Engine torque command handling for a series hybrid electric bus

The series hybrid electric vehicle makes it easier to have fully independent controls for the engine–generator unit and for the traction motors; this is not feasible in parallel hybrid electric vehicles or series–parallel hybrid electric vehicles. The existing research does not consider this feature. Therefore, a novel control method called engine torque command handling is developed in this study and is added to the optimal energy management strategy, namely dynamic programming; this makes the most of the inertia of the engine–generator unit. The hidden fuel economy improvement factor, as demonstrated by the the difference between the command and the behaviour, can then be found. As a result, a considerable improvement in the fuel economy with straightforward but powerful concepts, such as modification of the engine operating points and the on–off period, is developed in the series hybrid electric bus. The simulation is evaluated by AMEsim–Simulink co-simulation with the well-known urban bus test profiles: the Manhattan cycle, the Braunschweig cycle and the Orange County cycle. The results show the significant potential for reduction in the energy consumption without changing the components or the structure of the vehicle system. This method can be applied to any type of vehicle that allows independent engine power generation without interruption.