Optimal Design Of External Rotor Switched Reluctance Motor For Electric Bicycle

With the promulgation and implementation of the new national standard for electric bicycle,the development of the industry is increasingly standardized and improved.New bicycles need to be more green,energy-saving,safe and reliable to meet people’s riding requirements.As the core part of the electric bicycle,the motor drive system will directly affect the driving performance of the whole vehicle and the rider’s comfort experience,so it is more and more important to choose the motor with good performance.Switched reluctance motor(SRM)has the characteristics of low cost,high fault tolerance and high starting torque.The outer rotor SRM can be directly used as hub drive motor.However,SRM has large torque ripple due to its double salient structure.In order to better apply in the field of electric bicycle,improving the motor torque output performance becomes an urgent problem.In this paper,the working principle of external rotor SRM is introduced,the quasi-linear mathematical model is derived,and the analytical formula of inductance theory is obtained;The flux density distribution,flux linkage characteristics and torque characteristics of traditional 6/8 pole external rotor SRM are analyzed by finite element simulation.Secondly,the structural design of the new 6/16 outer rotor SRM is described.The topological structure and electromagnetic characteristics of the new motor are analyzed in detail.The results show that the new motor has higher instantaneous output torque and larger flux change rate.The initial structure parameters are established by referring to the parameters of traditional 6/8 pole prototype,the design of rotor pole number and pole arc angle,and the design of slot depth.In addition,Simplorer and Maxwell co-simulation are used to set the same control parameters to reduce the experimental error;This paper discusses the influence on the output performance of the motor from three aspects: turn on and turn off angle analysis,mutual inductance analysis and single variable parameter sensitivity analysis,and gives the simulation results.Thirdly,the structural parameters of the new motor are optimized.Through the co-simulation of design expert and ANSYS Maxwell,the regression model is established,and the effectiveness of the model is analyzed to determine the response surface equation.Considering the complexity of the structural parameters of outer rotor SRM,the improved multi-objective fish swarm algorithm is used to optimize the established model.Through error analysis,comparison of results before and after optimization and actual design requirements,the optimal combination solution is selected.The ANSYS Maxwell electromagnetic field simulation results show that the optimized SRM has lower torque ripple and higher output torque.Finally,the direct instantaneous torque control method is used to control the speed of the motor to optimize the torque output performance of the motor.