WO1997049158A1 - Circuit de protection pour piles rechargeables d'une batterie - Google Patents

Circuit de protection pour piles rechargeables d'une batterie Download PDF

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Publication number
WO1997049158A1
WO1997049158A1 PCT/IB1996/000585 IB9600585W WO9749158A1 WO 1997049158 A1 WO1997049158 A1 WO 1997049158A1 IB 9600585 W IB9600585 W IB 9600585W WO 9749158 A1 WO9749158 A1 WO 9749158A1
Authority
WO
WIPO (PCT)
Prior art keywords
voltage
protection circuit
cell
battery cells
terminals
Prior art date
Application number
PCT/IB1996/000585
Other languages
English (en)
Inventor
Karl V. Kordesch
Josef Daniel-Ivad
David Zhang
Original Assignee
Battery Technologies Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Battery Technologies Inc. filed Critical Battery Technologies Inc.
Priority to AU59081/96A priority Critical patent/AU5908196A/en
Priority to PCT/IB1996/000585 priority patent/WO1997049158A1/fr
Priority to ARP970102725A priority patent/AR007437A1/es
Priority to TW086114765A priority patent/TW370732B/zh
Publication of WO1997049158A1 publication Critical patent/WO1997049158A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially

Definitions

  • the invention relates to a protection circuit for rechargeable battery cells, especially for rechargeable alkaline manganese dioxide-zinc (RAM) cells or nickel- zinc battery cells, which battery cell types are sensitive against overcharging.
  • RAM manganese dioxide-zinc
  • the problems connected with an appropriate cell protection have been known for a long time.
  • the series connection of battery cells is the most general way of their use, since in such connection the terminal voltage will be the sum of the individual cell voltages, which alone, is generally too low for most applications.
  • the series connection functions in an excellent way if all battery cells in the series chain are identical and have initially equal charges stored therein. If this is not the case, during the discharge process the cell with the rninimum charge will get fully discharged while the other cells have still certain charge reserve, and if the load is not disconnected, the continued discharging current will cause reversal of the discharged cell i.e. that cell will have opposite polarity. A cell reversal can result in irreversible electrochemical changes.
  • a series chain of battery cells can thus be discharged as long as determined by the charge state (capacity) of the weakest one of its cells.
  • cell protection circuits have been designed to provide solutions against the above described problems, and some of them provide excellent protection but their presence may cause further problems.
  • One of the problems caused by known cell protection circuits is that such circuits may represent a certain load to the cells, and if the cells are not removed from the charger after having been fully charged, and the charger is disconnected from the mains, the cells will get gradually discharged through the protection circuit.
  • Such a cell protection will function if the maximum charging current is limited to about 60-70 mA, since without such a limitation the effective cell voltage can exceed the permitted maximum limit. Such a limitation may increase the effective charging time.
  • battery cells are charged by a rectified but not filtered DC voltage, which consists of half sine-wave pulses. The charging occurs only in the peak periods when the actual voltage is higher then the cell voltage. If the charging current is limited, the charging process will require too long time.
  • an additional shunt path has been provided across each battery cell consisting of three series diodes, all forward biased and a fourth diode connecting the series chain to the battery cell. Let us assume that the forward voltage of each of such diodes is about .85 V.
  • This additional shunt path has no substantial shunting or current limiting effect as long as the charger voltage/cell is less than about 2.4-2.5 V, and in the initial phase of the charging process when the battery voltage is still low, higher charging currents can flow in the battery cell to speed up charging because this additional path will not present a bypass path.
  • the .85V is the forward voltage of the fourth (coupling) diode. At this voltage the three diodes will conduct and provide the required current limitation.
  • a further problem connected witch overcharge protection circuits wherein the threshold voltage for limitation is defined by the forward bias voltage of a diode or of a combination of diodes lies in the excessive temperature dependence of the so obtained threshold voltage.
  • Battery cells are used in wide temperature ranges, and during the charging process itself, some heat is generated in the cells. If the protection circuit is arranged in the proximity of the battery cells, their elevated temperature might increase the temperature of the components of the circuit. Obviously, the accuracy of the overcharge protection decreases with varying threshold voltage.
  • the object of the invention is to provide an effective but much more simple cell protection circuit for battery cells charged in series or in combination of series and parallel connections, which can ensure an effective protection against overcharging and cell reversal, does not constitute any load for the associated cells when the charger is switched off or there is no charging voltage, and which does not limit the charging current unless the charging voltage gets close to the permitted maximum value.
  • a further object is to provide a cell protection circuit, in which the threshold voltage for the overcharge protection has a reduced temperature dependency.
