Trajectory Optimization-Based Auxiliary Power Unit Control Strategy for an Extended Range Electric Vehicle

Abstract

In the pursuit of fuel economy improvement and emission reduction, a trajectory optimization-based engine multioperating-point control strategy is proposed in this paper for the auxiliary power unit (APU) in an extended range electric vehicle. This strategy design deeply considers the transient process of the operating point switching that somehow influences the engine fuel economy and emission, and was often ignored. First, a combined cost MAP fully integrating several indices, including fuel consumption rate, CO, HC, and NOx emissions, is presented to synthetically evaluate the effect of the operation trajectory. Then an improved genetic algorithm, in terms of computational load reduction and convergence improvement, is employed to optimize the engine trajectory in the transient operating point switching process of the APU system, so that it is able to perform with the best fuel consumption and emissions. Finally, simulated and experimental results indicate that the proposed control strategy has obvious improvements in fuel economy and emissions, compared with conventional ones.