Constant SOC control of a series Hybrid Electric Vehicle with long driving range

The efficiency improvement of Hybrid Electric Vehicle (HEV) is strongly dependent on the system-level control of the power flow in both the mechanical and the electrical paths of the vehicle. This is realized by the HEV control strategy. In this paper, a control strategy is proposed for a medium sized Series Hybrid Electric Vehicle (SHEV) designed for campus and gymnasium. The control strategy is composed of two parts: constant SOC control and driving range optimization. In constant SOC control, fuzzy logic is used to regulate the power flow and maintain the SOC of batteries always at a high level. Fuel economy and emissions are also considered by the controller. Both off-line and real-time simulations are performed and the results verify the design idea. In driving range optimization, Ant Colony Algorithm (ACA) is used to find the appropriate power sequence of Auxiliary Power Unit (APU). By comparing to thermostat control strategy, with the same fuel consumption the vehicle after optimization may have longer driving range.