Research On Dynamic Modeling Of A Magnetic Bearing For Vehicle Flywheel Battery Based On Temperature And Speed

The shift from traditional vehicles based on fossil fuels to clean,electric vehicles are seen as one of the key steps towards decarbonisation amid a growing global warming problem.However,with the strong growth of the electric vehicle market,the automobile power battery has become one of the main factors limiting the widespread use of electric vehicles.Today,research on automotive power batteries includes batteries,fuel cells and flywheel batteries.Compared with other on-board power batteries,flywheel batteries have the advantages of high specific energy,large specific power,short charging time and no environmental pollution.The unique advantages make them have broad application prospects in electric vehicles.Flywheel batteries are used in automobiles,and the frequent switching conditions of vehicles and complex road conditions will affect the flywheel batteries.Therefore,the support system,suspension force model and control algorithm of the flywheel battery are highly required in vehicle applications.This dissertation mainly focuses on the structural design of the support system of the flywheel battery and the accurate modeling under dynamic working conditions.The main research work is as follows:Firstly,the research background of vehicle flywheel battery is introduced,the working principle of vehicle flywheel battery is explained in detail,the research status and development trend at home and abroad are summarized,the main technical difficulties of vehicle flywheel battery support system are discussed,and the research significance and purpose of this dissertation are pointed out.Secondly,to overcome the problem that the rotor of the vehicle flywheel battery is easily destabilized,a new type the pure spherical centripetal force type-magnetic bearing is proposed,and the structure,magnetic circuit and working principle of the magnetic bearing are introduced.Compared with the magnetic bearing of the traditional cylindrical topology,the reason why this structure can effectively reduce the gyro effect is analyzed from the aspect of the magnetic field.Thirdly,the finite element software is applied to simulate the difference between the actual operation and standby state of the magnetic bearing system,and several error sources that are easily missed during the modeling of suspension force are pointed out.The degree of influence of the error source on the suspension force is analyzed in detail,here is the influence of temperature and speed on the stator and rotor shape.The simulation results are theorized and the deformation rules of rotor under temperature rise,rotor deformation and centrifugal force are deduced.Considering the deformation of the stator and rotor into the suspension force modeling process,a multi-dimensional dynamic suspension force model based on temperature and speed is established.Different from the traditional static suspension force modeling,not only the conventional variables such as current and displacement are taken into account in the proposed dynamic suspension force model,but the two dynamic variables,temperature and speed,are also added.Perfect and precise variables make the suspension force model closer to the working state of the magnetic bearing system.Finally,the experimental platform of the pure spherical centripetal force type-magnetic bearing is built,and the overall experimental scheme is introduced,including the vertical experimental platform and the control method.To ensure the accuracy of the experimental results,the error correction of the temperature detected by the on-line infrared thermometer is carried out.The force-displacement/current stiffness experiment is carried out on the platform and the results are compared and analyzed in detail.