  • a protection circuit for rechargeable battery cells of the type sensitive if being charged by a charging source with a voltage exceeding a predetermined threshold level, that comprises a battery cell to be protected and a shunt path connected to the terminals of the battery cell, the shunt path is substantially non-conductive if the charging voltage is below the threshold level and it is conductive if the voltage approaches or exceeds said level so that current will flow dominantly through the shunt path instead of through the battery cell, wherein the improvement lies in that the shunt path comprises: a semiconductor switch means with an input junction and with a pair of output terminals, the input junction is connectable to the source of charging voltage for getting forward biased thereby, the output terminals of the switch are connected in the shunt path, the switch means is conductive on condition if the input junction is forward biased and if the voltage across the output terminals is not less than a predetermined threshold voltage lower than said threshold level, the switching means has a flat non-linear voltage-to-current characteristic ; and diode
  • silicon diodes have their forward bias voltage in the range of .8-1 V, germanium diodes in the range of .3-.4V and Schottky diodes in the range of .4-.5 V.
  • the series chain comprises at least three battery cells, further comprises a reverse diode with a forward bias voltage connected in parallel to the shunt path to prevent damage of the battery cell by limiting the voltage to the forward bias value if the polarity of the battery cell gets reversed during discharge.
  • a preferable embodiment comprises a Darlington transistor as switching means, wherein a ground terminal of the input junction is common with the ground terminal of the output terminals, the input junction has a remaining control terminal connectable through a resistor to the charging source.
  • the cell protection circuit is designed as integrated protection modules associated with respective cells of a series chain of battery cells, each module comprises a resistor with a first end coupled to a control terminal of the input junction and a second terminal that constitutes the control input of the module, the control inputs of each module are interconnected and connectable to the charging source.
  • the whole protection circuit or portions thereof can be made by integrated circuit technology and the integrated components can be built in a battery cell package or in the charger circuit.
  • the charging voltage source is a source of pulsating voltage.
  • the battery cells are rechargeable alkaline manganese dioxide or nickel-zinc battery cells, and the threshold level is between about 1.65 and 1.75 V or 1.85- 1.95V, respectively.
  • FIG. 1 shows the cell protection module according to the invention
  • FIG. la shows alternative embodiments for the diode D2 of FIG.1
  • FIG. 2 shows a battery cell arrangement with six modules connected to a charger
  • FIG. 3 is a battery cell arrangement with two series and two parallel cells.
  • the protection module M as shown in FIG. 1 in the box of the dash-dot line has three connection terminals A, C and K, and it is connected to positive and negative poles of a rechargeable alkaline battery cell BC at terminals C and A.
  • the module M comprises a reverse diode D l coupled across terminals C and A and a series path in parallel to the reverse diode D 1 consisting of a second diode D2 and a Darlington transistor Ql realized by a single element comprising a pair of transistors arranged in a well-known Darlington circuit.
  • the control or base terminal of the Darlington transistor Ql is connected through a resistor R to the third or control terminal K of the protection module M.
  • the whole module M is made by surface mounted technique as a single element with a length of about 20 mm, a width of about 4 mm and a height of about 3 mm.
  • the module M has a flat base and a rounded profile and looks like an elongated half cylinder.
  • the diodes Dl, D2 can be the type of RLS4148, the Darlington transistor can be MMBTA14LT1 and the resistor R can be 243K 0.1W.
  • FIG. 2 shows six battery cells BC1 to BC6 connected in series, and respective protection modules Ml to M6 are connected to each battery cells.
  • the series chain of the battery cells is connected through a diode D3 and an interference filter IF to a direct current power supply PS fed by an AC outlet.
  • the control inputs of the protection modules Ml to M6 are interconnected and coupled to the positive terminal of the interference filter, i.e. before the diode D3 which has the role of separating the battery chain from the power supply to prevent reverse flow of current if the AC supply is disconnected.
  • the voltage of the power supply PS and the maximum load are adjusted to correspond to the needs of the battery chain.
  • FIG. 3 uses only two of the protection modules M 1 and M2, and each of them is connected to respective pairs of parallel battery cells BC1- BC2 and BC3-BC4.
  • the two pairs of battery cells are connected in series.
  • Respective light emitting diodes LI and L2 can be connected in parallel with the two series members by activating a switch SW to indicate the charge state of the associated battery cells.
  • the direct current is provided by a full wave rectifier bridge coupled through the diode D3 to the positive and negative end terminals of the battery chain.
  • the control inputs of the protection modules Ml and M2 are connected through a resistor R2 to the positive terminal of the rectifier bridge.
  • the control voltage can be filtered by a capacitor Cl.
  • the operation of the protection circuit according to the invention is as follows.
