Real-Time Discharge/Charge Rate Management for Hybrid Energy Storage in Electric Vehicles

Abstract

Electric vehicles (EVs) are equipped with a large number of expensive battery cells, necessitating an effective battery management system (BMS) which protects the battery cells from harsh conditions while providing the required power efficiently. The discharge/charge rate affects battery health significantly, and existing BMSes employ simple discharge/charge rate scheduling so as to prevent weak cells from excessive discharge/charge. In this paper, we design and evaluate the real-time management of battery discharge/charge rate to extend battery life for EVs based on the physical dynamics and operation history of batteries. We first explore a modern energy storage system for EVs to capture physical dynamics and their impact on the battery discharge/charge rate, for example, a regenerative braking system for reusing the dissipated energy leads to current surges into the batteries, which shortens battery life. Based on understanding of the effects of discharge/charge rate in an energy storage system, we devise control knobs for manipulating the rate. Then, we design an adaptive discharge/charge rate management algorithm that determines the control knobs with a reconfigurable energy storage architecture. Our in-depth evaluation results demonstrate that the proposed discharge/charge rate management improves battery life up to 37.7% at little additional cost over the existing energy storage systems.