Peak PWM current control of switched reluctance and AC machines

Fast response and insensitivity to parameter variation are among the most desired characteristics for current regulators in electric drives. This paper presents a new switching strategy with current regulation for switched reluctance machines (SRM), and the same concept is extended to other inverter fed AC machines to achieve instantaneous torque response. The technique is based on detecting the peak current in each phase and regulating the current by turning off the phase when the phase current reaches the commanded current, and turning on the phase at the leading edge of the clock signal at a fixed frequency. This peak-PWM current regulation (PPWMCR) strategy offers instantaneous torque response, fixed switching frequency, robustness, stability, inherent protection, no tuning, and simple implementation. The paper discusses detailed PPWMCR implementation for SRM and AC machines. Experimental results are presented to compare PPWMCR with hysteresis (HCR), delta modulation (DCR), and proportional-integral-PWM (PI-PWMCR) current regulators for a four phase SRM.