JP2012010525A - Battery pack with output stop switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a function of stopping an output from a secondary battery under such condition as a battery pack is not loaded on an electrical apparatus, without complicating circuit configuration.SOLUTION: There are provided a battery cell 2 in which a single or a plurality of secondary batteries are connected, a switch circuit 3 that is inserted into a charging/discharging path running from the battery cell to an external terminal, and a protection circuit 4 which contains at least one kind of abnormality detecting parts 6, 6, and 8 for detecting abnormality of the battery cell or of its peripheral condition, and controls a switch circuit 3 according to the signal inputted into the abnormality detection part. The protection circuit controls the switch circuit to be a conductive state when the signal inputted in the abnormality detection part shows a normal state, but controls it to be a non-conductive state when an abnormal condition is indicated. An external switch 10 is provided which is connected to the protection circuit and can operate on/off from outside. When the external switch is turned off, a signal indicating abnormal condition is inputted into the abnormality detection part, and the protection circuit controls the switch circuit to a non-conductive state.

Description

  The present invention relates to a battery pack in which a secondary battery such as a lithium ion battery is accommodated, and more particularly, to a battery pack having a function of stopping output from a secondary battery when the battery is not attached to an electrical device.

  Generally, the battery pack is provided in a state in which discharge is possible between positive and negative terminals. When a battery pack in a state where discharge is possible is connected to a battery pack having a low impedance, sparks due to air breakdown may occur in the gap immediately before connection. Also, when battery packs are connected in parallel, the same phenomenon occurs if there is any difference in the potential difference between the battery packs connected. In particular, since the battery pack often has a plurality of batteries connected in series to increase the output voltage, sparks are likely to occur. This may cause an electric shock to the person who operates the battery pack when the person operates the battery pack.

  In order to avoid an electric shock, for example, Patent Documents 1 and 2 disclose battery packs that cannot be discharged when detached from an electrical device. In the configurations disclosed in Patent Documents 1 and 2, an attachment / detachment switch that is turned on / off according to attachment / detachment of the battery pack to / from the electric device is provided. The charge / discharge control element connected in series with the secondary battery and controlling charge / discharge is controlled by turning on / off the detachable switch. That is, in a state where the battery pack is removed from the electric device, the charge / discharge control element is controlled to be off, and the output from the battery pack is shut off.

  A circuit diagram of the battery pack 20 disclosed in Patent Document 1 is shown in FIG. The battery pack 20 includes a switching element 23 inserted between the negative electrode of the battery 21 and the charge / discharge terminal 22. The switching element 23 includes two FETs connected in series with each other. A control circuit 24 is connected to the control input terminal of the switching element 23. The control circuit 24 includes two AND circuits 25 connected to the gates of the FETs of the switching element 23, and a detection switch 26 connected between the positive side of the battery 21 and one input terminal of the AND circuit 25. Has been. An overcharge / overdischarge prevention circuit 27 is connected to the other input terminal of the AND circuit 25.

  When the battery pack 20 is mounted on the electrical device 28, the charge / discharge terminal 22 is connected to the power supply terminal 29, and the push piece 26 a of the detection switch 26 is provided on the electrical device 28. Pushed in. Thereby, the detection switch 26 is turned on when the battery pack 20 is attached to the electric device 28 and turned off when the battery pack 20 is removed from the electric device 29. When the detection switch 26 is on, the positive side of the battery 21 is connected to one input terminal of the AND circuit 25, and a signal of “H” level is input. On the other hand, when the detection switch 26 is off, one input terminal of the AND circuit 25 is at the “L” level.

  The overcharge / overdischarge prevention circuit 27 outputs an H level signal to the input terminal of the AND circuit 25 when the battery pack 20 is in a normal state. On the other hand, when overcharge or overdischarge is detected for the battery 21, the overcharge / overdischarge prevention circuit 27 outputs an L level signal to the input terminal of the AND circuit 25. Therefore, if the battery pack 20 is attached to the electrical device 28 and no overcharge or overdischarge is detected, the AND circuit 25 is turned on, both FETs of the switching element 23 are controlled to be turned on, and the battery 21 Power is supplied to 28.

