Control method for reducing torque ripple and switching loss of permanent magnet auxiliary switched reluctance motor

Abstract

The invention relates to the technical field of motor control, and provides a control method for reducing torque ripple and switching loss of a permanent magnet auxiliary switched reluctance motor, and the system framework of the method comprises a position detection module, a speed detection module, a PI controller, a power converter and a torque calculation module. The method comprises the following steps: performing interval control on the operation of a motor, using different torque distribution functions based on hyperbolic tangent function transformation in each interval, controlling an output signal through a PWM wave with a fixed frequency, improving the PWM wave by adopting a zero-voltage dispersion modulation mode, adaptively adjusting the duty ratio of the PWM wave, and adjusting the duty ratio of the PWM wave. And finally, the motor is controlled through the power converter. The current fluctuation, the switching frequency and the torque ripple of the permanent magnet auxiliary switched reluctance motor adopting the control method are reduced, so that the stability and the efficiency of the motor during operation are improved, the energy loss is reduced, and the service life of the motor is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and particularly to a control method for reducing torque ripple and switching losses of a permanent magnet assisted switched reluctance motor. Background Art

[0002] The permanent magnet assisted switched reluctance motor, as a new type of motor that combines the characteristics of permanent magnet synchronous motors and switched reluctance motors, has shown broad application prospects in many fields such as aerospace, oil and mining, and rail transit due to its advantages of simple structure, high efficiency, and fast response speed. This motor not only inherits the advantages of traditional switched reluctance motors such as large torque, high reliability, and low cost, but also improves the power density and efficiency of the motor through the auxiliary excitation of permanent magnets. The energy-saving technology and good power supply characteristics of permanent magnet assisted synchronous reluctance motors make them have significant advantages in reducing power consumption and maintenance costs.

[0003] However, despite the many advantages of the permanent magnet assisted switched reluctance motor, it also has some drawbacks. One of the main problems is torque ripple, which is caused by the double salient pole structure of the motor and the nonlinear and saturation effects of the magnetic circuit. In the two-phase commutation region, the torque ripple is particularly obvious, which not only affects the stability and efficiency of the motor, but also may cause vibration and noise problems. In addition, the switched reluctance motor operates under a pulse power supply mode, with large instantaneous torque ripple, especially at low speeds, which limits its development in some application fields with high precision requirements.

[0004] Another problem is switching losses. Due to the high switching frequency of the switched reluctance motor, it will accelerate the aging of switching devices, shorten their service life, and cause large energy losses. Switching losses not only affect the efficiency of the motor, but also may cause the motor to overheat, affecting the reliability and stability of the system.

[0005] In the research on torque ripple suppression of switched reluctance motors, the traditional torque distribution function control strategy reasonably distributes the torque of each phase with a fixed function curve in the two-phase commutation region. In theory, it can achieve the effect of suppressing torque ripple, but this control method does not fully consider the electromagnetic characteristics of the switched reluctance motor and the torque output capabilities of adjacent phases, and the effect of torque ripple suppression needs to be improved. At the same time, after torque distribution, a hysteresis controller is used to control the output signal, which easily makes the switching frequency of the switched reluctance motor not fixed, requires high hardware requirements for the controller, and causes large switching losses.

[0006] Therefore, developing a control method that can effectively suppress torque ripple and reduce switching losses is of great significance for improving the performance of permanent magnet assisted switched reluctance motors and expanding their application range. Summary of the Invention

[0007] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a control method for reducing the torque ripple and switching loss of a permanent magnet assisted switched reluctance motor. The system framework of this method includes a position detection module, a speed detection module, a PI controller, a power converter, and a torque calculation module. This method includes: dividing the operation of the motor into intervals, using different torque distribution functions based on the hyperbolic tangent function transformation in each interval, optimizing the PWM modulation method, and adaptively adjusting the duty cycle D of the PWM wave u , and finally completing the control of the motor through the power converter. The specific steps are as follows:

[0008] S1, obtaining the actual speed w * and the given speed w ref to form a speed loop, and inputting the difference between the two into the PI controller to output the reference torque T ref .

