Research On Permanent Magnet Rotor And Dual Stator Starter Generator And Control Technology For Electric Vehicle Range Extender

The flywheel type double stator permanent magnet starting generator integrates the engine flywheel and the generator rotor,which not only reduces the mechanical transmission structure and transmission loss,but also makes full use of the limited space between the engine body and the flywheel.It is compact in structure,versatile in one machine,and has the advantages of high efficiency,high power density,flexible control mode,etc.It has broad application prospects in the field of starting generators for electric vehicles range extender.A new structure of a single rotor dual stator permanent magnet starting generator is proposed,which includes pole slot matching,air gap length,armature winding,stator slot structure,etc.Based on the technical indicators of the starter generator for the electric vehicle range extender,the main structural dimensions of the motor are calculated using the electromagnetic design principle of the motor,and the wiring embedding method of the inner and outer stator armature windings is selected to complete the matching of the overall parameters of the dual stator permanent magnet starter generator.The equivalent magnetic circuit method is used to establish the equivalent magnetic circuit models of the external stator magnetic field,internal stator magnetic field,and composite magnetic field.The magnetic flux equations are established,and the calculation formulas for magnetic electromotive force,magnetic permeability,and leakage magnetic permeability are given.The main magnetic flux and leakage magnetic flux are solved,and the leakage magnetic coefficient is calculated.The results show that the error of the equivalent magnetic circuit method is relatively small compared to the finite element method,and this method has high calculation accuracy.According to the results of magnetic flux leakage analysis and magnetic flux leakage calculation,it is proposed that increasing magnetic flux leakage reluctance is an effective way to reduce magnetic flux leakage and magnetic flux leakage coefficient.Reasonably optimize the distance between the wedge-shaped magnetic separation air gap at the outer end of the permanent magnet and the trapezoidal magnetic separation air gap at the inner end,reduce magnetic leakage,and improve the rotor magnetic flux density.With the goal of reducing the distortion rate of the induced electromotive force waveform of the starting generator,an analytical expression for the harmonic electromotive force distribution along the circumferential direction of the main air gap is derived.The main influencing parameters and the influence of each parameter on the distortion rate of the no-load induced electromotive force waveform of the magnetic field are analyzed.A design method for the rotor outer circle eccentricity is proposed to weaken the specific harmonic of the air gap magnetic density and reduce the harmonic content of the induced electromotive force.The optimal structural parameters of the rotor are determined through multi-objective optimization,optimize the parameters of the inner and outer stator slots using the Taguchi method to reduce the harmonic distortion rate of the induced electromotive force.After optimization,the no-load induced electromotive force curve is smooth,with less harmonic content and high sinusoidal characteristics.Mathematical model for the starting and generating conditions of a dual stator permanent magnet starting generator is established,the response characteristics of the starting conditions,time and space loads,as well as the output voltage stability at different speeds and loads during the generating conditions are analyzed.The prototype was trial-produced and tested,and the results showed that the dual stator starting generator has good output response characteristics and voltage stability performance.