  On the other hand, if overcharge or overdischarge is detected with the battery pack 20 attached to the electrical device 28, the output signal of the overcharge and overdischarge prevention circuit 27 becomes L level, and the AND circuit 25 The switching element 23 is turned off. Alternatively, when the battery pack 20 is removed from the electrical device, the detection switch 26 is turned off, so that the AND circuit 25 is turned off and the switching element 23 is controlled to be turned off. Therefore, in any case, power supply from the battery 21 to the electrical device 28 is interrupted. Thereby, generation | occurrence | production of a spark in the state which removed the battery pack 20 from the electric equipment 28 is prevented.

  The switching element 23 of the battery pack 20 having this structure is provided in order to prevent the overcharge / overdischarge of the battery 21 by the overcharge / overdischarge prevention circuit 27. Used in combination to add a function to cut off the discharge. Therefore, only by adding the AND circuit 25 and the detection switch 26, the connection structure between the battery pack 20 and the electric device 28 is not complicated, and the safety when the battery pack 20 is removed from the electric device 28 is improved. It becomes possible to improve.

JP-A-7-29554 JP 2002-330546 A

  However, in the battery pack having the above-described configuration of the conventional example, the AND circuit 25 is provided so that the overcharge / overdischarge prevention switching element 23 can be used in combination. Conventionally, the function of the overcharge / overdischarge prevention circuit 27 is generally obtained using a standardized protection IC. For this reason, adding the AND circuit 25 increases the number of circuit elements provided together with the protection IC, which causes circuit complexity and cost increase.

  Therefore, an object of the present invention is to provide a battery pack that realizes a function of stopping output from a secondary battery in a state where it is not attached to an electric device without complicating the circuit configuration.

  The battery pack of the present invention includes a battery cell to which a single or a plurality of secondary batteries are connected, a switch circuit inserted in a charge / discharge path extending from the battery cell to an external terminal, and the state of the battery cell or its surroundings. A protection circuit that controls at least one type of abnormality detection unit that detects an abnormality and controls the switch circuit in accordance with a signal input to the abnormality detection unit; and the protection circuit is input to the abnormality detection unit. The switch circuit is controlled to be energized when the signal indicates a normal state, and the switch circuit is controlled to be de-energized when the signal indicates an abnormal state.

  In order to solve the above problems, the battery pack of the present invention includes an external switch that is connected to the protection circuit and can be turned on / off from the outside, and when the external switch is turned off, A signal indicating an abnormal state is input to the abnormality detection unit, and the protection circuit controls the switch circuit to a non-energized state.

  According to the above configuration, when the battery pack is connected to a device or when connected in parallel, the switch circuit is turned off by an external switch, and the switch circuit is turned on after the operation is completed. Thus, the occurrence of sparks can be avoided. In addition, since it is configured to control the on / off of the switch circuit using a protection function against abnormality detection such as a temperature detection function that the battery pack normally has, it is possible to avoid complication of the circuit configuration.

1 is a block diagram showing a configuration of a battery pack according to Embodiment 1 of the present invention. Circuit diagram showing in detail the configuration of the main part of the battery pack Block diagram showing the configuration of the battery pack according to Embodiment 2 of the present invention. Circuit diagram of conventional battery pack

  The battery pack of the present invention can take the following aspects based on the above configuration.

  That is, it is preferable that a temperature detection unit is provided as a kind of the abnormality detection unit, and the temperature detection unit is set to a state in which an abnormality is detected by the on / off state of the external switch.

  A temperature sensor disposed outside the protection circuit and having a negative temperature characteristic of a detection signal voltage; and the temperature detection unit detects a temperature abnormality when the detection signal of the temperature sensor falls below a reference voltage. The detection signal of the temperature sensor can be set to the ground potential according to the on / off state of the external switch.

