Multilevel Inverter for EV Charging via Hybrid Storage Unit (Fuel Cell, Battery, Ultracapacitor)

This paper deals with the design and numerical simulation of a multilevel inverter used for EV charging. A mobile charging station (MCS) is our application. The MCS is to be analyzed while being equipped with a fuel cell, and/or battery, and/or a supercapacitor, used to transfer the electric energy towards a battery type EV. A high-power multilevel inverter topology is proposed, to assure up to 43 kW ac charging (also called the 3<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rd</sup> ac charging mode), while complying with the IEC 61000-2-2 standard in terms of harmonic and amplitude for the 3-phase currents and voltages. For ordinary two-level inverters, a high power (with important costs and volume) LCL filter is needed. The motivation of using the multilevel converter (a 3-level one) resides on the necessity of assuring the charging energy quality standard with reduced volume, mass and cost for the filter, while accepting a more complex converter structure (with double number of switches). The study will be focused on the topologies of multilevel inverters (especially on the 3-level inverter), on the design of its filter and on the simulated results, while considering different storage units (fuel cell, battery and supercapacitor), in the 3<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rd</sup> ac charging mode of EVs.