Optimal Design Of High-speed Permanent Magnet Synchronous Motor Based On Field-circuit Combination

High-speed permanent magnet synchronous motors have the characteristics of high power density and high efficiency,and have been widely used.However,the temperature rise caused by the rotor eddy current loss will affect the electromagnetic performance of the motor,and an excessively high temperature rise of the rotor may even cause the irreversible demagnetization of the permanent magnet.This paper mainly studies the electromagnetic design of high-speed permanent magnet synchronous motors,focusing on the rotor eddy current loss,and at the same time,optimizes the high-speed permanent magnet synchronous motors with the rotor eddy current loss as the optimization goal.Firstly,the air gap reluctance in the traditional generalized magnetic circuit method is modified by introducing the complex air gap relative permeance in the calculation.The improved generalized magnetic circuit method can be applied to analyze the no-load air gap magnetic field of the surface-mounted permanent magnet motor,which can consider the influence of magnetic circuit saturation,ferromagnetic material nonlinearity and stator slotting at the same time.The analytical calculation method proposed in this paper is consistent with the finite element simulation results.Experimental tests further verify the effectiveness and accuracy of the improved generalized magnetic circuit method.At the same time,the performance of surface-mounted permanent magnet motors is analyzed based on the generalized magnetic circuit method,consistent with the finite element simulation results.Secondly,based on the vector magnetic potential,the basic theory of the pseudo-constant electromagnetic field of the high-speed permanent magnet motor is described in detail,establishing analytical model of high-speed permanent magnet motor,and dividing the motor into the following five subdomains: slot subdomain,slot mouth subdomain,gap subdomains,protective sleeve subdomains and permanent magnet subdomains are used to establish the vector magnetic potential relationship of each subdomain according to the boundary conditions between the subdomains.In addition,the process of calculating the rotor eddy current loss formula based on Poynting’s theorem is introduced.Then,the no-load magnetic field,stator winding excitation magnetic field and load magnetic field model of the motor are established according to the different motor excitations.According to the characteristics of each model,the satisfied vector magnetic potential equation is derived,and the corresponding vector magnetic potential is solved to obtain the magnetic field distribution of the motor and the eddy current loss of each part of the rotor.Analyzing the results calculated by the analytical and finite element simulation,the correctness of the magnetic field analytical model of the high-speed permanent magnet motor based on vector magnetic potential is verified in this paper.Finally,a mathematical model of high-speed permanent magnet motor based on the combination of generalized magnetic circuit method and magnetic field analysis method is established.Combining the mathematical model based on field-circuit combination and genetic algorithm to optimize the design of high-speed permanent magnet motor,the optimization effect is very obvious.The correctness of the optimization results is verified by finite element simulation.