Bidirectional Charging Unit for Vehicle-to-X (V2X) Power Flow

Due to demand for decreasing CO2 emission and improving fuel-efficiency of vehicles, research and development of electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs) is being revitalized worldwide. In advance of widespread use of EVs and PHEVs, Europe, United States and Japan have cooperated and worked on the international standardization of the vehicle charging system. We have participated in this standardization activity since 2009. Conventionally, such standardization has pushed forward a viewpoint to charge on-board batteries with grid power. In contrast, in the near future, the concept of vehicle-to-X (V2X), which transmits electricity from an onboard battery to infrastructure, is expected to spread. V2X is a collective term for such as, vehicle to live (V2L), vehicle to home (V2H), and vehicle to grid (V2G) and expresses the power flow from vehicles to others (Fig. 1). For example, V2L is expected, as an emergency power source, to supply electricity from a vehicle to electric appliances directly. V2H and V2G technologies have started to be put to practical use, with the aim of demand peak-cut control, power distribution at electricity failure, and stabilization of grid power. Various demonstration experiments have been carried out and such technologies are now partly in use. To realize these concepts, we have developed various technologies related to EVs, PHEVs and infrastructure, such as wiring harness, connectors, communication units and electric power converters. This paper introduces our EV and PHEV bidirectional charging unit to be used for “V2X” power flow.