New flexible bidirectional converter for electric vehicle substations connecting microgrids.

Abstract

This paper proposes a flexible and energy-efficient power conversion system capable of bidirectional energy flow between AC and DC microgrids, as well as electric vehicles (EVs). The converter is designed by integrating fundamental DC/DC topologies-namely Push-Pull and Half-Bridge converters-with a multi-level DC/AC inverter. It supports multiple operating modes, enabling seamless integration of both fixed and mobile EV charging stations through dedicated DC/DC charging interfaces tailored to various system configurations. A hierarchical multi-agent control strategy is employed, with clearly defined roles for each converter control component to enable coordinated operation across diverse use cases. Simulation results conducted in MATLAB demonstrate a high power factor of up to 96.5% during both EV charging and discharging processes to the interconnected microgrids. The system accommodates EV input voltages ranging from 350 to 1500 VDC and currents from 15 to 45 A, covering a wide range of medium to fast charging levels. The optimal switching frequency is determined through a detailed power loss analysis across input and output stages. The proposed converter offers a compact design, supports a wide range of voltage levels with low battery-side ripple, and ensures efficient bidirectional energy conversion between various grids.