Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J7/00—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries
  • H02J7/60—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries including safety or protection arrangements
  • H02J7/663—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries including safety or protection arrangements using battery or load disconnect circuits
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/50—Current conducting connections for cells or batteries
  • H01M50/572—Means for preventing undesired use or discharge
  • H01M50/574—Devices or arrangements for the interruption of current
  • H01M50/581—Devices or arrangements for the interruption of current in response to temperature
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/50—Current conducting connections for cells or batteries
  • H01M50/572—Means for preventing undesired use or discharge
  • H01M50/574—Devices or arrangements for the interruption of current
  • H01M50/583—Devices or arrangements for the interruption of current in response to current, e.g. fuses
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
  • H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
  • H02H3/085—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current making use of a thermal sensor, e.g. thermistor, heated by the excess current
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H5/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection
  • H02H5/04—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to abnormal temperature
  • H02H5/042—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to abnormal temperature using temperature dependent resistors
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
  • H02H7/18—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for batteries; for accumulators
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J7/00—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries
  • H02J7/60—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries including safety or protection arrangements
  • H02J7/62—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries including safety or protection arrangements against overcurrent
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J7/00—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries
  • H02J7/60—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries including safety or protection arrangements
  • H02J7/65—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries including safety or protection arrangements against overtemperature
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2200/00—Safety devices for primary or secondary batteries
  • H01M2200/10—Temperature sensitive devices
  • H01M2200/106—PTC
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the present invention relates to a protection circuit for protecting a battery pack having a secondary battery from overcurrent or abnormal overheating, and more particularly, to a protection circuit for a battery pack using a positive temperature coefficient thermistor and a switch element, and a battery pack. It is about.
• Patent Document 1 shows the configuration.
• FIG. 11 shows an example of the battery pack protection circuit of Patent Document 1.
• a battery cell 131 is provided with first and second switch elements 134a and 134b on a charge / discharge path, and a protection control circuit 133 for controlling them.
• a protection element 132 composed of a positive temperature coefficient thermistor is connected near the battery cell 131 in series with the charge / discharge path. If the switch elements 134a and 134b are abnormally overheated, resulting in thermal runaway or failure, even if the protection control circuit 133 detects an abnormality, the switch elements 134a and 134b cannot be shut off and the protection function is activated. Even in such a case, even in such a case, the protection function against overcurrent and overheating of the battery cell can be ensured by the action of the protection element 132.
• Patent Document 2 discloses that a polymer PTC element is used as a positive temperature coefficient thermistor constituting the protection element 2.
• the protection control circuit is provided with first and second signal input terminals, and when a predetermined signal is applied to the first or second signal input terminal.
• a method for controlling a switch element and interrupting a current path is disclosed.
• the switch element is controlled and the current path is cut off.
• the current path is also cut off when a signal indicating the temperature of the entire battery pack is input to the second signal input terminal as the predetermined signal. That is, the protection circuit for the battery pack described in Patent Document 3 prevents the temperature rise of the entire battery pack.
• a configuration is disclosed in which a current path is detected when an abnormal temperature is detected by using a protection function of a protection control circuit.
• Patent Document 1 JP-A-2000-152516
• Patent Document 2 JP 2002-8608 A
• Patent Document 3 JP 2004-120849 A
• the polymer PTC element used as the protection element 2 has a large overall weight, a large volume, and is of a lead type. Therefore, when assembling the same into a battery pack, soldering or welding by hand is required. Work is required, and there has been a problem that the manufacturing cost increases. Further, even if a thermal fuse is used as the protection element 2, as in the case of the polymer PTC element, the overall weight is large and the volume is large, and the manufacturing cost is increased because of the element card type. There is also a problem that the force cannot be reused after the disconnection due to the abnormal temperature.
• Patent Document 1 in order to solve this problem, a third switch element using an FET is provided in place of the protection element 2, and a resistance to temperature of a negative characteristic thermistor or a positive characteristic thermistor provided in a battery pack is provided. A device that controls the third switch element by using a value change has been proposed. Accordingly, even when the protection control circuit 133 does not function, the overcurrent force battery pack at the time of charging and discharging can be protected.
• the third switch element is inserted in series with the charge / discharge current path of the battery cell, that is, it requires an expensive power FET, which causes a problem of increasing the cost. there were.
• the provision of the third switch element has a problem in that the factors of thermal runaway and failure due to abnormal overheating increase.
