Transformerless partial power converter topology for electric vehicle fast charge

Abstract

Increasing the power rating of electric vehicles (EV) fast charging stations to reduce charg-ing times is considered critical to accelerate the adoption of electric vehicles. Besidesincreasing the power, other drivers pushing the development of EV fast chargers includethe improvement of efficiency and reliability. Partial power converters (PPC) have emergedas an interesting option for some of the power converter stages in fast charging stationsdue to their potential to increase efficiency and power rating. However, some PPCs oper-ate as switched autotransformers by using high frequency (HF) isolation transformers butwithout providing galvanic isolation. This is a drawback due to cost, size and losses intro-duced by the transformer. This paper presents a transformerless DC–DC Type I step-upPPC for a DC–DC regulation converter for EV fast charging stations. The proposed con-verter replaces the transformer commonly used in Type I PPC by an impedance network,resulting in a more efficient, cheaper, and less complex converter option. This concept isverified through simulations and experimentally validated with a laboratory prototype