JP5639390B2 - Battery pack and connected battery pack - Google Patents

Description

  The present invention relates to a battery pack in which a secondary battery such as a lithium ion battery is stored, and in particular, a battery pack having a function of stopping output from a secondary battery when an abnormality is detected, and such a battery. The present invention relates to a linked battery pack in which a plurality of packs are connected.

  The battery pack is provided in a form in which a secondary battery such as a lithium ion battery is housed in a casing, and is widely applied as a power source for various portable electronic devices such as a mobile phone, a notebook computer, and a digital camera.

  On the other hand, Patent Literature 1 discloses a technique for solving a problem in providing a battery pack having a higher voltage than a power source of a portable electronic device. In the case of a portable electronic device, since a high power supply voltage is not required, it is at most a series type of four secondary batteries. If such a type of battery pack is to be adopted as a power source for a battery-assisted bicycle, for example, the voltage is low in the 4-shaft, so a multi-shaft type such as a 7-shaft is required.

  By the way, since the conventional battery pack is a standard type up to 4 straight, the protection IC built in the battery pack is for small and medium voltage that can support up to 4 straight. Therefore, in order to meet the demand for higher voltage battery packs, a plurality of batteries are divided into a plurality of blocks, and a small / medium voltage protection IC provided for each block is connected in units of 4 series. Will have to do.

  However, in the control microcomputer that manages and controls the battery pack by communicating with the outside, when processing signals from a plurality of small and medium voltage protection ICs, the voltage reference of each protection IC is different. There is a problem in that it hinders communication. The technique disclosed in Patent Document 1 is provided with a level conversion circuit that unifies the voltage reference of detection signals of a plurality of protection ICs in order to eliminate such a difference in voltage reference between the plurality of protection ICs. .

JP 2003-111294 A

  However, the technique disclosed in Patent Document 1 cannot cope with the following problems when a plurality of battery packs with built-in protection ICs are used in a multi-series, a multi-parallel, or a multi-series parallel. Absent.

  FIG. 3 shows a state in which two battery packs, that is, the first battery pack 20a and the second battery pack 20b are used in series. The first and second battery packs 20a and 20b have the same structure. For example, the first battery pack 20a includes a battery cell 21a including a plurality of secondary batteries. Electric power is supplied to the external load 24 via the charge / discharge terminals 22a and 23a corresponding to both electrodes of the battery cell 21a, or the battery cell 21a is charged from the outside.

  Further, the switch circuit 25 is inserted into the charge / discharge path on the positive electrode side, and the protection circuit 26 opens and closes the switch circuit 25, whereby the output from the battery cell 21a to the outside is controlled. The protection circuit 26 is generally provided in the battery pack in order to protect the secondary battery from overcharge and overdischarge.

  The protection circuit 26 monitors the charge / discharge voltage of the battery cell 21a, monitors the current through the resistor 27 inserted in the charge / discharge path on the negative electrode side, and monitors the temperature in the battery pack through the thermistor 28, etc. The function of detecting the occurrence of abnormality and controlling the opening and closing of the switch circuit 25 according to the detection signal is provided. The switch circuit 25 is controlled to be ON during normal discharge, and is controlled to be OFF when an abnormality is detected.

  By using the battery pack having the configuration as described above, and connecting the charge / discharge terminal 23a on the negative electrode side of the first battery pack 20a to the charge / discharge terminal 22b on the positive electrode side of the second battery pack 20b, two in series used. The voltage of the battery cell 21a of the first battery pack 20a is V1, and the voltage of the battery cell 21b of the second battery pack 20b is V2. For the sake of simplicity, ignoring the voltage drop in each switch circuit 25 and other circuits, the charge / discharge terminal 22a on the positive side of the first battery pack 20a connected to the positive electrode of the load 24, and the negative electrode of the load 24 The voltage between the charge / discharge terminals 23b on the negative electrode side of the second battery pack 20b connected to V becomes V1 + V2, and the voltage that can be supplied to the load can be increased.