• the temperature of the entire battery pack becomes high after the thermal runaway of the switch element, and even if the protection control circuit attempts to control the switch element, it may not be possible to control the switch element. That is, the protection circuit described in Patent Document 3 cannot protect the circuit by detecting local overheating, so that the protection function is not sufficient. Conversely, if the protection start temperature is set low, there is a possibility that the protection operation may work even if the temperature is overheated without any problem.
• an object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to eliminate the need to insert a resistance component in series in the current path and thus to increase the loss, and to prevent local abnormal overheating. It is an object of the present invention to provide a protection circuit capable of reliably protecting a battery pack even when it occurs.
• a battery pack protection circuit and a battery pack of the present invention are configured as follows.
• a protection circuit for a battery pack includes a first switch element for interrupting a discharge current flowing from a battery cell, a second switch element for interrupting a charging current flowing to the battery cell, and a battery cell.
• a protection control circuit for detecting the abnormal state of the voltage, current, or ambient temperature of the battery and controlling the first and second switch elements to protect the battery cell.
• the first or second switch element in which the switch element control circuit is inserted in the control signal path is shut off by increasing the resistance value of the switch element.
• the switch element control circuit is provided with a plurality of PTC thermistors connected in series, and the plurality of PTC thermistors are connected to the first switch element, the second switch element, and the battery cell. Thermally couple with at least two of each.
• the first switch element and the second switch element are FETs, and the protection control circuit is an integrated circuit having a gate control terminal for controlling a gate of the FET.
• the switch element control circuit includes a resistor connected between the gate and the source of the FET, and at least one positive characteristic inserted between the gate control terminal of the protection circuit and the gate of the FET. It consists of a thermistor.
• the switch element control circuit includes a control FET in which a drain and a source are connected between a gate and a source of the FET, respectively, and a switch connected between a gate and a source of the control FET. It consists of the above-mentioned positive characteristic thermistor.
• the battery pack protection circuit of the present invention has a control terminal, is connected in series to the positive or negative electrode of the battery, and is turned off at the time of an abnormality to provide a current path at the time of charging and discharging. And at least one of the at least one switch element so as to enable the at least one switch element to be turned off when an abnormal current flows in the current path.
• a protection control circuit connected to a control terminal, the protection control circuit having a signal input terminal to which a signal indicating that the protection control circuit is in an abnormal state other than the abnormal current is input, the signal input terminal having the abnormal current.
• a protection circuit for a battery pack configured to turn off the at least one switch element when a signal indicating an abnormal state other than the above is input.
• a first PTC thermistor thermally coupled to the switch element, wherein the first PTC thermistor detects a change in the resistance of the first PTC thermistor due to abnormal overheating of the thermally coupled switch element;
• a corresponding signal is input to the signal input terminal as a signal indicating the abnormal state.
• a plurality of switch elements for interrupting the current path are provided, the first PTC thermistor is thermally coupled to each switch element, and the first PTC thermistors are electrically connected in series.
• At least one second PTC thermistor thermally coupled to a heat generating portion other than the at least one switch element, and a first PTC thermistor thermally coupled to the switch element ,
• the at least one second positive temperature coefficient thermistor is connected in series.
• the heat generating portion is a battery, and the battery is thermally coupled with the second PTC thermistor.
• the resistance temperature characteristics of the first PTC thermistor thermally coupled to the switch element are different from the resistance temperature characteristics of the second PTC thermistor thermally coupled to the heat generating portion. I do.
• a battery pack according to the present invention includes a battery pack protection circuit having any one of the above configurations, and a battery cell protected thereby.
• the switch element control circuit is inserted into at least one of the first and second switch element control signal paths and includes a positive temperature coefficient thermistor, that is, provided in the charge / discharge path of the battery cell. Therefore, an extremely small chip element through which a weak current flows can be used, and the manufacturing cost can be reduced. In addition, since the third switch element inserted into the charge / discharge current path of the battery cell is not required, a small and low-cost device can be achieved.
• the first or second switch element is shut off by an increase in the resistance value of the first switch element, the second switch element, or the positive temperature coefficient thermistor when the battery cell is overheated. Even if the protection control circuit does not function, the protection function can be achieved by the switch element control circuit, the first or second switch element, and the positive temperature coefficient thermistor, so that the protection means can be doubled.
• the switch element control circuit is provided with a plurality of PTC thermistors connected in series, and the plurality of PTC thermistors are connected to the first switch element, the second switch element, and the battery cell.
