Coaxial double-switch reluctance motor torque ripple minimization control method

Abstract

The invention discloses a coaxial double-switch reluctance motor torque ripple minimization control method, which comprises the following steps: establishing a unified model for two switch reluctance motors, obtaining a reference torque through a proportional integral controller after making a difference between a reference rotating speed and an actual rotating speed, and establishing a phase current prediction model according to a phase voltage equation of the switch reluctance motors, based on the predicted current and the predicted angle, establishing a torque prediction model in a positive voltage excitation and zero voltage follow current mode in the conduction interval of each phase winding, and establishing a torque prediction model in a negative voltage demagnetization mode in the turn-off interval of each phase winding to obtain predicted torques of each phase winding in the conduction interval and the turn-off interval; and establishing a unified evaluation function by using the predicted torque and the reference torque of each phase winding of the two switched reluctance motors, and selecting an optimal switching state which enables the evaluation function to be minimum, thereby realizing the torque pulsation minimization control of the coaxial double-switched reluctance motor. The torque ripple minimization control method of the coaxial double-switch reluctance motor is not influenced by the phase difference of the double motors and the conduction range of each phase winding, can be easily expanded to a double-switch reluctance motor driving system with any phase number, and has good application prospect and engineering value.

Description

Technical Field

[0001] The invention relates to the field of torque control of a coaxial dual-switched reluctance motor, and in particular to a torque pulsation minimization control method for a coaxial dual-switched reluctance motor. Background Art

[0002] The coaxial dual switched reluctance motor has the advantages and characteristics of dual motor drive and switched reluctance motor. It has the advantages of strong load capacity, high reliability and good dynamic performance. It has good application prospects in electric vehicles, aerospace, wind power generation and other fields. Due to the motor structure and pulsed power supply mode of the switched reluctance motor, it has the disadvantage of large torque pulsation, which reduces the stability of the drive system operation. The traditional torque distribution function control method is affected by the phase difference of the dual motors, and each phase winding maintains a fixed conduction range, which will greatly limit the control method's suppression effect on torque pulsation, and it is difficult to achieve the goal of minimizing the torque pulsation of the coaxial dual switched reluctance motor in a wider conduction range. Therefore, in order to avoid the influence of the dual motor phase difference and the conduction range of each phase winding on the torque pulsation control of the coaxial dual switched reluctance motor, and to achieve the goal of minimizing the torque pulsation of the coaxial dual switched reluctance motor, it is urgent to propose an effective solution. Summary of the invention

[0003] The purpose of the present invention is to provide a torque ripple minimization control method for a coaxial dual-switched reluctance motor in view of the problems existing in the prior art.

[0004] The technical solution proposed by the present invention is:

[0005] A method for minimizing the torque pulsation of a coaxial dual switched reluctance motor is characterized in that: a unified model is established for the two switched reluctance motors, a reference torque is obtained by subtracting the reference speed from the actual speed through a proportional-integral controller, a phase current prediction model is established according to the phase voltage equation of the switched reluctance motor, a torque prediction model under positive voltage excitation and zero voltage freewheeling modes is established in the conduction interval of each phase winding based on the predicted current and the predicted angle, a torque prediction model under negative voltage demagnetization mode is established in the shutdown interval of each phase winding, and the predicted torque of each phase winding in the on and off intervals is obtained, a unified evaluation function is established using the predicted torque of each phase winding of the two switched reluctance motors and the reference torque, the optimal switching state that minimizes the evaluation function is selected, and the torque pulsation minimization control of the coaxial dual switched reluctance motor is realized.

[0006] A method for minimizing torque ripple of a coaxial dual-switched reluctance motor of the present invention comprises the following steps:

[0007] Step 1: Design a proportional-integral controller to generate reference torque;

[0008] Step 2: Design a torque prediction model to obtain the predicted torque of the dual switched reluctance motor;

[0009] Step 3: Establish a unified evaluation function and simultaneously obtain the optimal switching states of the two switched reluctance motors to achieve torque ripple minimization control of the coaxial dual switched reluctance motors;

[0010] The actual speed ω of the coaxial dual switched reluctance motor is input into the proportional integral controller, and the speed difference expression at the kth sampling moment is:

[0011] Δω(k)=ω ref (k)-ω(k) (1)

[0012] Where Δω(k) is the speed difference at time k; ω ref (k) is the reference speed of the motor at time k; ω(k) is the actual speed of the motor at time k.

