Aligned Position Estimation Based Fault-Tolerant Sensorless Control Strategy for SRM Drives

A sensorless control strategy with one-phase lacking fault-tolerant capability is proposed in this paper for the switched reluctance motors (SRM). This strategy consists of a phase inductance slope zero-crossing detection scheme and a series of phase inductance partition logic algorithms, which is capable of capturing at least one-phase aligned position under both normal operation and one-phase lacking fault operation. With the recorded index position in each electric period, the rotor position can be estimated for sensorless driving accordingly. To ensure stable calculation of the phase inductance in this method, the SRM should be started and operated under single pulse control mode. Thus, for sensorless starting, an idle phase inductance double thresholds based sensorless synthetic starting scheme is also developed. The proposed strategy is easy for implementation and can ensure stable sensorless operation in full speed range. Moreover, it does not need any prior measuring process, complicated logic algorithm, or complex mathematical calculation. The theoretical analysis is conducted, and experimental results are provided to verify the feasibility of the proposed control strategy.