Control development for a hybrid-electric sport-utility vehicle: strategy, implementation and field test results

The control strategy presented and evaluated was developed for a parallel hybrid vehicle designed for the FutureTruck 2000 competition. The control strategy implemented focuses on fuel efficiency optimization in the context of charge-sustaining operation. It is based on an equivalent consumption minimization strategy, accounting for both the actual fuel cost and a suitably formulated equivalent fuel cost for the electric machine. This formulation leads to an instantaneous univariate minimization, which allows one to minimize the fuel consumption while meeting the driver demand and nominally maintaining the state of charge. Actual road test results are presented, demonstrating significant fuel economy gains and charge-sustaining operation. The same formalism is then extended for emission reduction by use of suitably designed penalty function to account for the engine-out emissions added to the equivalent fuel cost. The results indicate that it is possible to reduce NO_x emissions by more than 10% without significantly degrading fuel economy