A Three-Phase Interleaved AC-DC Converter Based Off-Board Battery Charger Station With Balanced Supply and Submodules Currents

This paper introduces an off-board charger designed for electric vehicles (EVs), capable of charging a wide range, from low-voltage to high-voltage EVs. The charger utilizes an interleaved AC-DC converter, where each supply phase connects to an interleaved buck-boost converter via an isolating transformer, followed by a bridge rectifier. To maintain balanced current operation, the control strategy incorporates three distinct control loops. The outer loop is responsible for regulating the output voltage of the charger, while the middle cascaded loop manages the battery charging current. The final control loop ensures that the grid current remains sinusoidal with a unity power factor. Additionally, a phase shift scheme for the interleaved switches has been proposed to minimize output current ripple. Moreover, an inductive current equalizer has been implemented to address varying current stress on the interleave inductances caused by mismatched inductance values. Furthermore, the charger features a modular design that allows it to function effectively even in the event of a failure in one of the boost submodules. The performance of the charger, along with its ability to operate as a level ‘3’ charger, has been evaluated using PSCAD/EMTDC simulation software and a scaled-down experimental prototype.