Research On Optimization Design Of High Speed Permanent Magnet Motor Based On NSGA-? Algorithm

High speed permanent magnet motor has many advantages such as high power density,high efficiency and can be connected to high speed load.It is widely used in the high speed machine tool,high speed centrifuge,flywheel energy storage equipment,which has received extensive attention of scholars at home and abroad.The rotor speed of high speed permanent magnet motor is usually more than 10000r/min.moreover the speed of specially designed permanent magnet motor can even be higher,therefore the rotor will bear huge centrifugal force.The high-speed inner permanent magnet motor with permanent magnet embedded in the rotor,so the centrifugal effect can be overcome by high speed rotating permanent magnet to the mechanical structure more stable,popularization and application in the new energy vehicles.This paper first analyzes the high-speed inner permanent magnet motor optimization design background and significance,introduces domestic and foreign about high speed permanent magnet motor optimization design research,compares the advantages and disadvantages of various optimization methods,put forward optimized design method for multi objective motor.In this paper,the mathematical model of the high speed inner permanent magnet motor is derived.The winding function method is adoped to deduce the unsaturated d-axis and q-axis inductance.The equivalent circuit method(MEC)is adopted to deduce permanent magnet flux formula,and an analytical model of the motor,as the optimization objective function.On the basis of NSGA-? algorithm for high speed,high speed inner permanent magnet motor has been optimized.The optimization is divided into preliminary optimization parameters of the structure of the rotor and stator parameters;preliminary optimization selects the maximum torque and weak magnetic space under the condition of the minimum current control(MTPA)as the optimization goal.Optimization variables include the permanent magnet width and thickness of permanent magnet motor,air gap length and diameter of stator.Rotor structure was optimized by using the analytic formula,programming of the NSGA-? algorithm by MATLAB.The number of population is 50,the number of iterations is 50,and a group of optimal parameters of the rotor structure are selected by the NSGA-? algorithm in a Pareto front group to meet the performance requirements of the next set of solutions.Based on the Taguchi method for local optimization of motor stator structure.The maximum torque,maximum average torque,and the minimum torque ripple under the minimum current are selected as optimization targets.The optimization variables include stator addendum thickness,stator tooth width,height and width of stator yoke stator tooth.Maxwell/Ansoft are adopted to execute the finite element simulation.After the two times of optimization,a set of optimal motor structure parameters are achieved so as to optimize the motor performance.