Design of a transformer for high power density charger — Electric vehicles application
Résumé
This paper discusses the design of a high power density transformer for a high-frequency DC-DC charger for electric vehicles (EV). Because transformer is an important part of bulky components in charger, efforts are concentrated on it. In classical transformer design, core shape and windings are determined by the charger specifications. The best design is chosen according to core and copper losses. With the use of new GaN transistors, some charger specifications can be widely improved such as switching frequency and power level. A simulation model is built to optimize transformer in different operating points in order to find the most compact transformer. The model is verified by measurements on a transformer prototype. Finally, a 7.3kW transformer with a volume of 27cm 3 is chosen. At this power level, transformer losses are around 20W at 500 kHz achieving around 99.7% efficiency. Resulting transformer power density is 270kW/dm 3 .