• the positive temperature coefficient thermistor can be thermally strongly coupled to the switch element or the battery cell, respectively, and the responsiveness of overheat protection can be improved. Since only a plurality of positive temperature coefficient thermistors are connected in series, the circuit scale hardly increases.
• the first switch element and the second switch element are FETs, and the protection control circuit is an integrated circuit having a gate control terminal for controlling the gate of the FET.
• the voltage drop at the switch element is suppressed, and the overall size and weight can be reduced.
• the switch element control circuit includes a resistor connected between the gate and the source of the FET, and one or more positive temperature coefficient thermistors inserted between the gate control terminal of the protection circuit and the gate of the FET.
• the switch element control circuit includes a control FET in which a drain and a source are connected between a gate and a source of the FET, respectively, and a switch in which a gate and a source of the control FET are connected.
• At least one switch element that cuts off a current path and at least when an abnormal current flows, A protection control circuit connected to the switch element so as to enable one of the switch elements to be turned off.
• a protection control circuit connected to the switch element so as to enable one of the switch elements to be turned off.
• At least one of the switch elements establishes a current path by the protection control circuit. Operates to block.
• the protection control circuit has a signal input terminal for receiving a signal indicating an abnormal state other than the abnormal current, and a signal indicating an abnormal state other than the abnormal current is input to the signal input terminal. At least one switch element is turned off and the current path Is shut off.
• the first PTC thermistor is thermally coupled to at least one switch element, and when the switch element is overheated, a signal corresponding to a change in the resistance value of the first PTC thermistor. Is input to the signal input terminal. That is, not only when the abnormal current flows but also when at least one switch element is in an abnormally overheated state, the switch element is controlled by the protection control circuit and the current path is cut off.
• the first PTC thermistor is thermally coupled to at least one switch element, and the first PTC thermistor is inserted into a current path when charging and discharging the battery. Therefore, the loss due to the use of the positive temperature coefficient thermistor is unlikely to increase.
• a plurality of switch elements are provided, a first PTC thermistor is thermally coupled to each switch element, and a plurality of first PTC thermistors are electrically connected in series.
• the resistance-temperature characteristics of the PTC thermistor are steep, so if any one of a plurality of PTC thermistors connected in series detects an abnormal temperature and the resistance rises, this series connection
• the resistance value of the entire circuit including the positive characteristic thermistor greatly increases. Therefore, by simply detecting the change in the resistance of the series circuit, the battery pack can be reliably protected even if abnormal overheating occurs in any of the plurality of switch elements.
• NTC thermistor Since the resistance value of an NTC thermistor changes slowly with respect to temperature change, even if a circuit in which these are connected in series is assumed to have a series resistance. It is difficult to detect abnormal overheating with a small change in value. Therefore, for example, a circuit is provided that compares the change in the resistance value of each NTC thermistor with a predetermined value using a comparator, and then inputs the OR of each comparator to the protection IC. Need to be Therefore, there is a problem that the circuit configuration becomes complicated and miniaturization becomes difficult.
• At least one second PTC thermistor thermally coupled to a heat generating portion other than the at least one switch element, and the first PTC thermistor thermally coupled to the switch element
• the second PTC thermistor is only capable of detecting abnormal overheating of the switch element and protecting the battery pack. The battery pack can be protected even when the connected heat-generating part is overheated.
• the battery pack can be protected when the battery itself is abnormally overheated.
• the battery pack can be used as a battery pack that is small, lightweight, low-cost, and highly reliable. it can. Brief Description of Drawings
• FIG. 1 is a circuit diagram showing a configuration of a battery pack protection circuit and a battery pack according to a first embodiment.
• FIG. 2 is a circuit diagram showing a configuration of a battery pack protection circuit and a battery pack according to a second embodiment.
• FIG. 3 is a circuit diagram showing configurations of a battery pack protection circuit and a battery pack according to a third embodiment.
• FIG. 4 is a circuit diagram showing a configuration of a battery pack protection circuit and a battery pack according to a fourth embodiment.
• FIG. 5 is a circuit diagram showing a configuration of a battery pack protection circuit and a battery pack according to a fifth embodiment. It is a road map.
• FIG. 6 is a circuit diagram for explaining a protection circuit for a battery pack according to a sixth embodiment of the present invention.
