Charge equalization for series connected battery strings

Journal Article · Mon May 01 04:00:00 EDT 1995 · IEEE Transactions on Industry Applications

DOI:https://doi.org/10.1109/28.382117· OSTI ID:55487

Kutkut, N H; Divan, D M; Novotny, D W ^[1]

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1. Univ. of Wisconsin, Madison, WI (United States). Dept. of Electrical and Computer Engineering

A simple technique that provides charge equalization for a series string of battery cells is presented. The advantages of accurate charge equalization are very substantial and include reduced damage to battery cells in the stack, and a dramatic increase in battery life. The basic technique utilizes a simple isolated dc/dc converter with a capacitive output filter along with a multi-winding coaxial winding transformer (CWT). The coaxial winding transformer is known for its low and controlled leakage inductance. The transformer leakage inductance is used as the main driving impedance to control the total charging current for the individual cells. The use of one low-power converter to obtain charge equalization for the entire battery string is very attractive and leads to a low cost implementation. Applications such as electric vehicles (EV`s) will be using series connected battery strings with bus voltages in the range of 300 V to realize the main motive power source. Battery life is one of the major factors presently limiting the realization of economically viable EV`s. Series connected battery strings are prone to dramatic reduction in life and potential damage if high-rate charging is continued after the onset of gassing. Maintenance of cells at an equalized charge level is critical for enhancing battery life. This paper proposes a simple low-cost approach to implement charge equalization for a series connected battery string.

• OSTI ID: 55487
• Journal Information: IEEE Transactions on Industry Applications, Journal Name: IEEE Transactions on Industry Applications Journal Issue: 3 Vol. 31; ISSN 0093-9994; ISSN ITIACR
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
BATTERY CHARGE STATE
BATTERY CHARGERS
ELECTRIC BATTERIES
ELECTRIC-POWERED VEHICLES
SERVICE LIFE