  When battery packs are connected in this manner, for example, when an abnormality such as overcurrent, overcharge voltage, overdischarge voltage, or temperature occurs in the first battery pack 20a on the higher potential side, the following is performed. An unexpected situation occurs. First, the switch circuit 25 of the first battery pack 20a is turned off, and the supply of power to the load 24 is stopped. Thereby, when the potential of the negative electrode of the second battery pack 20b on the low potential side is set to 0V, the charge / discharge terminal 22a on the positive electrode side of the first battery pack 20a is set to 0V of the same potential.

  At this time, if no abnormality is detected in the second battery pack 20b, the switch circuit 25 of the second battery pack 20b remains ON. Therefore, the potential of the charge / discharge terminal 22b on the positive electrode side of the second battery pack 20b is V2, and the potential of the charge / discharge terminal 23a on the negative electrode side of the first battery pack 20a is also V2. Since the voltage of the battery cell 21a of the first battery pack 20a is V1, the voltage applied to both ends of the switch circuit 25 of the first battery pack 20a turned off is V1 + V2. For this reason, the number of battery packs that can be connected is limited so that the voltage applied to the switch circuit 25 does not exceed the rating.

  At this time, if the power source or signal line of the protection circuit 26 of the first battery pack 20a on the higher potential side is connected to the positive electrode of the first battery pack 20a, a voltage of -V2 is applied, and vice versa. A voltage may be generated and the protection circuit 26 may be destroyed.

  Therefore, the present invention relates to the switch circuit that controls the output of the battery cell, etc. even when the battery pack in which an abnormality has occurred stops the output when the battery pack is connected and used. An object of the present invention is to provide a battery pack that can prevent an excessive voltage or the like from being applied.

  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, a battery pack according to the present invention includes a temperature sensor , a temperature detection unit that is provided in the abnormality detection unit, detects a temperature abnormality based on a detection signal of the temperature sensor, and the protection circuit. A signal output circuit that is connected and outputs a signal to the outside of the battery pack; and a signal input circuit that is connected to the temperature sensor and receives a signal from the outside of the battery pack; and the signal input circuit includes the signal input circuit. When a signal indicating abnormality is input from the outside of the battery pack, a detection signal of the temperature sensor is set so that the temperature detection unit detects a temperature abnormality, and the temperature detection unit when detecting an abnormal, the abnormality detection unit signal indicating the abnormal state is entered, the protection circuit controls the switching circuit in a non-energized state, whether the signal output circuit A signal indicating the abnormality and outputs to the outside of the battery pack.

  According to the said structure, when connecting a some battery pack, the output of the abnormality signal output terminal of all the battery packs and the input to the abnormality signal output terminal can be connected in a loop shape. Thereby, when the switch circuit is controlled to be OFF due to the occurrence of an abnormality in any of the battery packs, the switch circuits of all other battery packs are controlled to be OFF. Thereby, it is avoided that the voltage applied to the switch circuit becomes larger than that when the battery pack is used alone, and there is no need to limit the number of battery packs that can be connected. As a result, when the battery pack is used in multiple series, multiple parallel, or multiple series parallel, it can be used safely.

1 is a block diagram showing a configuration of a battery pack according to Embodiment 1 of the present invention. A block diagram showing a connection state when two battery packs are connected in series Block diagram showing the state when using two battery packs connected in series

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

  That is, the protection circuit controls the switch circuit to a non-energized state when the signal supplied through the signal input circuit is below or exceeds a predetermined reference voltage, and detects an abnormality from the signal output circuit. The signal shown can be configured to be output to the outside of the battery pack.

Further, the temperature sensor is located outside of the protection circuit, the voltage of the detection signal have a negative temperature characteristic, the temperature detection section, the temperature when the detection signal of the temperature sensor falls below the reference voltage It can be set so that an abnormality is detected.

  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. The signal input circuit may be connected to the connection point of the voltage dividing resistor.

  In addition, the battery pack includes a plurality of battery packs having any of the above-described configurations, and each of the battery packs is connected to charge / discharge terminals so as to output a connected discharge voltage. Each of the signal output circuits can be connected to a signal input circuit of another battery pack through a terminal to constitute a connected battery pack.

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

(Embodiment)
FIG. 1 is a block diagram showing a basic configuration of battery pack 1 according to the embodiment of the present invention. The battery pack 1 includes, for example, a battery cell 2 configured by connecting one or more secondary batteries such as lithium ion batteries in series. Power is supplied to an external load via the charge / discharge terminals 3 and 4 connected to both electrodes of the battery cell 2, or the battery cell 2 is charged from the outside.

