Design of DC-DC converter-based interfacing for Vanadium Redox Flow Battery

Abstract

This paper contains a design of a charge controller system for Vanadium Redox Flow Battery (VRFB) based on dc-dc converter schemes. The pulse width modulated boost converter has been chosen for this purpose because of its ability to regulate the dc output voltage with high efficiency and simple control. Contrary to normal batteries used in same applicable fields, the point of contention in designing a VRFB system charge controller happen to be that charging current of the battery and the compatible electrolyte flow rate for keeping overall system efficiency high, while achieving maximum charging efficiency and energy transfer rate. This charging system scheme was formulated and executed on a 6 kWh VRFB storage setup. The charging scheme that was implemented in this setup uses a 3-stage energy transfer algorithm, and practical optimization of solar irradiance profiles have been incorporated here. The equivalent electrical model of the scheme has been simulated and tested in computer simulation software like MATLAB and Simulink and the results have been used to further optimize the charging scheme. The performance parameters like output terminal voltage of the total battery system, state of charge (SOC), power consumed at charging, power output at discharge, etc. are analyzed in results. A generalized VRFB charging system is presented in this paper and thus can be very useful in solar PV power system in terms of scalable VRFB storage application.