Dynamic Coordinated Control Based on Sliding Mode Controller During Mode Switching With ICE Starting for an HEV

Due to the friction-induced discontinuity of the clutch torque and ICE on/off, seamless mode transition of hybrid electric vehicles (HEVs) is difficult to achieve, which has a bad influence on the vehicle ride comfort. In the face of system uncontinuity and strong nonlinearity during mode switching with ICE starting, a control strategy of torque dynamic coordination is proposed by means of sliding mode control based on disturbance compensation. Firstly, the steady-state and transient models of parts and working modes are built, which improves modeling accuracy and adaptability to transient driving cycle. Furthermore, the switching process from pure electric driving to hybrid driving is divided into three phases including internal combustion engine (ICE) starting, speed synchronization and torque redistribution. The design of according disturbance observer and sliding mode controller is described in detail. Lastly, compared with other two control strategies, the rationality and validity of the control method designed are testified not only by computer simulations but also experimental tests under the comprehensive driving cycle of local passenger vehicles. The potential of the proposed control strategy in terms of power transfer smoothness and improving riding comfort is illustrated.