High Power Density Technologies on EV Bidirectional DC/DC Converters: Downsizing Effect using Close-Coupled Inductors

The development of Li-ion battery performance in next ten years will encourage improving a power density of Electric Vehicles (EVs). A higher voltage system with a boost voltage converter is favorable for the EV system if the converter has large power in small size. For increasing the converter power density, interleaved topologies using close-coupled inductors are shown to be superior. The inductor set of 3-phase type is proved to be smaller in size and lose less power in comparison to that of 2-phase type for high powered EV system having a 200∼400 volt battery. The prototype 3- phase converter using IGBT with 15 kHz switching frequency achieved a power density of 21.4 kW/liter at 120 kW output on a boost ratio of 1.38 with 98.0% efficiency, which also achieved more than 97% efficiency in a frequent usage zone.