A control method of a six-phase permanent magnet synchronous motor

Abstract

The application discloses a control method of a six-phase permanent magnet synchronous motor, two common three-phase permanent magnet synchronous frequency converters are used to connect symmetric stator windings of the six-phase permanent magnet synchronous motor, two three-phase permanent magnet synchronous motors are equivalently driven, then collaborative control is performed between the two master-slave frequency converters, power balance of the two equivalent three-phase permanent magnet synchronous motors is realized, and thus the six-phase permanent magnet synchronous motor can be stably operated. In the case of failure of one of the frequency converters, the other frequency converter can normally drive the motor, redundancy control is realized, and the system stability and reliability are improved.

Description

Technical Field

[0001] This invention relates to the field of motor control technology, and in particular to a method for rapidly extracting dynamic characteristic parameters of MOSFET devices. Background Technology

[0002] Six-phase motors are increasingly widely used, primarily due to their high reliability, high power density, and redundant design. Their application is growing in demanding applications, particularly in aerospace, marine, and automotive fields. Based on different drive control methods, six-phase permanent magnet synchronous motor (PMSM) control systems can be divided into redundant PMSM control systems and fault-tolerant PMSM control systems. Redundant PMSM systems, neglecting the mutual inductance between stator windings, adopt the concept of a three-phase PMSM control system, effectively treating the six-phase PMSM as two superimposed three-phase PMSMs. Fault-tolerant PMSM systems use each phase winding as the basic unit and employ an H-bridge inverter for drive. This invention is designed based on the redundant PMSM system control model.

[0003] In existing redundant permanent magnet synchronous motor system control models, six-phase motor control systems typically employ a single frequency converter to drive the six-phase motor, with the converter connected to the six-phase stator windings for control. If any component of the frequency converter fails, the converter will stop working, and the motor will be unable to operate. This poses a risk in applications with high redundancy and reliability requirements. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a control strategy that utilizes two sets of ordinary three-phase permanent magnet synchronous frequency converters connected to the two symmetrical three-phase stator windings of a six-phase motor. The two frequency converters then work together to control the six-phase permanent magnet synchronous motor. If one frequency converter fails, the other can continue to drive the six-phase motor normally without shutting down the system, thus achieving motor redundancy control and improving system reliability.

[0005] The control method for a six-phase permanent magnet synchronous motor of the present invention is as follows:

[0006] Two frequency converters are used. One frequency converter is connected to the three-phase symmetrical stator windings A, B, and C of the six-phase windings of the six-phase permanent magnet synchronous motor, and the other frequency converter is connected to the remaining three-phase symmetrical stator windings D, E, and F of the six-phase windings.

[0007] After connecting the two frequency converters and the six-phase windings, both frequency converters are oriented with the rotor flux linkage of the six-phase motor. Then, vector closed-loop control is adopted. One frequency converter controls the three-phase symmetrical stator windings A, B, and C, and the other frequency converter controls the three-phase symmetrical stator windings D, E, and F. The six-phase permanent magnet synchronous motor is controlled according to the superposition model of two sets of three-phase permanent magnet synchronous motors. The electromagnetic torque of the six-phase permanent magnet synchronous motor is the sum of the electromagnetic torque vectors generated by the two sets of three-phase permanent magnet synchronous motors.

[0008] Two frequency converters are used for master-slave control. The master and slave communicate with each other, exchanging operating frequencies, torque currents, and start commands. The master transmits the start command and operating frequency to the slave. Upon receiving the master's operating command, the slave operates according to the master's operating frequency and start command. Both the master and slave perform vector control based on the target speed, outputting three-phase voltages to their respective connected three-phase windings. The master transmits its torque current to the slave. The slave uses PI loop control for negative feedback regulation based on the relationship between the master's torque current and the feedback torque current sampled by the slave. The master's torque current serves as the input setpoint to the PI loop, while the slave's own feedback torque current serves as the input feedback quantity to the PI loop. The PI loop output is used to compensate for the target frequency, thereby adjusting the slave's operating frequency. The torque of the corresponding three-phase permanent magnet synchronous motor of the slave changes, achieving power balance between the master and slave.

