Research On Driving Unit With Fractional-Slot Windings Embedded Rare-Earth PM Rotor And Its Control Technology For Electric Vehicles

Permanent magnet synchronous motor(PMSM)has the characteristics of high efficiency,low inertia,high torque density and so on.It is a preferred choice for electric vehicles motor and has great application value.By analyzing the structural characteristics of PMSM,the paper designs the rectangular permanent magnets embedded in the rotor core with the radial rectangular groove,and punches shear the rectangular groove magnetism isolating air gap between adjacent permanent magnets on rotor core to improve the utilization rate of permanent magnet.It draws the star graph of electromotive force phasor and expanded diagram of three phase winding,by means of the inserted line design of armature winding with the phasor star graph method,the stator of fractional-slot winding with 3 phases,8 poles,27 plots is designed.With the establishment of the equivalent magnetic circuit model of PMSM,it gives the analysis and calculation of motor parameters with the permeance,leakage permeance,the main magnetic flux and magnetic leakage flux.At the same time,it optimizes the magnetic circuit of motor with the reduction of magnetic leakage flux and improved efficiency of motor.The two dimensional no-load and rated load magnetic fields are modeled and simulated with the magnetic finite element analysis software,obtaining the magnetic force lines graph,magnetic flux density vector and module value diagram of motor.With the analysis of flux linkage distribution,magnetic density vector distribution and nephogram distribution under the rated load,it checks the operating point of the permanent magnet.The induced electromotive force waveform,output torque and efficiency are obtained by post-processing with no-load and rated load,which all verifies the feasibility of the design.With the studies of the control mode and control circuit structure of PMSM,it builds the finite element field-circuit coupling control circuit.By setting four common fault conditions in the control circuit model of power devices open circuit,single-phase winding open circuit,single-phase turn-to-turn short circuit and single-phase winding short circuit,it provides the theoretical basis for the motor online fault analysis.