Analysis of an interior permanent magnet synchronous motor with MEMS based rotor flux sensing

Interior permanent magnet (IPM) synchronous motors have advantages such as high torque and power density over a wide speed range when compared to conventional permanent magnet, synchronous reluctance and induction machine technologies. However, the introduction of IPM machines into industrial and commercial products has been limited due to the complexity of controlling the nonlinear reluctance torque. This paper presents an analysis of the use of micro-electromechanical sensors (MEMS) to detect magnetic flux levels in the rotor of an interior permanent magnet synchronous motor. It is found that a small network of rotor flux sensors yields an estimate of the instantaneous torque. This provides a method for controlling the net electrical torque of the IPM machine thereby overcoming a significant obstacle in the industrial and commercial adoption of IPM motor technology.