Linear Permanent Magnet Motor With Enhanced Magnetic Field Modulation And Its Multi-Objective Optimization Design

Most of the existing long stroke linear rail transportation applications use asynchronous induction motors and linear switched reluctance motors,but their thrust force denisty and efficiency are relatively low.The field modulating permanent-magnet(PM)motor which based on the “magnetic gear effect” improves the thrust force density and efficiency of PM motor,but its power factor is generally low.This paper proposes an asymmetric double-side linear PM(DSLPM)motor with enhanced field modulatiton to improve the power factor and thrust force density by enhancing the magnetic field modulation effect.Therefore,this paper will launch research on the DSLPM motor and put forward a multi-objective optimization framework using the Response Surface methodology and a novel multi-objective differential evolution algorithm to improve the overall motor performance.The main research results of this paper include the following aspects:1 describe the magnetic field modulated motor in terms of structural characteristics and working principle by analyzing the connection between the magnetic gear compound motor and the magnetic field modulated PM motor.The generation mechanism of air-gap magnetic density of the magnetic field modulation motor is analyzed by analytical method.2 analyze the parameters that have an impact on the power factor,compare the difference between ordinary motor and vernier motor,and reveale the reason why the power factor of vernier motor is low.Take field modulating linear PM motor as an example to explore the influence of armature winding pole number and winding connection mode on the power factor.3 propose an asymmetric DSLPM motor with enhanced magnetic field modulation to solve the low power factor of the existing field modulated PM motor.Introduce the structure characteristics,winding connection mode and working principle of the motor and optimizethe key parameters by single parameter simulation.4 propose a framework of multi-objective optimization combined Response Surface methodology and a novel multi-objective differential evolution algorithm;the key parameters of the motor are optimized for high thrust force,and low thrust ripple and high power factor toimprove the overall performance of DSLPM motor and the optimization efficiency.The optimization results are compared with the traditional single-parameter scanning design to determine the final prototyped design.5 establish the finite element model of the final prototype design based on Ansoft Maxwell software and analyze the no-load back electromotive force(EMF),cogging force,thrust force,loss and other electromagnetic performance.6 the prototype is processed and the experimental platform is built.The no-load back EMF,the resistance and inductance and the static thrust force at different currents of DSLPM motor are measured to verify simulation results.