[0009] In the control method of the six-phase permanent magnet synchronous motor of the present invention, the master and slave communicate with each other and also transmit fault information of the two frequency converters.

[0010] When the slave unit malfunctions, the master unit independently connects three windings to drive the motor, achieving redundant control. When the master unit malfunctions, it automatically shuts down and transmits the fault information to the slave unit. The slave unit then disables the PI loop control and continues to operate independently with its own operating frequency and start command, achieving redundant control.

[0011] In the control method of the six-phase permanent magnet synchronous motor of the present invention, when ignoring the mutual inductance between each phase winding of the six-phase motor, the voltage formula of the six-phase permanent magnet synchronous motor is as follows (1) to (4), the electromagnetic torque formula of the six-phase permanent magnet synchronous motor is as follows (5) to (6), and the total electromagnetic torque of the six-phase permanent magnet synchronous motor is as follows (7):

[0012] (1)

[0013] (2)

[0014] (3)

[0015] (4)

[0016] (5)

[0017] (6)

[0018] (7)

[0019] Where: ud1, uq1, d1、 q1, id1, and iq1 represent the d-axis voltage, q-axis voltage, d-axis flux linkage, q-axis flux linkage, d-axis current, and q-axis current of the first three-phase permanent magnet synchronous motor, respectively; ud2, uq2, ... d2、 q2, id2, and iq2 are the d-axis voltage, q-axis voltage, d-axis flux linkage, q-axis flux linkage, d-axis current, and q-axis current of the second set of three-phase permanent magnet synchronous motors, respectively; Id1, Iq1 and Id2, Iq2 are the excitation current and torque current obtained by sampling and transforming the three-phase currents Ia1, Ib1, Ic1 and Ia2, Ib2, Ic2 output from the two frequency converters; ω is the operating frequency of the six-phase permanent magnet synchronous motor, p is the number of pole pairs of the motor, and ld and lq are the d-axis inductance and q-axis inductance of each three-phase symmetrical stator winding, respectively.

[0020] In the control method of the six-phase permanent magnet synchronous motor of the present invention, the transformation of the excitation current and torque current obtained after transformation includes Clark transformation and Park transformation.

[0021] In the control method of the six-phase permanent magnet synchronous motor of the present invention, the three-phase symmetrical stator windings A, B, and C are the same as the three-phase symmetrical stator windings D, E, and F.

[0022] In the control method of the six-phase permanent magnet synchronous motor of the present invention, the two frequency converters have the same structure, each including 6 IGBTs; each group consists of 2 IGBTs, and the collector (C) of one IGBT in each group is connected to the emitter (E) of the other IGBT. The emitter of one IGBT and the collector of the other IGBT are connected to the two ends of a DC drive power supply.

[0023] In the control method of the six-phase permanent magnet synchronous motor of the present invention, each winding is connected to the connection point of two IGBTs in a set of IGBTs.

[0024] Beneficial effects

[0025] The control method for the six-phase permanent magnet synchronous motor of this invention employs two ordinary three-phase permanent magnet synchronous frequency converters connected to the symmetrical stator windings of the six-phase permanent magnet synchronous motor, effectively driving two three-phase permanent magnet synchronous motors. Then, the two master and slave frequency converters coordinate control to achieve power balance between the two equivalent three-phase permanent magnet synchronous motors, thus ensuring stable operation of the six-phase permanent magnet synchronous motor. In the event of a failure in one frequency converter, the other frequency converter can still drive the motor normally, achieving redundant control and improving system stability and reliability. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the circuit structure of a six-phase permanent magnet synchronous motor.