[0009] S2, according to the electromagnetic characteristics and torque-current ratio characteristics of the motor, dividing the operation interval of the motor into three intervals, namely commutation zone 1, commutation zone 2, and single-phase conduction zone; the starting point of commutation zone 1 is the conduction angle θ on of the exciting phase, and the demarcation point between commutation zone 1 and commutation zone 2 is the point where the torque-current ratios of the two phases are equal, which is also the inductance boundary point θ m ; the demarcation point between commutation zone 2 and the single-phase conduction zone is the point where the demagnetizing phase and the stator are completely aligned, which is also the commutation overlap angle θ ov of the torque distribution function; the end point of the single-phase conduction zone is the turn-off angle θ of of the next exciting phase.

[0010] S3, designing different torque distribution functions in different intervals, and the obtained piecewise torque distribution function f j (θ) is:

[0011]

[0012] Among them, f jup1 (θ) is the torque distribution function in the rising stage of commutation zone 1, f jdown1 (θ) is the torque distribution function in the falling stage of commutation zone 1, f jup2 (θ) is the torque distribution function in the rising stage of commutation zone 2, f jdown2 (θ) is the torque distribution function in the falling stage of commutation zone 2; the hyperbolic tangent function k1 and k2 are the weight coefficients of commutation zone 1 and commutation zone 2 respectively; the inductance boundary point θ m is a fixed value; θ n is the next phase inductance boundary point; the commutation overlap angle θ ov is a fixed value; τ r is the rotor pole pitch.

[0013] S4. Obtain the reference torque Tref(a, b, c) of each phase through the torque distribution function module, obtain the actual torque Te* of each phase through the torque calculation module, and calculate the torque error by taking the difference between the reference torque Tref(a, b, c) and the actual torque Te*.

[0014] S5. Control the output signal through a fixed-frequency PWM wave, and improve the PWM wave by using the zero-voltage dispersion modulation method.

[0015] S6. According to the torque error adaptively control the duty cycle D of the PWM wave according to the rotational speed and load u , and further control the voltage across the phase winding.

[0016] S7. Control the conduction and turn-off of each phase switching device in the power converter according to the PWM output signal, and further control the startup of the permanent magnet assisted switched reluctance motor, thereby suppressing torque ripple and reducing switching losses.

[0017] Further, in step S2, the calculation formula for the torque current ratio (TCR) is:

[0018]

[0019] where T j is the electromagnetic torque generated by the j-th phase winding, i j is the current of the j-th phase winding, L is the winding inductance, θ is the rotor position angle, is the inductance change rate of the inductance with respect to the rotor position.

[0020] Further, in step S2, the torque current ratio of the demagnetization phase in the first region is greater than that of the magnetization phase, and the torque current ratio of the magnetization phase in the second region is greater than that of the demagnetization phase.

[0021] Further, in step S3, the weight coefficients k1 and k2 of the piecewise torque distribution function based on the hyperbolic tangent function transformation change according to the motor speed and load. The larger the value of k1, the more torque is distributed to the demagnetization phase, and the less torque is distributed to the magnetization phase accordingly; the larger the value of k2, the more torque is distributed to the magnetization phase, and the less torque is distributed to the demagnetization phase accordingly.

[0022] Further, in step S3, the inductance boundary point θ m is 2°, and the commutation overlap angle θ ov is 3°.

[0023] Further, in step S5, controlling the output signal by a PWM wave with a fixed frequency includes comparing a triangular carrier wave that varies at [0, 1] with modulation signals C1 and C2 to generate control signals for switching transistors S1 and S2. There is a quantitative relationship between C1, C2 and the duty cycle D, and their ranges are both within [0, 1]. u The quantitative relationship is within the range of [0, 1].

[0024] Further, in step S5, the zero-voltage spread modulation method is adopted to improve the PWM wave. For the switching transistor S1 on the power circuit, the intermediate duty cycle modulation method is used, that is, when the carrier value is greater than C1, the switching transistor S1 is turned on, and when it is less than C1, the switching transistor S1 is turned off.

[0025] Further, in step S5, for the switching transistor S2, the two-end duty cycle modulation method is adopted, that is, when the carrier value is less than C2, the switching transistor S2 is turned on, and when it is greater than C2, the switching transistor S2 is turned off.

