An Aging-Compatible Inductor-Based Equalization Mechanism for LFP Batteries

Abstract

This paper proposes an aging-compatible inductor-based equalization mechanism for LFP batteries. Due to the characteristic of flat voltage curve, voltage equalization does not always successfully balance a series-connected battery pack. The proposed inductor-based equalization mechanism is developed to smartly balance battery voltage in the right state-of-charge (SOC) region regardless of the extent of battery aging deterioration. The mechanism includes two parts: one is balancing trigger voltage search, and the other one is the balancing current control. Experimental results show that the proposed equalization mechanism can increase the 8.4% storage capacity of the fresh cell and the 3.6% storage capacity of the aging cell. The conventional equalization can increase the 8.3% storage capacity of the fresh cell but decrease the 2.7% storage capacity of the aging cell. The experimental results also prove that equalization at different stages are not always beneficial. Using the aging-compatible inductor-based equalization mechanism can obtain a better balancing performance.