Fuel Consumption and Emission Reduction in a Hybrid Electric Bus Through Peak Power Management of the Auxiliary Power Unit

This study examines the impact of a fuzzy logic-based control strategy on managing peak power consumption in the auxiliary power unit (APU) of a hybrid electric bus. The APU comprises three components: an air compressor, a power steering system, and an air conditioning system (AC) connected to an electric motor. Initially, these components are simulated in MATLAB-SIMULINK software. While the first two are deemed dependent and independent of vehicle speed, respectively, the stochastic behavior of the steering is emulated using the Monte Carlo method. Subsequently, a fuzzy controller is designed and incorporated into the APU to prevent the simultaneous operation of the three accessories as much as possible. The results of repeated simulations demonstrate that the designed fuzzy controller effectively distributes the operation of the accessories throughout the driving cycle, thereby reducing overlaps in auxiliary loads. Consequently, the APU s average and maximum power consumption exhibit significant reductions. Furthermore, through multiple simulations with an upgraded power system model integrating the new APU-controller package, it is established that the proposed strategy for managing auxiliary loads in the bus leads to lower fuel consumption and emissions.