DCT变速四驱HEV混动至纯电动模式切换优化控制

Optimal Control of Hybrid to Electric Mode Transition for DCT Four-wheel Drive HEV

双离合自动变速器(Dual clutch transmission,DCT)变速四轮分布式驱动混合动力汽车(Hybrid electric vehicle,HEV)直线行驶非紧急制动停车时,车辆常由发动机参与的前轮混合驱动模式切换至后轮轮毂电机纯电驱动模式,以提高整车能量转化效率。但该模式切换过程伴随着驱动转矩的前后轴转换和轴荷的前后转移,既涉及多动力源的转矩协调控制,也与车辆纵向动力学状态有关。若控制不当,常引起较大的车辆纵向冲击。针对DCT变速四驱HEV直线行驶工况混合动力至纯电动模式切换过程,基于5自由度车辆纵向动力学模型,利用ISG电机和轮毂电机转矩/转速快速响应的优势以补偿发动机转矩响应滞后以及离合器转矩波动,提出并开发了动力前后端多阶段切换过程模型预测优化控制策略。离线仿真及硬件在环试验结果表明,所开发的直线行驶工况模式切换模型预测控制策略不仅能较柔顺地完成动力由前轴向后轴的平滑过渡,将整车纵向冲击度限制在5 m/s^3以内,而且也对整车参数摄动和传感器量测噪声具有较好的鲁棒抑制作用。

When driving under non-emergency braking conditions in a straight line,dual clutch transmission(DCT)four-wheel drive hybrid electric vehicle(HEV)is often transited from the engine-worked four-wheel hybrid drive mode to the rear hub motor-worked electric drive mode to improve the energy conversion efficiency of the vehicle.However,the mode transition process is accompanied by the front-to-rear conversion of the driving torque and the load.The mode transition process involves both the torque coordinated control of the multi-power source and the vehicle longitudinal dynamics.If improperly controlled,it often causes a large longitudinal jerk of the vehicle.For the hybrid to pure electric drive mode transition process of DCT four-wheel drive HEV in straight driving condition,based on the five-degree-of-freedom vehicle longitudinal dynamics and the motor torque/speed fast response advantages to compensate for engine torque response hysteresis and clutch torque fluctuation,model predictive optimization control strategies for front and rear power sources transition process are developed.The off-line simulation and hardware-in-the-loop test results show that the proposed model predictive optimization control strategies can not only smoothly complete the transition of the power from front axle to rear axle,but also control the vehicle longitudinal jerk within 5 m/s^3.Besides,it also has a good robust suppression on vehicle parameter perturbation and sensor measurement noise.