Outer rotor high torque density PM motors with a peripheral position sensor

Abstract

A survey of mainly outer rotor permanent magnet (PM) motors, suitable for a patented sensor technology sensing the leakage field from the permanent magnets, is performed with a specified target of high torque density. One motor, known to yield high torque density is used as a reference motor; an electric bike transverse flux motor. Its simulated and measured results are compared with other PM motors such as the axial flux motor, the Vernier motor and flux switching motors. Academic, simulated designs as well as industry developed and manufactured designs are considered. It is found that the reference motor is coming out as a good choice for motors with similar weight and size. Those outer rotor motors that have higher torque density than the reference motor are larger than the reference motor and/or need liquid cooling.