Title of Invention

METHOD FOR CONTROLLING A RECHARGEABLE BATTERY AND RECHARGEABLE BATTERY FOR CARRYING OUT SAID METHOD

Abstract A method of controlling a rechargeable battery (1) comprising at least two modules (2a, ..., 2n) of electrochemical cells (3a, ..., 3p) connected in series, the electrochemical cells (3a, ..., 3p) being connected in parallel to each other within each module (2a, ..., 2n) and each module (2a, ..., 2n) of electrochemical cells (3a, ..., 3p) comprising a charge limiting circuit (4) for said module connected in parallel to said module, the method comprising the following steps: - (a) detecting a defective module (2a,..., 2n); - (b) having a discharge current pass through the defective module (2a, ..., 2n) so as to provoke an electrochemical reaction in the defective module (2a, ..., 2n), said reaction resulting in the formation of a short-circuit path between connection terminals of said defective module; - (c) using the battery (1) by passing an electric current, generated by the discharging of at least one module (2a,..., 2n) different from the defective module (2a, ..., 2n), through said defective module (2a,..., 2n); and being characterized in that a first partial discharge of the defective module (2a, ..., 2n) is performed before the step (b), a partial discharge current of the defective module (2a, ..., 2n) passing through the charge limiting circuit (4) of said defective module (2a,..., 2n), and being controlled by variation of a reference signal for the charge limiting circuit (4) of said defective module.
Full Text

The present invention relates to a method of managing a rechargeable battery
and a rechargeable battery suitable for implementing this method.
It relates more particularly to a method of managing a rechargeable battery
comprising at least two modules of electrochemical cells connected in series,
the electrochemical cells being connected in parallel to each other within each
module.
European Patent no. EP0498679 (A2) describes the terminal voltages of
battery cells 10-1 to 10-n constituting a set battery 10 are individually
monitored by cell-voltage detecting circuits 11-1 to 11-n and input to a current
control circuit 12. The current control circuit 12 detects any of the monitored
terminal voltages that attains a level indicating a fully charged state. A variable
constant-current control circuit 13 supplies a charging current ICH by
regulating power output by a main power supply 14. As the current control
circuit 12 detects a state in which one of the battery cells 10-1 to 10-n gets fully
charged, the variable constant-current control circuit 13 stops charging current
into the set battery 10.
Nevertheless, in such a battery, a defective cell continues to be passed through
by the current delivered by the battery. This causes the defective cell to heat up
and the efficiency of the battery as a whole to drop.
To avoid this drawback provoked by the presence of a defective cell within a
battery, the use of a device as represented in figure 1 to neutralize a cell or a
cell module that has become defective is known.
In figure 1, a battery 10 comprises n modules referenced 20a, ..., 20n,
connected in series to each other. Each module is itself made up of several
electrochemical cells referenced 30a, ..., 30p. The cells 30a, ..., 30p are
connected in parallel to each other within each module. Each module 20a, ...,
20n of cells also comprises a charge limiting circuit 40. At the input of each
module 20a,..., 20n, a switch 50 makes it possible to divert all the current that

passes through the battery into a module bypass branch. Thus, when a cell of a
given module becomes defective, the control of the corresponding switch
makes it possible to neutralize this module, so that the battery current no longer
passes through it. Such a battery arrangement comprises numerous electrical
and electronic components which make it cumbersome, costly and heavy.
These drawbacks are incompatible with many battery uses, including in
particular the energy supply for a satellite.
One aim of the present invention is to overcome these drawbacks.
For this, according to the invention, a method of the type concerned is
characterized in that it comprises the following steps:
- (a) detecting a defective module;
- (b) having a discharge current pass through the defective module so as to
provoke an electrochemical reaction in the defective module, said
reaction resulting in the formation of a short-circuit path between
connection terminals of said defective module;
- (c) using the battery by passing an electric current generated by the
discharging of at least one module different from the defective module
through said defective module.
With these arrangements, there is no need to provide a switch nor a bypass
branch for each module, designed to be activated when a cell of the module
becomes defective. The battery is therefore simpler, more lightweight and less
costly. In practice, with the formation of the short-circuit path between the
terminals of the module which includes the defective cell, this module is
neutralized internally. The operation of the other modules of the battery is then
not disturbed by the module which includes the defective cell.
In various embodiments of the inventive method, it is also possible to use one
or several of the following arrangements:

