2, at this time u 7. Winding reconstruction cannot be completed within the zero vector interval. The zero vector interval needs to be adjusted as follows: SVPWM u 7. The length of the zero vector interval is adjusted to t sw beginning and end u The zero vector intervals are adjusted to t respectively. sw / 2, that is, let the total zero vector action time be equal to twice t. sw , recorded as At this time, the effective voltage vector u 4 and u The duration of action of 6 was reduced by (t) sw -T0 / 2), denoted as and That is, after adjustment u 4 and u The duration of action of 6 is: (2).

[0020] The beneficial effects of this invention are: 1. The core of the control strategy of this invention includes the implementation of three modes of the motor drive system before and after winding reconfiguration and the winding reconfiguration method. The switching between modes is achieved by controlling the conduction and cutoff of the power electronic reconfiguration switch in the zero vector interval of SVPWM.

[0021] 2. This invention completely eliminates surge voltage and inrush current during motor winding reconfiguration without requiring any additional hardware buffer circuitry, resolving the potential damage to power electronic switches and motor winding insulation. It eliminates torque interruption and torque reduction issues present in traditional transient control methods, significantly shortening the transition time during winding reconfiguration—to less than 5µs for electric drive systems with wide-bandgap power devices. For new energy vehicle electric drive systems, there is no power interruption or jerking during motor winding reconfiguration, resulting in smooth switching and a superior driving experience. Furthermore, the method proposed in this invention involves a single, synchronous three-phase switching, eliminating asymmetrical motor operation and simplifying control. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a winding reconfiguration circuit for a permanent magnet synchronous motor. Figure 2 A spatial distribution diagram of the basic voltage vectors in different switching states of the bridge arm in the reconfiguration circuit of a permanent magnet synchronous motor winding; Figure 3 This is a schematic diagram of the switching sequence for a seven-segment SVPWM. Figure 4 This is a schematic diagram of the circuit structure for mode 1, where the windings are connected in series. Figure 5 This is a schematic diagram of the circuit structure for mode 2 - intermediate transition mode; Figure 6 This is a schematic diagram of the circuit structure for the mode 3-winding parallel connection mode; Figure 7 Transient timing diagram for winding reconfiguration Figure 8 Schematic diagram of the adjustment method for the zero vector interval Figure 9 To implement the program flowchart Figure 10 The waveform diagram for the series-to-parallel reconstruction experiment; Figure 11 The waveform diagram for the parallel-to-serial reconstruction experiment; Figure 12 The simulation waveform diagram shows the control signal during the transient reconfiguration of the windings from series to parallel. Figure 12 In the diagram, (a) represents the gate signal of the reconfiguration switch, and (b) represents the PWM signals of the inverter's ABC three phases. Figure 13 This is a flowchart illustrating a fast and flexible switching method for a permanent magnet synchronous motor winding reconfiguration circuit. Detailed Implementation

[0023] Specific implementation method one: as follows Figure 1 As shown in this embodiment, a fast and flexible switching method for a permanent magnet synchronous motor winding reconfiguration circuit is described, wherein the applied circuit includes: DC power supply U dc DC power supply U dc The positive terminal is connected to the common collector of the inverter, and the DC power supply U dc The negative terminal is connected to the common emitter of the inverter. The inverter consists of an upper bridge arm and a lower bridge arm. The upper bridge arm includes switching devices V1, V3, and V5, and the lower bridge arm includes switching devices V2, V4, and V6. The collectors of switching devices V1, V3, and V5 are connected to the DC power supply U. dc The positive terminals of switching devices V2, V4, and V6 are connected to the DC power supply U. dc The negative terminal of the switch device V1 is connected to the collector of the switch device V2 to form phase A bridge arm, the emitter of the switch device V3 is connected to the collector of the switch device V4 to form phase B bridge arm, and the emitter of the switch device V5 is connected to the collector of the switch device V6 to form phase C bridge arm.

