Research On Eccentricity And Active Control Of Electric Vehicle Hub Motor

The electric vehicle driven by the wheel hub motor has become one of the important directions for the future development of electric vehicles due to its advantages in vehicle layout,active chassis control and handling.However,under the excitation of uneven roads,tire jump,uneven load bending,bearing wear and installation errors will cause uneven air gap in the circumferential direction of the motor,the uneven air gap of the motor will cause the magnetic field distortion of the air gap,which will produce an electromagnetic force wave that is different from the normal operation of the gap.Therefore,it is necessary to study and control the air gap eccentricity of the hub motor.First,based on the structure and working principle of the permanent magnet synchronous in-wheel motor,a mathematical model of the in-wheel motor is established,then a 1/4 in-wheel motor electric vehicle model and a random road model are established,and the influence of road surface excitation on the in-wheel air gap eccentricity is analyzed.Then uses the magnetic potential multiplier method to establish the analytical model of the air gap magnetic field in the motor without eccentricity,and on this basis,the Maxwell stress tensor method is used to obtain the analytical model of the electromagnetic force without eccentricity.The characteristics of the air gap magnetic field and electromagnetic force of the hub motor without eccentricity are analyzed.Based on the analytical model of the air gap magnetic field and electromagnetic force of the hub motor when it is not eccentric,and using the magnetic permeability correction coefficient method,the analytical model of the motor air gap magnetic field and electromagnetic force under static eccentricity and dynamic eccentricity is established.Then,by establishing a finite element analysis model,the analytical model was verified.In this paper,the radial vibration models of the outer rotor permanent magnet synchronous hub motor rotor and the hub motor stator rotor system are established.The unbalanced electromagnetic force caused by different forms of eccentricity is used as an excitation to explore the influence of different eccentricity on the radial vibration characteristics of the hub motor.Finally,an air-gap eccentricity compensation control system for a hub motor based on additional windings was established when drawing on the principle of bearingless motor suspension control,.The control system was built through SINMULINK,and the effectiveness of the system was verified by simulation experiments.