Speed control scheme of the high speed 4/2 switched reluctance motor

This paper presents the balanced soft-chopping and modified PI controller for high speed 4/2 SRM using 16 pulses per revolution encoder. To reduce the current ripple, it used balanced soft-chopping circuit which can supply the twice times switching frequency in fixed switching frequency of power devices. To overcome the over-shoot current which is occurred by time delay of current sensing, modified PI controller has three modes, such as maximum voltage, back-emf voltage and PI control mode. Maximum voltage mode can supply the fast excitation current, back-emf voltage mode can suppress the over-shoot current, and PI control mode can adjust the phase current to desired value in fast switching frequency by proposed balanced soft-chopping technology. The proposed balanced soft-chopping is verified in air-blower system at 30,000[rpm] by computer simulation and experiments.