Temperature Field Analysis And Optimization Design Of Bearingless Switched Reluctance Motor

Flywheel battery is a modern energy storage device with high efficiency,high energy density,short charging and discharging time and long life.There are wide application prospects in many fields such as power generation,aerospace,electric vehicles and new energy sources.Single-Winding Bearingless Switched Reluctance Motors(SWBSRM)can be applied to flywheel batteries because of its simple topology,high efficiency,and small size.As a core component of high-speed large-capacity flywheel battery electromechanical energy conversion,SWBSRM directly affects the performance and efficiency of the flywheel battery.In view of the special structure of the flywheel battery internal structure,SWBSRM works under high vacuum conditions,the heat is difficult to dissipate,thus,the heat dissipation conditions are harsh,and the temperature rise is high,which threatens the safety and stability of the motor during operation.Therefore,the calculation of the loss and temperature field of SWBSRM is of great significance to the reliability and longevity of the flywheel battery.The main work contents are:Firstly,the suspension principle of SWBSRM is introduced.The mathematical model of the motor is established by the virtual displacement method.The design equation of principal size and basic size parameters is derived,and the preliminary design parameters of the motor are determined.The Ansoft finite element software is used to build the two-dimensional(2-D)model,and analyzed the basic electromagnetic characteristics of SWBSRM,verifying that the initial parameters of SWBSRM satisfied the design requirements.Secondly,the classical iron loss calculation model is given.In order to analyze the iron loss,the magnetic density variation law of the stator and rotor core is obtained by time-step finite element simulation.The iron loss is calculated according to the model,and the calculation results are verified by finite element(FEA).The variation of iron loss between analytical method and FEA at different speeds is given.Finally,the loss of heat source such as copper loss,mechanical loss and stray loss of the motor is calculated,which lays a foundation for subsequent temperature field analysis.Thirdly,based on the topology and electromagnetic characteristics of SWBSRM,based on a series of reasonable assumptions on the motor,a three-dimensional(3-D)temperature field model is established and the boundary conditions of the solution domain are given.The magneto-thermal unidirectional coupling method is used.The temperature field of SWBSRM under high vacuum condition and natural air cooling condition is analyzed and calculated,and the temperature variation law of main components of the motor under different working conditions is obtained.Since SWBSRM works in the flywheel battery,the temperature variation law of the motor under high vacuum conditions is further explored,which provide a useful reference for the design of the cooling structure of the motor.Finally,the influence of SWBSRM main structural parameters on temperature rise and radial levitation force is analyzed,and the structural parameters with great influence on motor performance are determined as optimization variables to improve the average torque and efficiency as the optimization target,and the levitation force is the constraint condition.The motor was optimized by Genetic-particle swarm optimization(GPSO).Studies have shown that while the optimized motor meets the requirements of the suspension force,the average torque and efficiency are improved.The optimized SWBSRM temperature field is verified.The results show that the steady-state temperature of each main component has decreased,which verifies the correctness of the optimized parameters and provides a useful reference for SWBSRM for flywheel batteries.