Self-sensing control of a four phase switched reluctance drive using high frequency signal injection including saturation effects

This paper presents a novel position and velocity estimation technique in four-phase switched reluctance drives based on high frequency signal injection methods. To estimate rotor position and velocity, an identical high frequency carrier voltage signal is superimposed on the main phase voltages and injected into the machine. As a result, the phase currents are composed of both main excitation currents for torque production and high frequency currents for rotor position estimation. An appropriate signal processing technique is shown to extract the spatial saliency of the machine, which is used to obtain robust position estimation via a saliency-tracing observer. The impact of saturation on machine saliencies is analyzed. Modified signal injection is developed to improve the position estimation performance in saturation. Simulation and experimental results are presented to evaluate the effectiveness of the proposed method for continuous rotor position estimation over a range of low speeds and load torques.