Research On Axial Flux Hybrid Excitation ISG Motor For Hybrid Electric Vehicle

Hybrid electric vehicles reduce fuel consumption and exhaust emissions on the basis of ensuring power performance compared with traditional fuel vehicles.Compared with pure electric vehicles,it avoids battery life limitation and long charging time.It is one of the effective ways to solve the current environmental pollution and energy depletion.Hybrid excitation axial flux motor retains the advantages of traditional electric excitation motors and axial permanent magnet motors.It has a wider speed adjustment range,which is in line with the integrated starter generator(ISG)in hybrid vehicles requirements.The internal magnetic flux density of the hybrid excitation axial flux motor is too large,resulting in excessive iron loss at high speed.Soft Magnetic Composite(SMC)can be used to make the stator iron loss lower at high frequency and high speed.However,the relative permeability of the SMC material is lower than that of the traditional silicon steel sheet,which impacts the torque property and output ability of the motor.How to get the utmost out of the superiorities of SMC materials,optimize the construction of the machine,and make the hybrid excitation axial flux ISG motor obtain better torque performance,wide speed region and large efficiency has high implication significance.Firstly,the structure of the designed hybrid excitation axial flux ISG motor is selected,and its operating principle is introduced.The working conditions of the ISG machine with disparate transport states of the automobile are studied.On the basis of the design demands of the ISG machine,the principal dimensions of the machine are acquired by means of analytical calculations.Based on the obtained structural parameters,a model is established to determine the important parameters and structures such as the rotor magnetic circuit,stator winding,pole slot coordination,the ply of PM and the specific value of PM to iron pole.Secondly,the magnetic modulation performance of the hybrid-excitation axial flux ISG motor is analyzed.The motor structure is optimize to increase the magnetization range,electromagnetic torque output capacity and reduce the back-EMF harmonics,torque ripple and coupling capacitance.And finite element method is employed to simulate and contrast the property of the machine before and after optimization.Thirdly,through the finite element software,the no-load performance,load performance,and field weakening performance of the optimized ISG motor are simulated and analyzed.When saturation is not considered,the speed regulation range of eight times the rated speed can be obtained.Compared the working status of the ISG motor corresponding to different vehicle operating conditions,the performance of the ISG motor with different conditions is analyzed.And contrasted with the traditional radial machine and the axial machine with the identical property parameters.Finally,under different operating conditions,the temperature rise when reaching the steady state and the force when the rotor exerts force in different directions are simulated and analyzed in multiphysics.It ensures that motor works within a safe temperature range,and provide guidance for the design of the rotor structure.