Permanent magnet synchronous motor based on fractional order PID controller and low-speed electric vehicle

Abstract

The invention provides a permanent magnet synchronous motor based on a fractional order PID (Proportion Integration Differentiation) controller. The permanent magnet synchronous motor comprises a closed-loop control circuit, an MCU (Microprogrammed Control Unit) and a permanent magnet synchronous motor body connected with a load, when the MCU detects that the load is changed, according to a preset dynamic parameter table, respectively searching adjustment values of preset parameters in the first fractional order PID controller, the second fractional order PID controller and the third fractional order PID controller, and correspondingly issuing the adjustment values; after a first fractional order PID controller, a second fractional order PID controller and a third fractional order PID controller of the closed-loop control circuit carry out self-adaptive adjustment based on the adjustment value of the MCU, a control signal required for adjusting the control circuit is obtained according to a rotating speed signal, a three-phase current signal, a speed reference signal and an exciting current reference signal of the permanent magnet synchronous motor body at the current period moment; and the adjustment control circuit adjusts and controls the rotating speed, the torque and the magnetic flux of the permanent magnet synchronous motor body before the next period is reached. By implementing the invention, the performance and the response speed of the motor can be improved by improving the traditional PID controller.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and in particular to a permanent magnet synchronous motor and a low-speed electric vehicle based on a fractional-order PID controller. Background Art

[0002] With the development of electric vehicle technology, higher requirements are placed on the performance and response speed of motor control. However, most of the existing permanent magnet synchronous motors use traditional PID controllers to control their performance and response speed. However, due to its integer-order characteristics, the dynamic response of traditional PID controllers is much slower, causing low-speed electric vehicles to take a long time to reach the rated speed under load.

[0003] Therefore, it is necessary to provide a new permanent magnet synchronous motor that can improve the performance and response speed of the motor by improving the traditional PID controller, so that low-speed electric vehicles can quickly reach the rated speed and improve the user experience. Summary of the invention The above-mentioned problem to be solved by the embodiments of the present invention is to provide a permanent magnet synchronous motor and a low-speed electric vehicle based on a fractional-order PID controller, which can improve the performance and response speed of the motor by improving the traditional PID controller, so that the low-speed electric vehicle can quickly reach the rated speed and improve the user experience.

[0004] In order to solve the above technical problems, an embodiment of the present invention provides a permanent magnet synchronous motor based on a fractional-order PID controller, including a closed-loop control circuit, an MCU and a permanent magnet synchronous motor body connected to a load; wherein, The closed-loop control circuit forms a closed-loop connection with the permanent magnet synchronous motor body, and is composed of a feedback circuit, a first fractional-order PID controller, a second fractional-order PID controller, a third fractional-order PID controller and an adjustment control circuit; the feedback current and the adjustment control circuit are both connected to the permanent magnet synchronous motor body; the first fractional-order PID controller, the second fractional-order PID controller and the third fractional-order PID controller are all arranged between the feedback circuit and the adjustment control circuit; one input end of the first fractional-order PID controller is connected to a speed signal source, the other input end is connected to the feedback circuit, and the output end is connected to an input end of the third fractional-order PID controller; one input end of the second fractional-order PID controller is connected to an excitation current signal source, the other input end is connected to the feedback circuit, and the output end is connected to the adjustment control circuit; the other input end of the third fractional-order PID controller is connected to the feedback circuit, and the output end is connected to the adjustment control circuit; One end of the MCU is connected to the load, and the other end is connected to the first fractional-order PID controller, the second fractional-order PID controller and the third fractional-order PID controller; Wherein, the MCU is used to detect the change of the load. If the load is detected to have changed, the adjustment values ​​of the preset parameters in the first fractional-order PID controller, the second fractional-order PID controller and the third fractional-order PID controller are respectively found according to the preset dynamic parameter table and issued accordingly; wherein the preset parameters in the first fractional-order PID controller, the second fractional-order PID controller and the third fractional-order PID controller all include proportional parameters, integral parameters, differential parameters, integral orders and differential orders; Among them, the closed-loop control circuit is used to automatically match the control signal required by the adjustment control circuit according to the speed signal and three-phase current signal of the permanent magnet synchronous motor body at the current cycle moment collected by the feedback circuit, and the reference speed signal output by the speed signal source and the reference excitation current signal output by the excitation current signal source after the first fractional-order PID controller, the second fractional-order PID controller and the third fractional-order PID controller respectively receive the adjustment values ​​correspondingly sent by the MCU at the current cycle moment for adaptive adjustment, and before the next cycle moment arrives, the adjustment control circuit adjusts the speed, torque and magnetic flux of the permanent magnet synchronous motor body according to the control signal.

