Method for suppressing torque ripple of a doubly salient reluctance motor

Abstract

A method for suppressing torque ripple in a doubly salient pole reluctance motor includes the following steps: Step S1: The armature winding and excitation winding of the doubly salient pole reluctance motor are wound in parallel to form an integrated winding. An excitation current containing AC and DC bias components is passed into the integrated winding, wherein the AC component is used to generate the armature magnetic field and the DC bias component is used to generate the excitation magnetic field; Step S2: Fourier harmonic analysis is performed on the inductance of the integrated winding to determine the main harmonic components of the inductance. The technical problem to be solved by this invention is to provide a method for suppressing torque ripple in a doubly salient pole reluctance motor. Based on the characteristics of the open-winding inverter topology, torque ripple is suppressed by injecting specific harmonics into the zero-sequence current, thereby achieving high-performance control of the doubly salient pole reluctance motor.

Description

Technical Field

[0001] This invention relates to the field of gas overhead pipeline technology, and in particular to a method for suppressing torque pulsation in a doubly salient pole reluctance motor. Background Technology

[0002] Compared to traditional induction motors and permanent magnet synchronous motors, dual salient pole reluctance motors (DSRMs) have advantages such as simple and reliable structure, wide speed range, and low cost. However, because both the rotor and stator of a DSRM are salient poles, the electromagnetic torque ripple of the motor is relatively large, which greatly limits its wide range of applications.

[0003] For power inverter topologies, open-winding inverters offer advantages such as lower inverter losses and more flexible control. Furthermore, the open connection between the ends of the two inverter windings provides a path for zero-sequence current, making them highly adaptable to the control of doubly salient reluctance motors. In recent years, with increasingly stringent requirements for motor performance, research on torque ripple suppression methods for reluctance motors has also grown. Large torque ripple leads to increased motor vibration, resulting in decreased output stability and increased motor losses. Therefore, suppressing torque ripple in doubly salient reluctance motors based on open-winding inverter topologies is essential. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for suppressing torque ripple in a doubly salient reluctance motor. Based on the characteristics of the open-winding inverter topology, the method suppresses torque ripple by injecting specific harmonics into the zero-sequence current, thereby achieving high-performance control of the doubly salient reluctance motor.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for suppressing torque pulsation in a doubly salient pole reluctance motor, comprising the following steps: Step S1: The armature winding and the excitation winding of the double salient pole reluctance motor are wound in parallel to form an integrated winding. An excitation current containing an AC component and a DC bias component is passed into the integrated winding, wherein the AC component is used to generate the armature magnetic field and the DC bias component is used to generate the excitation magnetic field. Step S2: Perform Fourier harmonic analysis on the inductance of the integrated winding to determine the main harmonic components of the inductance; Step S3: Convert the three-phase current in the three-phase stationary coordinate system into the current in the rotating coordinate system through coordinate transformation, derive the electromagnetic torque expression of the double salient pole reluctance motor, separate the effective torque and ripple torque from the electromagnetic torque expression, and determine the order of the ripple torque. Step S4: Inject a specific harmonic current with the same order, amplitude, and opposite phase as the ripple torque into the zero-sequence current in the rotating coordinate system to generate an additional torque that is opposite to the ripple torque, thereby canceling the original ripple torque in the output torque of the dual salient pole reluctance motor and achieving torque pulsation suppression.

[0006] Preferably, in step S1, the expression for the three-phase excitation current supplied to the integrated winding is: (1) in I ac , I dc , θ e These are for AC component, DC bias component, and motor electrical angle, respectively.

[0007] Preferably, in step S2, the inductance data of the integrated winding is obtained through finite element simulation of the dual-salient pole reluctance motor model. After performing Fourier harmonic analysis on the inductance data, it is determined that the mutual inductance between the armature winding and the excitation winding is approximately zero, and the self-inductance expression of the integrated winding is: (2) in L 0、 L 2. L 6 represents the DC component, second harmonic component, and sixth harmonic component of the motor inductance, respectively. θ e The electric angle is the motor angle.