[0026] Further, in step S6, first judge the obtained in step S4, and determine whether the duty cycle D needs to change according to whether it meets the preset value. The calculation formula for the duty cycle D is: u where ΔD u is the change amount of the duty cycle, λ, α, β are weighting factors, w

[0027]

[0028] is the real-time rotational speed, w u is the given rotational speed, n is the real-time load, ref is the given load, is the real-time load, is the given load, and respectively represent the duty cycle at the current moment and the duty cycle at the next moment.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] By controlling the operation of the motor in different intervals, using different torque distribution functions based on the hyperbolic tangent function transformation in each interval, controlling the output signal by a PWM wave with a fixed frequency, and at the same time adopting the zero-voltage spread modulation method to improve the PWM wave, adaptively adjusting the duty cycle of the PWM wave, and finally completing the control of the motor through the power converter. Compared with the traditional control method, the current fluctuation, switching frequency and torque ripple of the permanent magnet assisted switched reluctance motor using this control method are all reduced, thereby improving the stability and efficiency of the motor during operation, reducing energy loss, and extending the service life of the motor. Description of the Drawings

[0031] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for description in the specific embodiments or the prior art. Obviously, the drawings in the following description are only one embodiment of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0032] Figure 1 It is a system framework diagram of a method for reducing torque ripple and switching loss control of a permanent magnet assisted switched reluctance motor.

[0033] Figure 2 It is a characteristic partition diagram of the torque current ratio.

[0034] Figure 3 It is a schematic diagram of a segmented TSF based on hyperbolic tangent function transformation.

[0035] Figure 4 It is a schematic diagram of the PWM modulation method during phase winding excitation.

[0036] Figure 5 It is a schematic diagram of the PWM modulation method during phase winding demagnetization.

[0037] Figure 6 It is a block diagram of adaptive duty cycle control.

[0038] Figure 7 It is a torque and voltage waveform diagram under the traditional PWM modulation method when the motor running speed is 1000 r / min.

[0039] Figure 8 It is a torque and voltage waveform diagram under the zero voltage modulation method proposed by the present invention when the motor running speed is 1000 r / min.

[0040] Figure 9 It is an experimental diagram of the traditional PWM modulation method when the motor running speed is 500 r / min.

[0041] Figure 10 It is an experimental diagram of the zero voltage modulation method proposed by the present invention when the motor running speed is 500 r / min. Specific Embodiments

[0042] To make the technical means, creative features, achieved purposes and effects of the present invention easy to understand, the following will clearly and completely describe the technical solutions in the specific embodiments of the present invention in combination with experiments to further elaborate the present invention. The three-phase permanent magnet assisted switched reluctance motor model used in the experiments is 6 / 20Pma-SRM.

[0043] As Figure 1As shown in the figure, the system framework of a control method for reducing torque ripple and switching losses of a permanent magnet assisted switched reluctance motor provided by the present invention includes a position detection module, a speed detection module, a PI controller, a power converter, and a torque calculation module. This method includes dividing the operation of the motor into different intervals, using different torque distribution functions based on the hyperbolic tangent function transformation in each interval, optimizing the PWM modulation method, adaptively adjusting the duty cycle of the PWM wave, and finally completing the control of the motor through the power converter. Specifically, it includes the following steps:

[0044] S1. The actual speed w of the motor is obtained through the speed sensor based on the electrical angle θ fed back by the position detection module, and then it is subtracted from the given speed w. The difference between the two is input into the PI controller, and the reference torque T is output. * , and then subtracted from the given speed w ref . The difference between the two is input into the PI controller, and the reference torque T is output. ref .

[0045] S2. As shown in the figure Figure 2 , according to the electromagnetic characteristics and torque-current ratio characteristics of the motor, the operation interval of the motor is divided into three intervals, namely commutation zone 1, commutation zone 2, and single-phase conduction zone. The starting point of commutation zone 1 is the conduction angle θ of the exciting phase on , and the demarcation point between commutation zone 1 and commutation zone 2 is the point where the torque-current ratios of the two phases are equal, and it is also the inductance boundary point θ m ; the demarcation point between commutation zone 2 and the single-phase conduction zone is the point where the demagnetizing phase is completely aligned with the stator, and it is also the commutation overlap angle θ in the torque distribution function ov ; the end point of the single-phase conduction zone is the turn-off angle θ of the next exciting phase of . That is, the region where the torque-current ratio of the demagnetizing phase is greater than that of the exciting phase is commutation zone 1, and the region where the torque-current ratio of the demagnetizing phase is less than that of the exciting phase is commutation zone 2.