[0005] Wherein, the feedback circuit includes a speed detection circuit, a three-phase current detection circuit and a Clark-park converter; wherein, The input end of the speed detection circuit is connected to the permanent magnet synchronous motor body, and the output end is connected to the first fractional-order PID controller, for detecting the speed of the permanent magnet synchronous motor body at each cycle moment and sending it to the first fractional-order PID controller, so that the first fractional-order PID controller can adjust the speed at each cycle moment based on the reference speed signal output by the speed signal source, so as to output an expected speed value corresponding to each cycle moment; wherein each expected speed value is represented by a current signal; The input end of the three-phase current detection circuit is connected to the permanent magnet synchronous motor body, and the output end is connected to the input end of the Clark-park converter, so as to detect the three-phase current of the permanent magnet synchronous motor body at each cycle moment and send it to the Clark-park converter to realize Id and Iq axis decomposition; One output end of the Clark-park converter is connected to the second fractional-order PID controller, and the other output end is connected to the third fractional-order PID controller, for decomposing the three-phase current of the permanent magnet synchronous motor body at each cycle moment into an excitation current Id and a torque current Iq, and sending the decomposed excitation current Id at each cycle moment to the second fractional-order PID controller, so that the second fractional-order PID controller can adjust the excitation current Id at each cycle moment based on the reference excitation current signal output by the excitation current signal source, so as to output a desired excitation current Id value at each cycle moment; and send the decomposed torque current Iq at each cycle moment to the third fractional-order PID controller, so that the third fractional-order PID controller can adjust the decomposed torque current Iq at each cycle moment based on the current signal corresponding to the output of the first fractional-order PID controller, so as to output a desired torque current Iq value at each cycle moment.

[0006] Wherein, the adjustment control circuit includes an inverse Clark converter, an SVPWM wave generator, a power battery pack, a three-phase inverter and a three-phase full-bridge drive circuit; wherein, One input end of the inverse Clark transformer is connected to the output end of the second fractional-order PID controller, the other input end is connected to the output end of the third fractional-order PID controller, and the output end is connected to the input end of the SVPWM wave generator, and is used to perform inverse Park transformation on the excitation current Id output by the second fractional-order PID controller and the torque current Iq output by the third fractional-order PID controller at each cycle, and output them to the SVPWM wave generator; The output end of the SVPWM wave generator is connected to the control end of the three-phase full-bridge drive circuit, and is used to generate a PWM signal, and adjust the duty cycle of the PWM signal after receiving the signal after the inverse Clark converter performs inverse Park transformation at each cycle moment; One end of the power battery pack is connected to one end of the three-phase inverter to provide direct current; One end of the three-phase inverter is connected to the voltage input end of the three-phase full-bridge drive circuit, and is used to convert the direct current provided by the power battery pack into three-phase alternating current, and output it to the voltage input end of the three-phase full-bridge drive circuit; The voltage output end of the three-phase full-bridge drive circuit is connected to the permanent magnet synchronous motor body, and is used to adjust the on-off time and waveform direction of the three-phase alternating current output by the three-phase inverter to the permanent magnet synchronous motor body based on the PWM signal with duty cycle adjusted output by the SVPWM wave generator, so as to achieve adjustment and control of the speed, torque and magnetic flux of the permanent magnet synchronous motor body.

[0007] Wherein, the three-phase full-bridge driving circuit is composed of six MOS.

[0008] The magnitude of the reference excitation current signal output by the excitation current signal source is 0.

[0009] An embodiment of the present invention further provides a low-speed electric vehicle, which includes the aforementioned permanent magnet synchronous motor based on fractional-order PID controller.

