Research On Optimal Design Of Double Stator Low-speed High-torque Synchronous Motor Based On Surrogate Model

In low-speed transmission fields such as hoisting machinery,metallurgical steel rolling,oilfields and mines,direct drive systems composed of low-speed and high-torque permanent magnet synchronous motors are gradually replacing traditional indirect drive system consisting of asynchronous motor and reducers due to their high transmission efficiency and compact structure.The low-speed high-torque permanent magnet synchronous motor is the core part of the entire direct drive system,which is mostly short and thick,with a large internal cavity space inside the motor.In order to make full use of this space and increase the torque density of the motor,the permanent magnet/reluctance hybrid rotor double stator low-speed high-torque permanent synchronous motor has emerged.This paper takes the hybrid rotor double stator lowspeed high-torque synchronous motor for elevator traction machine as the research object,and takes the improvement of average torque and the reduction of torque ripple as the optimization goals.A more in-depth and systematic study on the optimization design of this kind of motor is constructed in this paper.The main work of the paper is as follows:First of all,the topology and operating principle of the double stator low-speed high-torque synchronous motor are introduced in detail.The electromagnetic design of the motor for an elevator traction machine with a power of 50 k W is carried out,and initial design scheme is determined.Secondly,on the basis of comparing the advantages and disadvantages of the surrogate models commonly used in engineering,the surrogate model suitable for the research object of this paper is determined,and the sensitivity analysis of the key parameters of the motor is carried out by using the Latin hypercube design and the analysis of variance method.The parameters that have a greater impact on the optimization goal are determined as optimization variables,and then high-precision surrogate models of average torque and torque ripple are established,and the surrogate models are simplified to facilitate the later optimization.Then,in view of the numerous optimization variables of the double stator low-speed hightorque synchronous motor,which leads to the use of intelligent algorithms to solve the problem with a long time,an optimization algorithm combining genetic algorithm and sequential subspace optimization method is proposed.The calculation time of the proposed optimization algorithm is compared with that of the traditional genetic algorithm and analyzed.The timeliness of the proposed optimization algorithm is verified.Finally,the obtained optimal solution is substituted into the finite element model for calculation,and air gap flux density waveform,back electromotive force waveform,magnetic field line distribution diagram and magnetic flux density cloud diagram of motor after optimization are analyzed,and the motor efficiency is calculated.The average torque and torque ripple after optimization are compared and analyzed with those before optimization,which proves the effectiveness and correctness of the proposed optimization method.