Modeling and Simulation of Vehicular Power Systems - webfiles its ...

power during acceleration and regenerative energy is a constraint in this type of hybridvehicle [11].2.4.2 Parallel Hybrid VehiclesIn this topology, figure 2-7 and 2-8, the main energy source and the secondary energysource are connected in parallel to the transmission system. It means that both the internalcombustion engine and the traction motor apply a torque to the shaft of the transmissionsystem. In this configuration the combustion engine is responsible to provide the tractionpower and the power needed to keep the battery charged. The performance and fueleconomy of the vehicles depend heavily on the applied energy management strategy.There are many energy management strategies used to improve the fuel economy of thevehicle [14]. One strategy is “on/off” or “Thermostat”. Under this strategy the engine willturn on and off based on the SOC status of the battery. There is another strategy called“power split”. Under this “Power Split” strategy the engine and the battery operate at thehigh efficient operating points. These operating points are selected based on theefficiency maps of the components. As the combustion engine is responsible to providemost of the traction power and also keep the state of charge of the battery (usually 65%)so the power rating of the ICE is higher than that of electric traction motor [14].Figure 2-7: Functional block diagram of a parallel hybrid vehicle9