[0027] Figure 2 This is the control topology diagram of the slave frequency converter;

[0028] Figure 3 This is the control topology diagram of the main inverter. Detailed Implementation

[0029] To make the technical means, creative features, achieved objectives, and effects of this invention easier to understand, the invention is further described below with reference to specific embodiments and accompanying drawings. However, the following embodiments are merely preferred embodiments of this invention and not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments described herein without creative effort are all within the protection scope of this invention.

[0030] The specific embodiments of the present invention are described below with reference to the accompanying drawings, and a certain type of MOSFET device is used as an example for illustration.

[0031] The control method for a six-phase permanent magnet synchronous motor of the present invention is as follows:

[0032] refer to Figure 1 Two three-phase permanent magnet synchronous motor frequency converters are used. One frequency converter is connected to the three-phase symmetrical stator windings A, B, and C of the six-phase permanent magnet synchronous motor, and the other frequency converter is connected to the remaining three-phase symmetrical stator windings D, E, and F. The three-phase symmetrical stator windings A, B, and C are the same as those D, E, and F. The two frequency converters have the same structure, and the models can be the same or different according to actual needs. Both include 6 IGBTs. In this embodiment, N-type IGBTs are used. Each group consists of 2 IGBTs. The collector (C) of one IGBT in each group is connected to the emitter (E) of the other IGBT. The two terminals of the DC drive power supply are connected between the emitter (E) and collector (C) of the IGBTs. The gate (G) of the IGBTs is connected to the control signal. Each winding is connected to the connection point of the two IGBTs in each group. This is consistent with the common control method in the prior art, and will not be elaborated further here.

[0033] After connecting the two frequency converters and the six-phase windings, the three-phase currents Ia1, Ib1, Ic1 and Ia2, Ib2, Ic2 output by the two frequency converters are sampled and obtained. Then, the excitation current and torque currents d1, Iq1 and Id2, Iq2 are obtained through Clark transformation and Park transformation. Both frequency converters are oriented with the rotor flux linkage of the six-phase motor and then vector closed-loop control is adopted. Each frequency converter is equivalent to controlling a three-phase permanent magnet synchronous motor. One frequency converter controls the three-phase symmetrical stator windings A, B, and C, and the other frequency converter controls the three-phase symmetrical stator windings D, E, and F. The six-phase permanent magnet synchronous motor is controlled according to the superposition model of two three-phase permanent magnet synchronous motors. The voltage formula of the six-phase permanent magnet synchronous motor is as follows (1) to (4):

[0034] (1)

[0035] (2)

[0036] (3)

[0037] (4)

[0038] Where: ud1, uq1, d1、 q1, id1, and iq1 represent the d-axis voltage, q-axis voltage, d-axis flux linkage, q-axis flux linkage, d-axis current, and q-axis current of the first three-phase permanent magnet synchronous motor, respectively; ud2, uq2, ... d2、 q2, id2, and iq2 are the d-axis voltage, q-axis voltage, d-axis flux linkage, q-axis flux linkage, d-axis current, and q-axis current of the second set of three-phase permanent magnet synchronous motors, respectively; ω is the operating frequency of the six-phase permanent magnet synchronous motor, and p is the number of pole pairs of the motor.

[0039] The electromagnetic torque formulas for a six-phase permanent magnet synchronous motor are as follows: (5) to (6):

[0040] (5)

[0041] (6)

[0042] ld and lq are the d-axis inductance and q-axis inductance of each three-phase symmetrical winding, respectively. The above formulas are obtained by ignoring the mutual inductance between each phase winding of the six-phase motor. The total electromagnetic torque of the six-phase permanent magnet synchronous motor is equivalent to the sum of the electromagnetic torques generated by two three-phase permanent magnet synchronous motors, as shown in the following formula (7):

[0043] (7)

[0044] The goal is to achieve coordinated control of two frequency converters, ensuring balanced output power for the motors driven by the two converters. If the operating frequencies are inconsistent or the converter power is unbalanced, the torques of the two equivalent three-phase permanent magnet synchronous motors will be out of sync, or even opposite in direction, ultimately leading to control failure.