  • the Darlington transistor Q operates in switching mode.
  • the transistor will be conducting if two conditions are fulfilled: (a) if a positive current flows in the control teirninal K that provides a forward bias to the base-emitter junction, and (b) if the voltage across its output terminals is at least about 0.8-0.85V. In conducting state this output voltage remains substantially unchanged even if the current varies within a wide range.
  • the diode D2 is used as a voltage step. This diode D2 also has a forward voltage of about 0.8-0.85V which can be measured if current starts to flow through it.
  • the two forward bias voltages are superimposed on each other so that current will flow through the diode D2 and the Darlington transistor Q if the voltage across the terminals C and A is in the range of about 1.65-1.75 V (the accurate limit voltage depends on the type of these elements and it is chosen to be in this range) and if the Darlington transistor Q receives a forward bias.
  • This second condition is always fulfilled in the circuits shown in FIGs. 2 and 3 if the power supplies are connected to the AC mains and the momentary value of the DC wave is higher than about 60-70% of the peak voltage.
  • a suitable type for the diode D2 should be chosen.
  • the forward bias voltage of the diode D2 should be adjusted by at most 15-20%, then the circuit shown in FIG. la can be used.
  • a series resistor RS is connected in series with a diode D4, and this series member is used instead of the diode D2. If the series resistor RS has a small resistance value and the voltage drop thereon is not more than about 20% of the forward bias voltage of the diode D4, then the resulting voltage-to- current curve of this series member will be similar to that of a single diode.
  • the series resistor RS a voltage adjustment of .1-.2V can be attained.
  • FIG. la shows a further way of replacing the forward biased diode D2: by using a pair of diodes DS1 and DS2 connected in series.
  • a wide range of threshold voltages can be realized.
  • the battery cell In a later phase of the charging process the battery cell will be close to the fully charged state, and its terminal voltage will reach the threshold value of about 1.65 V. At this moment the series member of D2 and Q will open and a shunt path with non-linear current-to-voltage characteristic will be present. In case if the charging process goes on, the current through the shunt path will increase rapidly even if the voltage increase is slight and very soon a major or dominant portion of the current will flow through this shunt path instead of through the cell. This property of the series chain will prevent the battery cell BC from being overcharged.
  • a preferable property of the protection circuit shown in FIG. 1 lies in that the collector-to-emitter voltage of the Darlington transistor Q increases with increasing temperature, while the forward bias voltage of the diode D2 changes in opposite direction. The resulting voltage between the terminals C and A will thus have a reduced temperature dependency than the individual components have. With the preferable components suggested for the elements of FIG. 1 the change of the threshold voltage will be in the range of 5 to 10 mV if the ambient temperature changes from 0 to 60 °C.
  • the Darlington transistor Q with the series diode Dl form ideal overcharge protection for the associated battery cell. It is worth mentioning that the control inputs of all protection modules Ml to M6 in the arrangement of FIG. 2 can be interconnected, since when the DC voltage across the chain is sufficiently high to drive current through the diode D3, i.e. higher than the resulting voltage of the series battery cell chain, this voltage can open the base-emitter junctions of all Darlington transistors in the chain. If the resistor R in the input path has a sufficiently high value, the current therethrough cannot be too high to cause damages to the Darlington transistor.
  • the reverse diodes D 1 in each protection module have no role in the charging process.
  • the protection modules are always connected to the associated battery cells i.e. even if they are loaded. If in the circuit of FIG. 2 the battery chain is loaded and one of the battery cells looses all of the stored charge and the loading process goes on, the terminal voltage of this discharged cell gets reversed. Without the presence of the reverse diode Dl this voltage would increase under the effect of the loading current.
  • the reverse diode will open at a voltage of about -0.8V and the loading current will flow through the diode instead of the cell. Alkaline cells will have no chemical damage if the reverse voltage is limited under about 1-1.2 V. At the end of the loading process the cells can be charged again as if nothing had happen.
  • FIG. 3 shows a mixed connection i.e. parallel connection of two cells to have a common cell protection module. This can be done easily, the operation will not change, however, it might be more preferable to have respective protection modules associated with each cell also in such cases.
  • the protection module of FIG. 1 can be built integrally with the associated battery cells and such battery cells can be regarded as elements with three terminals, A,C and K.
  • the optional use of the light emitting diodes LI, L2 upon activation of the switch SW is preferable if visual indication should be given on the charge state of the battery cells. These diodes will light only if the associated battery cells are fully charged.
  • the main advantage of the protection module lies in its simple and cheap design and in the reliable operation.
  • the use of such modules will prevent the battery cells from being:

