Multi-Stage CC-CV Charging of an Off-Board Charger Using Modulated Model Predictive Control

The most popular configuration for the off-board charging is a two-stage power conversion system, which consists of a three-phase, two-level voltage source rectifier (2L-VSR) followed by a non-isolated DC-DC buck converter. This paper presents a new duty-cycle controlled model predictive control (MPC) of 2L-VSR and buck converter to obtain a fixed switching frequency operation. This method optimizes the grid and battery currents based on duty cycles and cost functions. It combines the classical MPC's fast dynamic response with the traditional linear control's fixed switching frequency operation. To verify the feasibility of the developed MPC method, simulation studies are conducted on a 50 kW off-board charging system under constant current (CC) - constant voltage (CV) and multi-stage constant current (MSCC) charging profiles. Finally, the charger's performance using the proposed MPC method is compared with classical linear and MPC methods under the MSCC and CC-CV charging profiles.