[0046] The calculation formula of the torque-current ratio (TCR) is:

[0047]

[0048] where T j is the electromagnetic torque generated by the jth phase winding, i j is the current of the jth phase winding, L is the inductance, θ is the rotor position angle, is the inductance change rate of the inductance with respect to the rotor position.

[0049] S3. As shown in the figure Figure 3 , different torque distribution functions are designed in different intervals, and the piecewise torque distribution function f j (θ) based on the hyperbolic tangent function transformation is:

[0050]

[0051] Among them, f jup1 (θ) is the torque distribution function in the rising stage of the first commutation zone, and f jdown1 (θ) is the torque distribution function in the falling stage of the first commutation zone, and f jup2 (θ) is the torque distribution function in the rising stage of the second commutation zone, and f jdown2 (θ) is the torque distribution function in the falling stage of the second commutation zone; the hyperbolic tangent function In this embodiment, the inductance boundary point θ m is equal to 2°; the commutation overlap angle θ ov is equal to 3°, and θ n is the inductance boundary point of the next phase winding; τ r is the rotor pole pitch; k1 and k2 are the weight coefficients of the first commutation zone and the second commutation zone respectively. The weight coefficients k1 and k2 change according to the motor speed and load. The larger the value of k1, the more torque is distributed to the demagnetizing phase, and the less torque is distributed to the exciting phase accordingly; the larger the value of k2, the more torque is distributed to the exciting phase, and the less torque is distributed to the demagnetizing phase accordingly. Adjusting the weight coefficients k1 and k2 according to the motor speed and load can make full use of the output capacity of each phase torque and improve the torque tracking performance.

[0052] S4. Obtain the reference torque Tref(a, b, c) of each phase through the torque distribution function module, obtain the actual torque Te* of each phase through the torque calculation module, and subtract the actual torque Te* from the reference torque Tref(a, b, c) to obtain the torque error That is

[0053] S5. In order to reduce the switching loss, control the output signal through a fixed-frequency PWM wave. At the same time, in order to generate a suitable control signal, the zero-voltage dispersion modulation method is used to improve the PWM wave.

[0054] Compare the triangular carrier wave that changes at [0, 1] with the modulation signal C1 and the modulation signal C2 to generate the control signals of the switching tube S1 and the switching tube S2. C1, C2 and the duty cycle D u are in a quantitative relationship, and their ranges are both within [0, 1].

[0055] For the switching tube S1 on the power circuit, the middle-duty-cycle modulation method is adopted, that is, when the carrier wave value is greater than C1, the switching tube S1 is turned on, and when it is less than C1, the switching tube S1 is turned off; for the switching tube S2, the two-end duty-cycle modulation method is adopted, that is, when the carrier wave value is less than C2, the switching tube S2 is turned on, and when it is greater than C2, the switching tube S2 is turned off.

[0056] Within a control period, the duty cycles of the two modulation methods are the same, and the average voltage range applied to one phase can be [-Udc, Udc]. When the phase winding is magnetized and demagnetized, the output voltage signal waveforms are as shown in Figure 4 , Figure 5 , where α and β are the duty cycle D u magnitudes. When the phase winding is in the magnetizing state, α is greater than 0.5; when the phase winding is in the demagnetizing state, β is less than 0.5, and T s is the control period.

[0057] S6, as shown in Figure 6 , adaptively control the duty cycle D of the PWM wave according to the torque error rotational speed and load, and then control the voltage across the phase winding. u

[0058] First, judge the obtained in step S4, and decide whether the duty cycle D u needs to change according to whether it meets the preset value. If it meets, the duty cycle D u remains unchanged; if it does not meet, the duty cycle D u needs to change. The calculation formula for the duty cycle D u is:

[0059]

[0060] where ΔD u is the change amount of the duty cycle, λ, α, and β are weighting factors, w n is the real-time rotational speed, w ref is the given rotational speed, is the real-time load, is the given load, and respectively represent the duty cycle at the current moment and the duty cycle at the next moment.