[0010] Implementing the embodiments of the present invention has the following beneficial effects: Different from motors using traditional PID controllers, when the load of the permanent magnet synchronous motor of the present invention changes, the first, second and third fractional-order PID controllers perform adaptive adjustment of preset parameters based on the adjustment values ​​sent by the MCU, and then quickly adjust and control the speed, torque and magnetic flux of the main body at the next cycle moment according to the speed signal and three-phase current signal of the main body at the current cycle moment and the corresponding reference signal, thereby quickly improving the performance and response speed of the permanent magnet synchronous motor, enabling the low-speed electric vehicle to quickly reach the rated speed, and improving the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the present invention.

[0012] Figure 1 A circuit logic connection diagram of a permanent magnet synchronous motor based on a fractional-order PID controller provided in an embodiment of the present invention; Figure 2 A switching state diagram of six MOS tubes in a three-phase full-bridge drive circuit of a permanent magnet synchronous motor based on a fractional-order PID controller provided in an embodiment of the present invention; Figure 3 This is a diagram of simulation test results of a permanent magnet synchronous motor based on a fractional-order PID controller provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0013] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0014] like Figure 1 As shown in the figure, a permanent magnet synchronous motor based on a fractional-order PID controller is provided in an embodiment of the present invention, comprising a closed-loop control circuit 1, an MCU 2 and a permanent magnet synchronous motor body 3 connected to a load; wherein, The closed-loop control circuit 1 forms a closed-loop connection with the permanent magnet synchronous motor body 3, and is composed of a feedback circuit 11, a first fractional-order PID controller 12, a second fractional-order PID controller 13, a third fractional-order PID controller 14 and an adjustment control circuit 15; the feedback current 11 and the adjustment control circuit 15 are both connected to the permanent magnet synchronous motor body 3; the first fractional-order PID controller 12, the second fractional-order PID controller 13 and the third fractional-order PID controller 14 are all arranged between the feedback current 11 and the adjustment control circuit 15; one input end of the first fractional-order PID controller 12 is connected to a speed signal source S1, the other input end is connected to the feedback circuit 11, and the output end is connected to one input end of the third fractional-order PID controller 14; one input end of the second fractional-order PID controller 13 is connected to an excitation current signal source S2, the other input end is connected to the feedback circuit 11, and the output end is connected to the adjustment control circuit 15; the other input end of the third fractional-order PID controller 14 is connected to the feedback circuit 11, and the output end is connected to the adjustment control circuit 15; One end of the MCU2 is connected to the load, and the other end is connected to the first fractional-order PID controller 12, the second fractional-order PID controller 13 and the third fractional-order PID controller 14; Among them, MCU2 is used to detect the change of load. If the load is detected to have changed, according to the preset dynamic parameter table, the adjustment values ​​of the preset parameters in the first fractional-order PID controller 12, the second fractional-order PID controller 13 and the third fractional-order PID controller 14 are respectively found and issued accordingly; wherein the preset parameters in the first fractional-order PID controller 12, the second fractional-order PID controller 13 and the third fractional-order PID controller 14 include the proportional parameter Kp, the integral parameter Ki, the differential parameter Kd, the integral order lambda and the differential order mu; Among them, the closed-loop control circuit 1 is used to automatically match the control signal required by the adjustment control circuit 15 after the first fractional-order PID controller 12, the second fractional-order PID controller 13 and the third fractional-order PID controller 14 respectively receive the adjustment values ​​correspondingly sent by the MCU2 at the current cycle moment for adaptive adjustment, and collect the speed signal and three-phase current signal of the permanent magnet synchronous motor body 3 at the current cycle moment according to the feedback circuit 11, and combine the reference speed signal output by the speed signal source S1 and the reference excitation current signal (whose magnitude is 0) output by the excitation current signal source S2, and before the next cycle moment arrives, the adjustment control circuit 15 adjusts the speed, torque and magnetic flux of the permanent magnet synchronous motor body 3 according to the above control signals.

