Integrated Control Of Electromagnetic Suspension Of In Wheel Motor Electric Vehicle

With the world’s attention on energy and environmental issues,electric vehicles develops rapidly.China and Europe have also introduced policies to promote the development of electric vehicles.It is expected that by 2025,electric vehicles will become the major product of auto companies.In-wheel-motor electric vehicle has become one of the main forms of electric vehicles due to its compact structure and high operating efficiency.However,the radial vibration of switched reluctance motor(SRM)caused by it’s structure has great influence on the comfort and stability of electric vehicle.It is a effective method that using electromagnetic suspension to generate controllable suspension force to suppress the vibration of SRM.However,the linear motor,electromagnetic active suspension’s actuator,is often used in low-power,fine-acting fields such as surgical robots and CNC.It is not suitable to high power and high frequency system,and there are little research results on it.In order to solve this problem,based on the analysis of the nonlinear characteristics of linear motor,this paper proposes a integrated controller which is suitable for in wheel motor electric vehicle.The paper mainly carries out the following work:(1)The vehicle nonlinear model was built.The vehicle model includes the SRM vert ical force model and the tire force model.The vertical force model analyzed the verti cal component of the SRM unbalanced radial force generated by the eccentricity of ai r gap.The "magic formula" model was used to describe the tire force considering the tire slip ratio and the side yaw.Based on the analysis of model characteristics,the model was verified by vehicle experiments.(2)The effects of nonlinear characteristics of the electromagnetic suspension on its performance was analyzed.A quarter-vehicle model and electromagnetic suspension model considering the vertical force of the SRM were built.The nonlinear characteristics of the electromagnetic suspension were analyzed from two aspect of nonlinear friction and electromagnetic force.By simulating the quarter-vehicle model which considered the nonlinear characteristics,the effects of nonlinear characteristics on electromagnetic suspension was discussed.(3)An integrated control strategy for electromagnetic suspension was proposed.The weighting coefficients of the Linear Quadratic Gaussian(LQG)controller of electromagnetic suspension was calculated by Analytic Hierarchy Process(AHP),and the LQG controller was built in matlab/simulink.Based on the analysis of the nonlinear characteristics of electromagnetic suspension,the adaptive filter based on the improved Recursive Least Squares was used to compensate the current for LQG controller,and form an integrated controller with LQG controller for the electromagnetic suspension.The power of the electromagnetic suspension and its control accuracy improved,and the effects of the electromagnetic suspension on vehicle was analyzed.Finally,the work of the paper was concluded,and the innovations of the paper and the problems that need deep study were pointed out.