基于模糊自适应滑模方法的混联式混合动力客车模式切换协调控制

Mode Transition Control for Series-parallel Hybrid Electric Bus Using Fuzzy Adaptive Sliding Mode Approach

在混联式混合动力汽车纯电动至并联驱动模式切换过程中,由于发动机、电动机及离合器瞬态特性的影响,可能导致动力系统输出转矩的突变从而使车辆产生较大的纵向冲击。以混联式混合动力客车为研究对象,考虑发动机和电动机瞬态响应特性的显著不同,针对离合器在结合过程中的运行状态,以提高驾驶性能为目标设计出混合动力客车纯电动至并联驱动模式切换协调控制策略。协调控制采用模糊自适应滑模方法,其中模糊自适应系统用于估计系统参数不确定性引起的偏差以及发动机实际输出转矩与目标转矩的偏差,估计出的偏差值用于调整滑模控制器的控制量,从而提高控制系统的控制精度和鲁棒性。通过仿真及实车试验验证控制策略的有效性。结果表明,设计的控制策略在模式切换过程中满足驾驶员动力需求的前提下使动力系统输出转矩的波动范围和最大冲击度分别下降85%和78%,从而显著提高了混合动力客车的驾驶性能。

Due to the transient characteristics of engines, motors, and clutches, the output torque fluctuations in hybrid poworains and the resulting vehicle jerks may occur during the transition from pure electric mode to parallel mode for series-parallel hybrid electric vehicles. A coordinated control strategy for a series-parallel hybrid electric bus is proposed to improve drivability during the transition from pure electric mode to parallel mode. The mode-transition control strategy is developed according to the operating status of the clutch, and on the consideration of the transient response characteristics of the engine and motor. In this control strategy, a fuzzy adaptive system is developed to estimate the uncertainties by varying parameters and the difference between the actual and target engine torques. Then, the estimated differences are utilized to regulate the control variables of the sliding mode controller to improve the control accuracy and robustness. Simulation and experimental results show that the range of torque fluctuations in the powertrain and the maximum vehicle jerk are reduced by 85% and 78% respectively while satisfying the driver＇s torque request during the mode transition with the proposed control strategy. Thus, the drivability of the hybrid bus can be significantly improved.