[0024] The A-phase reconfiguration circuit includes motor winding A1, motor winding A2, series reconfiguration switch S1, parallel reconfiguration switch P1, and parallel reconfiguration switch P2; the B-phase reconfiguration circuit includes motor winding B1, motor winding B2, series reconfiguration switch S2, parallel reconfiguration switch P3, and parallel reconfiguration switch P4; the C-phase reconfiguration circuit includes motor winding C1, motor winding C2, series reconfiguration switch S3, parallel reconfiguration switch P5, and parallel reconfiguration switch P6. Series reconfiguration switches S1-S3 are used to control the series circuits of phase A winding, phase B winding, and phase C winding, respectively. Parallel reconfiguration switches P1-P6 are used to control the parallel circuits of each sub-winding in phase A winding, phase B winding, and phase C winding, respectively. When series reconfiguration switches S1-S3 are closed and parallel reconfiguration switches P1-P6 are closed, motor windings A1 and A2 are connected in series, motor windings B1 and B2 are connected in series, and motor windings C1 and C2 are connected in series, and the motor is in winding series mode. When parallel reconfiguration switches P1-P6 are closed and series reconfiguration switches S1-S3 are closed, motor windings A1 and A2 are connected in parallel, motor windings B1 and B2 are connected in parallel, and motor windings C1 and C2 are connected in parallel, and the motor is in winding parallel mode. The series reconfiguration switches S1-S3 and the parallel reconfiguration switches P1-P6 are one of the following: anti-parallel IGBTs, common-emitter IGBTs with anti-parallel diodes, and common-source MOSFETs with anti-parallel diodes.

[0025] Specific implementation method two: such as Figure 13 As shown in this embodiment, a fast and flexible switching method for a permanent magnet synchronous motor winding reconfiguration circuit includes: S1: In the zero vector interval of space vector pulse width modulation, the permanent magnet synchronous motor winding reconfiguration circuit enters the reconfiguration transient state; S2: By combining the switching states of the motor windings, inverter, series reconfiguration switch and parallel reconfiguration switch, three different natural freewheeling circuits, namely mode 1, mode 2 and mode 3, are formed. The length of the zero vector interval required for winding reconfiguration is adjusted according to the operating conditions. S3: Complete all reconstruction transients within the zero vector interval of space vector pulse width modulation to achieve the switching of motor winding connection mode.

[0026] Switching between motor winding connection methods includes switching from series mode to parallel mode and switching from parallel mode to series mode. The switching between these two modes is... u 7. Zero vector interval completed. The working principle and implementation method of this invention will be explained below using the single inverter nine-switch reconfiguration circuit topology of a permanent magnet synchronous motor as an example. However, the applicability of this invention is not limited to the single inverter nine-switch reconfiguration circuit topology of a permanent magnet synchronous motor, and it has wide applicability to other motor types and other winding reconfiguration topologies.

[0027] A two-level voltage source inverter can generate eight basic voltage vectors by combining different switching states of its six bridge arms, including six effective voltage vectors. u 1- u 6) and two zero-voltage vectors ( u 0、 u 7) Figure 2 The basic voltage vector space distribution diagram is shown. Based on the closed / open states of switching devices V1-V6, the six effective voltage vectors of the inverter are obtained. u 1- u 6 and two zero-voltage vectors u 0 and u 7, of which six effective voltage vectors u 1- u The six effective voltage vectors of the inverter are uniformly distributed on the α-β vector plane, with the angle between adjacent effective voltage vectors being 60°. u 1- u 6 and two zero-voltage vectors u 0 and u The vector space containing 7 is divided into 6 sectors, where sector I is the composite voltage vector. U ref Located at the effective voltage vector u 4 and voltage vector u The region enclosed by 6 sectors, sector II is the composite voltage vector. U ref Located at the effective voltage vector u 6 and voltage vector u The region enclosed by 2, sector III is the composite voltage vector. U ref Located at the effective voltage vectoru 3 and voltage vector u The region enclosed by 2, sector IV is the composite voltage vector. U ref Located at the effective voltage vector u 1 and voltage vector u The region enclosed by 3 sectors, where sector V is the resultant voltage vector. U ref Located at the effective voltage vector u 1 and voltage vector u Within the area enclosed by 5, sector VI represents the composite voltage vector. U ref Located at the effective voltage vector u 4 and voltage vector u The area enclosed by 5; the reference voltage vector is synthesized proportionally from two adjacent effective voltage vectors and the zero vector, depending on the sector it belongs to. Based on the principle of minimum switching operations, the switching sequence of the seven-segment SVPWM is as follows: Figure 3 As shown (taking the synthesized voltage vector in the first sector as an example).