• FIG. 7 (a) is a diagram showing the resistance temperature characteristics of the positive temperature coefficient thermistor used in the sixth embodiment, and (b) is a graph showing the change in voltage Vp at the connection point P in FIG. 6 with temperature.
• FIG. 8 is a circuit diagram showing a modification of the protection circuit of the battery pack of the sixth embodiment.
• FIG. 9 is a circuit diagram showing another modification of the protection circuit for the battery pack of the sixth embodiment.
• FIG. 10 is a circuit diagram for explaining a battery pack protection circuit according to a seventh embodiment of the present invention.
• FIG. 11 is a circuit diagram showing a configuration of a conventional battery pack protection circuit.
• FIG. 1 is a circuit diagram of a battery pack provided with a battery pack protection circuit.
• a first switch element 34a and a second switch element 34b are provided in series with the charge / discharge path of the battery cell 31.
• the protection control circuit 33 connects its ground terminal Vss to the negative pole of the battery cell 31, and connects Vdd to the positive pole of the battery cell 31 via the resistor R2. Also, connect a capacitor C1 for removing noise signals between Vdd and Vss! Also, a resistor R3 is connected between the V- terminal of the protection control circuit 33 and the negative (-) terminal of the battery pack 10.
• the first and second switch elements 34a and 34b are each composed of an FET.
• the protection control circuit 33 also serves as a semiconductor integrated circuit, and has gate control terminals Dout and Cout for the first and second switch elements 34a and 34b. Dout is connected to the gate of the first switch element 34a.
• a ceramic positive temperature coefficient thermistor Rcp is connected in series between the other gate control terminal Cout and the gate of the second switch element 34b.
• a resistor Rib is connected between the gate and the source of the second switch element 34b. This resistor Rib and ceramic positive characteristic
• a switch element control circuit 35b is constituted by one miscellor Rcpb.
• the protection control circuit 33 operates using a voltage between Vdd and Vss as a power supply, detects a charging current and a discharging current based on a potential difference between Vss and the V- terminal, and detects an overcurrent during charging. At this time, the Cout terminal is set to the low level to shut off the second switch element 34b. Also, when an overcurrent at the time of discharging is detected, the Dout terminal is set to a low level to set the first switch element 3
• the gate control terminals Cout and Dout of the protection control circuit 33 are both set to the low level and the first and second switch elements 34a and 34b are both turned on. This enables normal charge and discharge.
• the protection control circuit 33 sets the Cout terminal to low level. As a result, the switch element 34b is turned off, and its overcurrent is prevented. Also, if the potential difference between the Vss and V ⁇ terminals of the protection control circuit 33 exceeds a predetermined threshold value as the discharge current increases, the protection control circuit 33 sets the Dout terminal to low level. As a result, the switch element 34a is turned off and its overcurrent is prevented.
• the charging current becomes an overcurrent state
• the first switch element 34a or the second switch element 34b becomes an overheated state.
• the ceramic positive temperature coefficient thermistor Rcpb which is thermally coupled to it, rises above its Curie point, its resistance rises sharply.
• the gate-source voltage of the second switch element 34b decreases, and the second switch element 34b is turned off.
• the current flowing through the battery cell 31 is cut off, and the abnormal state is avoided.
• the resistance Rib is set to 500 k ⁇
• the size is surface mount type. Then, it is arranged on the substrate so as to be thermally coupled to both the first and second switch elements 34a and 34b.
• first and second switch elements 34a and 34b reach a temperature at which thermal runaway or a failure occurs, energization of the first and second switch elements 34a and 34b can be cut off, so that the battery cell 31 and the first and second switches are turned off. Element 34a , 34b can be protected with permanent destructive power.
• the force obtained by thermally coupling the ceramic positive temperature coefficient thermistor Rcpb to both the first and second switch elements 34a and 34b is applied to only one of the switch elements. You may make it match. Even in such a case, the first and second switch elements 34a and 34b generate heat together due to an overcurrent at the time of charging or discharging, and thus have the same effect as the above-described case.
• the ceramic positive thermistor Rcpb may be thermally coupled to the battery cell 31 together with the first and second switch elements 34a and 34b. This makes it possible to detect and protect the heat generation of the battery cell 31 due to the overcurrent at the time of charging or discharging.
