A comparative evaluation of state‑of‑health estimation methods for lithium-ion batteries of electric vehicles

Zusammenfassung

The strengthening of enforcement of environmental laws and regulations has led to an acceleration in the worldwide switch to electrically-powered vehicles, commonly referred to as the “EV shift”, and consequently has escalated the importance of rechargeable batteries used as drive power for EVs. Lithium-ion batteries (LiBs), the most representative in automotive use because of their light weight, high energy and high power density, need a battery management system (EMS) to accurately estimate the condition of the battery, especially state of charge (SOC) and state of health (SOH) in order to ensure efficient, reliable and safe performance. In comparison with the number of research reports on SOC, there are relatively few reports on SOH, because establishing the correspondence between the characteristic parameters and battery health is considerably difficult. This paper focuses on synchronous estimation methods for SOC and SOH, takes a close look at their general principles and scope of application for an in-vehicle unit, then performs experimental evaluation through case study of LiBs with different deterioration properties.