  Further, the switch circuit 5 is inserted into the charge / discharge path on the positive electrode side, and the switch circuit 5 is opened / closed by the protection circuit 6 so that the output from the battery cell 2 to the outside is controlled. The protection circuit 6 includes a switch circuit control unit 7, an overcharge / overdischarge voltage detection unit 8, an overcurrent detection unit 9, and a temperature detection unit 10. As the protection circuit 6, a standardized protection IC can be used.

  The overcharge / overdischarge voltage detector 8 monitors the charge / discharge voltage of the battery cell 2 and generates a predetermined control signal when the overdischarge or overcharge voltage is detected. The overcurrent detection unit 9 monitors the current flowing through the battery cell 2 via the current detection resistor 11 inserted in the charge / discharge path on the negative electrode side, and generates a predetermined control signal when the overcurrent is detected. To do. The temperature detection unit 10 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 8, the overcurrent detection unit 9, and the temperature detection unit 10 are examples of an abnormality detection unit for detecting an abnormality in the state of the battery cell 2 or its surroundings. However, it is not limited to these.

  Control signals generated by the overcharge / overdischarge voltage detection unit 8, the overcurrent detection unit 9, and the temperature detection unit 10 are supplied to the switch circuit control unit 7, and the switch circuit control unit 7 switches the switch circuit based on the control signals. 5 energization or non-energization (shut off) is controlled. 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 12 disposed outside the protection circuit 6 is connected to the temperature detection unit 10 as a temperature sensor. The temperature inside the battery pack 1 is monitored by the thermistor 12, and a voltage value is supplied to the temperature detector 10 as a temperature detection signal. The temperature detection unit 10 compares the voltage value obtained from the thermistor 12 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 control unit 7 and the switch circuit 5 is turned off. Charging / discharging of the battery pack 1 is prohibited in an energized state.

  In order to detect a change in resistance value according to the temperature of the thermistor 12, a voltage dividing resistor 13 is connected in series to the thermistor 12, and a voltage between the thermistor 12 and the voltage dividing resistor 13 is input to the temperature detection unit 10. The The voltage applied from the temperature detector 10 is resistance-divided by the voltage dividing resistor 13 and the thermistor 12, and the voltage between the thermistor 12 and the ground becomes the temperature detection signal. In this circuit, the temperature detection unit 10 is set to detect a temperature abnormality when the voltage of the temperature detection signal falls below the reference voltage. Therefore, as the thermistor 12, a thermistor having a negative temperature characteristic is used.

  The control signal output from the switch circuit control unit 7 to the switch circuit 5 is also supplied to the abnormal signal output circuit 14 at the same time. The abnormal signal output circuit 14 generates an abnormal signal from this control signal and outputs it from the abnormal signal output terminal 15 to the outside. On the other hand, an abnormal signal input terminal 16 is provided, and an abnormal signal can be input from the outside. The abnormal signal to be input is a signal having a function that allows the protection circuit 6 to generate a signal for controlling the switch circuit 5.

  The abnormal signal input terminal 16 is connected between the thermistor 12 and the voltage dividing resistor 13. In this configuration, the abnormal signal output circuit 14 generates a ground potential signal as the abnormal signal, so that the temperature detection signal becomes the ground potential due to the abnormal signal input via the abnormal signal input terminal 16. Therefore, the temperature detection signal is lower than the reference voltage, and the temperature detection unit 10 detects that the temperature is abnormal. As a result, the switch circuit controller 7 controls the switch circuit 5 to be in a non-conductive state.

  As described above, in order to control the switch circuit 5 from the protection circuit 6 to OFF when an abnormality occurs in the voltage of the battery cell 2 or the current or temperature of the battery pack 1 during charging / discharging of the battery pack 1. Based on the output signal, an abnormal signal that is set to a state in which the protection circuit 6 of the other battery pack 1 has detected an abnormality is output from the abnormal signal output terminal 15 to the outside. Further, an abnormal signal output from the other battery pack 1 is input to the protection circuit 6 via the abnormal signal input terminal 16, and the switch circuit 5 is controlled to be OFF in accordance with the abnormal signal.

