Design And Research Of Low-speed High-torque Permanent Magnet Synchronous Motor With Outer Rotor

In recent years,with the rapid development of high-performance rare earth permanent magnet motors,permanent magnet motors have been widely used in various fields.The low-speed,high-torque permanent magnet motor eliminates the deceleration device and provides a possibility for the motor to drive at a low speed.Because the permanent magnet motor has the advantages of high efficiency,high reliability,low noise,easy to realize multi-pole,reliable operation at low speed,and large output torque,it has become a research hotspot in the field of electric motors and has high use value.This article is based on the design requirements of surface-mounted low-speed large-torque permanent magnet synchronous motors(PMSM),an external rotor low-speed and high-torque PMSM is designed.The design characteristics of the stator and rotor of the motor are introduced in detail,including stator slot shape,stator winding,rotor magnetic circuit structure and permanent magnet shape.Based on this,the electromagnetic design of the motor was carried out by means of the combination of field and road.Finally,an outer rotor surface-mounted low-speed high-torque PMSM with rated power of 20 k W,rated torque of 3183 Nm and rated speed of 60 rpm was determined.Using the motor-related parameters determined by the motor design,the motor is modeled in two dimensions and three dimensions,and the motor is simulated by finite element software to calculate the magnetic field distribution at a certain moment under the no-load and load operation of the motor.Air gap magnetic density,motor no-load cogging torque,electromagnetic torque of the motor,and electromagnetic force density in space and time.The electromagnetic force under time-varying is loaded as a load on the stator tooth of the three-dimensional finite element model,and the transient dynamics simulation of the motor is performed to calculate the vibration displacement curve under time-varying.Using the results of the above simulations,it is concluded that the rationality of the motor design is verified.According to the electromagnetic force density distribution law and vibration magnitude of the motor,this paper proposes a vibration reduction design of the permanent magnet segment structure,and calculates and compares the cogging torque amplitude and motor output torque average before and after motor optimization.And torque fluctuations,as well as the magnitude of the electromagnetic force received by the teeth of the motor and its spectral analysis.The optimized electromagnetic force is used as the load condition,and then loaded into the stator tooth portion to calculate the vibration displacement of the motor.The reliability of the vibration damping structure proposed in this paper is verified by comparing the vibration displacement before and after optimization.