• a force using a single ceramic positive temperature coefficient thermistor In the example shown in FIG. 1, a force using a single ceramic positive temperature coefficient thermistor
• a plurality of ceramic positive temperature coefficient thermistors thermally coupled to different portions are used. That is, a series circuit of the battery cell positive temperature coefficient thermistor Rcp1 and the switch element ceramic positive temperature coefficient thermistor Rcp2 is inserted between the gate control terminal Cout of the protection control circuit 33 and the gate of the second switch element 34b. I have. Then, a resistor Rib is connected between the gate and the source of the second switch element 34b! The resistor Rib and two ceramic positive temperature coefficient thermistors Rcpl and Rcp2 constitute a switch element control circuit 35b. Other configurations are the same as those shown in FIG.
• the ceramic positive temperature coefficient thermistor Rcpl for a battery cell is thermally coupled to the battery cell 31.
• the ceramic positive temperature coefficient thermistor Rcp2 for the switch element is thermally coupled to the first and second switch elements 34a and 34b, respectively.
• each of the above two thermistors which are individually thermally coupled, is a ceramic positive temperature coefficient thermistor.
• Ceramic PTC thermistors Since the rate of increase in resistance with respect to temperature rise is very large, a circuit can be configured by simply connecting in series. In other words, any one of the serially connected ceramic positive temperature coefficient thermistors can satisfy the OR (logical sum) condition that the protection operation is performed when the Curie point is exceeded. It is impossible to construct a circuit that performs such a protection operation by using a thermistor with a negative characteristic.
• the rate of change of the resistance value with respect to temperature change in a negative thermistor is much smaller than that of a ceramic positive thermistor, even if two negative thermistors are connected in series, the temperature change force of the two negative thermistors is 2 It only appears as a change in the combined resistance value of the two negative temperature coefficient thermistors.From this change in the combined resistance value, two points of heat are detected at the same time, and a protection operation is performed when one of the temperatures exceeds a predetermined upper limit. It is impossible at all.
• the control signal path of the first switch element 34a is also provided.
• a switch element control circuit 35a is provided. That is, a ceramic positive temperature coefficient thermistor Rcpa that is thermally coupled to the first switch element 34a is inserted between the gate of the first switch element 34a and the gate control terminal Dout of the protection control circuit 33.
• the resistor Rla is connected between the gate and the source of the child 34a.
• the resistor Rla and the ceramic positive temperature coefficient thermistor Rcpa form a switch element control circuit 35a.
• Other configurations are the same as those shown in FIG.
• the resistance of the ceramic positive temperature coefficient thermistor Rcpa increases due to overheating of the first switch element 34a due to overcurrent at the time of discharging.
• the first switch element 34a can be turned off to protect the overcurrent force.
• the protection operation during charging is the same as in the second embodiment.
• the switch element control circuit is constituted by the ceramic positive temperature coefficient thermistor and the resistor.
• the first and second switch elements 34a, 34b Switch element control circuits 35a and 35b are provided in both control signal paths.
• Further switch elements 36a and 36b are provided in the switch element control circuit.
• the switch elements 36a and 36b are control FETs for controlling the switch elements 34a and 34b, respectively.
• the switch element control circuit 35b connects the drain and source of the switch element 36b between the gate and source of the switch element 34b, and connects between the gate of the switch element 34b and the gate control terminal Cout of the protection control circuit 33.
• the resistor R5b is connected, the resistor R34b is connected between the gate control terminal Cout and the gate of the switch element 36b, and the ceramic positive temperature coefficient thermistor Rcpb is connected between the gate and the source of the switch element 36b.
• the switch element control circuit 35a connects the drain and source of the switch element 36a between the gate and source of the switch element 34a, and connects the gate of the switch element 34a and the gate control terminal Dout of the protection control circuit 33 to each other.
• a resistor R4a is connected, and a ceramic positive temperature coefficient thermistor Rcpa is connected between the gate and the source of the switch element 36a.
• Ceramic positive temperature coefficient thermistor Rcpa is thermally coupled to switch element 34a.
• the ceramic positive temperature coefficient thermistor Rcpb is thermally coupled to the switch element 34b.
• the gate control terminals Cout and Dout of the protection control circuit 33 are both set to the low level and the first and second switch elements 34a and 34b are both turned on. This enables normal charge and discharge.
• the protection control circuit 33 sets the Cout terminal to a low level. As a result, the switch element 34b is turned off, and its overcurrent is prevented. Also, if the potential difference between the Vss and V ⁇ terminals of the protection control circuit 33 exceeds a predetermined threshold value as the discharge current increases, the protection control circuit 33 sets the Dout terminal to low level. As a result, the switch element 34a is turned off and its overcurrent is prevented.