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)
  • Protection Of Static Devices (AREA)

Abstract

L'invention concerne un circuit de protection des piles rechargeables d'une batterie qui sont sensibles aux surtensions éventuelles de la source de chargement lorsque la tension dépasse un niveau de seuil prédéterminé. Le dispositif comprend la pile de batterie à protéger et un circuit de dérivation connecté aux bornes de la pile de la batterie. Le circuit de dérivation est sensiblement non conducteur si la tension se maintient à un niveau inférieur au niveau de seuil et devient conducteur si la tension approche ou dépasse ledit niveau de seuil, de sorte que le courant s'écoulera de manière prédominante à travers le circuit de dérivation au lieu de traverser la pile. Le perfectionnement de l'invention réside dans le fait que le circuit de dérivation comporte trois composants. Un premier composant de commutation à semi-conducteurs possède une jonction d'alimentation et une paire de bornes de sortie. La jonction d'alimentation est connectable à la source de tension de chargement pour fournir une polarisation directe et les bornes de sortie du dispositif de commutation sont connectées au circuit de dérivation. Le composant de commutation devient conducteur lorsque la jonction d'entrée est en polarisation directe et que la tension aux bornes de sortie n'est pas inférieure à une tension prédéterminée fixée par ledit niveau de seuil. Le composant de commutation présente alors une caractéristique tension-courant non linéaire. Un deuxième composant à diodes possède une paire de bornes connectées en série avec le dispositif de commutation. Le composant à diodes possède une tension de polarisation directe mesurable auxdites bornes si le courant y circule. Un troisième composant permet que la tension en polarisation directe du composant à diodes et que le seuil de tension du composant de commutation aient des coefficients de température différents et définissent conjointement ledit niveau de seuil.
PCT/IB1996/000585 1996-06-20 1996-06-20 Circuit de protection pour piles rechargeables d'une batterie WO1997049158A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
AU59081/96A AU5908196A (en) 1996-06-20 1996-06-20 Protection circuit for rechargeable battery cells
PCT/IB1996/000585 WO1997049158A1 (fr) 1996-06-20 1996-06-20 Circuit de protection pour piles rechargeables d'une batterie
ARP970102725A AR007437A1 (es) 1996-06-20 1997-06-20 Circuito de proteccion para baterias recargables
TW086114765A TW370732B (en) 1996-06-20 1997-10-08 Protection circuit for rechargeable battery cells