[0008] Preferably, the coordinate transformation in step S3 is a Park transformation, where the rotational angular velocity of the rotating coordinate system is twice the angular velocity of the dual salient pole reluctance motor. The Park transformation converts the three-phase AC current in the three-phase stationary coordinate system into a direct-axis current in the rotating coordinate system. i d quadrature axis current i q and zero-sequence current i 0.

[0009] Preferably, in step S3, the self-inductance expression of the integrated winding and the current expression after Park transformation are substituted into the torque equation of the dual salient pole reluctance motor to obtain the output torque expression as follows: (6) in i 0 represents zero-sequence current. i d For direct-axis current, i q For quadrature axis current, T e1For effective torque, T e2 , T e3 Ripple torque is the source of torque pulsation and should be suppressed. As can be seen from the expression, the order of ripple torque is the sixth harmonic.

[0010] Preferably, the control process of the double salient pole reluctance motor adopts i d The control strategy is =0, at which point the output torque of the dual salient pole reluctance motor is determined by the zero-sequence current. i 0 and quadrature axis current i q A joint decision.

[0011] Preferably, while keeping the effective value of the motor phase current constant, the change is achieved through finite element simulation. i 0 and i q The ratio of the two values ​​determines when i 0 / i q The ratio is close to 1 / At this time, the output torque of the double salient pole reluctance motor is at its maximum.

[0012] Preferably, in step S4, the zero-sequence current is directed... i The specific harmonic current injected is the sixth harmonic current, and the expression for the dq0-axis current after the harmonic current is injected is: (8) in, I q This represents the DC component of the quadrature-axis current. I 0 represents the DC component of the zero-sequence current. I 06 The amplitude of the injected sixth harmonic current is α, and the initial phase angle of the sixth harmonic is opposite to the phase of the original ripple torque, so that the generated additional torque has the same amplitude and opposite direction to the original ripple torque.

[0013] Preferably, the torque ripple coefficient is used to characterize the magnitude of the torque ripple. Defined as: (9) in T max , T min These represent the instantaneous maximum and minimum values ​​of the torque. T avg This represents the average value of the torque.

[0014] Preferably, the open-winding inverter consists of two sets of three-phase full-bridge inverters. The positive input terminal and negative output terminal of the two sets of three-phase full-bridge inverters are respectively connected to the positive and negative terminals of the DC power supply. The midpoints of the three-phase bridge arms of the two sets of inverters are respectively connected to the two ends of the integrated winding of the double salient pole reluctance motor, providing a flow path for zero-sequence current.

[0015] This invention provides a method for suppressing torque pulsation in a doubly salient pole reluctance motor, which has the following beneficial effects: 1. Significant torque ripple suppression effect: By injecting a sixth harmonic current with an order matching and opposite phase to the ripple torque into the zero-sequence current, a reverse additional torque is generated to offset the original ripple torque. Experiments have verified that this method can significantly reduce the motor torque fluctuation coefficient from 0.67 to 0.27, fundamentally solving the inherent torque ripple problem of doubly salient pole reluctance motors caused by their doubly salient pole structure.

[0016] 2. Comprehensive improvement of motor operation quality: Effective suppression of torque pulsation directly reduces vibration and noise during motor operation, making the output torque more stable. At the same time, it reduces internal mechanical wear and electrical losses caused by torque pulsation, extends the service life of the motor, and improves the reliability and stability of motor operation.

[0017] 3. Balancing high output efficiency and current utilization: Adopting... i d The control strategy with a value of 0 was determined through finite element simulation to identify the optimal value. i 0 / i q The ratio, while suppressing torque ripple, ensures the maximization of motor output torque, avoiding the drawbacks of traditional suppression methods that sacrifice output performance, and significantly improves the motor's current utilization rate and overall operating efficiency.

[0018] 4. Strong hardware adaptability and low implementation cost: It fully utilizes the inherent advantages of open-winding inverter topology, such as fewer switching devices, lower inverter losses, and more flexible control strategies. It relies on its natural zero-sequence current flow path to achieve harmonic current injection without the need for additional complex hardware circuits. The control scheme is easy to implement in engineering and has low modification costs.