• the charging current becomes an overcurrent state
• the second switch element 34b becomes an overheated state, and is thermally coupled to the second switch element 34b.
• the temperature rises above the Curie point of the ceramic positive temperature coefficient thermistor Rcpb . Its resistance value rises sharply.
• the gate-source voltage of the switch element 36b rises and turns on.
• the gate-source voltage of the switch element 34b decreases, and the switch element 34b is turned off.
• the current flowing through the battery cell 31 is cut off, and the abnormal state is avoided.
• the switch elements 36a and 36b which are control FETs, in the switch element control circuit, the voltage between the gate and the source of the switch elements 34a and 34b can be further reduced in the event of an abnormality.
• the elements 34a and 34b can be more reliably cut off.
• the ceramic positive temperature coefficient thermistor part is composed of a series circuit of two ceramic positive temperature coefficient thermistors, one of which is thermally coupled to the first and second switch elements 34a '34b. And the other is thermally coupled to the battery cell 31.
• the ceramic positive temperature coefficient thermistor Rcp2a, Rcp2b for the switch element which is thermally coupled to at least one of the first and second switch elements 34a, 34b, Ceramic positive temperature coefficient thermistor for battery cell Rcp la and Rcplb, and by connecting the two ceramic positive temperature coefficient thermistors electrically in series, the ceramic positive temperature coefficient thermistors for switch elements Rcp2a and Rcp2b are connected to the switch elements 34a and 34b and the ceramic positive temperature coefficient thermistors for battery cells.
• the characteristic thermistors Rcpla and Rcplb are strongly thermally bonded to the battery cell 31, respectively, so that the responsiveness of the overheat protection can be enhanced.
• the above two ceramic positive temperature coefficient thermistors are simply connected in series, so that the circuit scale hardly increases.
• FIG. 6 is a circuit diagram illustrating a protection circuit for a battery pack according to a sixth embodiment of the present invention.
• the battery pack 51 has a battery cell 52 and a protection circuit shown for protecting the battery cell 52.
• the positive electrode of the battery cell 52 is connected to the first terminal 53, and the negative electrode is connected to the second terminal 54.
• the path connecting the battery cell 52 and the terminals 53 and 54 constitutes a current path through which current flows during charging and discharging.
• the first and second switch elements 55, 56 each composed of an FET. Is provided. That is, the first switch element 55 and the second switch element 56 are connected in series between the negative electrode of the battery cell 52 and the terminal 54. More specifically, the source electrode of switch element 55 is connected to the negative electrode of battery cell 52, the drain electrode of switch element 55 is connected to the drain electrode of switch element 56, and the The source electrode is connected to terminal 54!
• the gate electrodes of the switch elements 55 and 56 are connected to a protection control circuit 57 which also has a protection IC power.
• the protection control circuit 57 applies a signal for turning on or off the switch elements 55 and 56 to the gate electrodes of the switch elements 55 and 56, thereby realizing the current path cutoff operation by the switch elements 55 and 56.
• the protection control circuit has first and second input terminals 57a and 57b.
• the first input terminal 57a is connected to a connection point 58 between the positive electrode of the battery cell 52 and the terminal 53, and a resistor 59 is connected between the connection point 58 and the input terminal 57a.
• a positive temperature coefficient thermistor 60 is connected to a second signal input terminal 57b of the protection control circuit 57.
• This positive characteristic thermistor 60 is the first positive characteristic thermistor of the present invention.
• Positive characteristic thermistor 60 The other end is connected to a connection point 61 between the source electrode of the second switch element 56 and the terminal 54.
• the positive temperature coefficient thermistor 60 is connected between the signal input terminal 57b and the source electrode of the switch element 56.In other words, the positive temperature coefficient thermistor 60 is connected in series with the current path when charging and discharging the battery cell 52. Has not been inserted. The positive temperature coefficient thermistor 60 is thermally coupled to the second switch element 56.
• a resistor 62 is connected in series to an end of the positive characteristic thermistor 60 connected to the signal input terminal 57b. The other end of the resistor 62 is connected to a connection point 63 between the positive electrode of the battery cell 52 and the terminal 53.
• the resistor 62 and the positive temperature coefficient thermistor 60 are connected in series with each other, and are connected in parallel between the positive electrode and the negative electrode of the battery cell 52.
