Research On Electromagnetic Analysis And Rotor Strength Of Modular High Speed Permanent Magnet Synchronous Motors

The High speed permanent magnet synchronous motor has the advantages of fast speed,high efficiency,high power density and so on,so it has been widely used in automobile,aerospace and other fields.However,the conventional high speed permanent magnet motor can not meet the requirements for the occasions of high fault tolerance and reliability of the motor.Modular high speed permanent magnet motor has attracted much attention because of its advantages of high fault tolerance.Due to the special problems in the electromagnetic design of the motor caused by modular structure,it needs to be focused on.Therefore,the electromagnetic analysis and rotor strength research of modular high speed permanent magnet motor is of great significance in this paper.In this dissertation,A modular high speed permanent magnet motor with rated power of 300 k W is taken as an example.Based on the design theory of conventional high speed permanent magnet motor,the main size of the motor is estimated,the suitable rotor magnetic circuit structure is selected and the advantages and disadvantages of different winding structures in the modular motor are analyzed under the consideration of the special requirements of modular structure for motor design.Finally,the electromagnetic design scheme of the modular motor is established by comparing the influence of different pole groove matches on the torque of the modular motor,which provides a reference for the similar motor design.The magnetic dense cloud diagram,air gap magnetic density and no-load back electromotive force of the modular high speed permanent magnet motor were calculated.When the motor is running under load,the mechanical characteristics,power Angle characteristics and efficiency characteristics of the motor are calculated by using finite element method,and the structural parameters satisfying the motor design index are determined.The influences of the polar arc coefficient of permanent magnet and slot width on the electromagnetic torque and groove torque of the modular motor are analyzed.The calculation results show that the motor has the best electromagnetic performance when the slot width and the polar arc coefficient of permanent magnet are 3.5mm and 0.8mm respectively.Based on the high fault tolerance of the modular motor,the torque output capacity of the motor was compared with that of the whole machine,and the electromagnetic performance of the motor before and after open-circuit fault was analyzed.For the single-phase open-circuit fault of the motor winding,the influence of intra-module and inter-module compensation on the torque output capacity was compared.Two compensation methods,namely winding recombination and intra-module compensation,were proposed for the double-phase and multi-phase open-circuit faults of inter module windings,and the torque output capacity of the motor under the two compensation methods was compared.Based on the compensation method of winding reconstruction,the torque of the modular motor under the limit open circuit fault is analyzed.The proposed method can improve the torque output capacity of the motor.Considering the modular of high-speed permanent magnet motor rotor speed faster,to prevent damage of the rotor,permanent magnet rotor stress calculation,choose the suitable thickness of sheath,counter rotating subsystem and the modal analysis,to calculate the critical speed of the rotor system,satisfied strength requirement of rotor parameters,analysis of bearing different sensitive factors influence on rotor critical speed,analysis shows that,Bearing stiffness has a greater effect on critical speed than damping.