Efficient Mode Transition Control for DM-PHEV With Mechanical Hysteresis Based on Piecewise Affine <i>H</i> <sub>∞</sub> Strategy
Cong Liang, Xing Xu, Daniel J. Auger, Feng Wang, Shaohua Wang
Abstract
A dual motor plug-in hybrid electric vehicle (DM-PHEVs) can achieve higher power and better fuel economy through Mode Transition Process (MTP) from pure electric to hybrid driving modes. In a DM-PHEV, the MTP is more complex, with more components to be managed. As well as being a combination of a discrete stage transition and a system with continuous state evolution, the several actuators exhibit significant discontinuous dynamics and different characteristics from each other, particularly mechanical hysteresis. This makes the design of a coordinated controller challenging. In this paper, a two-layer coordinated control strategy is proposed. The upper layer is based on a stage-dependent piecewise-affine (PWA) model which is used to develop a PWA-static output feedback H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> strategy (PWA-SOF). The lower layer is based on a simplified actuator lag model, and a H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> design technique is used to develop a robust torque controller that reduces the effect of mechanical hysteresis. The resulting strategy is described as a piecewise-affine modified static output feedback (PW-MSOF) algorithm. (While the individual elements are not novel contributions to control theory, the combination and application to this problem is.) Performance indices are defined and hardware-in-the-loop (HiL) test shows that the new controller can effectively suppress the vehicle jerk without adversely affecting other aspects of system behaviour.