Research On Novel Hybrid Double-rotor Permanent Magnet Synchronous Reluctance Motor

Permanent magnet synchronous motors are greatly favored in various fields because of their high torque density,high efficiency,good steady-state performance and high operational reliability.However,the expensive price of rare earth permanent magnets increases the cost of permanent magnet motors,and faces the problem of difficulty in field weakening and speed regulation,which brings great challenges to the development of permanent magnet motors.The synchronous reluctance motor does not use permanent magnets and has a wide speed range,but its torque density,efficiency and po wer factor are low.In order to improve the performance of the motor,permanent magnets are embedded in the rotor barrier of the synchronous reluctance motor,and the permanent magnet-assisted synchronous reluctance motor(PMA-SynRM)has been developed,which has a higher torque density and a wider speed range.However,the permanent magnets of this kind of motor are embedded in the magnetic isolation bridge,and the air gap flux density and back EMF are low,at the same time,the current phase angle corresponding to the maximum value of the permanent magnet torque and the maximum value of the reluctance torque is theoretically different by 45°,which makes the two torque components not fully utilized.Therefore,based on the problems of traditional PMA-SynRM,,combined with the characteristics of the permanent magnet synchronous motor and the reluctance motor,this paper studies a novel hybrid dual-rotor permanent magnet synchronous reluctance motor,the outer rotor is a surface-mounted permanent magnet rotor with a high permanent magnet torque,with the use of the inner rotor reluctance rotor,it makes full use of the internal space of the motor and can increase the speed regulation range,and through the reasonable configuration of the inner and outer rotors,make the permanent magnet torque and reluctance torque reach the maximum value under the same current phase angle,which can realize the purpose of making full use of the two torque components.The specific research content is as follows:(1)Research on the basic principle of the novel hybrid permanent magnet synchronous reluctance motor.In order to highlight the advantages of the new hybrid dual-rotor permanent magnet synchronous reluctance motor,this article first introduces the structural characteristics and torque characteristics of the traditional PMA-SynRM.Based on this,a novel hybrid dual-rotor permanent magnet synchronous reluctance motor is studied.The topological structure is composed of a middle stator and two inner and outer rotors.The principle of torque superposition is analyzed by freezing magnetic permeability,and the key structural parameters that affect the torque superposition mechanism are obtained,and its speed regulation characteristics are analyzed.(2)Analysis of the electromagnetic performance of the novel hybrid dual-rotor permanent magnet synchronous reluctance motor.First,analyze the no-load and load characteristics of the research model,and analyze the impact of key parameters on the utilization rate of the torque component to achieve the purpose of making full use of the torque component,compared with the traditional PMA-SynRM,the studied new hybrid dual-rotor permanent magnet synchronous reluctance motor has significantly improved electromagnetic torque;Then,the electromagnetic performance of the outer rotor and the inner rotor with different structures were compared,and the outer rotor was selected as a surface-mounted permanent magnet rotor and the inner rotor was a salient pole rotor for follow-up research;Finally,the electromagnetic torque,torque ripple and efficiency of the studied motor under different winding connection modes are compared to determine the final winding connection mode.(3)Multi-objective optimization and analysis of the novel hybrid dual-rotor permanent magnet synchronous reluctance motor.By selecting the width angle and thickness of the outer rotor permanent magnet,the height and width of the salient pole of the inner rotor as optimization variables,the optimization is carried out with the goal of maximum torque and minimum torque ripple.First,the sensitivity analysis of the four parameters is carried out,and get the influence law of permanent magnet width angle,permanent magnet thickness and salient pole height,salient pole width on electromagnetic torque and torque ripple respectively to determine the optimization range of the four parameters;then,the multi-objective genetic algorithm is used to optimize the structural parameters of the novel hybrid dual-rotor permanent magnet synchronous reluctance motor to reduce torque ripple..(4)Analysis of vibration characteristics of the novel hybrid double-rotor permanent magnet synchronous reluctance motor.The studied new hybrid dual-rotor permanent magnet synchronous reluctance motor has two internal and external air gaps,and the influence of the internal and external air gaps on the vibration of the motor needs to be considered at the same time.In this paper,the finite element method is used to simulate and analyze the no-load and load electromagnetic force distribution of the air gap inside and outside of the motor,and the radial electromagnetic force of the air gap inside and outside the motor is subjected to two-dimensional Fourier decomposition to obtain the time harmonic frequency order and the spatial harmonic order;then,the stator mode of the motor is analyzed to obtain the natural vibration frequency under different modes;finally,the vibration performance of the novel hybrid dual-rotor permanent magnet synchronous reluctance motor is analyzed by comparing the electromagnetic force distribution of the inner and outer air gaps and the natural vibration frequency of the stator.