CVT车辆由发动机制动下坡时的控制研究与仿真

Simulation and Control Strategy Research of CVT Vehicle During Downhill by Engine Braking

研究了CVT车辆在下坡时的速比控制策略及其仿真问题,为了改善CVT车辆下坡时速比PID控制策略存在的误差大及响应慢的缺陷,并根据PID控制器中积分项的特点提出了采用积分分离的PID速比控制方法。通过采用车速、CVT速比和发动机转速进行反馈,建立了车辆下坡时的动力学模型和Simulink仿真模型,仿真结果表明积分分离的PID速比控制策略在速比响应速度、稳态误差和超调量上比单独的PID控制具有优越性,经实验证明该控制策略能实现车辆下坡时对目标车速控制的要求,进而提高了CVT车辆下坡时的安全性和操控方便性。

The speed ratio control strategy and the simulation problem of CVT vehicles during downhill is re- searched. In order to improve the PID control strategies of CVT transmission ratio which have the defects of big error and slow response, and according to the features of integral action in PID controller, integral separation PID speed ratio control method is proposed. The vehicle dynamics model during downhill and Simulink model are established by the use of vehicle speed, CVT speed ratio and the engine speed as feedback. The simulation results show that integral sep- aration PID speed ratio control strategy is superior than separate PID control in ratio response speed, steady - state error and overshoot, and this control strategy can realize vehicle speed control requirements during downhill, and the security and manipulate convenience during downhill of CVT vehicles are improved.