Multi-coupled Modeling And Chassis Cooperative Control Of In-wheel Motors Drive Electric Vehicle

The rotational speed and torque of each wheel of In-Wheel-Motors Drive Electric Vehicle(IWMEV)can be controlled separately,so that the vehicle has superior potential for space stability control.Related research has become a research hotspot in the field of automotive dynamics.At present,the above studies mainly focus on upper layer control strategies such as torque distribution of drive wheels,few studies have been conducted on the implementation of the underlying system control.This dissertation analyzes the operating conditions and performance constraints of IWMEV,builds a dynamic model,evaluates the handling and smoothness of the virtual prototype,optimizes system structure,develops a prototype vehicle and completes dynamic verification,testes the key subsystem performance,designs a chassis cooperative control strategy and improves the yaw-roll stability of the vehicle.The main content of this dissertation includes:(1)Combining the structural features and driving conditions of the IWMEV,a 15 DOF vehicle model was established to analyze the dynamic coupling characteristics of the suspension-steer-wheel-motor system,and the CarSim/Simulink simulation platform was built to objectively evaluates the impact of the introduction of in-wheel motors on the handling and smoothness of the vehicle through a variety of conditions simulation analysis.(2)To the solve problem that the steering and ride performance deteriorated by the mechanical structure limit,redesign the driving system and optimizes it.Based on this,an IWMEV test platform was developed,and the steering performance,maneuverability and ride comfort performance have been verified through real vehicle tests.(3)The actual vehicle test proves that the mass distribution of vehicle leads to a small ratio of sprung mass and unsprung mass,resulting in significant deterioration of vehicle ride comfort.Based on the linear motor,this paper designs a regenerative active suspension system designs a conditioning circuit,and designs the optimal controller using LQG algorithm with the goal of minimizing energy consumption and smoothness.The simulation experiment proves that the regenerative active suspension is effective in improving the ride and energy efficiency.(4)Based on the vehicle dynamics analysis and subsystem verification,a layered cooperative control strategy is researched.Then the effectiveness of the control coordinated control strategy on vehicle yaw and roll stability is verified by the simulation of CarSim /Simulink by applying differential drive,active suspension and double steering principle,with the constraints of tire force and vehicle dynamics,using optimization algorithm to distribute the actuator's power and torque.Based on combination of theoretical analysis and real vehicle testing,this dissertation realizes the collaborative control of the bottom-layer execution system of IWMEV,which lays the foundation for the implementation of the upper-layer control strategy,it has theoretical reference value and engineering application significance for related research.