Emissions and fuel economy trade-off for hybrid vehicles using fuzzy logic

In this paper, a generalized fuzzy logic controller (FLC) is used to optimize the fuel economy and reduce the emissions of hybrid vehicles with parallel configuration. Using the driver input, the state of charge (SOC) of the energy storage, the motor/generator speed, the current gear ratio and vehicle speed, a set of 44 rules have been developed, in a fuzzy controller, to effectively determine the power split between the electric machine and the internal combustion engine (ICE). The underlying theme of the fuzzy controller is to optimize the fuel flow and reduce NOx emission. The parameters in the fuzzy rules can be adjusted to trade-off the fuel economy and the NOx emission of the vehicle. Simulation results are used to assess the performance of the controller. A forward-looking hybrid vehicle simulation model is used to implement the control strategies. By using fuzzy logic, trade-off between fuel economy and emission improvement has been shown. (C) 2003 IMACS. Published by Elsevier B.V. All rights reserved.