[0061] S7, control the conduction and turn-off of each phase switching device in the power converter according to the output signal of the PWM, and then control the startup of the permanent magnet assisted switched reluctance motor, thereby suppressing torque ripple and reducing switching losses.

[0062] Set the switching state of the power converter. When both the upper and lower switching tubes of a bridge arm of the power converter are conducting, S = 1, which is the magnetizing state; when one switching tube is conducting and the other is turned off, S = 0, which is the freewheeling state; when both switching tubes are turned off, S = -1, which is the demagnetizing state. According to the PWM wave signal output in step S6, turn off and turn on the switching tubes in the power converter according to the above conduction method to control the operation of the motor.

[0063] Build a torque control simulation model in the Matlab / Simulink environment, and conduct simulation verification on the traditional control method and the control method proposed in the present invention respectively, and conduct quantitative analysis on the torque ripple T rip The calculation formula is as follows:

[0064]

[0065] Among them, T max 、T min and T avg are the maximum torque, minimum torque and average torque respectively.

[0066] Figure 7 、 Figure 8 respectively give the current, voltage and torque waveforms of the traditional hard chopping modulation method and the zero-voltage modulation method proposed in the present invention under the conditions of a rotational speed of 1000 r / min and a load of 4 N·m. From the simulation results, it can be seen that the torque ripple of the traditional hard chopping modulation method is 25%, and the torque ripple of the zero-voltage modulation method proposed in the present invention is 6%. From the voltage waveform, it can be seen that the switching frequency of the traditional modulation method is significantly greater than that of the zero-voltage modulation method proposed in the present invention.

[0067] Figure 9 、 Figure 10 respectively give the experimental waveforms of the current and voltage of the traditional hard chopping modulation method and the zero-voltage modulation method proposed in the present invention at a rotational speed of 500 r / min. It can be seen that both the current fluctuation and the switching frequency of the control method proposed in the present invention are reduced compared with the traditional control method.

[0068] The above describes the main technical features, basic principles and related advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary specific embodiments, and can be implemented in other specific forms without departing from the concept or basic features of the present invention. Therefore, in any aspect, the above specific embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention.

[0069] In addition, it should be understood that although this specification is described according to each embodiment, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A control method for reducing torque ripple and switching loss of a permanent magnet assisted switched reluctance motor, characterized in that: The system framework of the method includes a position detection module, a speed detection module, a PI controller, a power converter and a torque calculation module. The method includes dividing the operation of the motor into intervals for control, using different torque distribution functions based on hyperbolic tangent function transformation in each interval, optimizing the PWM modulation mode, and adaptively adjusting the duty cycle D of the PWM wave. u Finally, the motor is controlled by the power converter, which specifically includes the following steps: S1. Get the actual speed w * With given speed w ref The speed loop is formed, and the difference between the two is input into the PI controller to output the reference torque T ref ; S2. According to the electromagnetic characteristics and torque-current ratio characteristics of the motor, the motor's operating range is divided into three ranges, namely, exchange zone 1, exchange zone 2, and single-phase conduction zone; the starting point of exchange zone 1 is the opening angle θ of the excitation phase. on The boundary point between the exchange zone 1 and the exchange zone 2 is the point where the torque current ratio of the two phases is equal, which is also the inductance boundary point θ m The boundary between the second exchange zone and the single-phase conduction zone is the point where the stator and rotor of the demagnetization phase are completely aligned, which is also the commutation overlap angle θ in the torque distribution function. ov ; The end point of the single-phase conduction zone is the turn-off angle θ of the next excitation phase of ; S3. Design different torque distribution functions in different intervals, and obtain the segmented torque distribution function f based on the hyperbolic tangent function transformation j (θ) is: Among them, f jup1 (θ) is the torque distribution function in the rising phase of the exchange zone, f jdown1 (θ) is the torque distribution function in the descending phase of the exchange zone, f jup2 (θ) is the torque distribution function in the rising phase of the second exchange zone, f jdown2 (θ) is the torque distribution function of the lowering phase of the exchange zone 2; hyperbolic tangent function k1 and k2 are the weight coefficients of exchange zone 1 and exchange zone 2 respectively; the inductor boundary point θ m is a fixed value; θ n is the next phase inductance boundary point; the commutation overlap angle θ ov is a fixed value; τ r is the rotor pole pitch; S4. The reference torque Tref(a, b, c) of each phase is obtained through the torque allocation function module, and the actual torque Te* of each phase is obtained through the torque calculation module. The reference torque Tref(a, b, c) is subtracted from the actual torque Te* to obtain the torque error. S5, controlling the output signal through a fixed frequency PWM wave, and improving the PWM wave by adopting a zero voltage dispersion modulation method; S6, according to the torque error Speed ​​and load adaptively control the duty cycle D of the PWM wave u , and then control the voltage across the phase winding; S7. According to the output signal of PWM, the on and off of the switching devices of each phase in the power converter are controlled, and then the starting of the permanent magnet assisted switched reluctance motor is controlled, so as to suppress torque pulsation and reduce switching loss.

