Hybrid Energy Storage System Based on a Novel Reduced Rating Multi-Input Converter

Abstract

Batteries are assisted by supercapacitors (SC) to supply the surge power requirement of the loads, which can be much larger than the steady-state power and severely deteriorate the battery life. A novel multi-input converter (MIC) is proposed in this article for interfacing a battery-SC combination, also known as hybrid energy storage system (HESS) that reduces the required converter rating to meet the surge power needs of the load. In a conventional active HESS, individual interfacing converters are used, where generally, the SC supplies the complete surge power. Therefore, the SC converter is mostly rated for the full surge power, which leads to a costly system. In the proposed converter, the SC is connected to the load through a series-connected converter during surge loading, which reduces the required converter power rating and ensures the SC utilization over a wide voltage range. Under normal loading conditions, the battery is operated in current control mode such that the battery current does not experience a sudden rise in case of load changes, which enhances its life. The load voltage is controlled by the SC. The operation of the proposed converter is validated under normal, surge, and negative loading through experiments on a lab prototype.