Study On Design And Operating Characteristics Of Permanent Magnet Synchronous Motor Applied In Electric Vehicle

Being a kind of clean energy vehicle,electric vehicle could achieve high energy utilization,low noise and zero waste emissions.It has become the main direction of the development of new energy vehicles all over the world.Permanent magnet synchronous motor(PMSM)has been widely concerned by the motor industry due to its advantages of simple structure,high efficiency,high power density and excellent performance in speed measuring.It also has a lot of applications in the field of electric vehicles.In this thesis,design analysis and studies on operating characteristics of PMSM by field-circuit coupled method are carried out,which is based on finite element analysis method.Influences on the performance of the motor caused by variation of magnetic circuit structure and electromagnetic parameters is also analyzed.This thesis designs a high efficiency,high power density and high overload multiple permanent magnet synchronous motor for electric vehicle,and gives a summary of design method which is suitable for driving PMSM of electric vehicle to lay the foundation for the later development of series products.The main research work of this thesis is as follows:According to the key technology of electric vehicle's development,special working conditions and dynamic driving requirements,this thesis makes comparison of driving performance between different types of motors and chooses interior PMSM as the research object.Besides,the design requirements and mission objectives of the drive motor are also obtained by analyzing its structure characteristics and working principle,which makes the design highlight the characteristics of the electric vehicle driving motor.Based on the finite element software Ansys/Maxwell 2D,the design scheme of the motor,including the main dimensions of the motor,the inner and outer diameter of the stator,the width of the air gap,the parameters of the winding and the size of the permanent magnet,etc.are determined by using field-circuit coupled method and auxiliary electromagnetic optimization design method with Matlab software according to the theory of motor and related theory of electromagnetic fields.The finite element model of 2D Maxwell is also established,its finite element analysis is carried out through the former design scheme.By using the 2D magnetostatic and transient field solver,the motor's no-load,load and overload conditions is simulated.Distribution of the magnetic field,air gap magnetic density and cogging torque are analyzed and the key parameters,including no-load back-EMF,d-q axis inductance,effective pole-arc coefficient and no-load leakage flux coefficient are also calculated.Meantime,this thesis gives studies on effects to the electromagnetic parameters such as d-q axis inductance and no-load leakage flux coefficient,ectc.,which were caused by motor structure variation.The principle and performance of flux-weakening is discussed from motor ontology structure and control performance,the output characteristic curve and the efficiency MAP are obtained through simulation.The thesis also made a comparison between finite element analysis results and test performance of the prototype motor,which verified the rationality of the design method of the prototype motor.Finally,a prototype motor of rated power 60kW and rated speed 1600rpm is made according to the design result and experiments test of the motor performance are carried out.The test results indicate that the prototype motor has a large load factor and wide operation area of high efficiency,which could approximately achieve the expected design target.