[0015] In the embodiment of the present invention, the feedback circuit 11 includes a speed detection circuit 111, a three-phase current detection circuit 112 and a Clark-park converter 113; wherein, The input end of the speed detection circuit 111 is connected to the permanent magnet synchronous motor body 3, and the output end is connected to the first fractional-order PID controller 12, which is used to detect the speed of the permanent magnet synchronous motor body 3 at each cycle moment and send it to the first fractional-order PID controller 12, so that the first fractional-order PID controller 12 can adjust the speed at each cycle moment based on the reference speed signal output by the speed signal source S1, so as to output an expected speed value corresponding to each cycle moment; wherein each expected speed value is represented by a current signal, that is, the first fractional-order PID controller 12 outputs a current signal representing the size of the expected speed value; The input end of the three-phase current detection circuit 112 is connected to the permanent magnet synchronous motor body 3, and the output end is connected to the input end of the Clark-park converter 113, which is used to detect the three-phase current of the permanent magnet synchronous motor body 3 at each cycle moment and send it to the Clark-park converter 113 to achieve Id and Iq axis decomposition; For example, the three-phase current values ​​Ia, Ib and Ic are converted into dq-axis currents Iq (related to torque) and Id (related to flux) in a rotating coordinate system through Clark transformation and Park transformation: The Clarke transform is expressed as follows: (1) The expression of Park transform is shown in the following formula (2): (2); One output end of the Clark-park converter 113 is connected to the second fractional-order PID controller 13, and the other output end is connected to the third fractional-order PID controller 14, which is used to decompose the three-phase current of the permanent magnet synchronous motor body 3 at each cycle moment into the excitation current Id and the torque current Iq, and send the decomposed excitation current Id at each cycle moment to the second fractional-order PID controller 13, so that the second fractional-order PID controller 13 can adjust the excitation current Id at each cycle moment based on the reference excitation current signal output by the excitation current signal source S1, so as to output a desired excitation current Id value at each cycle moment; and send the decomposed torque current Iq at each cycle moment to the third fractional-order PID controller 14, so that the third fractional-order PID controller 14 can adjust the decomposed torque current Iq at each cycle moment based on the current signal corresponding to the output of the first fractional-order PID controller 12, so as to output a desired torque current Iq value at each cycle moment.

[0016] In the embodiment of the present invention, the adjustment control circuit 15 includes an inverse Clark converter 151, an SVPWM wave generator 152, a power battery pack 153, a three-phase inverter 154 and a three-phase full-bridge drive circuit 155; wherein, An input end of the inverse Clark transformer 151 is connected to the output end of the second fractional-order PID controller 13, another input end is connected to the output end of the third fractional-order PID controller 14, and an output end is connected to the input end of the SVPWM wave generator 152, and is used to perform Park inverse transformation on the excitation current Id output by the second fractional-order PID controller 13 and the torque current Iq output by the third fractional-order PID controller 14 at each cycle moment, and output them to the SVPWM wave generator 152; The output end of the SVPWM wave generator 152 is connected to the control end of the three-phase full-bridge drive circuit 155, and is used to generate a PWM signal, and adjust the duty cycle of the PWM signal after receiving the signal after the inverse Clark converter 151 performs the inverse Park transformation at each cycle. One end of the power battery pack 153 is connected to one end of the three-phase inverter 154 to provide direct current; One end of the three-phase inverter 154 is connected to the voltage input end of the three-phase full-bridge drive circuit 155, and is used to convert the DC power provided by the power battery pack 153 into three-phase AC power, and output it to the voltage input end of the three-phase full-bridge drive circuit 155; The voltage output end of the three-phase full-bridge drive circuit 155 is connected to the permanent magnet synchronous motor body 3. It is composed of six MOS and is used to adjust the on-off time and waveform direction of the three-phase alternating current output by the three-phase inverter 154 to the permanent magnet synchronous motor body 3 based on the PWM signal after duty cycle adjustment output by the SVPWM wave generator 152, so as to achieve adjustment and control of the speed, torque and magnetic flux of the permanent magnet synchronous motor body 3.

[0017] In summary, through the feedback circuit 11, the actual speed value and the rated speed (reference speed signal) set by the user are respectively used as the input of the first fractional-order PID controller 12; the output of the first fractional-order PID controller 12 is used as the rated current at the desired speed, and the actual q-axis current is used as the input of the second fractional-order PID controller 13; the actual d-axis current and the reference d-axis current are respectively used as the input of the third fractional-order PID controller 14. At this time, the outputs of the second fractional-order PID controller 13 and the third fractional-order PID controller 14 control the switching states of the six MOS tubes in the three-phase full-bridge drive circuit through Clarke inverse transformation and SVPWM wave generator (Park inverse transformation + SVPWM wave transmission).

