Designing efficient hybrid electric vehicles

Hybrid electric vehicles (HEVs) are increasingly gaining popularity due to their lower fuel consumption. Current hybrid vehicles mostly use their battery or the energy storage system (ESS) as a secondary source of power. If the ESS were to be used as a primary source of power, then the ESS size would be one of the important features in the design of an HEV. In addition, HEVs have to employ an intelligent energy management strategy to provide the best fuel economy in all driving situations. This article presents an investigation on the effect of the variation of the ESS size on the fuel economy of an HEV and the important design criteria involved in the design of the ESS. Simulations carried out using advanced vehicle simulator (ADVISOR) software show that fuel economy is not linearly related to ESS size and therefore the ESS needs to be designed based on the average daily driving distance and the driver behavior.