[0019] 5. Significantly expand motor application scenarios: It retains the core advantages of the double salient pole reluctance motor, such as simple and reliable structure, wide speed range and low manufacturing cost, and solves the key problem of its application being limited due to large torque ripple. It significantly improves the applicability of the motor in important occasions with high requirements for motor performance, such as aerospace, electric vehicles and industrial transmission. Attached Figure Description

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1This is a schematic diagram of the control system structure of the dual salient pole reluctance motor based on the open winding inverter of the present invention; Figure 2 This is a schematic diagram of the double salient pole reluctance motor of the present invention; Figure 3 This is a schematic diagram of the open-winding inverter topology of the present invention; Figure 4 This is a schematic diagram of the Fourier harmonic analysis results of the motor inductance of the present invention; Figure 5 For the purposes of this invention i q / i Schematic diagram of motor torque at a ratio of 0; Figure 6(a) is a schematic diagram of the dq0 axis current before the injection of harmonics in this invention; Figure 6(b) is a schematic diagram of the dq0 axis current after the injection of harmonics according to the present invention; Figure 7(a) is a schematic diagram of the three-phase current and torque before the injection of harmonics in this invention; Figure 7(b) is a schematic diagram of the three-phase current and torque after the injection of harmonics according to the present invention. Detailed Implementation

[0021] A method for suppressing torque ripple in a doubly salient reluctance motor, based on a doubly salient reluctance motor control system with an open-winding inverter topology, the control system comprising a doubly salient reluctance motor, an open-winding inverter, a DC power supply, and sensors, includes the following steps: Step S1: The armature winding and the excitation winding of the double salient pole reluctance motor are wound in parallel to form an integrated winding. An excitation current containing an AC component and a DC bias component is passed into the integrated winding, wherein the AC component is used to generate the armature magnetic field and the DC bias component is used to generate the excitation magnetic field. Step S2: Perform Fourier harmonic analysis on the inductance of the integrated winding to determine the main harmonic components of the inductance; Step S3: Convert the three-phase current in the three-phase stationary coordinate system into the current in the rotating coordinate system through coordinate transformation, derive the electromagnetic torque expression of the double salient pole reluctance motor, separate the effective torque and ripple torque from the electromagnetic torque expression, and determine the order of the ripple torque. Step S4: Inject a specific harmonic current with the same order, amplitude, and opposite phase as the ripple torque into the zero-sequence current in the rotating coordinate system to generate an additional torque that is opposite to the ripple torque, thereby canceling the original ripple torque in the output torque of the dual salient pole reluctance motor and achieving torque pulsation suppression.

[0022] Preferably, in step S1, the expression for the three-phase excitation current supplied to the integrated winding is: (1) in I ac , I dc , θ e These are for AC component, DC bias component, and motor electrical angle, respectively.

[0023] Preferably, in step S2, the inductance data of the integrated winding is obtained through finite element simulation of the dual-salient pole reluctance motor model. After performing Fourier harmonic analysis on the inductance data, it is determined that the mutual inductance between the armature winding and the excitation winding is approximately zero, and the self-inductance expression of the integrated winding is: (2) in L 0、 L 2. L 6 represents the DC component, second harmonic component, and sixth harmonic component of the motor inductance, respectively. θ e The electric angle is the motor angle.

[0024] Preferably, the coordinate transformation in step S3 is the Park transformation, and the rotational angular velocity of the rotating coordinate system is twice the angular velocity of the dual salient pole reluctance motor. The Park transformation converts the three-phase AC current in the three-phase stationary coordinate system into the direct-axis current id, quadrature-axis current iq, and zero-sequence current i0 in the rotating coordinate system.

[0025] In step S3, the motor torque equation can be expressed as: (3) ; in W m This represents the magnetic energy of the motor. n p This represents the number of pole pairs of the motor. For ease of control, a Park transformation is used to convert the three-phase AC current in the stationary three-phase coordinate system into DC current in the rotating coordinate system. At this point, the rotational angular velocity is twice the motor's angular velocity. The Park transformation matrix T is: (4) In a synchronous rotating coordinate system, the expression for the electromagnetic torque of the DSRM is: (5) ; Preferably, in step S3, the self-inductance expression of the integrated winding and the current expression after Park transformation are substituted into the torque equation of the dual salient pole reluctance motor, and formulas (2) and (4) are substituted into formula (5) to obtain the output torque expression as follows: (6) in i 0 represents zero-sequence current. i d For direct-axis current, i q For quadrature axis current, T e1 For effective torque, T e2 , T e3 Ripple torque is the source of torque pulsation and should be suppressed. As can be seen from the expression, the order of ripple torque is the sixth harmonic.

