Modeling and Control of a Three-Phase Interleaved Buck Converter as a Battery Charger

In this paper, a control design methodology is proposed for the implementation of a three-phase interleaved buck converter as a battery charger. The control strategy consists of a multiple-loop controller in cascade configuration to implement the constant-current constant-voltage (CC-CV) protocol for the fast charging of an electric vehicle (EV) battery. To compensate for the inherent asymmetric distribution of the current between the phases, the first control loop (inner loop) is dedicated to implement the democratic current sharing technique, while the two outer loops constitute a seamless controller, which allows a soft transition from CC mode to CV mode when charging the battery. The controllers are designed using the root locus method and conventional rules for cascade controllers. The design methodology is validated and tested by numerical simulations of the switched model system implemented in PSIM© software. The obtained results put in evidence a robust performance in front of input voltage and load variations, failure conditions and other parametric uncertainties. A 1.5 kW experimental prototype is implemented to charge a battery of 48 V from a 100 V DC input voltage and to validate the theoretical predictions and the simulation results. The proposal opens the way for subsequent research in ultrafast charging of batteries.