Fuzzy Rule-Based Energy Management Strategy for a Parallel Mild-Hybrid Electric Bus

In response to increasingly stringent emissions regulations that seek to minimize the use of fossil fuels, there is a significant desire for alternative drivetrain technologies that are capable of vastly reducing fuel consumption. One such technology that has received considerable interest is hybrid electric vehicles. City buses are ideally suited for hybridization due to the potential to recover significant kinetic energy during the frequent stop/start events typically experienced by a city bus. The fuel economy and emissions benefits of a hybrid electric vehicle are largely determined by the performance of the energy management strategy employed on the vehicle. Within this paper, a specific hybrid electric bus is introduced, and a new fuzzy rule-based energy management strategy to determine the motor torque request during acceleration and cruise events is proposed. The proposed strategy is evaluated using a validated vehicle model and the MLTB drive cycle. Results from simulation indicate a 2.2% cumulative fuel consumption reduction in comparison to the existing energy management strategy present on the physical vehicle. The results from this test demonstrate that the proposed strategy is capable of reducing the fuel consumption and emissions on this vehicle.