Low-Cost Realization of Feature Position Estimation Scheme for Switched Reluctance Motor

This letter proposes a low-cost feature position estimation scheme for singly excited SRM without using lookup tables. This scheme uses the particular flux linkage versus current curve, corresponding to the commutation angle, to generate a flux-linkage reference. Phase commutation is executed at the instant when the online estimated flux linkage reaches this reference threshold. So, this letter, initially, proposes a novel analytical method to compute the reference flux linkage from phase currents. Then, a new approach is presented that maps the individual measured phase currents and estimated flux linkages into corresponding unified signals to reduce the computational burden. Thereafter, the mutual coupling among phases is shown as a cause of serious error in the thresholding operation, and a design criterion to avoid this error is derived. Performance of the proposed sensorless scheme is experimentally validated on a 1 kW, 3000 r/min, 6/4 SRM-based laboratory prototype.