1. Large-capacity, Space-efficient Multiport Charging to Boost Uptake of EVs
Along with making electric vehicle (EV) charging systems smaller and lighter, Hitachi has developed more flexible ways of adjusting charging capacity and the number of charging ports. It has also produced a prototype 350-kW multiport EV charging system.
To reduce the size of the bulky transformer, Hitachi utilized silicon carbide (SiC) power electronics to develop a solid-state transformer (SST) with an operating frequency increased to 50 kHz. This achieved world-leading small size and light weight (as of October 2021, based on research by Hitachi, Ltd.), with a reduction of approximately 40% in installation footprint and 70% in weight.
A multi-level circuit was also developed that divides the 6.6-kV input voltage by arranging the power conversion units fitted with SST into blocks of seven connected in series. The charging system has three of these blocks for a total of 21 power conversion units, with output controlled by a switch that provides the flexibility to adjust the charging capacity and number of ports as required to meet user needs. When configured as 50-kW fast chargers, for example, the system can charge seven EVs at a time. Alternatively, the switch can also configure the system as a 350-kW ultra-fast charger for the rapid charging of an EV equipped with the large-capacity batteries that will likely become more common in the future.