Increasing the power rating of electric vehicles (EV) fast charging stations to reduce charging times is considered critical to accelerate the adoption of electric vehicles. Besides increasing the power, other drivers pushing the development of EV fast chargers include the improvement of efficiency and reliability. Partial power converters (PPC) have emerged as an interesting option for some of the power converter stages in fast charging stations due to their potential to increase efficiency and power rating. However, some PPCs operate as switched autotransformers by using high frequency (HF) isolation transformers but without providing galvanic isolation. This is a drawback due to cost, size and losses introduced by the transformer. This paper presents a transformerless DC–DC Type I step-up PPC for a DC–DC regulation converter for EV fast charging stations. The proposed converter 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 is verified through simulations and experimentally validated with a laboratory prototype.

This paper proposes a new buck-boost flying-capacitor (FC) converter for the DC-DC stage of an Electric Vehicle (EV) fast charging station. The proposed converter is capable of delivering a wide output range of voltage to charge different battery configurations. The converter has two modes of operation, buck and boost. Thanks to this feature, the proposed converter allows higher efficiency and a wide operating range. The proposed converter is capable of supplying a voltage range from 200 V to 1000 V at its output, which shows the feasibility of occupying the converter inside a charging station that allows charging 400 V and 800 V battery systems. The average efficiency reported is over 97%. It is concluded that the proposed buck-boost FC converter is suitable for modern wide-output EV fast charging applications.

This paper proposes a new transformerless partial power converter for the DC-DC stage of a Electric Vehicle (EV) fast charging station. Partial power converters (PPC) are very attractive for this purpose thanks to their high efficiency. Based on this concept, it is proposed a new transformerless PPC using an impedance network instead of the transformer used in classical PPC. The proposed solution allows similar efficiency compared to traditional PPC, but improved power density since no transformer is required. Simulation results show the effectiveness of the proposed converter in both cases of 400V and 800V DC-DC fast charging stations. Efficiency of the proposed converter has been evaluated, and results show high efficiency over a wide range of operation, with a maximum of 98%. It is conclude that the proposed transfromerless partial power converter is suitable for EV fast charging application.

This paper presents a new partial power converter (PPC) for the DC-DC stage of electric vehicle (EV) fast charging stations. The proposed converter handles only a fraction of the total power delivered from the grid to the battery, increasing the overall system efficiency and power density, while potentially reducing the cost of the charger. The proposed topology is based on a switched capacitor between the AC terminals of an H-bridge converter, and does not require high frequency isolation transformers to provide a controllable voltage source between the DC-link and the battery. The proposed concept can be implemented using interleaved power cells, which can improve the power quality, reduce inductor size, and enable scalability for higher power rating chargers. The operating principle, partial operation analysis, control scheme, and simulation results are presented to validate the proposed concept.