Pm Hub Motor Design For Electric Two-wheelers Based On Measured Driving Cycles

Electric two wheeled vehicle,as an economical means to solve the problem of green commuting,has a broad market prospect.The efficiency and cost of its driving motor are two key performance indicators.In the actual operation process of electric two wheeled vehicle,the starting and stopping are frequent and the load rate changes greatly,so it does not always work near the rated working point.If we can optimize the design according to the operation conditions,it is of great significance to improve the total efficiency and reduce energy consumption.Axial flux permanent magnet synchronous motor is easy to be integrated into the hub,and has high efficiency and torque density,so it is suitable for electric two wheeled vehicle drive motor.In this thesis,the axial flux permanent magnet synchronous motor for electric two wheeled vehicle driving based on working conditions is taken as the object(1)Taking the axial flux permanent magnet motor with common structure as the research object,the advantages and disadvantages of various topologies are analyzed and compared,and then the double rotor single stator ns topology suitable for the application of electric two wheeled vehicle is selected.In order to solve the problems of slow 3D electromagnetic calculation and inaccurate 2D calculation of axial flux permanent magnet motor,the multi section method is proposed for equivalent calculation.The number of different sections is compared,and the appropriate number of sections is selected considering the calculation accuracy and time.On this basis,the parametric automatic modeling and calculation software is developed;(2)The urban commuting operation data of electric two wheeled vehicle is collected,and the operation condition is established based on the vehicle dynamics model.Based on the clustering analysis of the motor working points,the representative working points are extracted,and the motor design index based on the working conditions and the total efficiency calculation method based on the representative working points are proposed.The preliminary design scheme of the motor is put forward from the aspects of motor structure,pole slot matching and winding parameters;(3)Considering the influence of nonlinear factors such as magnetic circuit saturation and cross coupling,as well as nonlinear control strategies such as MTPA and flux weakening,the models of flux linkage,torque and iron loss are established by combining finite element simulation and mathematical fitting.The efficiency map of the motor is quickly calculated by look-up table method,and the total efficiency of the whole operation condition is quickly calculated by mapping with the operation condition;(4)Taking the total efficiency and effective material cost of the motor as the optimization objectives,and the motor structure parameters as the optimization variables,the motor optimization design is carried out.In order to reduce the number of optimization variables,Taguchi method was used to analyze the parameter sensitivity,and NSGA-II method was used to optimize the parameters with high parameter sensitivity.The three-dimensional finite element calculation is carried out for the selected optimization scheme to verify the feasibility of the optimization algorithm and the calculation method of total operating efficiency under all working conditions;According to the optimization scheme,a prototype of stator yoke free and modular axial flux permanent magnet motor was processed,which solved the problems of stator core manufacturing and pouring molding.The experimental platform is built,and the no-load and on-load capacity of the prototype are tested.The measured results of back EMF,output torque and efficiency map are in line with the expected simulation results.