- the cells are of the lithium-ion type;
- the discharge current provoking the reaction forming the short-circuit path is
generated by the discharging of at least one module of the battery different
from the defective module;
- the discharge current provoking the reaction forming the short-circuit path is
also used to power a device external to the battery;
- a first partial discharge of the defective module is performed before step (b);
- each module of electrochemical cells comprises a charge limiting circuit for
said module, connected in parallel to said module, and the partial discharge
current from the defective module passes through the charge limiting circuit of
said defective module;
- the partial discharge current from the defective module is controlled by
variation of a reference signal for the charge limiting circuit;
- the discharge current provoking the reaction forming the short-circuit path in
the defective module generates a reversal of the defective module;
- the short-circuit path comprises conductive dendrites formed in at least one
cell of the defective module;
- the conductive dendrites are metallic;
- the number of cells per module is between 3 and 13; and
- the number of modules in the battery is between 9 and 24.

The invention also proposes a rechargeable battery comprising at least two
modules of electrochemical cells connected in series. The electrochemical cells
are connected in parallel to each other within each module. Each module also
comprises a charge limiting circuit for said module connected in parallel to said
module, which comprises:
- a bypass branch connected between an input terminal and an output terminal
of the corresponding battery module;
- a reference signal source;
- a regulating device suitable for controlling a current in said bypass branch on
the basis of a control signal received on a control terminal of the regulating
device; and
- at least one differential operator comprising an output terminal linked to the
control terminal of the regulating device, a first input terminal connected to
receive a signal representative of the voltage at the terminals of said module of
the battery, and a second input terminal connected to receive said reference
signal, the differential operator being suitable for generating the control signal
according to a difference between the signals received on said first and second
input terminals of the differential operator;
the battery being characterized in that the reference signal source of each
battery module can be varied.
In various embodiments of the inventive battery, it is also possible to use one
or several of the following arrangements:
- the bypass branch comprises at least one resistive element;
- the signal representative of the output voltage of each module is obtained by a
voltage divider bridge connected in parallel to said module;

-the battery comprises at least one radio receiver, the respective reference
signal sources of the modules of electrochemical cells being linked to the radio
receiver, and suitable for varyng the corresponding reference signal according
to a received radio control;
- the differential operator of each charge limiting circuit comprises a feedback
loop;
- the feedback loop comprises a resistor and a capacitor connected in series;
- the regulating device of the charge limiting circuit of each module comprises
at least one transistor, said transistor having two main terminals connected to
the bypass branch of said module;
- the regulating device of each charge limiting circuit comprises at least two
associated transistors in Darlington configuration;
- the number of cells per module is between 3 and 13; and
- the number of modules per battery is between 9 and 24.
Moreover, another subject of the invention is a satellite that comprises at least
one battery as described previously.
The satellite can also include a defective module detector and a radio
transmitter arranged to transmit identification codes of a defective module in
the battery.
The satellite can also include a radio receiver to which are linked the reference
signal sources of the modules of cells, each reference signal source being

suitable for varying the corresponding reference signal according to a received
radio control.
Other features and advantages of the invention will become apparent from the
following description of one embodiment, given by way of nonlimiting
example, in light of the appended drawings.
In the drawings:
- figure 1, already described, represents a battery as known from the prior art;
- figure 2 represents a battery according to the invention;
- figure 3 is a diagram showing the trend of the voltage at the terminals of a
battery module on implementing a battery management method according to
the invention; and
- figure 4 is an electrical circuit diagram of a charge limiting circuit that can be
used to implement the invention.
In figure 2, a battery 1 comprises several modules 2a, ..., 2n, connected in
series to each other. Each module 2a,..., 2n can itself comprise several cells 3a,
..., 3p connected in parallel to each other. The cells 3a, ..., 3p can be of the
lithium-ion type.
A charge limiting circuit 4 is connected to the terminals of each of the modules
2a, ..., 2n. This makes it possible to avoid an overload of the module to which it
is connected. With reference to figure 4, each charge limiting circuit 4
comprises a bypass branch, which comprises at least one resistor 5. A
regulating device 6 controls the current in the resistor 5 based on a control
signal delivered by a differential operator 7. This differential operator 7

