Electromagnetic Performance And Temperature Analysis Of Outer-Rotor Flux-Switching Permanent Magnet Motor

Recently,with the energy crisis and environmental pollution issues getting more serious,the global governments and auto manufacturers are working hard to promote the new energy automobile for better energy conservation and environmental protection.In-wheel motors with high spatial integration,flexible control,fast response,direct drive,and other advantages have a great potential application in the field of motor drives.The outer rotor flux-switching permanent magnet(OR-FSPM)motor which features the high output torque,high efficiency and high power density has been utilized in the in-wheel driven.It has a simple rotor structure and can satisfy the requirements of the direct drive application.However,the heat emission condition of the motor is unsatisfactory due to the distinctive structure,space and work environment.This leads to high motor temperature rise.The high temperature rise not only affects the safety and reliability of the motor operation,but also directly causes the variety of the material performances and the decline of the motor output characteristics.Furthermore,it may result in motor damage.Thus,the comprehensive analysis under the actual application circumstances of the motor thermal performances has an important theoretical and practical significance.In this paper,the OR-FSPM motor is investigated.The basic electromagnetic performances,temperature field distribution and the influences of the temperature rise on the motor electromagnetic performances are analyzed.The main points are listed as the follow.Firstly,the 2D finite element model of the OR-FSPM is built.The electromagnetic performances including air-gap magnetic flux density,back-EMF,inductance,torque,and losses of the motor are discussed.This lays the foundation for the electrical-thermal bi-directional analysis of the OR-FSPM motor.Secondly,the finite element thermal model is established based on the topology and electromagnetic performances of the OR-FSPM motor.The thermal parameters of the OR-FSPM motor such as coefficients of heat conduction and convection are determined based on the principle of heat transfer.The thermal analysis of the OR-FSPM motor is conducted under the different load.Moreover,In view of the variety of the material characteristics in the different temperature,the electromagnetic-thermal bi-directional coupling method was employed to study the relationship between the output characteristics of the OR-FSPM motor and the temperature.Furthermore,the analytical thermal model of the OR-FSPM motor is established based on the equivalent thermal network method.The thermal parameters of the equivalent thermal model such as heat convection coefficient,thermal resistance and thermal capacitance are deduced.The temperature of each node in the thermal network is calculated by importing the loss obtained by the FEA analysis.Considering the complex and variable driving conditions in the motor actual driving,the NEDC(New European Driving Cycle)is introduced as the typical driving cycle to investigate the temperature rise of the OR-FSPM motor.Finally,the prototype is manufactured and the experiment platform is built.The experiments are conducted and the results verify the reliability of the motor structure.