[0013] The reference torque expression of the coaxial dual switched reluctance motor is:

[0014]

[0015] In the formula, K P is the proportional gain; K I is the integral gain; j is the serial number of the sampling time; T s is the sampling period; T ref is the reference torque.

[0016] The phase voltage balance equation of the coaxial dual switched reluctance motor is:

[0017]

[0018] Where U is the phase voltage of the switched reluctance motor, i is the phase current, R is the resistance of the phase winding, ψ is the flux linkage of the phase winding, and θ is the rotor position angle.

[0019] Formula (3) can be expressed as:

[0020]

[0021] Discretize equation (4) to obtain the expression of the predicted value of the phase current at the next moment:

[0022]

[0023] Where U(k) is the actual value of the phase voltage at time k, i(k) is the actual value of the phase current at time k, ψ(k) is the actual value of the phase winding flux at time k, θ(k) is the actual value of the rotor position angle at time k, and i(k+1) is the predicted value of the phase current at time (k+1).

[0024] The expression of the predicted value of the rotor position angle of the coaxial dual switched reluctance motor at the next moment is:

[0025] θ(k+1)=θ(k)+ω(k)T s (6)

[0026] Where θ(k+1) is the predicted value of the rotor position angle at time (k+1).

[0027] Based on the predicted current and predicted angle, a torque prediction model is established in the positive voltage excitation and zero voltage freewheeling modes in the conduction interval of each phase winding, and a torque prediction model is established in the negative voltage demagnetization mode in the shutdown interval of each phase winding; the predicted current and predicted angle of each phase winding of the first switched reluctance motor are substituted into the T(i,θ) table to obtain the predicted torque of each phase winding of the first switched reluctance motor in the conduction and shutdown intervals at time (k+1); the predicted current and predicted angle of each phase winding of another switched reluctance motor are substituted into the T(i,θ) table to obtain the predicted torque of each phase winding of the other switched reluctance motor in the conduction and shutdown intervals at time (k+1).

[0028] A unified evaluation function is established for the predicted torque of each phase winding of the two switched reluctance motors:

[0029] J=[T ref -(T a1 (k+1)+T b1 (k+1)+T c1 (k+1)+T a2 (k+1)+T b2 (k+1)+T c2 (k+1))] 2 (7)

[0030] Where, T a1 (k+1), T b1 (k+1), T c1 (k+1) is the predicted torque of each phase winding of the first motor at time (k+1); T a2 (k+1), T b2 (k+1), T c2 (k+1) is the predicted torque of each phase winding of the other motor at time (k+1); the predicted torque of each phase winding of the two switched reluctance motors is substituted into the evaluation function at the same time, and the voltage vector that minimizes the evaluation function is selected to obtain a unified switching state table to realize the torque pulsation minimization control of the coaxial dual switched reluctance motor.

[0031] Beneficial effect: Due to the adoption of the above technical solution, the present invention is applicable to a coaxial dual-switched reluctance torque pulsation minimization control method, which effectively solves the problem that the traditional torque distribution function control method is affected by the phase difference of the dual motors and the conduction range of each phase winding, and is easily extended to a dual-switched reluctance motor drive system with any number of phases. A unified model is established for the two switched reluctance motors, and the predicted torque of each phase winding in the on and off intervals is obtained through the torque prediction model established for each phase winding in the on and off intervals. A unified evaluation function is established using the predicted torque of each phase winding of the two switched reluctance motors and the reference torque, and the optimal switching state that minimizes the evaluation function is selected to achieve the torque pulsation minimization control of the coaxial dual-switched reluctance motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a block diagram of a coaxial dual-switch reluctance torque pulsation minimization control method of the present invention.

[0033] Figure 2 It is a specific implementation flow chart of a coaxial dual-switch reluctance torque pulsation minimization control method of the present invention. DETAILED DESCRIPTION

[0034] An example of a three-phase 12 / 8 coaxial double-switched reluctance motor applicable to the present invention is further described below in conjunction with the accompanying drawings:

[0035] Figure 1 The block diagram of a coaxial dual-switched reluctance torque ripple minimization control method is shown in Figure 1. The proportional-integral controller inputs the actual speed ω of the coaxial dual-switched reluctance motor into the proportional-integral controller. The speed difference expression at the kth sampling moment is:

[0036] Δω(k)=ω ref (k)-ω(k) (1)

[0037] Where Δω(k) is the speed difference at time k; ω ref (k) is the reference speed of the motor at time k; ω(k) is the actual speed of the motor at time k.

