A Novel Universal Sensor Concept for Survivable PMSM Drives

Permanent-magnet synchronous machines (PMSMs) are widely used as propulsion motors in hybrid electric, plug-in hybrid, and electric vehicles and as generators in renewable energy applications. Since position and current information is typically indispensable for PMSM control strategies such as vector control or direct torque control, failure of an encoder/resolver or current sensors could lead to a catastrophic failure, if no protection or backup plan is established. This paper lays groundwork for developing a novel backup universal sensor concept for PMSM with position and current estimation. Estimated position and current could be used for sensor fault detection or survivable drive, giving its drive system a "+1" fault tolerance. This technique uses search coils, which are implemented to directly monitor magnetic flux through stator teeth. Adaptive position estimator and a current estimator have been designed based on the search coil model, which overcomes the issue of resistance variation that exists in many estimators reported in literature. Simulation and experimental verification are presented to verify feasibility of the proposed strategy.