Control method for torque pulse of segmented harmonic current suppression switched reluctance machine

Abstract

The invention discloses a control method for torque pulse of a segmented harmonic current suppression switched reluctance machine. According to the method, real-time torque difference of a motor torque is calculated on the basis of a set average torque, the torque difference is converted to current difference according to a torque-current relation, and a non-linear current compensation value of each phase is solved out. A harmonic current which is injected according to segments is superposed to a rectangular reference current, the harmonic injection size and the harmonic current coefficient of a corresponding segment are determined, so that the form of a current waveform of a zone is more accurately controlled; and under current chopping control, the torque output of the motor is further changed, and the problem of motor torque pulse caused by phase current fluctuation in a commutation period during running of the switched reluctance machine is improved. The purpose of suppressing the torque pulse can be achieved under the current chopping control, and the algorithm has wide universality and transportability.

Description

technical field [0001] The invention relates to the control field of electric motors of large and medium-sized electric vehicles, in particular to a control method for suppressing torque ripple of switched reluctance motors by segmented harmonic currents. Background technique [0002] The switched reluctance motor (Switched Reluctance Motor, SRM) has a large starting torque, a good speed range, frequent forward and reverse starts, flexible control, high efficiency, and mechanical characteristics that can meet the requirements of different loads. It has gradually become the field of modern drive speed regulation. one of the hotspots. However, due to the double salient pole structure, highly nonlinear electromagnetic characteristics and switching power supply characteristics of the switched reluctance motor, the motor has large torque ripple and noise during operation. Due to the strong nonlinearity of the electromagnetic characteristics of the switched reluctance motor, a ma...

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Problems solved by technology

[0006] 1. The current chopper control strategy also has the following outstanding problems: During the one-phase conduction period of the motor, the effective value of the current is limited to a unique amplitude

According to the running process of the motor, it can be seen that the inductance change rate is small in the inductance rising start area and the rising end area, and it is in these two intervals that the current is also in the process of rising and falling, so when the motor turns to the commutation position, the current one When the falling rate of the open-phase current is not equal to the rising rate of the next open-phase current, the combined current in the commutation period will produce relative pulsations, which will cause the output instantaneous torque value of a phase winding to change during the start of conduction and the freewheeling period, resulting in the combined current Severe torque ripple appears in the output torque waveform

[0007] 2. The optimal harmonic current injection control strategy is still difficult to obtain the ideal current waveform shape that fully conforms to theoretical calculations in practical applications, and there are still problems of torque over-compensation and under-compensation, resulting in the suppression effect of motor torque ripple and theory. The analysis is different, so the optimization effect of torque ripple cannot be optimal

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