[0038] The reference torque expression of the coaxial dual switched reluctance motor is:

[0039]

[0040] In the formula, K P is the proportional gain; K I is the integral gain; j is the serial number of the sampling time; T s is the sampling period; T ref is the reference torque.

[0041] The phase voltage balance equation of the coaxial dual switched reluctance motor is:

[0042]

[0043] Where U is the phase voltage of the switched reluctance motor, i is the phase current, R is the resistance of the phase winding, ψ is the flux linkage of the phase winding, and θ is the rotor position angle.

[0044] Formula (3) can be expressed as:

[0045]

[0046] Discretize equation (4) to obtain the expression of the predicted value of the phase current at the next moment:

[0047]

[0048] Where U(k) is the actual value of the phase voltage at time k, i(k) is the actual value of the phase current at time k, ψ(k) is the actual value of the phase winding flux at time k, θ(k) is the actual value of the rotor position angle at time k, and i(k+1) is the predicted value of the phase current at time (k+1).

[0049] The expression of the predicted value of the rotor position angle of the coaxial dual switched reluctance motor at the next moment is:

[0050] θ(k+1)=θ(k)+ω(k)T s (6)

[0051] Where θ(k+1) is the predicted value of the rotor position angle at time (k+1).

[0052] Based on the predicted current and predicted angle, a torque prediction model is established in the positive voltage excitation and zero voltage freewheeling modes in the conduction interval of each phase winding, and a torque prediction model is established in the negative voltage demagnetization mode in the shutdown interval of each phase winding; the predicted current and predicted angle of each phase winding of the first switched reluctance motor are substituted into the T(i,θ) table to obtain the predicted torque of each phase winding of the first switched reluctance motor in the conduction and shutdown intervals at time (k+1); the predicted current and predicted angle of each phase winding of another switched reluctance motor are substituted into the T(i,θ) table to obtain the predicted torque of each phase winding of the other switched reluctance motor in the conduction and shutdown intervals at time (k+1).

[0053] A unified evaluation function is established for the predicted torque of each phase winding of the two switched reluctance motors:

[0054] J=[T ref -(T a1 (k+1)+T b1 (k+1)+T c1 (k+1)+T a2 (k+1)+T b2 (k+1)+Tc2 (k+1))] 2 (7)

[0055] Where, T a1 (k+1), T b1 (k+1), T c1 (k+1) is the predicted torque of each phase winding of the first motor at time (k+1); T a2 (k+1), T b2 (k+1), T c2 (k+1) is the predicted torque of each phase winding of the other motor at time (k+1); the predicted torque of each phase winding of the two switched reluctance motors is substituted into the evaluation function at the same time, and the voltage vector that minimizes the evaluation function is selected to obtain a unified switching state table to realize the torque pulsation minimization control of the coaxial dual switched reluctance motor.

[0056] Figure 2 This is a flowchart for the specific implementation of a torque pulsation minimization control method for a coaxial dual switched reluctance motor. A unified model is established for the two switched reluctance motors, and the reference torque is obtained by using a proportional integral controller after the reference speed is subtracted from the actual speed. A phase current prediction model is established based on the phase voltage equation of the switched reluctance motor. Based on the predicted current and predicted angle, a torque prediction model under positive voltage excitation and zero voltage freewheeling mode is established in the conduction interval of each phase winding. A torque prediction model under negative voltage demagnetization mode is established in the shutdown interval of each phase winding, and the predicted torque of each phase winding in the on and off intervals is obtained. A unified evaluation function is established using the predicted torque of each phase winding of the two switched reluctance motors and the reference torque, and the optimal switching state that minimizes the evaluation function is selected to achieve torque pulsation minimization control of the coaxial dual switched reluctance motor.

[0057] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should fall within the protection scope of the technical scheme of the present invention.

