The Fuzzy Torque Control Strategy for Parallel Hybrid Electric Vehicles

A novel fuzzy torque control strategy(FTCS) for parallel hybrid electric vehicles(PHEV) and its design method were presented.Based upon the operating modes of the hybrid powertrain,a fuzzy inference engine with 22 rules is constructed using the ratio of the driver torque request to the optimal engine torque and the battery state-of-charge(SOC) as the inputs,and the normalized electric machine(EM) torque as the output.It works as the kernel of a fuzzy torque distribution controller to determine the optimal distribution of the driver torque request between the engine and the EM to optimize the overall energy conversion efficiency of the PHEV.The simulation results reveal that,compared with the conventional strategy which uses precise threshold parameters,the proposed FTCS improves fuel economy and maintains battery SOC within its operation range more effectively.