Active SOC Balancing Structure Using Parallel Low-power DCDC Converter for Electric Vehicles

This paper presents an active state-of-charge (SOC) balancing structure using low power DC-DC converter for electric vehicles (EVs). In this architecture, multiple battery cells or modules are connected in series to provide regulated high power to the load through one single high-power converter. At the same time, several low power converters are connected in parallel with battery cells or modules to achieve active SOC balancing by regulating the duty cycles of each converter without extra balancing circuits. The outputs of all low power converters are connected together to charge another load (such as a 12V battery in EVs). Therefore, no extra energy is wasted during SOC balancing and the balancing speed can be increased compared with the conventional passive balancing method by utilizing resistors. The operational principle of the architecture and test results are provided and discussed all through the paper to verify and validate presented SOC balancing method.