Four-Quadrant Control of 4/2 Switched Reluctance Machines

The main challenge in designing a four-quadrant (4Q) speed control algorithm for a 4/2 switched reluctance machine (SRM) lies in the existence of “dead” torque zones where the machine's capability to produce torque is considerably reduced. This makes its startup challenging and has so far hindered its 4Q control. This paper provides a solution for the 4/2 SRM startup problem and uses it to enable its 4Q operation. The proposed control algorithm respects the varying average torque bounds and explicitly enforces the maximum phase current limit. A parametric, open-loop, average torque control scheme is derived and employed to ensure efficient production of torque required to track the desired speed reference. The effectiveness of the proposed solution is verified experimentally on a high-speed hardware setup.