  Further, a negative characteristic thermistor is used as the temperature sensor, one end of the negative characteristic thermistor is connected to a ground potential, and a predetermined voltage is applied to the other end via a voltage dividing resistor, in parallel with the negative characteristic thermistor. The external switch can be connected.

  Further, it is possible to control at least a part of the protection circuit and elements related to its operation to operate in a low power consumption mode, and the switch circuit is controlled to be in a non-energized state by operating the external switch. When it is done, it can be configured to shift to the low power consumption mode.

  In the low power consumption mode, at least one type of abnormality detection operation of the abnormality detection unit may be stopped.

  In addition, a temperature detection unit is provided as a kind of the abnormality detection unit, and the temperature detection unit is set to a state in which an abnormality is detected according to the on / off state of the external switch. In the low power consumption mode, the temperature detection unit On the basis of the abnormality detection signal output from, the abnormality detection operation of the other abnormality detection unit can be stopped.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a basic block diagram showing a configuration of battery pack 1 according to Embodiment 1 of the present invention. The battery pack 1 incorporates, for example, a battery cell 2 configured by connecting one or more secondary batteries such as lithium ion batteries in series. Charging / discharging terminals T1, T2 are connected to both electrode terminals of the battery cell 2, and power is supplied to an external load or charging to the battery cell 2 from the outside is performed via the charging / discharging terminals T1, T2.

  Similarly to the general configuration, the switch circuit 3 is inserted into the charge / discharge path on the positive electrode side, and the switch circuit 3 is opened and closed by the protection circuit 4 so that the output of the battery cell 2 is controlled. The protection circuit 4 includes a switch circuit control unit 5, an overcharge / overdischarge voltage detection unit 6, an overcurrent detection unit 7, and a temperature detection unit 8. As the protection circuit 4, a standardized protection IC is usually used.

  The overcharge / overdischarge voltage detector 6 monitors the charge / discharge voltage of the battery cell 2 and generates a predetermined control signal when an overdischarge or overcharge voltage is detected. The overcurrent detection unit 7 monitors the current flowing through the battery cell 2 through a resistor inserted in the charge / discharge path on the negative electrode side, and generates a predetermined control signal when an overcurrent is detected. The temperature detection unit 8 monitors the temperature in the battery pack 1 and generates a predetermined control signal when a temperature abnormality is detected. The overcharge / overdischarge voltage detection unit 6, the overcurrent detection unit 7, and the temperature detection unit 8 are examples of an abnormality detection unit for detecting an abnormality in the state of the battery cell 2 or its surroundings, and are not limited thereto. It is not a thing.

  Control signals generated by the overcharge / overdischarge voltage detection unit 6, the overcurrent detection unit 7, and the temperature detection unit 8 are supplied to the switch circuit control unit 5, and the switch circuit control unit 5 switches the switch circuit based on the control signals. 3 is controlled to be energized or de-energized (shut off). Thereby, the charging / discharging path | route is interrupted | blocked at the time of abnormalities, such as an overcharge or overdischarge, and the protection of the battery cell 2 or accident occurrence is prevented.

  The thermistor 9 disposed outside the protection circuit 4 is usually connected to the temperature detector 8 as a temperature sensor. The thermistor 9 monitors the temperature inside the battery pack 1, and a voltage value is supplied to the temperature detector 8 as temperature detection information. The temperature detector 8 compares the voltage value obtained from the thermistor 9 with the set reference voltage, and as a result, when it is determined that the temperature is abnormal, a control signal is supplied to the switch circuit controller 5 and the switch circuit 3 is turned off. Charging / discharging of the battery pack 1 is prohibited in an energized state.

  In the present embodiment, an external switch 10 that can be turned on / off from the outside is connected to the temperature detector 8. By operating on / off of the external switch 10, the detection signal output from the thermistor 9 is set to a state in which the temperature detection unit 8 has detected an abnormality. Thereby, the switch circuit control unit 5 controls the switch circuit 3 to a non-energized state. The external switch 10 can be turned on / off manually by the user.