[0026] Preferably, the control process of the double salient pole reluctance motor adopts i d The control strategy is =0, at which point the output torque of the dual salient pole reluctance motor is determined by the zero-sequence current. i 0 and quadrature axis current i q A joint decision.

[0027] Preferably, while keeping the effective value of the motor phase current constant, the change is achieved through finite element simulation. i 0 and i q The ratio of the two values ​​determines when i 0 / i q The ratio is close to 1 / At this time, the output torque of the double salient pole reluctance motor is at its maximum.

[0028] Under this control strategy, the torque expression for DSRM is: (7) Preferably, in step S4, the zero-sequence current is directed... i The specific harmonic current injected is the sixth harmonic current, and the expression for the dq0-axis current after the harmonic current is injected is: (8) in, I q This represents the DC component of the quadrature-axis current. I 0 represents the DC component of the zero-sequence current. I 06 The amplitude of the injected sixth harmonic current is α, and the initial phase angle of the sixth harmonic is opposite to the phase of the original ripple torque, so that the generated additional torque has the same amplitude and opposite direction to the original ripple torque.

[0029] Preferably, the torque ripple coefficient is used to characterize the magnitude of the torque ripple. Defined as: (9) in T max , T min These represent the instantaneous maximum and minimum values ​​of the torque. T avg This represents the average value of the torque.

[0030] Preferably, the open-winding inverter consists of two sets of three-phase full-bridge inverters. The positive input terminal and negative output terminal of the two sets of three-phase full-bridge inverters are respectively connected to the positive and negative terminals of the DC power supply. The midpoints of the three-phase bridge arms of the two sets of inverters are respectively connected to the two ends of the integrated winding of the double salient pole reluctance motor, providing a flow path for zero-sequence current.

[0031] Specific implementation examples Figure 1 As shown, the control system mainly consists of a doubly salient pole reluctance motor, a three-phase four-arm inverter, an SVPWM module, a PI controller module, a coordinate transformation module, a position detection module, and a current detection module. This invention is based on a 12 / 10 doubly salient pole reluctance motor. The three-phase four-arm inverter mainly consists of one DC power supply, 12 IGBTs, and 12 freewheeling diodes. The position detection module is mainly used to determine the motor rotor position, the current detection module is mainly used to measure the three-phase current of the motor, and the SVPWM module, PI controller module, and coordinate transformation module are implemented through software programs.

[0032] The dual salient pole reluctance motor used in this embodiment, such as Figure 2 As shown, this embodiment uses a 12 / 10 doubly salient pole reluctance motor, where the stator has 12 salient pole teeth and the rotor has 10 salient pole teeth. Both the stator and rotor are doubly salient pole structures, and the rotor has no permanent magnets or coils. This motor is characterized by its simple structure, good robustness, and convenient heat dissipation.

[0033] like Figure 3 As shown, the open-winding inverter topology consists of two sets of three-phase full-bridge inverters. The positive input and negative output terminals of the two sets of inverters are used to connect to the DC power supply. The three bridge arms of the inverter are connected between the positive and negative terminals. The A, B, and C three-phase windings drawn from the midpoint of the first three bridge arms are connected in a Y-shape. The winding ends of the two sets of inverters are then connected together. Each bridge arm consists of two upper and two lower switching transistors and two freewheeling diodes.

[0034] like Figure 4 As shown, using Matlab simulation software, Fourier harmonic analysis was performed on the inductance of a double salient pole reluctance motor during a single cycle. The analysis results show that the phase inductance contains a large number of harmonic components, mainly including DC components. L 0. Second harmonic componentL 2. Sixth harmonic component L 6. Among them, the second and sixth harmonics in the motor inductance are the sources of torque pulsation.