comprises two input terminals and one output terminal. The first input terminal
of the differential operator 7 is connected to a reference signal source 8, such
as, for example, a voltage source. The second input terminal is connected to the
intermediate point of a voltage divider bridge, itself connected in parallel
between the terminals of the cell module. Thus, the second input terminal of
the differential operator 7 receives a signal representative of the voltage at the
terminals of the module, namely a predetermined fraction of the latter. The
output terminal of the differential operator 7 is linked to the control input of the
regulating device 6.
A feedback loop 9 links the second input terminal to the output terminal of the
differential operator 7. This feedback loop 9 can be of the proportional integral
loop type, which comprises a resistor connected in series with a capacitor. Such
a feedback loop 9 provides the charge limiting circuit 4 with a particularly
suitable response dynamic range. In particular, with such a feedback loop, the
load current of the module is progressively tapped by the bypass branch, in a
proportion that increases as the voltage between the terminals of the module
approaches the saturation voltage.
The regulating device 6 can comprise transistors connected in a Darlington
configuration. Such a cascaded transistor configuration provides an operating
characteristic with progressive transition between a first state, in which no
current passes through the bypass branch, and a second state, in which all the
battery charge current is conducted by the bypass branch.
Furthermore, the Darlington configuration makes it possible to interlink two
levels of the regulating device 6: a first level, called control level, comprising
the differential operator 7, the reference signal source 8, the feedback loop 9
and the voltage divider bridge, and a second level, called power level,
comprising the bypass branch.


The charge limiting circuit 4 has two functions. On the one hand, it prevents
the overloading of the electrochemical cells of the module. When the cells 3a,
..., 3p of the module are all charged, the voltage at the terminals of the module
is equal to the saturation value. The voltage representative of the charge of the
module is compared with the reference voltage supplied by the reference
source 8. When it is greater than a predetermined threshold, for example 4V in
the case of a lithium-ion battery, the differential operator 7 controls the
regulating device 6 so that the charge current is tapped in the bypass branch.
Thus, an overload of the cells of the module is avoided.
Also, the charge limiting circuit 4 makes it possible to provoke the formation of
a short circuit in a module of the battery that has become defective. For this, a
suitable detector identifies a defective module on the basis, for example, of the
voltage, the pressure, the temperature and/or the current of each module of the
battery. It transmits an identification of the defective module to a control
station which, in return, produces a defective module neutralization control.
On receiving this control, the voltage source 8 reduces the reference voltage so
as to partially discharge the defective module. The new reference voltage can
be 3V, for example, in the case of a lithium-ion battery. The voltage at the
terminals of the defective module is then greater than the reference voltage.
The differential operator 7 then controls the switching of the regulating device,
and the transistors of the bypass branch become conductive. The current that
passes through the resistor 5 provokes the discharging of the cells of the
defective module. This corresponds to the phase 1 indicated in the graph of
figure 3. During this discharge, the current Id in the charge limiting current can
be roughly constant. The voltage at the terminals of the module drops
according to the characteristic discharge curve of a battery. When the voltage at
the terminals of the module reaches the value of the reduced reference voltage,
it is possible, if necessary, to stop this discharge by increasing the voltage of


the reference signal again. A waiting phase 2 is possible. During this phase 2, a
next use of the battery by the satellite is awaited.
When this battery is used (phase 3) to power an external device, the current
Imodule from the module increases. This discharge current can be roughly
constant, according to the usage conditions of the latter. It passes through the
battery, provoking an overdischarge of the electrochemical cells of the
defective module. During this phase, the voltage at the terminals of the
defective module can be reversed, that is, become negative. This is what is
called the reversal effect. For a battery of the lithium-ion type, this reflects the
formation of metallic dendrites in at least one of the cells of the defective
module. The size of the dendrites increases as long as the overdischarge current
is maintained, until a short-circuit path is formed between the electrodes of one
of the cells of the defective module.
When the metallic dendrites form a bridge between the electrodes of an
electrochemical cell, a short circuit appears (phase 4 of figure 3). The defective
module, duly short-circuited, is equivalent to a conductor wire of low
resistance, of the order of 10 mΩ, for example.
Such a battery is suitable for use on board a satellite. A satellite normally
comprises a radio transceiver for communicating with a ground control station.
This radio transceiver is arranged to send the identification of the defective
module to the control station, which, as appropriate, returns a control to
neutralize the defective module.
The number of modules that make up the battery is fixed by the power supply
voltage of the device powered by the latter. Thus, normally, the battery consists
of 9 to 24 modules.


