Simple initial rotor position estimation method for three-phase star-connected switched reluctance machine

This paper proposes a simple method to estimate the initial rotor position of a three-phase star-connected switched reluctance motor at standstill without position or current sensor. The key principle of the initial rotor position estimation is based on the stator inductance variation related to the actual rotor position. In the proposed method, only two narrow pulse voltage injections are applied in sequence and the initial rotor position can be estimated by comparing phase voltages and simple calculation. The method is suitable for low-cost applications where motor parameters and phase current data are not required. The proposed method is implemented for a 6-stator-pole, 4-rotor-pole, and 1.5 kW three-phase star-connected switched reluctance motor. The experimental results show the effectiveness of the proposed method. The accuracy of the initial rotor position estimation is within 2.5 electrical degrees, which is sufficient to start-up the switched reluctance motor without rotor back-kicking.