A V2G Enabled Bidirectional Single/Three-Phase EV Charging Interface Using Modular Multilevel Buck PFC Rectifier

The battery charging power electronics interface of an electric vehicle (EV) must be capable of bidirectional power flow to enable both grid-to-vehicle (G2V) and vehicle-to-grid (V2G) operations. In the presence of a single/three-phase AC supply, the front-end of the EV charger employs a power factor correction (PFC) rectifier, which should have the bidirectional capability to facilitate V2G mode. A conventional active rectifier functions in boost mode while performing PFC and voltage regulation. In most of the currently available EVs, however, the battery nominal voltage is low and, hence, a downstream high step-down DC-DC converter and high voltage DC bus capacitor are required in the charging interface. To overcome these issues, this work proposes a bidirectional AC-to-DC buck rectifier topology that can operate in G2V and V2G modes, both in single- and three-phase versions. The proposed topology utilizes the switched capacitors principle to achieve self-balancing of voltages in the capacitors. In addition, it is highly modular in structure. This paper describes the proposed topology, its working and modulation and its applications. The hardware proto model is used to validate the proposed power converter and the control approach to achieve PFC and voltage regulation. In addition, a comparison with other topologies is presented to demonstrate its competence

Single-source three-phase switched-capacitor-based MLI

This article proposes a novel three-phase inverter based on the concept of switched capacitors (SCs), which uses a single DC source. A three-phase, seven-level line-to-line output voltage waveform is synthesised by the proposed topology, which includes eight switches, two capacitors, and one diode per phase leg. The proposed topology offers advantages in terms of inherent voltage gain, lower voltage stresses on power switches, and a reduced number of switching components. Additionally, the switched capacitors are self-balanced, thereby eliminating the need for a separate balancing circuit. The proposed structure and its operating principle, the self-balancing mechanism of the capacitors, and the control strategy are all thoroughly explained in the article. The proposed topology has also been compared with some recent SC topologies. Lastly, the proposed topology has been shown to be feasible through simulation and experimentation