Moreover, the number of electrochemical cells in each module depends on the
intensity of the power supply current that has to be delivered. Furthermore, it is
preferably not too high, given that the failure of a cell causes the entire module
to be neutralized. Normally, the number of cells per module is between 3 and
13.

WE CLAIM:
1. A method of controlling a rechargeable battery (1) comprising at least
two modules (2a, ..., 2n) of electrochemical cells (3a, ..., 3p) connected
in series, the electrochemical cells (3a, ..., 3p) being connected in
parallel to each other within each module (2a, ..., 2n) and each module
(2a, ..., 2n) of electrochemical cells (3a, ..., 3p) comprising a charge
limiting circuit (4) for said module connected in parallel to said module,
the method comprising the following steps:
- (a) detecting a defective module (2a,..., 2n);
- (b) having a discharge current pass through the defective module
(2a, ..., 2n) so as to provoke an electrochemical reaction in the
defective module (2a, ..., 2n), said reaction resulting in the
formation of a short-circuit path between connection terminals
of said defective module;
- (c) using the battery (1) by passing an electric current, generated by
the discharging of at least one module (2a,..., 2n) different from
the defective module (2a,..., 2n), through said defective module
(2a,..., 2n);
and being characterized in that a first partial discharge of the defective
module (2a, ..., 2n) is performed before the step (b), a partial discharge
current of the defective module (2a, ..., 2n) passing through the charge
limiting circuit (4) of said defective module (2a, ..., 2n), and being
controlled by variation of a reference signal for the charge limiting
circuit (4) of said defective module.
2. The method as claimed in claim 1, wherein the cells (3a, ..., 3p) are of
the lithium-ion type.
3. The method as claimed in claim 1 or 2, wherein the discharge current
provoking the reaction forming the short-circuit path is generated by the

discharging of at least one module (2a, ..., 2n) of the battery (1) different
from the defective module (2a,..., 2n).
4. The method as claimed in claim 3, wherein the discharge current
provoking the reaction forming the short circuit path is also used to
power a device external to the battery (1).
5. The method as claimed in any one of the preceding claims, wherein the
discharge current provoking the reaction forming the short-circuit path
in the defective module (2a, ..., 2n) generates a reversal of the defective
module (2a,..., 2n).
6. The method as claimed in any one of the preceding claims, wherein the
short-circuit path comprises conductive dendrites formed in at least one
cell (3a,..., 3p) of the defective module (2a, ..., 2n).
7. The method as claimed in claim 6, wherein the conductive dendrites are
metallic.
8. The method as claimed in any one of the preceding claims, wherein the
number of cells (3a,..., 3p) per module (2a,..., 2n) is between 3 and 13.
9. The method as claimed in any one of the preceding claims, wherein the
number of modules (2a, ..., 2n) in the battery (1) is between 9 and 24.
10. A rechargeable battery (1) for implementing the method as claimed in
one of the preceding claims, comprising at least two modules (2a,..., 2n)
of electrochemical cells (3a, ..., 3p) connected in series, the
electrochemical cells (3a, ..., 3p) being connected in parallel to each
other within each module, each module (2a, ..., 2n) also comprising a

