Design And Analysis Of Bearingless Switched Reluctance Motor For Flywheel Battery

As a new energy storage technology,flywheel battery has the advantages of high efficiency,long life and strong environmental friendliness.It has an application market in the fields of aerospace and rail transportation.As the core component of flywheel battery,the motor can determine the efficiency of the flywheel battery and undertake the energy conversion between electrical energy and kinetic energy.Recent years,the Bearingless Switched Reluctance Motor(BSRM)has become the preferred motor for flywheel batteries due to the simple structure,reliable operation and high efficiency.Among them,the 12/14 hybrid stator pole type BSRM realizes the decoupling of torque and suspension force through the topology.Therefore,this paper proposes a 12/14 hybrid stator pole type BSRM for flywheel battery.According to the design parameters of the flywheel battery,the structure parameters of the motor are determined.As the 12/14 hybrid stator pole type BSRM for flywheel batteries runs at high speed,the temperature will increase due to the increased loss.At the same time,the high-vacuum environment has harsh heat dissipation condition,which affects the working efficiency and stability of the motor.Therefore,it is necessary to study the loss and temperature field of 12/14 hybrids stator pole type BSRM.In this paper,the 12/14 hybrid stator pole type BSRM is taken as the research object.And its mathematical model,structural parameter design,electromagnetic performance,loss,and temperature field are studied,and then,it is optimized.The specific work is as follows:(1)The basic working principle of the 12/14 hybrid stator pole type BSRM is introduced,the mathematical model of the torque and suspension force is derived by using the equivalent magnetic circuit method.On the basis of the design method of the switched reluctance motor,the preliminary design parameters of the 12/14 hybrid stator pole type BSRM are determined.The 2-D model is constructed by Ansoft software and its electromagnetic characteristics are analyzed,including air gap magnetic density,torque,suspension force and coupling characteristics,thus ensuring that the 12/14 hybrid stator type BSRM meets the performance requirements of flywheel battery motors.(2)The magnetic flux density at the typical position of the 12/14 hybrid stator pole type BSRM stator rotor core are analyzed,so as to obtain the magnetic flux change waveform and its change law at each point.Three analytical methods of core loss calculation are also introduced,Finite element analysis is used to obtain the core loss distribution at different position angles;in addition,other losses including copper loss,mechanical loss and stray loss are calculated.(3)The 3-D thermal model of 12/14 hybrid stator pole type BSRM is constructed through Workbench software,and the loss heat sources are coupled to the thermal analysis model by using the magnetic-thermal one-way coupling method.The temperature field distribution of the stator and rotor under different conditions are analyzed.The research shows that the highest temperature of the stator appears in the middle,and the rotor pole temperature is also high,and the cause of the temperature distribution is analyzed.At the same time,the temperature of each part of the motor under different operating conditions are compared,and The temperature of the motor under high-vacuum environment is significantly higher than the natural air-cooled environment,which affects the efficiency of the motor and is not conducive to the stable operation of the motor.(4)The structural parameters of the 12/14 hybrid stator pole type BSRM are analyzed on the influence of suspension force,torque and iron loss,and then the structural parameters with high sensitivity are selected.To improve the torque and suspension force and reduce core loss are the optimization goal.The motor is optimized using the PSO-DE algorithm.By comparing the suspension force,torque and temperature field before and after the optimization of the motor,it is concluded that the suspension force and torque of the motor have been improved and the temperature of each part has decreased,thus verifying the feasibility of optimization.