Electromagnetic Design And Analysis Of Low-Speed And High-Torque Density Motor With Permanent Magnet/Reluctance Hybrid Double Rotor

With the wide application of rare earth permanent magnet materials,the research on low-speed and high-torque permanent magnet synchronous motors has gradually deepened.In low-speed transmission fields such as mining,oil field and metallurgy,low-speed and high-torque permanent magnet synchronous motor direct drive system is gradually replacing the traditional indirect transmission system with the advantages of high efficiency,high power factor and compact system structure.However,the conventional low-speed high-torque permanent magnet synchronous motor has a wide radial dimension and a flat overall structure,the inner space of the motor is too large,and the power density of the whole machine is low.In order to make full use of the motor cavity space and effectively improve the power density of the motor,this thesis proposes a new structure with permanent magnet/reluctance hybrid double rotor low-speed and high-torque synchronous motor,the electromagnetic design and optimization methods are deeply researched.The main work of the thesis are as follows:Firstly,the basic structure of the permanent magnet/reluctance hybrid dual-rotor low-speed high-torque motor is introduced in detail,and the basic working principle of the inner and outer unit motors is described.According to the particularity of the motor structure,the corresponding mathematical model and phase Quantitative diagram are established.Secondly,the electromagnetic design of the 52 kW permanent magnet/reluctance hybrid double rotor low-speed and high-torque synchronous motor is carried out.The power distribution principle of inner and outer unit motors is explored.The main dimensions,the pole-slot matching scheme,the slot type and the winding parameters of the motor are determined.In order to improve the output torque of the multi-pole synchronous reluctance motor,the magnetic barrier shape,the number of magnetic barrier layers,the pole arc coefficient,the proportion of the magnetic conductive layer and the thickness of the magnetic bridge of the inner unit motor are studied in detail.In order to make full use of materials and improve the power density of the whole machine,the torque-angle displacement charac-teristic of the motor is analyzed.Then,in order to verify the rationality of the electromagnetic design scheme,the electromagnetic characteristics of the motor under no-load operation and rated load operation are analyzed.The loss distribution of the motor is researched,and the loss and efficiency of the motor are calculated by the analytical method and the finite element method.Finally,in view of the complex structure and numerous design parameters of the motor,an optimal design method of the motor based on surrogate model is proposed.On the basis of parameter sensitivity analysis,the surrogate model of the motor’s output torque and torque ripple is established.In addition,in order to solve the problem of slow convergence of genetic algorithm in the process of solving,an improved genetic algorithm combined with sequential thought is proposed.