[0045] To achieve power balance between the two frequency converters driving the motor, a master-slave control system is implemented between the two frequency converters. The master and slave converters need to communicate with each other, exchanging information such as the operating frequency (i.e., target frequency), torque current, start commands, and fault information. The control topology diagrams for the slave and master frequency converters are shown below. Figure 2 and Figure 3 .

[0046] First, the master unit transmits its start command and operating frequency to the slave unit. Upon receiving the master unit's operating command, the slave unit operates according to the master unit's operating frequency and start command. Both the master and slave units perform vector control based on the target speed, outputting three-phase voltage to their respective connected three-phase windings. On one hand, due to communication signal delays, the slave unit's target frequency lags, potentially causing asynchrony between the master and slave inverters' target frequencies during acceleration and deceleration. Without software-coordinated control, this can lead to torque imbalance between the two inverters, resulting in one equivalent motor having insufficient torque and the other having excessive torque. In severe cases, the torque directions may even be opposite, causing motor malfunction. On the other hand, since the master and slave units perform vector control independently, errors exist in the sampling of bus voltage and output current by the master and slave inverters, and slight differences may exist in the hardware drive circuits. All of these factors can lead to an imbalance in the final output torque of the two equivalent motors.

[0047] To achieve coordinated control between the master and slave units and realize power balance between the equivalent two three-phase permanent magnet synchronous motors, the master unit transmits its torque current to the slave unit. The slave unit uses PI loop control for negative feedback regulation based on the relationship between the master unit's torque current and the feedback torque current sampled by the slave unit. The master unit's torque current serves as the input setpoint to the PI loop, while the slave unit's own feedback torque current serves as the input feedback quantity to the PI loop. The PI loop output is used to compensate for the target frequency, thereby adjusting the operating frequency of the slave unit. The torque of the corresponding three-phase permanent magnet synchronous motor of the slave unit changes, achieving power balance between the master and slave units, and ultimately realizing stable operation of the six-phase permanent magnet synchronous motor.

[0048] Redundant control is implemented so that if one of the two frequency converters fails, it can automatically shut down, while the other can operate independently. When the slave unit fails, the master unit independently connects three windings to drive the motor, achieving redundant control. When the master unit fails, it automatically shuts down, transmits the fault information to the slave unit, disables the PI loop control, and continues to operate independently with its own operating frequency and start command, achieving redundant control.

[0049] The control method for the six-phase permanent magnet synchronous motor of this invention employs two ordinary three-phase permanent magnet synchronous frequency converters connected to the symmetrical stator windings of the six-phase permanent magnet synchronous motor, effectively driving two three-phase permanent magnet synchronous motors. Then, the two master and slave frequency converters coordinate control to achieve power balance between the two equivalent three-phase permanent magnet synchronous motors, thus ensuring stable operation of the six-phase permanent magnet synchronous motor. In the event of a failure in one frequency converter, the other frequency converter can still drive the motor normally, achieving redundant control and improving system stability and reliability.

