Design Of Permanent Magnet In-wheel Motor Of Electric Vehicles And Research On The Cogging Torque

China is a country with a large population.The gradual improvement of the people’s economic level has increased the demand for cars,but limited resources have become a major obstacle to the development of fuel vehicles.Secondly,the problem of environmental pollution has become increasingly serious.Therefore,promoting the development of electric vehicles is one of the effective methods to solve the problems.Drive motor is an important part of electric vehicles,while compared with traditional drive motor,in-wheel motor is driven by direct drive,which has many advantages,such as higher transmission efficiency and lower vehicle quality.However,the existence of cogging torque may affect the control accuracy of the motor,which causing vibration and noise problems,and reducing comfort of the car.Therefore,the cogging torque is an important consideration when designing an in-wheel motor.According to the requirements of electric vehicle driving motors,the cogging torque,electromagnetic design,no-load and load performance of the permanent magnet in-wheel motor are studied in this paper,and the work mainly includes the following aspects:Firstly,by analyzing an interior v-shaped permanent magnet in-wheel motor,the influence of the pole arc coefficient of permanent magnet and opening auxiliary slots in the stator is studied.As the same time,based on the idea of using asymmetrical magnetic poles to offset part of the cogging torque harmonics,the method of changing the single magnetic pole width and angle,while other magnetic poles unchanged to weaken the cogging torque of the permanent magnet in-wheel motor is studied.Through the research of a variety of cogging torque suppression measures,the influence of the pole arc coefficient,the number of auxiliary slots,and the single magnetic width and angle on the cogging torque is summarized,which is used to guide the design of the permanent magnet in-wheel motor.Secondly,the electromagnetic design of the permanent magnet in-wheel motor is made.The effects of different magnetic circuit structures on the motor torque performance,the cogging torque and the field weakening expansion capability are compared.The main dimensions and windings of the motor are designed,and the performances of air gap flux density and the cogging torque with different pole-slots are compared.The air gap flux density,no-load and load performance of the designed permanent magnet in-wheel motor are simulated and analyzed.At the same time,according to the characteristics of the designed motor,the method of changing the single pole is adopted to weaken the cogging torque of the motor.Finally,the performance of the permanent magnet in-wheel motor is analyzed.Through the finite element simulation method,the high-efficiency area,the field weakening expansion capability,the motor torque output capacity under different working conditions,the antidemagnetization ability of the permanent magnet and the rapid response capability of the in-wheel motor are analyzed.