金属带式CVT速比的改进PID控制

An Improved PID Algorithm for the Ratio Control of Metal Belt CVT

针对无级变速器（CVT）常规速比控制器的局限性，提出了一种既能满足大规模生产要求，又具有广泛适应性的改进PID速比控制算法。通过分析经典PID控制器原理，确定了该控制器的优点和局限性。为了保留经典PID控制器的优点，同时克服其局限性，在经典PID控制算法的基础上加入了积分分离和微分先行的控制环节，改进后的控制器能有效避免偏差的累积和目标速比阶跃变化等影响，使车辆能够适应多变的交通条件。设计了速比跟踪试验，目标速比以30S为周期在最大和最小速比（2.5～0.4）之间阶跃变化，用以上2种控制器分别对目标速比跟踪。试验结果证明：改进PID比经典PID速比控制器的响应速度显著提高，而且有效地避免了超调的发生。

Aiming at the shortcoming of general ratio controller for Continuously Variable Transmission （CVT）, an improved PID control algorithm was presented, which was more suitable for mass production requirements and more adaptive. Firstly, the theory of classical PID ratio controller was analyzed, and the advantage and the disadvantage of the algorithm were discussed. To reserve the classical PID algorithm advantage and overcome its disadvantage, integral separation and differential in advance means were introduced to the classical PID control algorithm. Through integral separation, the error accumulation could be limited in a range and the differential in advance made the response more rapid. All these characters made the improved PID more suitable for automobile demands in multiple traffic conditions. Finally, an experiment of step ratio tracking were designed, in which the classical and improved PID controllers tracked the object ratio respectively, and the object ratio varied step between the max and min ratio （2.5 -- 0.4） and in the cycle .of 30 s. The experiment result proved that the improved PID shortened the response time significantly, and avoided overshoot efficiently.