Switched reluctance motor: a reduced torque ripple drive

SRM main features are good robustness and high specific torque and power; however, its simple structure is intrinsically characterized by a highly non-uniform torque. The above characteristics are very important for medium power, high reliability applications, but in robotics a high torque ripple is not admissible, especially in direct coupled actuators and/or in position controls. In this paper the approach of adopting a control of the phase current shape, while keeping the original simple magnetic structure, is presented. The solution shows the capability to keep torque non-uniformity under a few percent, thus achieving remarkable improvements in machine controllability at low speed, down to standstill. The experimental test of an accurate position control is reported