[0028] As can be seen, a zero vector is applied at the beginning, end, and middle of each SVPWM cycle, i.e. u 0 or u 7. At this time, the corresponding switching state of the inverter is either that the three lower bridge arms have an on signal applied or the three upper bridge arms have an on signal applied. The current in the three-phase load freewheels through the three lower bridge arms or the three upper bridge arms.

[0029] This embodiment is as follows: Figure 3 The zero-voltage vector shown u 0 or u The circuit 7 switches between series and parallel winding modes, eliminating problems such as surge voltage, torque interruption / drop, unbalanced operation, and long transient times inherent in traditional switching control methods. Due to the application of... u The zero vector interval of 0 is evenly distributed between the beginning and end of the SVPWM cycle, while the applied... u The zero vector interval of 7 is entirely located in the middle of the SVPWM period, with a longer continuous time. Therefore, this invention chooses to apply... u The winding connection method is switched in the zero vector interval of 7. It should be noted that when applying... u Reconstructing the winding in the zero vector interval of 0 has the same effect.

[0030] During the switching of motor winding connection modes, including Mode 1, Mode 2, and Mode 3, the single inverter nine-switch reconfiguration circuit in Mode 1 is as follows: Figure 4 As shown, the motor windings are in series connection mode, and the inverter output voltage vector is zero. u7. When an on signal is applied to the upper arm of the inverter and an off signal is applied to the lower arm, the series reconfiguration switches S1-S3 are turned on, and the parallel reconfiguration switches P1-P6 are turned off. At this time, the current forms a freewheeling circuit through the three upper arms of the inverter, the motor windings, and the series switches S1-S3. The current path and direction are as follows: Figure 4 As indicated by the dashed arrow.

[0031] The permanent magnet synchronous motor winding reconfiguration circuit in mode 2 is as follows: Figure 5 As shown, the motor windings are in transition mode, and the inverter output voltage vector is zero. u 7. An on signal is applied to the upper arm of the inverter, and an off signal is applied to the lower arm. The series reconfiguration switches S1-S3 and the parallel reconfiguration switches P1-P6 are all turned on. At this time, the current forms a freewheeling loop through the three upper arms of the inverter, the motor windings, S1-S3, and P1-P6. The current path and direction are as follows: Figure 5 As indicated by the dashed arrow.

[0032] The permanent magnet synchronous motor winding reconfiguration circuit in mode 3 is as follows: Figure 6 As shown, the motor windings are in parallel connection mode, and the inverter output voltage vector is zero. u 7. An on signal is applied to the upper arm of the inverter, and an off signal is applied to the lower arm. The series reconfiguration switches S1-S3 are turned off, and the parallel reconfiguration switches P1-P6 are turned on. At this time, the current forms a freewheeling loop through the three upper arms of the inverter, the motor windings, and P1-P6. The current path and direction are as follows: Figure 6 As indicated by the dashed arrow.

[0033] Based on the above analysis, the control logic of each reconfiguration switch before and after the process of reconfiguring the motor winding connection from series mode to parallel mode is summarized in Table 1: Table 1

[0034] Similarly, the motor winding connection method has also been reconfigured from parallel mode to series mode. u The zero-vector interval is completed and goes through 3 modes. The difference is that the series reconfiguration switches S1-S3 are turned on first, and then the parallel reconfiguration switches P1-P6 are turned off. The switching sequence is shown in Table 2: Table 2

[0035] During the process of the motor windings switching from series mode reconfiguration to parallel mode, the system sequentially experiences mode 1, mode 2, and mode 3, which occurs within one SVPWM cycle. uWithin the zero vector interval, the switching from winding series mode to winding parallel mode is completed; during the process of the motor windings switching from parallel mode reconfiguration to series mode, the system sequentially experiences mode 3, mode 2, and mode 1, that is, within one SVPWM cycle. u Within the zero vector range, the switching from the parallel winding mode to the series winding mode is completed.

