Research On Dynamic Characteristics Analysis And Control Of In-wheel Motor Drive System Based On Electromagnetic Active Suspension

With the increasingly severe environmental and energy issues and the stricter emission standards of various countries,the development of electric vehicles has become the key to breaking through this dilemma.china has also listed electric vehicles as one of the country’s seven strategic emerging industries.In-wheel electric vehicles have become a unique direction in the research of electric vehicles because of their compact power transmission system,fast and accurate drive motor response,high control system integration,low vehicle quality,and high space utilization.It is regarded as the ultimate driving form of electric vehicles.On the other hand,the unique structure of the in-wheel motor drive system also brings some negative problems: because the drive motor is directly integrated into the wheel,the increase in unsprung mass causes the vehicle’s vertical vibration to deteriorate.Secondly,the special electromagnetic excitation of the motor directly acts on the wheels and couples with the vehicle dynamics system to cause high-frequency vibration.These two problems are collectively referred to as the negative vibration effect of the in-wheel motor drive system.These problems affect the comfort,stability and safety of the vehicle,and restrict the application and development of in-wheel-drive electric vehicles.Aiming at the problem of the negative vibration effect of the in-wheel motor drive system,this paper takes the dynamic characteristics of the wheel drive system as the starting point,analyzes the mechanism of the vibration negative effect problem,and studies the vibration negative effect based on the suspension structure research and active control,suppression methods to improve the dynamic performance of wheel-driven electric vehicles,the thesis work mainly from the following aspects:(1)Taking the in-wheel motor,a key component of the system,as a starting point,an electromechanical coupled vehicle dynamics model considering the electromagnetic excitation of the motor is established.Study the influence of unsprung mass increase and electromagnetic excitation on vehicle dynamics,analyze the excitation characteristics and influence range of electromagnetic excitation,reveal the electromechanical coupling characteristics of electromagnetic system and vehicle dynamics system,in order to understand the dynamic characteristics of in-wheel motor drive system and chassis The development of control theory provides the basis.(2)From the perspectives of active control and suspension structure optimization,the key methods to suppress the negative effects of vibration are extracted,and the active and passive integrated wheel hub drive system based on the combination of dynamic damping system and electromagnetic active suspension is proposed,analyze the dynamic characteristics of the integrated wheel hub drive system under dynamic conditions.The research results suppressed the deterioration of the vertical vibration of the wheel-driven electric vehicle,eliminated the high-frequency electromagnetic vibration of the system,and alleviated the negative vibration effect of the wheel-driven system.(3)The linear actuator is a key component of the electromagnetic active suspension in the drive system,and its nonlinear characteristics should be considered in practical applications.Taking linear actuators as the research object,the nonlinear characteristics of its own and its influence on vehicle dynamics are studied,and corresponding control strategies are proposed to meet the performance requirements of the integrated wheel hub drive system.(4)Taking the coupled dynamic model based on the active and passive integrated wheel hub drive system as the research object.Aiming at the contradiction between ride comfort and handling stability and the contradiction between the control performance and control efficiency of the electromagnetic active suspension which caused by the change of the suspension structure.The research on the optimization of the suspension structure parameter matching and optimization is carried out on the basis of ensuring the stability of the in-wheel motor,Improve the ride comfort and stability of electric vehicles,and improve the control efficiency of electromagnetic active suspension.