charge limiting circuit (4) for said module (2a, ..., 2n) connected in
parallel to said module, each charge limiting circuit (4) comprising:
- a bypass branch connected between an input terminal and an output
terminal of the corresponding battery (1) module (2a, ..., 2n);
- a reference signal source (8);
- a regulating device (6) suitable for controlling a current in said bypass
branch on the basis of a control signal received on a control terminal
of the regulating device (6); and
- at least one differential operator (7) comprising an output terminal
linked to the control terminal of the regulating device (6), a first input
terminal connected to receive a signal representative of the voltage at
the terminals of said module (2a, ..., 2n) of the battery (1), and a
second input terminal connected to receive said reference signal, the
differential operator (7) being suitable for generating the control
signal according to a difference between the signals received on said
first and second input terminals of the differential operator (7);
and wherein the reference signal source (8) of the charge limiting circuit
of each module (2a, ..., 2n) of the battery (1) can be varied so as to
partially discharge a defective module.
11. The battery (1) as claimed in claim 10, wherein the bypass branch
comprises at least one resistive element (5).
12. The battery (1) as claimed in claim 10 or 11, wherein the signal
representative of the output voltage of each module (2a, ..., 2n) is
obtained by a voltage divider bridge connected in parallel to said
module.
13. The battery (1) as claimed in any one of claims 10 to 12, comprising at
least one radio receiver, wherein the respective reference signal sources
of the modules (2a, ..., 2n) of electrochemical cells (3a, ..., 3p) are linked

to the radio receiver, and are suitable for varying the corresponding
reference signal according to a received radio control.
14. The battery (1) as claimed in any one of claims 10 to 13, wherein the
differential operator (7) of each charge limiting circuit (4) comprises a
feedback loop (9).
15. The battery (1) as claimed in claim 14, wherein the feedback loop (9)
comprises a resistor and a capacitor connected in series.
16. The battery (1) as claimed in any one of claims 10 to 15, wherein the
regulating device (6) of the charge limiting circuit (4) of each module
(2a, ..., 2n) comprises at least one transistor, said transistor having two
main terminals connected to the bypass branch of said module.
17. The battery (1) as claimed in claim 16, wherein the regulating device (6)
of each charge limiting circuit (4) comprises at least two associated
transistors in Darlington configuration.
18. The battery (1) as claimed in any one of claims 10 to 17, wherein the
number of cells (3a,..., 3p) per module (2a,..., 2n) is between 3 and 13.
19. The battery (1) as claimed in any one of claims 10 to 18, wherein the
number of modules (2a,..., 2n) per battery (1) is between 9 and 24.
20. A satellite comprising at least one battery (1) as claimed in any one of
claims 10 to 19.
21. The satellite as claimed in claim 20, also comprising a defective module
detector (2a, ..., 2n) and a radio transmitter arranged to transmit
identification codes of a defective module (2a, ..., 2n) in the battery (1).

22. The satellite as claimed in claim 20 or 21, also comprising a radio
receiver, wherein the respective reference signal sources of the modules
(2a, ..., 2n) of electrochemical cells (3a, ..., 3p) are linked to the radio
receiver, and are each suitable for varying the corresponding reference
signal according to a received radio control.



ABSTRACT


"METHOD FOR CONTROLLING A RECHARGEABLE BATTERY AND
RECHARGEABLE BATTERY FOR CARRYING OUT SAID METHOD"
A method of controlling a rechargeable battery (1) comprising at least
two modules (2a, ..., 2n) of electrochemical cells (3a, ..., 3p) connected
in series, the electrochemical cells (3a, ..., 3p) being connected in
parallel to each other within each module (2a, ..., 2n) and each module
(2a, ..., 2n) of electrochemical cells (3a, ..., 3p) comprising a charge
limiting circuit (4) for said module connected in parallel to said module,
the method comprising the following steps:
- (a) detecting a defective module (2a,..., 2n);
- (b) having a discharge current pass through the defective module
(2a, ..., 2n) so as to provoke an electrochemical reaction in the
defective module (2a, ..., 2n), said reaction resulting in the
formation of a short-circuit path between connection terminals
of said defective module;
- (c) using the battery (1) by passing an electric current, generated by
the discharging of at least one module (2a,..., 2n) different from
the defective module (2a, ..., 2n), through said defective module
(2a,..., 2n);
and being characterized in that a first partial discharge of the defective
module (2a, ..., 2n) is performed before the step (b), a partial discharge current
of the defective module (2a, ..., 2n) passing through the charge limiting circuit
(4) of said defective module (2a,..., 2n), and being controlled by variation of a
reference signal for the charge limiting circuit (4) of said defective module.