[0050] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0051] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A control method for a six-phase permanent magnet synchronous motor, characterized in that, Specifically as follows: Two frequency converters are used. One frequency converter is connected to the three-phase symmetrical stator windings A, B, and C of the six-phase windings of the six-phase permanent magnet synchronous motor, and the other frequency converter is connected to the remaining three-phase symmetrical stator windings D, E, and F of the six-phase windings. After connecting the two frequency converters and the six-phase windings, both frequency converters are oriented with the rotor flux linkage of the six-phase motor. Then, vector closed-loop control is adopted. One frequency converter controls the three-phase symmetrical stator windings A, B, and C, and the other frequency converter controls the three-phase symmetrical stator windings D, E, and F. The six-phase permanent magnet synchronous motor is controlled according to the superposition model of two sets of three-phase permanent magnet synchronous motors. The electromagnetic torque of the six-phase permanent magnet synchronous motor is the sum of the electromagnetic torque vectors generated by the two sets of three-phase permanent magnet synchronous motors. The two frequency converters are controlled by a master and slave. The master and slave communicate with each other and transmit the operating frequency, torque current and start command of the two frequency converters. The start command and operating frequency of the master are transmitted to the slave. After receiving the operating command of the master, the slave runs according to the operating frequency and start command of the master. Both the master and slave perform vector control according to the target speed and output three-phase voltage to their respective connected three-phase windings. The master unit transmits its torque current to the slave unit. The slave unit uses a PI loop control to perform negative feedback regulation based on the relationship between the master unit's torque current and the feedback torque current sampled by the slave unit. The master unit's torque current serves as the input setpoint to the PI loop, while the slave unit's own feedback torque current serves as the input feedback quantity to the PI loop. The PI loop output is used to compensate for the target frequency, thereby adjusting the operating frequency of the slave unit. The torque of the corresponding three-phase permanent magnet synchronous motor of the slave unit changes, achieving power balance between the master and slave units.

2. The control method for a six-phase permanent magnet synchronous motor according to claim 1, characterized in that, The host and slave communicate with each other and also transmit fault information of the two frequency converters. When the slave unit malfunctions, the master unit independently connects three windings to drive the motor, achieving redundant control. When the master unit malfunctions, it automatically shuts down and transmits the fault information to the slave unit. The slave unit then disables the PI loop control and continues to operate independently with its own operating frequency and start command, achieving redundant control.

3. The control method for a six-phase permanent magnet synchronous motor according to claim 1, characterized in that, Ignoring the mutual inductance between each phase winding of the six-phase motor, the voltage formulas of the six-phase permanent magnet synchronous motor are as follows (1) to (4), the electromagnetic torque formulas of the six-phase permanent magnet synchronous motor are as follows (5) to (6), and the total electromagnetic torque of the six-phase permanent magnet synchronous motor is as follows (7): (1) (2) (3) (4) (5) (6) （7） Where: ud1, uq1, d1、 q1, id1, and iq1 represent the d-axis voltage, q-axis voltage, d-axis flux linkage, q-axis flux linkage, d-axis current, and q-axis current of the first three-phase permanent magnet synchronous motor, respectively; ud2, uq2, ... d2、 q2, id2, and iq2 are the d-axis voltage, q-axis voltage, d-axis flux linkage, q-axis flux linkage, d-axis current, and q-axis current of the second set of three-phase permanent magnet synchronous motors, respectively; Id1, Iq1 and Id2, Iq2 are the excitation current and torque current obtained by sampling and transforming the three-phase currents Ia1, Ib1, Ic1 and Ia2, Ib2, Ic2 output from the two frequency converters; ω is the operating frequency of the six-phase permanent magnet synchronous motor, p is the number of pole pairs of the motor, and ld and lq are the d-axis inductance and q-axis inductance of each three-phase symmetrical stator winding, respectively.

4. The control method for a six-phase permanent magnet synchronous motor according to claim 3, characterized in that, The transformations of the excitation current and torque current obtained after the transformation include Clark transformation and Park transformation.

5. The control method for a six-phase permanent magnet synchronous motor according to claim 1, characterized in that, The three-phase symmetrical stator windings A, B, and C are the same as the three-phase symmetrical stator windings D, E, and F.

6. The control method for a six-phase permanent magnet synchronous motor according to claim 1, characterized in that, The two frequency converters have the same structure, each including 6 IGBTs; each pair of IGBTs is grouped together, with the collector (C) of one IGBT in each group connected to the emitter (E) of the other IGBT, and the emitter of one IGBT and the collector of the other IGBT are connected to the two ends of a DC drive power supply.

7. The control method for a six-phase permanent magnet synchronous motor according to claim 6, characterized in that, Each winding is connected to the connection point of two IGBTs within a set of IGBTs.

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