[0035] like Figure 5 As shown, based on the above analysis, different i 0 / i q The value of this parameter directly affects the motor's output torque. To determine the optimal value... i 0 and i q The combination of these parameters, through finite element analysis, maintains the motor phase current at a constant value of 18A, while changing... i 0 / i q The ratio gradually increases from 0.5 to 1, resulting in increased output torque. T e along with i 0 / i q The ratio changes as the ratio changes; according to the analysis results, when... i 0 / i q The ratio is close to 1 / At that time, the output torque T e At its maximum, the motor's output efficiency is at its maximum.

[0036] To further verify the correctness of injecting harmonic currents of specific order and amplitude into zero-sequence current to suppress torque ripple, the experimental platform hardware mainly includes a dual salient pole reluctance motor, torque sensor, drive circuit, sampling circuit, magnetic powder brake, and a main circuit composed of two sets of three-phase full-bridge inverters. During the experiment, the DC power supply input was maintained at 50V, the given speed of the DSRM was 170 r / min, and the electromagnetic torque was adjusted through the magnetic powder brake. Referring to Figure 6(a), in the dq0 coordinate system, i 0 represents the DC bias component, which is 8A before the harmonic current injection. The d-axis current fluctuates around zero, while the q-axis current is 10A. Referring to Figure 6(b), after the harmonic current injection, i The current is 7A at 0, the d-axis current remains basically unchanged, and the q-axis current is 10A. However, due to the injection of harmonic current, the current fluctuation increases.

[0037] With the DC power input maintained at 50V, before the injection of harmonic current, the torque and three-phase current of the DSRM are shown in Figure 7(a), where the output torque is 3 N·m, the peak value of the three-phase current is 38 A, including an 8 A DC bias component, and the torque fluctuation coefficient is... The value is 0.67. After inputting harmonic current, the torque and three-phase current of the DSRM are shown in Figure 7(b). The output torque remains at 3 N·m, and the peak value of the three-phase current is 40 A, which includes an 8 A DC bias component. The torque ripple coefficient is... The value was 0.27, indicating that torque ripple was significantly suppressed.

[0038] Leveraging the flexibility of open-winding inverters and dual salient pole reluctance motor (DSRM) control, this invention proposes a method for suppressing torque ripple in DSRMs. First, Fourier analysis was performed on the self-inductance of the DSRM motor to obtain the expression for the three-phase inductance. Based on this, the output torque of the DSRM in a synchronous rotating coordinate system was analyzed, and the ripple torque in the output torque was determined to be a sixth harmonic through expression substitution. Simultaneously, to maximize the motor's output efficiency, the optimal iq / i0 ratio was obtained through finite element analysis, thus determining the amplitude and phase of the harmonic current to be injected with zero-sequence current. The injected harmonic current generates a compensating torque with the same amplitude but opposite direction to the ripple torque, effectively suppressing torque ripple. Finally, the correctness of this strategy was verified through experiments, providing technical support for ensuring high-performance control of the motor in certain applications.

[0039] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A method for suppressing torque pulsation in a doubly salient pole reluctance motor, characterized in that, Includes the following steps: Step S1: The armature winding and the excitation winding of the double salient pole reluctance motor are wound in parallel to form an integrated winding. An excitation current containing an AC component and a DC bias component is passed into the integrated winding, wherein the AC component is used to generate the armature magnetic field and the DC bias component is used to generate the excitation magnetic field. Step S2: Perform Fourier harmonic analysis on the inductance of the integrated winding to determine the main harmonic components of the inductance; Step S3: Convert the three-phase current in the three-phase stationary coordinate system into the current in the rotating coordinate system through coordinate transformation, derive the electromagnetic torque expression of the double salient pole reluctance motor, separate the effective torque and ripple torque from the electromagnetic torque expression, and determine the order of the ripple torque. Step S4: Inject a specific harmonic current with the same order, amplitude, and opposite phase as the ripple torque into the zero-sequence current in the rotating coordinate system to generate an additional torque that is opposite to the ripple torque, thereby canceling the original ripple torque in the output torque of the dual salient pole reluctance motor and achieving torque pulsation suppression.

