A modular battery charger for electric vehicles

Over the next five years, there will be a substantial increase in the number of all-electric (EVs) and hybrid electric vehicles (HEVs). These vehicles will be utilizing onboard electrochemical energy storage devices (batteries) that require full or part recharging by connection to a low voltage utility network that supples domestic or light industrial users. Therefore a suitable uni- or bi-directional power electronic converter is needed to act as a battery charger and convert the AC supply to DC, or vice versa. This paper discusses the design of a 9kW battery charger that is modular, has a balanced three-phase input, is near unity power factor and has no electrolytic capacitors. Also 3 novel power converter snubber designs for use in a single phase leg of the battery charger are demonstrated. Important factors that dictate the design of such converters are discussed and simulation and practical results are considered.