[0036] Mode 2 is an intermediate transitional state of winding reconfiguration. Compared with Mode 1 and Mode 3, although the current flow path has changed from the perspective of the overall circuit topology, the current flow direction and magnitude in each motor winding have not changed. Therefore, no surge voltage will be generated, the motor will not run unbalanced, and there will be no torque interruption or torque reduction.

[0037] In practical engineering systems, determining the time required for winding reconfiguration transients requires considering the dead time of SVPWM, the turn-on and turn-off times of inverter power components V1-V6, and reconfiguration switches S1-S3 and P1-P6. Taking the example of the synthesized voltage vector being in sector I and the motor windings being reconfigured from a series connection to a parallel connection, as shown below... Figure 7 As shown, the three signals from top to bottom, the first one is... Figure 3 The switching sequence of phase C is as follows: the second path represents the PWM signal of the upper arm of phase C, and the third path represents the PWM signal of the lower arm of phase C. The PWM signals are generated according to the principle of "high effective complementarity". t At time 1, it is the zero vector. u The starting moment of 7, at t At time 2, an on-time signal is applied to the power element V5 of the upper arm of phase C. t At time 3, an on-state signal is applied to the parallel switches P1-P6. t At time 4, a turn-off signal is applied to the series switches S1-S3. t Time 5 represents the complete end of the reconfiguration transient state, and the motor enters the steady state of parallel winding connection. t At time 6, the vector is zero. u The end of 7. Time interval. t dz This refers to the dead time of the PWM. t x1 This refers to the turn-on time of inverter power element V5. t x2 The turn-on time of parallel reconfiguration switches P1-P6 t y The turn-off time of the series reconfigurable switches S1-S3.

[0038] The time required for winding reconfiguration transient is t sw As shown in the following formula: (1); In formula (1), t dz For SVPWM dead time, t x1 This represents the total turn-on time of the switching device V5 in the upper arm of phase C. t x2 The total turn-on time for parallel reconfiguration switches P1-P6 is given. t y To determine the total turn-off time of the series reconfigurable switches S1-S3, t dz , t x1 , t x2 , t y The specific timeframe can be determined based on the datasheet of the power components used, but signal transmission delay and necessary safety margin must be taken into account.

[0039] Generally, based on the winding reconstruction method and the synthesized voltage vector... U ref Depending on the sector, the time variables on the right side of the equal sign in equation (1) will differ. t dz , t x1 , t x2 , t y The specific meanings can be summarized as shown in Table 3: Table 3

[0040] Adjustment of the zero vector interval length: If the motor is operating under light load or at low speed, the zero vector action time is relatively long, t sw If the value is ≤T0 / 2, then no adjustment to the zero vector interval is needed; however, if the motor is operating in a heavy-load or high-speed region, t will occur. sw >T0 / 2, at this time u 7. Winding reconfiguration cannot be completed within the zero vector range; the zero vector range needs adjustment. Details are as follows: like Figure 8 As shown. The SVPWM... u 7. The length of the zero vector interval is adjusted to t sw beginning and end u The zero vector intervals are adjusted to t respectively. sw / 2, that is, let the total zero vector action time be equal to twice t. sw , recorded as At this time, the effective voltage vector u 4 and uThe duration of action of 6 was reduced by (t) sw -T0 / 2), denoted as and That is, after adjustment u 4 and u The duration of action of 6 is: (2); Based on the above, the implementation flowchart of the fast and flexible switching method for the permanent magnet synchronous motor winding reconfiguration circuit can be used. Figure 9 express: To verify the effectiveness of the fast and flexible switching method of the permanent magnet synchronous motor winding reconfiguration circuit of this invention, this embodiment conducted series-to-parallel reconfiguration experiments and parallel-to-series reconfiguration experiments. The experimental waveforms are shown below. Figure 10 and Figure 11 As shown, Figure 10 This refers to the process of reconfiguring the motor windings from a series connection to a parallel connection. Figure 11 This diagram illustrates the process of reconfiguring motor windings from a parallel connection to a series connection. In the diagram, channel A represents the current within the motor windings, channel B is the motor winding reconfiguration command signal, channel C is the voltage across the series reconfiguration switch, and channel D is the voltage across the parallel reconfiguration switch. It can be seen that there are no surge voltages or inrush currents at the moment of winding reconfiguration, indicating that this method solves the problem of potential damage to power electronic switches and motor winding insulation during motor winding reconfiguration. The current within the motor windings is smooth and uninterrupted at the reconfiguration point, meaning that there is no torque interruption, torque reduction, or torque fluctuation during the reconfiguration transient. This achieves flexible switching of the motor windings.

