DMC-PID串级控制在CVT速比控制系统中的应用

Application of DMC-PID Cascade Control in CVT Speed Ratio Control System

通过分析CVT速比控制系统的结构及基本控制原理,确定该系统具有时滞弱非线性特性,论述了常规PID控制算法以及单一的DMC控制算法应用于该系统的局限性.针对这一问题,设计了DMC-PID串级预测控制算法,该算法将经过PID校正的速比控制系统作为广义的控制对象,用DMC预测算法在线滚动优化控制参数,在优化过程中利用实测信息不断进行反馈校正,充分发挥DMC算法的超前预测性和强鲁棒性以及PID控制算法的抗干扰能力.台架实验结果表明,与常规的PID算法相比,该算法能有效减小速比跟踪过程中的波动,超调量由14%下降为4%,过渡时间由6 s缩短为4.5 s,提高了系统的动静态性能.

The structure and the basic working principle of CVT speed ratio control system were analyzed, and the analysis results showed that the system performed a feeble nonlinear characteristic with pure time-delay. The disadvantages of the general PID control algorithm and the pure DMC control algorithm were explained one by one when they were applied in this system. Therefore, a DMC-PID cascade prediction control algorithm was designed for CVT speed ratio control, which regarded the speed ratio control system adjusted by PID as the generalized object, made use of DMC prediction algorithm to optimize the control input on line, and utilized the feedback adjustment to correct the prediction model using real-time output information. The proposed control algorithm took advantage of the strong robustness and predictability of DMC, and the strong anti-jamming ability of PID, It has been shown from the bench test that the proposed control algorithm accomplishes better steady and dynamic performances than general PID： the fluctuation reduces in ramp tracking, the overshoot decreases from 14 % to 4 %, and the transition time decreases from 6s to 4.5 s approximately.