2. The method for suppressing torque pulsation in a doubly salient pole reluctance motor according to claim 1, characterized in that, In step S1, the expression for the three-phase excitation current supplied to the integrated winding is: ； （1） in I ac , I dc , θ e These are for AC component, DC bias component, and motor electrical angle, respectively.

3. The method for suppressing torque pulsation in a doubly salient pole reluctance motor according to claim 1, characterized in that, In step S2, the inductance data of the integrated winding is obtained through finite element simulation of the dual-salient pole reluctance motor model. After performing Fourier harmonic analysis on the inductance data, it is determined that the mutual inductance between the armature winding and the excitation winding is approximately zero. The self-inductance expression of the integrated winding is: ；（2） in L 0、 L 2. L 6 represents the DC component, second harmonic component, and sixth harmonic component of the motor inductance, respectively. θ e The electric angle is the motor angle.

4. The method for suppressing torque pulsation in a doubly salient pole reluctance motor according to claim 1, characterized in that, The coordinate transformation in step S3 is a Park transformation. The rotational angular velocity of the rotating coordinate system is twice the angular velocity of the dual salient pole reluctance motor. The Park transformation converts the three-phase AC current in the three-phase stationary coordinate system into the direct-axis current in the rotating coordinate system. i d quadrature axis current i q and zero-sequence current i 0.

5. The method for suppressing torque pulsation in a doubly salient pole reluctance motor according to claim 4, characterized in that, In step S3, the self-inductance expression of the integrated winding and the current expression after Park transformation are substituted into the torque equation of the dual salient pole reluctance motor to obtain the output torque expression: ；（6） in i 0 represents zero-sequence current. i d For direct-axis current, i q For quadrature axis current, T e1 For effective torque, T e2 , T e3 Ripple torque is the source of torque pulsation and should be suppressed. As can be seen from the expression, the order of ripple torque is the sixth harmonic.

6. The method for suppressing torque pulsation in a doubly salient pole reluctance motor according to claim 4, characterized in that, The control process of the double salient pole reluctance motor adopts i d The control strategy is =0, at which point the output torque of the dual salient pole reluctance motor is determined by the zero-sequence current. i 0 and quadrature axis current i q A joint decision.

7. The method for suppressing torque pulsation in a doubly salient pole reluctance motor according to claim 6, characterized in that, While keeping the effective value of the motor phase current constant, the finite element simulation is used to change... i 0 and i q The ratio of the two values ​​determines when i 0 / i q The ratio is close to 1 / At this time, the output torque of the double salient pole reluctance motor is at its maximum.

8. The method for suppressing torque pulsation in a doubly salient pole reluctance motor according to claim 4, characterized in that, In step S4, the zero-sequence current is directed towards... i The specific harmonic current injected is the sixth harmonic current, and the expression for the dq0-axis current after the harmonic current is injected is: ；（8） in, I q This represents the DC component of the quadrature-axis current. I 0 represents the DC component of the zero-sequence current. I 06 The amplitude of the injected sixth harmonic current is α, and the initial phase angle of the sixth harmonic is opposite to the phase of the original ripple torque, so that the generated additional torque has the same amplitude and opposite direction to the original ripple torque.

9. The method for suppressing torque pulsation in a doubly salient pole reluctance motor according to claim 1, characterized in that, The torque ripple coefficient is used to characterize the magnitude of torque ripple. Defined as: ； （9） in T max , T min These represent the instantaneous maximum and minimum values ​​of the torque. T avg This represents the average value of the torque.

10. The method for suppressing torque pulsation in a doubly salient pole reluctance motor according to claim 1, characterized in that, The open-winding inverter consists of two sets of three-phase full-bridge inverters. The positive input and negative output terminals of the two sets of three-phase full-bridge inverters are respectively connected to the positive and negative terminals of the DC power supply. The midpoints of the three-phase bridge arms of the two sets of inverters are respectively connected to the two ends of the integrated winding of the double salient pole reluctance motor, providing a flow path for zero-sequence current.

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