Analysis of MEMS based rotor flux sensing in a hybrid reluctance permanent magnet motor

Hybrid reluctance permanent magnet (HRPM) motors have potential advantages for electric vehicle propulsion. However, their introduction into practical applications has been limited due to the complexity of controlling the nonlinear reluctance torque. This paper presents the results of an investigation into the use of micro-electromechanical sensors (MEMS) to detect magnetic flux levels in the rotor of a hybrid reluctance permanent magnet motor. It is found that a small network of rotor flux sensors provides an accurate estimate of the instantaneous reluctance effect torque in the machine. This provides a method for controlling the torque of the HRPM machine by separating the linear permanent magnet portion from the nonlinear reluctance torque component, thereby overcoming a significant obstacle in the commercial adoption of HRPM technology.