[0018] According to the switch status of the six MOS tubes, there are a total of status (such as Figure 2 As shown). These 8 states can be decomposed into six sectors on the space vector, with the zero vector at the center. One cycle of the 8 states counterclockwise or clockwise means one rotation of the motor. If you want the motor to rotate smoothly and continuously, you must constantly observe the rotor angle to determine the sector in which the motor is running. To achieve rotor flux orientation, ensure that the rotor flux rotation vector always coincides with the d-axis in the dq coordinate system and is orthogonal to the q-axis. That is, the direction of the magnetic field generated by power-on must be 90° to the magnetic field of the permanent magnet.

[0019] like Figure 3 , which is a simulation test result diagram of a permanent magnet synchronous motor based on a fractional-order PID controller provided in an embodiment of the present invention. Figure 3 It can be seen that in the speed closed-loop control test, fractional-order PID control has better dynamic response and lower overshoot than traditional PID control. This means that the vehicle can reach the specified speed in a shorter time (good dynamic response, especially for high load conditions, this performance is particularly important), and the vehicle speed will not increase significantly (low overshoot).

[0020] Corresponding to a permanent magnet synchronous motor based on a fractional-order PID controller provided in an embodiment of the present invention, an embodiment of the present invention also provides a low-speed electric vehicle, which includes a permanent magnet synchronous motor based on a fractional-order PID controller provided in an embodiment of the present invention. For specific details, please refer to the aforementioned related content, which will not be repeated here.

[0021] Implementing the embodiments of the present invention has the following beneficial effects: Different from motors using traditional PID controllers, when the load of the permanent magnet synchronous motor of the present invention changes, the first, second and third fractional-order PID controllers perform adaptive adjustment of preset parameters based on the adjustment values ​​sent by the MCU, and then quickly adjust and control the speed, torque and magnetic flux of the main body at the next cycle moment according to the speed signal and three-phase current signal of the main body at the current cycle moment and the corresponding reference signal, thereby quickly improving the performance and response speed of the permanent magnet synchronous motor, enabling the low-speed electric vehicle to quickly reach the rated speed, and improving the user experience.

[0022] The above disclosure is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A permanent magnet synchronous motor based on a fractional-order PID controller, characterized in that: It includes a closed-loop control circuit, an MCU and a permanent magnet synchronous motor body connected to a load; wherein, The closed-loop control circuit forms a closed-loop connection with the permanent magnet synchronous motor body, and is composed of a feedback circuit, a first fractional-order PID controller, a second fractional-order PID controller, a third fractional-order PID controller and an adjustment control circuit; the feedback current and the adjustment control circuit are both connected to the permanent magnet synchronous motor body; the first fractional-order PID controller, the second fractional-order PID controller and the third fractional-order PID controller are all arranged between the feedback circuit and the adjustment control circuit; one input end of the first fractional-order PID controller is connected to a speed signal source, the other input end is connected to the feedback circuit, and the output end is connected to an input end of the third fractional-order PID controller; one input end of the second fractional-order PID controller is connected to an excitation current signal source, the other input end is connected to the feedback circuit, and the output end is connected to the adjustment control circuit; the other input end of the third fractional-order PID controller is connected to the feedback circuit, and the output end is connected to the adjustment control circuit; One end of the MCU is connected to the load, and the other end is connected to the first fractional-order PID controller, the second fractional-order PID controller and the third fractional-order PID controller; Wherein, the MCU is used to detect the change of the load. If the load is detected to have changed, the adjustment values ​​of the preset parameters in the first fractional-order PID controller, the second fractional-order PID controller and the third fractional-order PID controller are respectively found according to the preset dynamic parameter table and issued accordingly; wherein the preset parameters in the first fractional-order PID controller, the second fractional-order PID controller and the third fractional-order PID controller all include proportional parameters, integral parameters, differential parameters, integral orders and differential orders; Among them, the closed-loop control circuit is used to automatically match the control signal required by the adjustment control circuit according to the speed signal and three-phase current signal of the permanent magnet synchronous motor body at the current cycle moment collected by the feedback circuit, and the reference speed signal output by the speed signal source and the reference excitation current signal output by the excitation current signal source after the first fractional-order PID controller, the second fractional-order PID controller and the third fractional-order PID controller respectively receive the adjustment values ​​correspondingly sent by the MCU at the current cycle moment for adaptive adjustment, and before the next cycle moment arrives, the adjustment control circuit adjusts the speed, torque and magnetic flux of the permanent magnet synchronous motor body according to the control signal.