  In the present embodiment, the abnormal signal input from the abnormal signal input terminal 16 is input to the temperature detection unit 10 as a signal equivalent to the temperature detection signal. Accordingly, the protection function is activated by causing the protection circuit 6 to recognize an external abnormality signal as a temperature abnormality without providing a new abnormality signal processing input terminal in the protection circuit 6. Accordingly, a useful new function can be obtained by adding the minimum simple components as the battery pack 1 and using the standard protection IC for the protection circuit 6.

  In addition, as the switch circuit 5, what can be controlled from the protection circuit 6, such as semiconductor switches, such as IGBT and MOSFET, and physical switches, such as a relay, can be used, for example.

  Further, the signal input to the abnormal signal output circuit 14 may have any characteristic or form as long as the signal having a function that the protection circuit 6 can generate a signal for controlling the switch circuit 5. However, it is desirable that the input abnormal signal has the same characteristics as the abnormal signal output from the abnormal signal output circuit 14.

  As an example of connecting and using a plurality of battery packs of the present embodiment as described above, a case where two battery packs are used in series will be described with reference to FIG. FIG. 2 shows a state where two battery packs having the configuration shown in FIG. 1, that is, the first battery pack 1 a and the second battery pack 1 b are connected in series, and the load 17 is discharged.

  About the internal structure of the 1st and 2nd battery pack 1a, 1b, about the element same as FIG. 1, the same referential mark is attached | subjected and description of description is abbreviate | omitted. However, for convenience of explanation, the charge / discharge terminals 3a, 4a, 3b, 4b, the switch circuits 5a, 5b, the abnormal signal output terminals 15a, 15b, and the abnormal signal input terminals 16a, 16b are the first and second battery packs 1a. Description will be made with reference numerals distinguished corresponding to 1b.

  The charge / discharge terminal 3b on the positive electrode side of the second battery pack 1b and the charge / discharge terminal 4a on the negative electrode side of the first battery pack 1a are connected, and the charge / discharge terminal 3a on the positive electrode side of the first battery pack 1a is connected to the positive electrode of the load 17. However, the charge / discharge terminal 4 b on the negative electrode side of the second battery pack 1 b is connected to the negative electrode of the load 17. When the voltage of the battery cell 2 of the first battery pack 1a is V1, and the voltage of the battery cell 2 of the second battery pack 1b is V2, the charge / discharge terminal on the positive side of the first battery pack 1a connected to the positive electrode of the load 17 The voltage between 3a and the charge / discharge terminal 4b on the negative electrode side of the second battery pack 1b connected to the negative electrode of the load 17 is V1 + V2.

  The abnormal signal output terminal 15a of the first battery pack 1a is connected to the abnormal signal output terminal 16b of the second battery pack 1b. On the other hand, the abnormal signal output terminal 15b of the second battery pack 1b is connected to the abnormal signal output terminal 16a of the first battery pack 1a.

  When the battery packs are connected as shown in FIG. 2, for example, when an abnormality such as an overcurrent, an overcharge voltage, an overdischarge voltage, or a temperature occurs in the first battery pack 1a, the first battery The switch circuit 5a of the pack 1a is turned off, and the supply of power to the load 17 is stopped. At this time, an abnormal signal is output from the abnormal signal output circuit 14 based on the output signal from the protection circuit 6 that controls the switch circuit 5a to be OFF.

  The abnormal signal from the abnormal signal output circuit 14 is input to the protection circuit 6 of the second battery pack 1b via the abnormal signal output terminal 15a and the abnormal signal output terminal 16b of the second battery pack 1b. Thereby, even if it is a case where abnormality is not detected in the 2nd battery pack 1b, the switch circuit 5b of the 2nd battery pack 1b is controlled to OFF.

