A rule-based energy management strategy for parallel hybrid vehicles with supercapacitors

In order to improve the lifetime and performance of a hybrid electric vehicle, one of the most challenging tasks is to improve the performance of the electrical energy storage, regarding the electrical power and energy capacity. By introducing a supercapacitor as auxiliary source to increase the system power and to take over the battery stresses, the performance of the combined energy storage unit is improved. This paper introduces a completed model of energy storage system, including a pack of batteries, a pack of supercapacitors and a control strategy. The aim is to discharge the capacitors when the required power from energy storage is above a threshold meaning that the driver needs a boost of power for a period of time. Because of their high density of power supercapacitors have more efficiency in delivering it for short time. This has a positive impact on the fuel consumption and the state of charge at the end of the drive cycle.