Single-Phase Grid Forming Control Strategy for an Isolated and Bidirectional EV Battery Charger

Abstract

This paper proposes a novel approach to implement a single-phase grid-forming (GFM) control strategy in an isolated two-stage DC-AC structure, intended for an Electric Vehicle Bidirectional Charger (EVBC). The structure is composed of a voltage source inverter (VSI) cascaded to a dual-active-bridge series-resonant (DABSR) DC-DC converter. In the proposed approach, the VSI implements the GFM strategy whereas the DABSR controls the DC-Link voltage. Since VSI implements a GFM control strategy, the "Vehicle-to-everything" (V2X) functionalities can be validated with a unique control strategy. Design criteria are given for the DC-Link voltage controller, active-reactive power controllers and droop controllers. The control strategy was validated in a 2.2kW test setup and for a stand-alone vehicle-to-home (V2H) mode.