Research On Low Speed And High Torque Transmission System Based On Cycloidal Magnetic Gear And Permanent Magnet Motor

Asynchronous AC motor and mechanical gear is the mainstream mode of existing electromechanical transmission.Its shortcomings mainly include the following two aspects:? Asynchronous notor has low torque density(generally only 30 kN·m/m3),resulting in its operating efficiency and power factor.Both are low;?the mechanical gear has a higher torque density(the general parallel shaft single-tooth transmission mechanical gear can be as high as 200 kN·m/m3 or more),but for direct contact transmission,there are broken teeth,pitting,gluing and problems such as wear and tear,and high maintenance costs,the resulting noise and oil leakage also seriously pollute the environment.In order to solve the above problems,this paper proposes a transmission mode combining the cycloidal permanent magnet gear and the permanent magnet synchronous motor;the designed cycloid magnetic gear(CMG)has a torque density of up to 225 kN·m/m3),basically comparable to mechanical gears;while permanent magnet motors are known for their high torque density,high operating efficiency and high power factor,so combining them with CMG can effectively solve the above-mentioned asynchronous motor and mechanical gear Two drive defects.This paper firstly summarizes the development status of permanent magnet gears and permanent magnet motors at home and abroad,analyzes and expounds the transmission mode,operating mechanism and torque density of various permanent magnet gears.Based on CMG's high torque density and transmission,the mechanical structure of CMG and permanent magnet motor is designed.Based on the CMG operating mechanism,the CMG magnetic field model and torque model of the eccentric air gap are established.According to the design requirements and mechanical structure,the CMG structural parameters are preliminarily determined,and the required inner and outer permanent magnet sizes and magnetic poles are determined.The two-dimensional finite element simulation model corresponding to the above parameters is established and static simulation analysis is carried out to verify the correctness of the model.The geometric parameters of inner and outer permanent magnet rings and the thickness of permanent magnet are optimized by using the method of double control variables,which further improves the torque density of CMG.Because the inner permanent magnet coil of CMG is a compound movement mode of translation and rotation.This paper transforms its equivalent and establishes a dynamic simulation model to verify its high transmission ratio and high torque characteristics.The eddy current loss mechanism indicates that the main reason for the high efficiency of CMG transmission is that its eddy current loss is particularly low.Based on the theory of permanent magnet motor and the requirements of low speed and high torque,the main dimensions of the corresponding permanent magnet motor are given,and the key parameters of the electromechanical structure including stator size,slot structure,winding form and Permanent magnet size are given.The analysis and calculation are carried out,and the determined parameters are imported into RMxprt to verify the rationality of the motor design parameters.The two-dimensional finite element simulation model of the above permanent magnet motor is established in the Maxwell environment.The no-load and load characteristics are analyzed,and the stator notch and rotor parameters are optimized to reduce the influence of cogging torque on the motor.At the rated load,the main loss of the designed permanent magnet motor is concentrated on the stator,and the rotor is low,so it has the advantages of high transmission efficiency and high power factor.Combined with the designed CMG,it can better form a low speed and high torque transmission system to achieve the set technical requirements.