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介绍了新型机械电子无级变速器(EM-CVT)的结构特点和工作原理,建立了速比、夹紧力和调速电机数学模型,研究了EM-CVT速比控制策略。针对无级变速器常规PID速比控制算法的不足,对其进行了改进,并在Matlab/Simulink环境下建立的EM-CVT速比模型中,对改进PID速比控制算法进行了仿真分析。仿真中,EMCVT的目标速比呈阶跃变化以模拟汽车大速比变化率(大偏差)和零速比变化率(小偏差)等极端情况。结果显示改进PID速比控制算法具有良好的控制性能,实际速比能有效避免振荡、滞后和超调,准确快速地跟随目标速比。
The structural features and working principle of the EM-CVT are introduced. The mathematical models of speed ratio, clamping force and speed motor are established. The control strategy of EM-CVT is studied. Aiming at the insufficiency of conventional PID speed ratio control algorithm of CVT, this paper improves on it and simulates the improved PID speed ratio control algorithm in EM-CVT speed ratio model established in Matlab / Simulink environment. In the simulation, the target speed ratio of EMCVT shows a step change to simulate extreme cases such as the rate of change of large speed ratio (large deviation) and the rate of change of zero speed ratio (small deviation). The results show that the improved PID speed ratio control algorithm has good control performance. The actual speed ratio can effectively avoid the oscillation, hysteresis and overshoot, and follow the target speed ratio accurately and quickly.