Application of a voltage adaptive sensorless current controller to a multi-phase permanent-magnet synchronous machine

Multi-phase machines and sensorless controllers have the common goal to increase the reliability and robustness of the drive. Nevertheless, few sensorless drives have been developed for the purpose of multi-phase machines. This paper discusses the application of a recently developed sensorless current controller to a multi-phase permanent-magnet synchronous machine rotating at low speed. In this method, multi-phase voltage test signals are injected by modifying the pulse-width modulation. The modification results in a significant multi-phase current ripple from which amplitude the rotor position can be estimated. Simulation results of the machine in steady state and transient state show the effectiveness of the drive in controlling the multi-phase current in a sensorless way.