  As described above, it is possible to prevent the occurrence of sparks in a state where the battery pack 1 is disconnected from the electric device by interrupting the charge / discharge path by operating the external switch 10. This function is realized by making maximum use of a circuit for a protection function normally provided in a battery pack against overcharge, overdischarge, and the like. In the above configuration, the original function of the temperature detection unit 8 which is one of the abnormality detection units is used as it is. Therefore, only by adding the external switch 10 as an output stop switch, a sufficient effect can be obtained with a very simple change compared to the addition of the AND circuit 25 in the conventional example shown in FIG.

  Note that the abnormality detection unit that is set to a state in which an abnormality has been detected by operating the external switch 10 is not limited to the temperature detection unit 8, and other abnormality detection units can be configured as such.

  FIG. 2 shows a specific example of the connection state between the temperature detector 8, the thermistor 9, and the external switch 10 of the protection circuit 4. However, in order to simplify the description, FIG. 2 shows a configuration in which capacitors, diodes, resistors, and the like, such as an ESD protection circuit, an anti-noise circuit, and a chattering prevention circuit, are omitted.

  The temperature detection unit 8 includes a temperature detection output terminal 11 that outputs a voltage and a temperature detection input terminal 12 that inputs a voltage. A voltage dividing resistor 13 and the thermistor 9 are connected in series between the temperature detecting output terminal 11 and the ground potential, and a temperature detecting input terminal 12 is connected to a connection point between the voltage dividing resistor 13 and the thermistor 9. The external switch 10 is connected in parallel with the thermistor, that is, inserted between the connection point of the voltage dividing resistor 13 and the thermistor 9 and the ground potential.

  In this circuit, the temperature detector 8 is set to detect a temperature abnormality when the input voltage to the temperature detection input terminal 12 falls below the reference voltage. Therefore, as the thermistor 9, a thermistor having a negative temperature characteristic is used. The voltage applied from the temperature detection output terminal 11 is resistance-divided by the voltage dividing resistor 13 and the thermistor 9, and the voltage between the thermistor 9 and the ground is input to the temperature detection output terminal 11 as a temperature detection signal. The resistance value of the voltage dividing resistor 13 is adjusted as appropriate so that the voltage input to the temperature detection input terminal 12 becomes the reference voltage at the temperature to be detected due to the characteristics of the thermistor 9.

  With this configuration, when the external switch 10 is conductive, the temperature detection signal from the thermistor 9 is set to the ground potential. Therefore, the temperature detection signal is lower than the reference voltage, and the temperature detection unit 8 detects that the temperature is abnormal. As a result, the switch circuit control unit 5 controls the switch circuit 3 to be in a non-conductive state.

  When the external switch 10 is turned off and the non-conductive state of the external switch 10 is turned on, the battery pack 1 operates normally when the external switch 10 is on, that is, a state in which output from the battery cell 2 is possible. become. On the other hand, when the external switch 10 is OFF, the output of the battery cell 2 is stopped. In other words, when the battery pack 1 is connected to a device or when the switch circuit is connected in parallel, the external switch 10 can be turned off to work safely.

(Embodiment 2)
FIG. 3 is a block diagram showing a configuration of battery pack 14 according to Embodiment 2 of the present invention. The configuration of battery pack 14 is generally the same as that of battery pack 1 in the first embodiment described above. Therefore, the same reference numerals are assigned to the same elements to avoid repeated description.

  The battery pack 14 of the present embodiment differs from the first embodiment in that the battery pack 14 operates in the low power consumption mode when the switch circuit 3 is controlled to be in a non-energized state by operating the external switch 10. To be controlled.