Documents:

01489-kolnp-2007-abstract.pdf

01489-kolnp-2007-claims.pdf

01489-kolnp-2007-correspondence others 1.1.pdf

01489-kolnp-2007-correspondence others 1.2.pdf

01489-kolnp-2007-correspondence others.pdf

01489-kolnp-2007-description complete.pdf

01489-kolnp-2007-drawings.pdf

01489-kolnp-2007-form 1 1.1.pdf

01489-kolnp-2007-form 1.pdf

01489-kolnp-2007-form 2.pdf

01489-kolnp-2007-form 3 1.1.pdf

01489-kolnp-2007-form 3.pdf

01489-kolnp-2007-form 5 1.1.pdf

01489-kolnp-2007-form 5.pdf

01489-kolnp-2007-gpa.pdf

01489-kolnp-2007-international publication.pdf

01489-kolnp-2007-international search report.pdf

01489-kolnp-2007-pct request.pdf

01489-kolnp-2007-priority document 1.1.pdf

01489-kolnp-2007-priority document.pdf

1489-KOLNP-2007-(17-06-2013)-ABSTRACT.pdf

1489-KOLNP-2007-(17-06-2013)-ANNEXURE TO FORM-3.pdf

1489-KOLNP-2007-(17-06-2013)-CLAIMS.pdf

1489-KOLNP-2007-(17-06-2013)-CORRESPONDENCE.pdf

1489-KOLNP-2007-(17-06-2013)-DESCRIPTION (COMPLETE).pdf

1489-KOLNP-2007-(17-06-2013)-DRAWINGS.pdf

1489-KOLNP-2007-(17-06-2013)-FORM-1.pdf

1489-KOLNP-2007-(17-06-2013)-FORM-2.pdf

1489-KOLNP-2007-(17-06-2013)-OTHERS.pdf

1489-KOLNP-2007-(17-06-2013)-PETITION UNDER RULE 137.pdf

1489-KOLNP-2007-(21-06-2012)-CORRESPONDENCE.pdf

1489-KOLNP-2007-CANCELLED PAGES.pdf

1489-KOLNP-2007-CORRESPONDENCE.pdf

1489-KOLNP-2007-EXAMINATION REPORT.pdf

1489-KOLNP-2007-FORM 18-1.1.pdf

1489-kolnp-2007-form 18.pdf

1489-KOLNP-2007-FORM 26.pdf

1489-KOLNP-2007-GRANTED-ABSTRACT.pdf

1489-KOLNP-2007-GRANTED-CLAIMS.pdf

1489-KOLNP-2007-GRANTED-DESCRIPTION (COMPLETE).pdf

1489-KOLNP-2007-GRANTED-DRAWINGS.pdf

1489-KOLNP-2007-GRANTED-FORM 1.pdf

1489-KOLNP-2007-GRANTED-FORM 2.pdf

1489-KOLNP-2007-GRANTED-FORM 3.pdf

1489-KOLNP-2007-GRANTED-FORM 5.pdf

1489-KOLNP-2007-GRANTED-SPECIFICATION-COMPLETE.pdf

1489-KOLNP-2007-INTERNATIONAL PUBLICATION.pdf

1489-KOLNP-2007-INTERNATIONAL SEARCH REPORT & OTHERS.pdf

1489-KOLNP-2007-OTHERS.pdf

1489-KOLNP-2007-PETITION UNDER RULE 8.pdf

1489-KOLNP-2007-PRIORITY DOCUMENT.pdf

1489-KOLNP-2007-REPLY TO EXAMINATION REPORT.pdf

1489-KOLNP-2007_1-(21-06-2012)-CORRESPONDENCE-1.pdf

abstract-01489-kolnp-2007.jpg


Patent Number 257709
Indian Patent Application Number 1489/KOLNP/2007
PG Journal Number 44/2013
Publication Date 01-Nov-2013
Grant Date 29-Oct-2013
Date of Filing 26-Apr-2007
Name of Patentee ASTRIUM SAS
Applicant Address 6 RUE LAURENT PICHAT, 75016 PARIS
Inventors:
# Inventor's Name Inventor's Address
1 DIRAISON JEAN-FRANCOIS 37 RUE ROLAND GARROS, 31200 TOULOUSE
2 STEPHAN JEAN-MARC 12 RÉSIDENCE DU CHÂTEAU, 31320 AUZEVILLE TOLOSANE
PCT International Classification Number H01M 10/48
PCT International Application Number PCT/FR2005/02610
PCT International Filing date 2005-10-20
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 0411534 2004-10-28 France