Harmonic control of chopping frequency and shaft speed in SRM

This paper focus on the harmony control of chopping frequency at low speed range in which SRM operates with voltage-PWM mode in time and frequency domains. The simulation results indicate that the total distribution of spectrum of phase current on nth harmony frequencies keeps the same shape when the ratio of chopping frequency to shaft speed is constant. Thus chopping frequency and shaft speed can be harmony controlled by applying a proper chopping frequency-speed ratio. The phase current fluctuation is decreased with the increase in chopping frequency at a constant shaft speed. The torque output capacity tends to be decreased with increase in the chopping frequency. The decreasing rate with respect to chopping frequency in the low chopping frequency range is larger than that in the high chopping frequency range. The torque output capacity of SRM tends to be constant when the chopping frequency is high enough. In practice, the chopping frequency applied that is close to the natural frequency of the stator should be avoided.