[0041] Figure 12 The simulation waveforms of the control signals during the transient reconfiguration from a series connection to a parallel connection winding within one PWM cycle are shown in Figure (a). In Figure (a), the solid and dashed lines represent the gate control signals of the series and parallel reconfiguration switches, respectively. In Figure (b), the solid, dashed, and dotted-dashed lines represent the three-phase PWM signals of the inverter (phases A, B, and C), respectively. It can be seen that the operation of both the series and parallel reconfiguration switches occurs within the PWM cycle. u 7. Zero vector interval u The length of the zero vector interval is only 7 µs, and the time difference between the series and parallel reconfiguration switches (the duration of mode 2) is only 3 µs. This demonstrates the speed of the method proposed in this invention.

[0042] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent substitutions, and improvements made to the above embodiments without departing from the scope of the present invention, based on the technical essence of the present invention and within the spirit and principles of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. A method for rapid and flexible switching of a permanent magnet synchronous motor winding reconfiguration circuit, characterized in that, include: Step 1: Establish the permanent magnet synchronous motor winding reconstruction circuit. In the zero vector interval of space vector pulse width modulation, the permanent magnet synchronous motor winding reconstruction circuit enters the reconstruction transient state. Step 2: By combining the switching states of the motor windings, inverter, series reconfiguration switch and parallel reconfiguration switch, three different natural freewheeling circuits, namely mode 1, mode 2 and mode 3, are formed. The length of the zero vector interval required for winding reconfiguration is adjusted according to the operating conditions. Step 3: Complete all reconstruction transients within the zero vector interval of space vector pulse width modulation to achieve the switching of motor winding connection mode.

2. The rapid flexible switching method for the winding reconfiguration circuit of a permanent magnet synchronous motor according to claim 1, characterized in that, The permanent magnet synchronous motor winding reconfiguration circuit in step 1 includes a DC power supply U. dc and inverter; The DC power supply U dc The positive terminal is connected to the common collector of the inverter, and the DC power supply U dc The negative terminal is connected to the common emitter of the inverter. The inverter consists of an upper bridge arm and a lower bridge arm. The upper bridge arm includes switching devices V1, V3 and V5, and the lower bridge arm includes switching devices V2, V4 and V6. The collectors of switching devices V1, V3, and V5 and the DC power supply U dc The positive terminals of switching devices V2, V4, and V6 are connected to the DC power supply U. dc The negative terminal of the switch is connected. The emitter of the switch device V1 is connected to the collector of the switch device V2 to form the A-phase bridge arm. The A-phase bridge arm is connected to the A-phase reconfiguration circuit. The emitter of the switch device V3 is connected to the collector of the switch device V4 to form the B-phase bridge arm. The B-phase bridge arm is connected to the B-phase reconfiguration circuit. The emitter of the switch device V5 is connected to the collector of the switch device V6 to form the C-phase bridge arm. The C-phase bridge arm is connected to the C-phase reconfiguration circuit.

