Research on reducing reluctance torque of permanent magnet toroidal motor

The permanent magnet toroidal motor (PMTM) is a special motor that combines a permanent magnet motor with a deceleration mechanism. Because of the special structure of the PMTM, its reluctance torque includes cogging torque and end torque. In order to reduce the reluctance torque ripple of the PMTM and improve its output stability, the cogging torque and end torque of the motor are optimized, respectively. The structure of eccentric permanent magnet teeth improves the sine of the air gap magnetic induction of the motor, thereby effectively reducing the fluctuation of the cogging torque. It is proposed to add compensation windings at both ends of the central worm stator to reduce the fluctuation of the end torque. The dynamic compensation effect and the change in air gap magnetic induction intensity with the current applied to the compensation windings are analyzed by finite element simulation. The relationship between the compensation current and the structure parameters of the motor is derived. Finally, it is verified that the output torque ripple can be effectively reduced by adding the magnetic isolation material between the compensation winding and the three-phase winding. The research results show that the reluctance torque fluctuation can be greatly reduced by using eccentric permanent magnet teeth and compensation windings. It provides an important reference basis for the optimization design of the electromagnetic structure of the PMTM.