Efficient Mode Transition Control for DM-PHEV With Mechanical Hysteresis Based on Piecewise Affine H∞ Strategy

A dual motor plug-in hybrid electric vehicle (DM-PHEV) can achieve higher power and better fuel economy through the 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 article, 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 (PWA-SOF)
${H_{\infty} }$
strategy. The lower layer is based on a simplified actuator lag model, and an
${H_{\infty} }$
design technique is used to develop a robust torque controller that reduces the effect of mechanical hysteresis. The resulting strategy is described as a PWA-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 are novel contributions.) Performance indices are defined, and the hardware-in-the-loop (HiL) test shows that the new controller can effectively suppress the vehicle jerk without adversely affecting other aspects of system behavior.