3. The rapid flexible switching method for the winding reconfiguration circuit of a permanent magnet synchronous motor according to claim 2, characterized in that, The A-phase reconfiguration circuit includes motor winding A1, motor winding A2, series reconfiguration switch S1, parallel reconfiguration switch P1, and parallel reconfiguration switch P2; the B-phase reconfiguration circuit includes motor winding B1, motor winding B2, series reconfiguration switch S2, parallel reconfiguration switch P3, and parallel reconfiguration switch P4; the C-phase reconfiguration circuit includes motor winding C1, motor winding C2, series reconfiguration switch S3, parallel reconfiguration switch P5, and parallel reconfiguration switch P6. The series reconfiguration switch S1 is connected in series with motor windings A1 and A2; the series reconfiguration switch S2 is connected in series with motor windings B1 and B2; and the series reconfiguration switch S3 is connected in series with motor windings C1 and C2. The parallel reconfiguration switches P1 and P2 are connected in parallel with motor windings A1 and A2; the parallel reconfiguration switches P3 and P4 are connected in parallel with motor windings B1 and B2; and the parallel reconfiguration switches P5 and P6 are connected in parallel with motor windings C1 and C2. When the series reconfiguration switches S1-S3 are closed and the parallel reconfiguration switches P1-P6 are closed, the motor windings A1 and A2 are connected in series, the motor windings B1 and B2 are connected in series, and the motor windings C1 and C2 are connected in series, and the motor is in the winding series mode. When the parallel reconfiguration switches P1-P6 are closed and the series reconfiguration switches S1-S3 are closed, motor windings A1 and A2 are connected in parallel, motor windings B1 and B2 are connected in parallel, and motor windings C1 and C2 are connected in parallel, and the motor is in the winding parallel mode.

4. The rapid flexible switching method for the winding reconfiguration circuit of a permanent magnet synchronous motor according to claim 1, characterized in that, In steps 1-3, select the option to apply. u 7. Switch the motor winding connection method in the zero vector range.

5. The rapid flexible switching method for the winding reconfiguration circuit of a permanent magnet synchronous motor according to claim 1, characterized in that, Step 2 involves switching the motor winding connection method, specifically including: Before and after the motor windings switch, three operating modes are formed, including mode 1, mode 2, and mode 3. Mode 1 includes the motor windings being in series connection mode and the inverter output voltage vector being zero. u 7. An on signal is applied to the upper arm of the inverter, and an off signal is applied to the lower arm. The series reconfiguration switches S1-S3 are turned on, and the parallel reconfiguration switches P1-P6 are turned off. The current forms a freewheeling circuit through the upper arm of the inverter, the motor winding, and the series reconfiguration switches. Mode 2 includes: the motor winding is in transition mode, and the inverter output voltage vector is zero. u 7. An on signal is applied to the upper arm of the inverter, and an off signal is applied to the lower arm. Series reconfiguration switches S1-S3 and parallel reconfiguration switches P1-P6 are all turned on. Current flows through the upper arm of the inverter, the motor windings, the series reconfiguration switches, and the parallel reconfiguration switches to form a freewheeling circuit. Mode 3 includes: the motor windings are in parallel connection mode, and the inverter output voltage vector is zero. u 7. When the upper arm of the inverter is given an on signal and the lower arm is given an off signal, the series reconfiguration switches S1-S3 are turned off and the parallel reconfiguration switches P1-P6 are turned on. The current flows through the upper arm of the inverter, the motor windings, and the parallel reconfiguration switches to form a freewheeling circuit. During the process of the motor windings switching from series mode reconfiguration to parallel mode, the system sequentially experiences mode 1, mode 2, and mode 3, which occurs within one SVPWM cycle. u Within the zero vector interval, the switching from winding series mode to winding parallel mode is completed; during the process of the motor windings switching from parallel mode reconfiguration to series mode, the system sequentially experiences mode 3, mode 2, and mode 1, that is, within one SVPWM cycle. u Within the zero vector range, the switching from the parallel winding mode to the series winding mode is completed.

6. The rapid flexible switching method for the winding reconfiguration circuit of a permanent magnet synchronous motor according to claim 5, characterized in that, In steps 1-3, during the completion of all reconstruction transient processes in the zero vector interval of space vector pulse width modulation, the six effective voltage vectors of the inverter are obtained according to the closed / open states of switching devices V1-V6. u 1- u 6 and two zero-voltage vectors u 0 and u 7, of which six effective voltage vectors u 1- u The six effective voltage vectors of the inverter are uniformly distributed on the α-β vector plane, with the angle between adjacent effective voltage vectors being 60°. u 1- u 6 and two zero-voltage vectors u 0 and u The vector space containing 7 is divided into 6 sectors, where sector I is the composite voltage vector. U ref Located at the effective voltage vector u 4 and voltage vector u The region enclosed by 6 sectors, sector II being the composite voltage vector. U ref Located at the effective voltage vector u 6 and voltage vector u The region enclosed by 2, sector III is the composite voltage vector. U ref Located at the effective voltage vector u 3 and voltage vector u The region enclosed by 2, sector IV is the composite voltage vector. U ref Located at the effective voltage vector u 1 and voltage vector u The region enclosed by 3 sectors, where sector V is the resultant voltage vector. U ref Located at the effective voltage vector u 1 and voltage vector u Within the area enclosed by 5, sector VI represents the composite voltage vector. U ref Located at the effective voltage vector u 4 and voltage vector u The area enclosed by 5.

