Four-Quadrant Position Sensorless Operation of Switched Reluctance Machine for Electric Vehicles Over a Wide Speed Range

This article focuses on developing a four-quadrant position sensorless technique for switched reluctance machine (SRM) to meet the operating requirements of electric vehicles (EVs). The technique combines two different sensorless schemes and is implemented by the sensorless rules based on the rotor position partition. At startup and low speeds, the zones are identified based on the comparison of unsaturated inductances obtained by pulse current slope difference method, and the segmented Fourier series inductance model or the segmented linear inductance model is selected for position estimation according to the identified zones. At medium to high speeds, the zones are identified based on the comparison of flux linkage generated by excitation current and auxiliary chopping current. Only the segmented linear flux-linkage model is used for position estimation to reduce the computational burden of the processor. The transition methods are also presented to achieve seamless combination between the two sensorless schemes and the smooth transition from motoring to braking. This technique can deliver high-resolution rotor positions in full cycle and is implemented fast and easily. The experimental results on a 1.2-kW 12/8-pole SRM prototype verify the feasibility and correctness of the proposed sensorless control technique.