基于扩张观测器的HMCVT换段离合器油压跟踪控制

Sliding Mode Control for HMCVT Shifting Clutch Pressure Tracking Based on Expanded Observer

针对液压机械无级变速器(HMCVT)换段离合器油压跟踪控制过程中,不匹配干扰造成实际油压与期望油压产生偏差的问题,提出了一种基于扩张观测器的全局终端滑模控制算法,以实现油压的高精度跟踪控制。通过建立带有不匹配干扰的非线性湿式离合器数学模型,推导了油压控制系统的状态方程,使用扩张观测器对不匹配干扰进行估计,设计了一种能够快速收敛的全局终端滑模控制算法,并将干扰估计值补偿到控制算法中以提高控制精度和降低滑模控制的抖振。基于全局终端滑模控制算法设计了换段离合器油压跟踪控制器,通过试验对控制器效果进行了验证。结果表明,扩张观测器能够有效观测不匹配干扰,与传统终端滑模控制算法相比,基于本文算法设计的油压跟踪控制器动态响应时间仅为0.13 s,超调量为0.08 MPa,且无明显抖振。在换段过程中,冲击度降低12.7%,滑摩功减少10.2%,表明所提油压跟踪控制算法具有较好鲁棒性,能够改善换段离合器的接合品质。

To eliminate the deviation between the actual pressure and the expected pressure of the shifting clutch of hydraulic mechanical continuously variable transmission(HMCVT) during the pressure tracking control process,a global terminal sliding mode control algorithm based on extended observer was proposed to achieve the high-precision tracking control of the pressure.By establishing the nonlinear mathematical model of wet clutch with uncertain disturbance,the state space equation of pressure control system was derived.The mismatched disturbance was estimated by extended observer,the linear term was introduced to accelerate the global convergence of terminal sliding mode control.Then a global terminal sliding mode pressure tracking controller based on extended observer was designed for HMCVT shifting clutch pressure system in real time.Finally,the effect of the controller was simulated and verified by bench test.The simulation and test results showed that the uncertain disturbance can be accurately observed by the extended observer.Compared with the traditional TSMC,the dynamic response time was only 0.13 s,the overshoot was only 0.08 MPa,and no chattering phenomenon occurred for the proposed algorithm.In addition,the control algorithm had good performance anti-interference capability,which was reflected by the smallest jerk(reduced by 12.7% at most) and sliding friction work(reduced by 10.2% at most).The results proved that pressure tracking control algorithm proposed had good robustness,and it can be applied to pressure tracking control of HMCVT shifting clutch.