拖拉机液压机械无级变速器控制策略仿真与试验

Simulation and Experiment of Hydro-mechanical CVT Control Strategy for Tractors

为了完善我校自主开发的拖拉机液压机械无级变速器(HMCVT),同时为该无级变速器后期的改进、推广提供一定的基础,对该变速器的控制策略进行了设计、仿真与试验研究。设计了基于发动机最佳经济性工作曲线的模糊控制系统,以油门踏板开度、发动机转速作为控制器输入,以泵马达系统排量比、离合器的选择作为控制器输出。在AMESim中建立了无级变速器的仿真模型,在Matlab中建立了模糊控制器,通过联合仿真验证了控制策略的正确性。选用西门子S7-200PLC作为主控制器,搭建了相应的控制系统,进行了台架试验,得出了该套控制系统能够根据油门踏板开度自动调节变速器传动比,使发动机稳定于当前油门开度下的最佳经济性转速。同时负载自适应性较强,能够根据负载的变化调节变速器传动比,保证发动机的经济性。

In order to perfect the design of hydro-mechanical continuously variable transmission （HMCVT）, also provide a theoretical basis for later improvement and promotion, this paper designed, simulated and tested the HMCVT control strategy. A fuzzy control system based on the fuel economy curve of the engine was designed. The inputs of the controller are the opening of accelerator pedal and the engine speeds, the outputs are the displacement ratio of the pump motor system and the selection of the clutch. The simulation model was established in AMEsim and the fuzzy controller was bulit in Matlab. Through cosimulation the authenticity of the control strategy was verified. Selecting $7-200 PLC as the main controller, a corresponding control system is built and a bench test is conducted. The test results show that the control system can automatically adjust the transmission ratio based on the accelerator pedal and stabilize the engine speed at fuel economy curve. Moreover, the control system with strong load adaptability can adjust the transmission ratio according to load change and ensure the fuel economy of the engine.