Method and apparatus for controlling the voltage of electrochemical cells in a rechargeable battery

a technology of electrochemical cells and batteries, applied in the direction of batteries, instruments, transportation and packaging, etc., can solve the problems affecting the performance of the battery, etc., to achieve the effect of reducing the voltage across the terminal

US20040251874A1Inactive Publication Date: 2004-12-16SAFT GRP SA
1 Cites 25 Cited by

Patent Information

Authority / Receiving Office
US · United States
Patent Type
Applications(United States)
Current Assignee / Owner
Publication Date
2004-12-16
Estimated Expiration
Not applicable · inactive patent
Patent Text Reader

Abstract

An apparatus is dedicated to controlling the voltage of a battery comprising at least two modules connected in series and each comprising at least one electrochemical cell, and each coupled to voltage balancing means. The apparatus comprises measurement means for determining first voltages across the terminals of each of the modules, calculation means for measuring a second voltage across the terminals of the battery and for determining a mean voltage per module representative of the second voltage divided by the number of modules, and processor means for comparing each measured first voltage with the mean voltage per module and for delivering to the balancing means signals representative of the result of the comparison whenever the first voltage of a module is greater than the mean voltage, such that the balancing means reduce the voltage across the terminals of the module.
Need to check novelty before this filing date? Find Prior Art

Description

[0001] The invention relates to the field of batteries of electrochemical cells, and more particularly to the field of apparatus for controlling the voltage of the electrochemical cells in certain rechargeable batteries.

[0002] As is known to the person skilled in the art, the voltage measured across the terminals of a battery depends on the state of charge of the electrochemical cells (also known as "secondary" or "rechargeable" cells, or even "accumulators") which constitute modules of the battery. The state of charge of the electrochemical cells is thus subject to continuous monitoring by voltage control apparatuses. More precisely, such apparatuses are designed to ensure that the electrochemical cells are not subjected to overcharging or to deep discharges that reduce battery performance, and above all that limit battery lifetime.

[0003] This applies in particular to the voltage control apparatus described in patent document EP-0 691 725. That apparatus comprises n-1 regulators as...

Examples

Embodiment Construction

[0027] The accompanying drawings contribute not only to describing the invention, but may also contribute to defining it, where appropriate.

[0028] The invention relates to controlling the voltage of a rechargeable battery comprising at least two modules connected in series, with each module comprising at least one electrochemical cell.

[0029] In the example shown in FIG. 1, the battery BAT comprises modules Mi (where i=1 to N, N not being less than 2; e.g. N=15), each module comprising an electrochemical cell Gi, e.g. a rechargeable lithium-ion (Li / Ion) type cell. However the invention also applies to batteries of modules Mi each comprising a plurality of electrochemical cells Gij connected in series and / or in parallel. Furthermore, the invention also applies to types of electrochemical cell other than lithium cells, and in particular it applies to silver / zinc cells and to polymer cells, and in general it applies to all batteries in which the various electrochemical cells need to pre...