A Single Stage High-Frequency Rectifier for EV Charging Applications

Abstract

In this work, a single-stage three-phase rectifier topology with high-frequency isolation for EV (Electric Vehicle) fast-charging stations is proposed. By using a multipulse approach, low-order harmonics in the input current are shown to be eliminated over a wide range. A SST (Solid State Transformer) is used to create a HF (High-frequency) galvanic isolation for the system with respect to the MV (Medium Voltage) grid. The proposed topology has the following advantages: no bulky DC-link capacitor, HF galvanic isolation, high power density, and simple control scheme. The novelty of the proposed topology is its low complexity, ease of control and robust operation due to its inherited 12-pulse rectifier behavior. The approach is easily scalable to several hundreds of kilowatts and is ideal for driving high power Level-3 EV fast-charging stations. A simplified output voltage regulation scheme for the proposed topology is discussed. This output voltage regulation capability enables the circuit to be used as a single-stage topology for Level-3 charge stations with AC bus architecture. Furthermore, the topology can also be considered as an alternative to improve the power density in Level-3 charge stations with DC bus architectures. Experimental results on a scale down laboratory prototype at 208V, 2kW are discussed.