2. The permanent magnet synchronous motor based on the fractional-order PID controller according to claim 1, characterized in that: The feedback circuit includes a speed detection circuit, a three-phase current detection circuit and a Clark-park converter; wherein, The input end of the speed detection circuit is connected to the permanent magnet synchronous motor body, and the output end is connected to the first fractional-order PID controller, for detecting the speed of the permanent magnet synchronous motor body at each cycle moment and sending it to the first fractional-order PID controller, so that the first fractional-order PID controller can adjust the speed at each cycle moment based on the reference speed signal output by the speed signal source, so as to output an expected speed value corresponding to each cycle moment; wherein each expected speed value is represented by a current signal; The input end of the three-phase current detection circuit is connected to the permanent magnet synchronous motor body, and the output end is connected to the input end of the Clark-park converter, so as to detect the three-phase current of the permanent magnet synchronous motor body at each cycle moment and send it to the Clark-park converter to realize Id and Iq axis decomposition; One output end of the Clark-park converter is connected to the second fractional-order PID controller, and the other output end is connected to the third fractional-order PID controller, for decomposing the three-phase current of the permanent magnet synchronous motor body at each cycle moment into an excitation current Id and a torque current Iq, and sending the decomposed excitation current Id at each cycle moment to the second fractional-order PID controller, so that the second fractional-order PID controller can adjust the excitation current Id at each cycle moment based on the reference excitation current signal output by the excitation current signal source, so as to output a desired excitation current Id value at each cycle moment; and send the decomposed torque current Iq at each cycle moment to the third fractional-order PID controller, so that the third fractional-order PID controller can adjust the decomposed torque current Iq at each cycle moment based on the current signal corresponding to the output of the first fractional-order PID controller, so as to output a desired torque current Iq value at each cycle moment.

3. The permanent magnet synchronous motor based on the fractional-order PID controller according to claim 2, characterized in that: The adjustment control circuit includes an inverse Clark converter, an SVPWM wave generator, a power battery pack, a three-phase inverter and a three-phase full-bridge drive circuit; wherein, One input end of the inverse Clark transformer is connected to the output end of the second fractional-order PID controller, the other input end is connected to the output end of the third fractional-order PID controller, and the output end is connected to the input end of the SVPWM wave generator, and is used to perform inverse Park transformation on the excitation current Id output by the second fractional-order PID controller and the torque current Iq output by the third fractional-order PID controller at each cycle, and output them to the SVPWM wave generator; The output end of the SVPWM wave generator is connected to the control end of the three-phase full-bridge drive circuit, and is used to generate a PWM signal, and adjust the duty cycle of the PWM signal after receiving the signal after the inverse Clark converter performs inverse Park transformation at each cycle moment; One end of the power battery pack is connected to one end of the three-phase inverter to provide direct current; One end of the three-phase inverter is connected to the voltage input end of the three-phase full-bridge drive circuit, and is used to convert the direct current provided by the power battery pack into three-phase alternating current, and output it to the voltage input end of the three-phase full-bridge drive circuit; The voltage output end of the three-phase full-bridge drive circuit is connected to the permanent magnet synchronous motor body, and is used to adjust the on-off time and waveform direction of the three-phase alternating current output by the three-phase inverter to the permanent magnet synchronous motor body based on the PWM signal with duty cycle adjusted output by the SVPWM wave generator, so as to achieve adjustment and control of the speed, torque and magnetic flux of the permanent magnet synchronous motor body.

4. The permanent magnet synchronous motor based on the fractional-order PID controller according to claim 3, characterized in that: The three-phase full-bridge driving circuit is composed of six MOSs.

5. The permanent magnet synchronous motor based on the fractional order PID controller according to claim 4, characterized in that: The magnitude of the reference excitation current signal output by the excitation current signal source is 0.

6. A low-speed electric vehicle, characterized in that: It comprises a permanent magnet synchronous motor based on a fractional-order PID controller as claimed in any one of claims 1 to 5.

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