2. A control method for reducing torque ripple and switching loss of a permanent magnet assisted switched reluctance motor according to claim 1, characterized in that: In step S2, the expression of torque-to-current ratio is: Where TCR represents the torque-to-current ratio, T j is the electromagnetic torque generated by the j-phase winding, i j is the current of the j-th phase winding, L is the inductance, θ is the rotor position angle, It represents the rate of change of inductance with rotor position.

3. A control method for reducing torque ripple and switching loss of a permanent magnet assisted switched reluctance motor according to claim 1, characterized in that: In step S2, the demagnetization phase torque current ratio in the exchange zone 1 is greater than the excitation phase torque current ratio, and the excitation phase torque current ratio in the exchange zone 2 is greater than the demagnetization phase torque current ratio.

4. A control method for reducing torque ripple and switching loss of a permanent magnet assisted switched reluctance motor according to claim 1, characterized in that: In step S3, the weight coefficients k1 and k2 of the segmented torque distribution function based on the hyperbolic tangent function transformation change according to the motor speed and load. The larger the k1 value is, the more the demagnetization phase torque is distributed, and the corresponding excitation phase torque is distributed less; the larger the k2 value is, the more the excitation phase torque is distributed, and the corresponding demagnetization phase torque is distributed less.

5. A control method for reducing torque ripple and switching loss of a permanent magnet assisted switched reluctance motor according to claim 1, characterized in that: In step S3, the inductor boundary point θ m The commutation overlap angle is 2°. ov It is 3°.

6. A control method for reducing torque ripple and switching loss of a permanent magnet assisted switched reluctance motor according to claim 1, characterized in that: In step S5, the output signal is controlled by a fixed frequency PWM wave, including comparing the triangular carrier wave changing at [0,1] with the modulation signal C1 and the modulation signal C2, generating control signals of the switch tube S1 and the switch tube S2, and C1, C2 and the duty cycle D u It is a quantitative relationship and its range is within [0,1].

7. A control method for reducing torque ripple and switching loss of a permanent magnet assisted switched reluctance motor according to claim 6, characterized in that: The PWM wave is improved by adopting zero voltage dispersion modulation, including adopting an intermediate duty cycle modulation method for the switch tube S1 on the power circuit, that is, when the carrier value is greater than C1, the switch tube S1 is turned on, and when it is less than C1, the switch tube S1 is turned off.

8. A control method for reducing torque ripple and switching loss of a permanent magnet assisted switched reluctance motor according to claim 7, characterized in that: For the switch tube S2, a modulation method of duty cycle at both ends is adopted, that is, when the carrier value is less than C2, the switch tube S2 is turned on, and when it is greater than C2, the switch tube S2 is turned off.

9. A control method for reducing torque ripple and switching loss of a permanent magnet assisted switched reluctance motor according to claim 1, characterized in that: In step S6, first the Make a judgment and determine the duty cycle D based on whether it meets the preset value u Whether it needs to be changed, duty cycle D u The calculation formula is: Where, ΔD u is the change of duty cycle, λ, α, β are weight factors, w n is the real-time speed, w ref For a given speed, For real-time load, For a given load, and They represent the duty cycle at the current moment and the duty cycle at the next moment respectively.

Images