State-of-Charge (SOC) and State-of-Health (SOH) Estimation Methods in Battery Management Systems for Electric Vehicles
Mohamed Rawidean Mohd Kassim, Wan Adil Wan Jamil, Roslee Mohd Sabri
Abstract
Consumers especially in developed nations have begun to aware that the carbon footprint left by fuel-combustion engine are dangerous to the environment. Based on these ground, the automotive industries are on the verge of migrating from fuel-combustion engine to fully electrical vehicles (EV). However, EV comes with a trade-off of battery overcharging and deep discharging. An efficient Battery Management System (BMS) guarantees the safe, reliable, efficient, and long-lasting operation of a battery. Furthermore, the BMS also provides information on the battery states, such as State of Charge (SOC) and State of Health (SOH). The SOC in BMS provides the percentage of battery capacity, while the SOH measures the battery health. In order to estimate crucial states of the battery system, BMS uses three critical measurements from the battery; voltage, current and temperature. The paper comprehensively present a review of common state estimation methods currently adapted by researchers in a BMS. Since SOC and SOH are strongly interrelated, both estimation methods are reviewed and discussed thoroughly. This paper also highlights various issues and challenges associated to SOC and SOH estimation with possible recommendations.