  As a result, when the potential of the negative electrode of the second battery pack 1b is set to 0V, the charge / discharge terminal 3a on the positive electrode side of the first battery pack 1a is set to 0V of the same potential. Further, since the switch circuit 5b of the second battery pack 1b is turned off, the charge / discharge terminal 3b on the positive electrode side is disconnected from the battery cell 2, and the potential of the charge / discharge terminal 4a on the negative electrode side of the first battery pack 1a is 0V. Become. Therefore, the voltage applied to both ends of the switch circuit 5a of the first battery pack 1a turned off is V1. Therefore, it is avoided that the voltage applied to the switch circuit 5a as described in the conventional example is larger than when the battery pack is used alone, and the number of battery packs that can be connected is not limited.

  At this time, even if the power supply or signal line of the protection circuit 6 of the first battery pack 1a is connected to the positive electrode of the first battery pack 1a, the switch circuit 5b of the second battery pack 1b is turned off. Therefore, the possibility that the protection circuit 6 is destroyed due to the generation of the reverse voltage is eliminated.

  The battery pack according to the present embodiment is not limited to the two battery packs as described above, and the same effect can be obtained when a larger number of battery packs are connected. That is, by connecting the output of the abnormal signal output terminal of all battery packs and the input to the abnormal signal output terminal with a loop, an abnormality occurs in one of the battery packs, and the battery pack in which the abnormality has occurred outputs the output. When the other battery pack receives the abnormality signal output as a temperature abnormality when the operation stops, the other battery pack also stops the output.

  By stopping the output of all battery packs, the overvoltage and reverse voltage to the switch circuit and protection circuit, which are generated when batteries are combined in series, can be used safely. it can. The same applies to parallel or serial-parallel use.

  According to the battery pack of the present invention, when a plurality of battery packs are connected and used, an excessive voltage or the like due to the plurality of connections is applied to elements such as a charge / discharge control switch circuit when an abnormality occurs. Therefore, it is useful as a power source for various portable electronic devices such as mobile phones, notebook computers, digital cameras, and battery-assisted bicycles.

DESCRIPTION OF SYMBOLS 1 Battery pack 1a 1st battery pack 1b 2nd battery pack 2 Battery cell 3, 3a, 3b, 4, 4a, 4b Charge / discharge terminal 5, 5a, 5b Switch circuit 6 Protection circuit 7 Switch circuit control part 8 Overcharge and overcharge Discharge voltage detection unit 9 Overcurrent detection unit 10 Temperature detection unit 11 Current detection resistor 12 Thermistor 13 Voltage division resistor 14 Abnormal signal output circuits 15, 15a, 15b Abnormal signal output terminals 16, 16a, 16b Abnormal signal input terminal 17 Load

Claims (5)

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
A temperature sensor;
A temperature detection unit that is provided in the abnormality detection unit and detects a temperature abnormality based on a detection signal of the temperature sensor;
A signal output circuit connected to the protection circuit and outputting a signal to the outside of the battery pack;
A signal input circuit connected to the temperature sensor , to which a signal from the outside of the battery pack is input,
When a signal indicating an abnormality is input from the outside of the battery pack to the signal input circuit, a detection signal of the temperature sensor is set so that the temperature detection unit detects a temperature abnormality,
When the temperature detection unit detects that the temperature is abnormal, a signal indicating an abnormal state is input to the abnormality detection unit, the protection circuit controls the switch circuit to a non-energized state, and the signal output circuit A battery pack that outputs a signal indicating abnormality from the battery pack to the outside of the battery pack.   The protection circuit controls the switch circuit to a non-energized state when the signal supplied via the signal input circuit is below or exceeds a predetermined reference voltage, and also indicates a signal indicating an abnormality from the signal output circuit. The battery pack according to claim 1, wherein the battery pack is output to the outside of the battery pack. The temperature sensor is located outside of the protection circuit, the voltage of the detection signal have a negative temperature characteristic,
The battery pack according to claim 1 or 2 , wherein the temperature detection unit is set to detect a temperature abnormality when a detection signal of the temperature sensor falls below a reference voltage. 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 signal input circuit is connected to a connection point between the negative characteristic thermistor and the voltage dividing resistor. A plurality of the battery packs according to any one of claims 1 to 4 ,
Each charge / discharge terminal of the battery pack is connected so as to output a connected discharge voltage of each of the battery cells, and
The signal output circuit of each of the battery packs is connected so as to form a loop among all the battery packs by being connected to a signal input circuit of another battery pack via a terminal. Linked battery pack.

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