Claims

1. A method for minimizing torque ripple of a coaxial dual-switched reluctance motor, characterized in that: A unified model is established for the two switched reluctance motors. The reference torque is obtained by subtracting the reference speed from the actual speed through a proportional-integral controller. A phase current prediction model is established based on the phase voltage equation of the switched reluctance motor. A torque prediction model under positive voltage excitation and zero voltage freewheeling modes is established in the conduction interval of each phase winding based on the predicted current and predicted angle. A torque prediction model under negative voltage demagnetization mode is established in the shutdown interval of each phase winding to obtain the predicted torque of each phase winding in the on and off intervals. A unified evaluation function is established using the predicted torque of each phase winding of the two switched reluctance motors and the reference torque. The optimal switching state that minimizes the evaluation function is selected to achieve torque pulsation minimization control of the coaxial dual switched reluctance motor.

2. The method for minimizing torque ripple of a coaxial dual switched reluctance motor according to claim 1 comprises the following steps: Step 1: Design a proportional-integral controller to generate reference torque; Step 2: Design a torque prediction model to obtain the predicted torque of the dual switched reluctance motor; Step 3: Establish a unified evaluation function and simultaneously obtain the optimal switching states of the two switched reluctance motors to achieve torque ripple minimization control of the coaxial dual switched reluctance motors; The specific operations of step 1 are: The actual speed ω of the coaxial dual switched reluctance motor is input into the proportional integral controller, and the speed difference expression at the kth sampling moment is: Give(k)=ω ref (k)-ω(k) (1) Where Δω(k) is the speed difference at time k; ω ref (k) is the reference speed of the motor at time k; ω(k) is the actual speed of the motor at time k; The reference torque expression of the coaxial dual switched reluctance motor is: In the formula, K P is the proportional gain; K I is the integral gain; j is the serial number of the sampling time; T s is the sampling period; T ref is the reference torque; The specific operations of step 2 are: The phase voltage balance equation of the coaxial dual switched reluctance motor is: Where U is the phase voltage of the switched reluctance motor, i is the phase current, R is the resistance of the phase winding, ψ is the flux linkage of the phase winding, and θ is the rotor position angle; Formula (3) can be expressed as: Discretize equation (4) to obtain the expression of the predicted value of the phase current at the next moment: Where U(k) is the actual value of the phase voltage at time k, i(k) is the actual value of the phase current at time k, ψ(k) is the actual value of the phase winding flux at time k, θ(k) is the actual value of the rotor position angle at time k, and i(k+1) is the predicted value of the phase current at time (k+1); The expression of the predicted value of the rotor position angle of each phase winding of the coaxial dual switched reluctance motor at the next moment is: θ(k+1)=θ(k)+ω(k)T s (6) Where θ(k+1) is the predicted value of the rotor position angle at time (k+1); Based on the predicted current and predicted angle, a torque prediction model is established in the positive voltage excitation and zero voltage freewheeling modes in the conduction interval of each phase winding, and a torque prediction model is established in the negative voltage demagnetization mode in the shutdown interval of each phase winding; the predicted current and predicted angle of each phase winding of the first switched reluctance motor are substituted into the T(i,θ) table to obtain the predicted torque of each phase winding of the first switched reluctance motor in the conduction and shutdown intervals at time (k+1); the predicted current and predicted angle of each phase winding of another switched reluctance motor are substituted into the T(i,θ) table to obtain the predicted torque of each phase winding of another switched reluctance motor in the conduction and shutdown intervals at time (k+1); The specific operations of step 3 are: A unified evaluation function is established for the predicted torque of each phase winding of the two switched reluctance motors: J=[T ref -(T a1 (k+1)+T b1 (k+1)+T c1 (k+1)+T a2 (k+1)+T b2 (k+1)+T c2 (k+1))] 2 (7) Where, T a1 (k+1), T b1 (k+1), T c1 (k+1) are the predicted torques of each phase winding of the first motor at time (k+1); T a2 (k+1), T b2 (k+1), T c2 (k+1) is the predicted torque of each phase winding of the other motor at time (k+1); the predicted torque of each phase winding of the two switched reluctance motors is substituted into the evaluation function at the same time, and the voltage vector that minimizes the evaluation function is selected to obtain a unified switching state table to realize the torque pulsation minimization control of the coaxial dual switched reluctance motor.

Images