• the terminal 57 c of the protection control circuit 57 is connected to the negative electrode of the battery cell 52 via a connection point 66. Further, a terminal 57d of the protection control circuit 57 is connected to the terminal 54 via a resistor 67.
• the protection control circuit 57 turns off at least one of the switch elements 55 and 56. . As a result, the current path is cut off, and the battery pack 51 is protected.
• the battery pack 51 can be protected not only when an abnormal current flows in the current path but also when the switch element 56 abnormally overheats. Therefore, before the entire battery pack reaches abnormal overheating, abnormal overheating of the switch element 56 is detected and maintained. Can be protected. Therefore, in the case where the high load state continues, the switch element 56 can be turned off before the switch element 56 runs out of heat or fails. The loss is hard to increase because the positive temperature coefficient thermistor is not inserted in the current path.
• FIG. 8 is a circuit diagram showing a modification of the protection circuit of the battery pack of the embodiment.
• the force in which one positive temperature coefficient thermistor 60 is thermally coupled to one switch element 56 As shown in FIG. 8, the positive temperature coefficient thermistor 60 is connected to the first and second switch elements. It may be thermally coupled to both 55 and 56. In this case, even if an abnormal overheat condition occurs in only one of the plurality of switch elements 55 and 56, or if an abnormal overheat condition occurs in both of the switch elements 55 and 56. In addition, the battery pack can be reliably protected.
• FIG. 9 is a circuit diagram showing still another modified example of the protection circuit of the battery pack of the embodiment.
• two characteristic thermistors 60 and 60A as a first thermistor are connected in series with each other.
• One positive temperature coefficient thermistor 60A is thermally coupled to the switch element 55, and the other positive temperature coefficient thermistor 60 is thermally coupled to the switch element 56 as in the first embodiment.
• FIG. 10 is a circuit diagram showing a circuit configuration of a battery pack according to the seventh embodiment of the present invention.
• the positive temperature coefficient thermistor 60 is thermally coupled to the switch element 56 as in the case of the sixth embodiment.
• the second PTC thermistor 72 is connected in series with the PTC thermistor 60.
• the second PTC thermistor 72 is thermally coupled to the battery cell 52.
• the protection circuit of the seventh embodiment is the same as the protection circuit of the sixth embodiment, and the same parts are denoted by the same reference numerals and will be described in detail. Is omitted.
• second positive temperature coefficient thermistor 72 is thermally coupled to battery cell 52. Therefore, even when the battery cell 52 itself is abnormally overheated, the resistance value of the positive temperature coefficient thermistor 72 sharply increases, and the voltage Vp sharply increases. Therefore, even when the battery cell 52 is abnormally overheated, the protection control circuit 57 turns off the switch elements 55 and 56, cuts off the current path, and performs protection.
• the heat coupling to the other heat-generating parts such as the battery cell 52, which is formed only by the first PTC thermistor thermally coupled to at least one switch element, A second PTC thermistor 72 may be further provided, and these may be connected in series.
• the battery pack can be protected by detecting abnormal overheating of the heat generating portion thermally coupled to the second PTC thermistor.
• the resistance-temperature characteristics of the two may be the same or different.
• the resistance temperature of the positive characteristic thermistors 60 and 72 be set so as to have the resistance temperature characteristic according to the switch element and each heat generating part. It is desirable to select a characteristic. Therefore, preferably, the resistance temperature characteristics of the first PTC thermistor 60 and the resistance temperature characteristics of the second PTC thermistor 72 are different.
• switch elements 55 and 56 are used as the switch elements.
• the switch element is not limited to a switch element. Also, three or more switch elements may be used, or only one switch element may be used.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Protection Of Static Devices (AREA)
• Battery Mounting, Suspending (AREA)
• Charge And Discharge Circuits For Batteries Or The Like (AREA)

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• 2005
  • 2005-05-23 EP EP05741433A patent/EP1758226A1/en not_active Withdrawn
  • 2005-05-23 WO PCT/JP2005/009326 patent/WO2005124964A1/ja not_active Ceased
  • 2005-05-23 KR KR1020067026446A patent/KR100862534B1/ko not_active Expired - Fee Related
  • 2005-06-16 TW TW094120056A patent/TW200614625A/zh not_active IP Right Cessation
• 2006
  • 2006-12-18 US US11/612,107 patent/US7391185B2/en not_active Expired - Lifetime
• 2008
  • 2008-01-15 US US12/014,342 patent/US7550950B2/en not_active Expired - Fee Related

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