7. The rapid flexible switching method for the winding reconfiguration circuit of a permanent magnet synchronous motor according to claim 6, characterized in that, Calculate the total time required for the transient reconfiguration of the motor windings based on the different winding reconfiguration methods and the sector where the reference voltage vector is located. During the reconfiguration process of the motor windings from series connection to parallel connection, when the resultant voltage vector is in sector I or sector II... t x1 This indicates the turn-on time of the switching device V5 in the upper arm of phase C. t x2 Indicates the turn-on time of parallel reconfiguration switches P1-P6. t y This indicates the total turn-off time of the series reconfiguration switches S1-S3; when the synthesized voltage vector is in sector III or sector IV, t x1 This indicates the turn-on time of the switching device V1 in the upper arm of phase A. t x2 Indicates the turn-on time of parallel reconfiguration switches P1-P6. t y This indicates the turn-off time of the series reconfiguration switches S1-S3; when the synthesized voltage vector is in sector V or sector VI, t x1 This indicates the turn-on time of the switching device V3 in the upper arm of phase B. t x2 Indicates the turn-on time of parallel reconfiguration switches P1-P6. t y This indicates the turn-off time of the series reconfiguration switches S1-S3; During the reconfiguration process of the motor windings from parallel connection to series connection, when the resultant voltage vector is in sector I or sector II... t x1 This indicates the turn-on time of the switching device V5 in the upper arm of phase C. t x2 This indicates the on-time of the series reconfiguration switches S1-S3. t y This indicates the turn-off time of the parallel reconfiguration switches P1-P6; when the synthesized voltage vector is in sector III or sector IV, t x1 This indicates the turn-on time of the switching device V1 in the upper arm of phase A. t x2 This indicates the on-time of the series reconfiguration switches S1-S3. t y This indicates the turn-off time of the parallel reconfiguration switches P1-P6; when the synthesized voltage vector is in sector V or sector VI, t x1 This indicates the turn-on time of the switching device V3 in the upper arm of phase B. t x2 This indicates the on-time of the series reconfiguration switches S1-S3. t y Indicates the turn-off time of the parallel reconfiguration switches P1-P6; The expression for the total time required for the motor winding reconfiguration transient is: （1）； In formula (1), t dz This indicates the dead time of SVPWM. t x1 , t x2 , t y Based on the winding reconstruction method and the synthesized voltage vector U ref The different sectors they occupy determine, and t dz , t x1 , t x2 , t y All can be determined based on the datasheet of the power components used.

8. The rapid flexible switching method for the winding reconfiguration circuit of a permanent magnet synchronous motor according to claim 1, characterized in that, Step 2 involves adjusting the length of the corresponding zero vector interval based on the operating conditions, specifically including: If the motor windings operate in a light-load or low-speed region, the zero-vector action time is relatively long, t sw If t ≤ T0 / 2, then no adjustment to the zero vector interval is needed; if the motor windings are operating in the heavy load or high speed range, t sw >T0 / 2, at this time u 7. Winding reconstruction cannot be completed within the zero vector interval. The zero vector interval needs to be adjusted as follows: SVPWM u 7. The length of the zero vector interval is adjusted to t sw beginning and end u The zero vector intervals are adjusted to t respectively. sw / 2, that is, let the total zero vector action time be equal to twice t. sw , recorded as At this time, the effective voltage vector u 4 and u The duration of action of 6 was reduced by (t) sw -T0 / 2), denoted as and That is, after adjustment u 4 and u The duration of action of 6 is: （2）。

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