  That is, in this battery pack 14, although a specific configuration is not shown, it is possible to operate the protection circuit 4 and at least some of the elements related to the operation thereof in the low power consumption mode. In order to operate in such a low power consumption mode, a well-known configuration can be employed. The feature of this embodiment is that the switch circuit 3 is in a non-energized state by operating the external switch 10 as one of the conditions for shifting to the low power consumption mode.

  In order to control to the low power consumption mode, the abnormality detection signal from the temperature detection unit 8 is not only supplied to the switch circuit control unit 5, but also overcharge / overdischarge voltage detection unit 6 through the detection signal line 15, and It is also supplied to the overcurrent detection unit 7. In response to the abnormality detection signal, the overcharge / overdischarge voltage detection unit 6 and the overcurrent detection unit 7 are configured to be cut off from the power supply and enter the low power consumption mode (not shown). Thereby, the power consumption in the state where the output from the battery cell 2 to the outside is stopped can be reduced.

  As described above, as an example of the operation in the low power consumption mode, at least one type of abnormality detection operation of the abnormality detection unit such as the overcharge / overdischarge voltage detection unit 6 and the overcurrent detection unit 7 can be stopped. However, other methods for reducing power consumption can be employed.

  The battery pack of the present invention can be used easily and safely by using a certain function, and is useful as a battery pack for industrial use such as an electric motorcycle.

DESCRIPTION OF SYMBOLS 1, 14 Battery pack 2 Battery cell 3 Switch circuit 4 Protection circuit 5 Switch circuit control part 6 Overcharge and overdischarge voltage detection part 7 Overcurrent detection part 8 Temperature detection part 9 Thermistor 10 External switch 11 Temperature detection output terminal 12 Temperature Input terminal for detection 13 Voltage dividing resistor 15 Detection signal line

Claims (7)

A battery cell to which one or more secondary batteries are connected;
A switch circuit inserted in a charge / discharge path from the battery cell to the external terminal;
It has at least one type of abnormality detection unit that detects an abnormality in the state of the battery cell or its surroundings, and includes a protection circuit that controls the switch circuit according to a signal input to the abnormality detection unit,
The protection circuit controls the switch circuit to an energized state when a signal input to the abnormality detection unit indicates a normal state, and controls the switch circuit to a non-energized state when the signal indicates an abnormal state. Battery pack
An external switch connected to the protection circuit and capable of on / off operation from the outside;
When the external switch is turned off, a signal indicating an abnormal state is input to the abnormality detection unit, and the protection circuit controls the switch circuit to a non-energized state. A temperature detection unit is provided as a kind of the abnormality detection unit,
The battery pack according to claim 1, wherein the temperature detection unit is set to a state in which an abnormality is detected according to an on / off state of the external switch. A temperature sensor disposed outside the protection circuit and having a negative temperature characteristic of the voltage of the detection signal;
The temperature detection unit is set to detect a temperature abnormality when a detection signal of the temperature sensor falls below a reference voltage,
The battery pack according to claim 2, wherein a detection signal of the temperature sensor can be set to a ground potential according to an on / off state of the external switch. A negative characteristic thermistor is used as the temperature sensor,
One end of the negative characteristic thermistor is connected to the ground potential, and a predetermined voltage is applied to the other end via a voltage dividing resistor,
The battery pack according to claim 3, wherein the external switch is connected in parallel with the negative characteristic thermistor. The protection circuit and at least some of the elements related to its operation can be controlled to operate in a low power consumption mode,
The battery pack according to claim 1, wherein when the switch circuit is controlled to be in a non-energized state by an operation of the external switch, the battery pack shifts to the low power consumption mode.   The battery pack according to claim 5, wherein in the low power consumption mode, at least one type of abnormality detection operation of the abnormality detection unit is stopped. A temperature detection unit is provided as a kind of the abnormality detection unit,
According to the on / off state of the external switch, the temperature detection unit is set to a state where an abnormality is detected,
The battery pack according to claim 6, wherein in the low power consumption mode, an abnormality detection operation of another abnormality detection unit is stopped based on an abnormality detection signal output from the temperature detection unit.

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