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/IB1996/000585 WO1997049158A1 (fr) 1996-06-20 1996-06-20 Circuit de protection pour piles rechargeables d'une batterie

Publications (1)

Publication Number Publication Date
WO1997049158A1 true WO1997049158A1 (fr) 1997-12-24

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Application Number Title Priority Date Filing Date
PCT/IB1996/000585 WO1997049158A1 (fr) 1996-06-20 1996-06-20 Circuit de protection pour piles rechargeables d'une batterie

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AR (1) AR007437A1 (fr)
AU (1) AU5908196A (fr)
TW (1) TW370732B (fr)
WO (1) WO1997049158A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9065292B2 (en) 2010-08-23 2015-06-23 California Institute Of Technology Methods and systems for charging electrochemical cells
WO2020030762A1 (fr) * 2018-08-08 2020-02-13 Renewable Energy Dynamics Technology Ltd Batterie à flux et procédé d'équilibrage du soc

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100786941B1 (ko) 2005-05-10 2007-12-17 주식회사 엘지화학 이차전지 보호회로 및 이를 구비한 이차전지

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3237078A (en) * 1963-03-14 1966-02-22 Mallory & Co Inc P R Rechargeable batteries and regulated charging means therefor
US3493837A (en) * 1966-10-03 1970-02-03 Trw Inc Battery charge control system
US4017779A (en) * 1976-03-22 1977-04-12 Motorola, Inc. Battery isolator
US4238721A (en) * 1979-02-06 1980-12-09 The United States Of America As Represented By The United States Department Of Energy System and method for charging electrochemical cells in series
US5063340A (en) * 1990-10-25 1991-11-05 Motorola, Inc. Capacitive power supply having charge equalization circuit
US5519563A (en) * 1994-07-06 1996-05-21 Mitsumi Electric Co., Ltd. Protection circuit for electric cells from overcharge and overdischarge using a plurality of detection units of a single chip type

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3237078A (en) * 1963-03-14 1966-02-22 Mallory & Co Inc P R Rechargeable batteries and regulated charging means therefor
US3493837A (en) * 1966-10-03 1970-02-03 Trw Inc Battery charge control system
US4017779A (en) * 1976-03-22 1977-04-12 Motorola, Inc. Battery isolator
US4238721A (en) * 1979-02-06 1980-12-09 The United States Of America As Represented By The United States Department Of Energy System and method for charging electrochemical cells in series
US5063340A (en) * 1990-10-25 1991-11-05 Motorola, Inc. Capacitive power supply having charge equalization circuit
US5519563A (en) * 1994-07-06 1996-05-21 Mitsumi Electric Co., Ltd. Protection circuit for electric cells from overcharge and overdischarge using a plurality of detection units of a single chip type

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9065292B2 (en) 2010-08-23 2015-06-23 California Institute Of Technology Methods and systems for charging electrochemical cells
WO2020030762A1 (fr) * 2018-08-08 2020-02-13 Renewable Energy Dynamics Technology Ltd Batterie à flux et procédé d'équilibrage du soc
CN112567554A (zh) * 2018-08-08 2021-03-26 英维尼迪能源系统(爱尔兰)有限公司 液流电池和用于平衡soc的方法
US20210226239A1 (en) * 2018-08-08 2021-07-22 Invinity Energy Systems (Ireland) Limited Flow battery
JP2021534565A (ja) * 2018-08-08 2021-12-09 インヴィニティ エナジー システムズ （アイルランド） リミテッド フロー電池及び充電状態均衡化の方法
CN112567554B (zh) * 2018-08-08 2023-10-27 英维尼迪能源系统(爱尔兰)有限公司 液流电池和用于平衡soc的方法
US11817605B2 (en) 2018-08-08 2023-11-14 Invinity Energy Systems (Ireland) Limited Flow battery

Also Published As

Publication number Publication date
AU5908196A (en) 1998-01-07
TW370732B (en) 1999-09-21
AR007437A1 (es) 1999-10-27

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