Design And Optimization Of Hybrid Permanent Magnet Assisted Synchronous Reluctance Motor For Electric Vehicles

At present,permanent magnet synchronous motors are mostly used in electric vehicles.The price of rare earth materials are costly.Therefore,it leads to an increase in the cost of electric vehicle drive motors.In recent years,ferrite has received attention from some scholars due to its cost advantage.However,ferrite material is easy to demagnetize and has poor torque output capability.In order to solve the problem,Nd Fe B and ferrite hybrid is proposed.It is used in a hybrid permanent magnet assisted synchronous reluctance motor.Furthermore,the torque pulsation of hybrid permanent magnet assisted synchronous reluctance motor is high.The mixing degree of Nd Fe B and ferrite and the reasonable position of magnets,the lower pulsation of torque are important issue to solve.Firstly,the matching design is carried out for the parameters related to the 70 kW electric vehicle drive motor.A "U+V+I" rotor structure is designed and three different magnet mixing schemes are proposed.The static and transient electromagnetic performance of these three schemes are compared.The ferrite demagnetization under peak torque conditions of the three schemes is simulated.The optimal scheme is picked.The temperature rise simulation is simulated for the NEDC condition and US06 condition of the optimal solution.The limit temperature rise is established for the two different conditions under water-cooled condition.The demagnetization is simulated for the peak torque and speed conditions at this temperature rise.To ensure the safety of rotor operation,a round-bottom convex slot is added to the d-axis of the rotor.And it reduces the peak stress.The rotor topology of the optimal solution is optimized in a focused manner.Then the optimized solution is compared with the Nd Fe B motor.Secondly,various methods are proposed to reduce the torque pulsation of the hybrid permanent magnet assisted synchronous reluctance motor.The orientation of the stator-rotor topology for the composition of the torque pulsation is changed.Then,simulation is performed for the reduction of torque pulsation when each scheme is used alone.The radial magnetic density,reluctance torque,and cogging torque of the stator and rotor are analyzed.They determine the ability of each scheme to reduce torque pulsation.Finally,multiple optimization schemes are applied to the same stator and rotor to determine the range of optimization parameters.Furthermore,the target values for the multi-objective optimization of torque,and the response surface of average torque and torque pulsation is established using the optiSlang module in Workbench.Based on the response surface,genetic algorithm and particle swarm optimization are used to optimize the torque.Then,the optimal solution of the two optimization algorithms is selected to compare with the optimal solution of the response surface.The electromagnetic and weakening magnetic related performance of the solutions is simulated.In the end,the best solution is ensured.