JP6810475B2 - Battery pack - Google Patents

Description

The present invention relates to a battery pack having a battery such as a lithium ion battery as a power source for driving an electric device and having a function of protecting the battery.

The battery pack is generally used as a built-in power source for portable electric devices such as mobile phones, portable AV devices, and electric tools, and can be removed from the electric devices. As disclosed in Patent Document 1, the battery pack is usually composed of a cell portion, which is the battery itself, and a protection circuit portion. The cell portion is formed by connecting a plurality of rechargeable and dischargeable batteries, for example, a lithium ion battery in series. The protection circuit section includes an electric circuit formed on the substrate and is electrically and mechanically connected to the terminals of each battery in the cell section, such as charge current value, discharge current value, temperature, etc. of each battery in the cell section. The parameters of the above are monitored to prevent overcharging and overdischarging. Further, the protection circuit unit has a device connection terminal that is mechanically and electrically connected to the power supply terminal of the electric device when the battery pack is attached to the electric device.

Japanese Unexamined Patent Publication No. 2011-9023

Recently, it has been considered to use a battery pack as a power source for medical instruments such as surgical drills. Among medical equipment, medical equipment that is brought into the operating room must be sterilized at a high temperature of 135 ° C for several tens of minutes, so when using it as a power source for such medical equipment, the battery pack is also the same. Will be sterilized. However, experiments have shown that when a battery undergoing high-temperature sterilization is charged or discharged, the life of the battery is shortened or a problem such as liquid leakage occurs, resulting in a battery that cannot be used at all. .. In order not to cause such a problem, the battery pack is removed from the main body of the medical device and the battery pack is sterilized by itself.

However, in the battery pack, since the cell unit and the protection circuit unit are always connected, a current can flow through the protection circuit unit even with the battery pack alone. Therefore, in the battery pack, for example, a minute current of about several tens of μA to several hundreds of μA continues to leak from the cell portion to the protection circuit portion. This leakage current does not affect the cell part under normal temperature environment, but the amount of leakage current flowing from the cell part to the protection circuit part increases in the sterilization process, for example, at a high temperature of 135 ° C, and the battery life is extended. It may be shortened or cause problems such as liquid leakage as described above.

Further, even when the battery pack is stored for a long period of time, a small amount of current constantly flows from the cell portion to the protection circuit portion, and the amount of stored electricity gradually decreases, resulting in over-discharge.

Therefore, an object of the present invention is to provide a battery pack in which the leakage current flowing from the cell portion to the protection circuit portion is reduced in a single state when the electric device is removed.

The battery pack of the present invention is electrically connected to a cell portion including a single or a plurality of rechargeable batteries, a terminal for electrical connection between the cell portion and an electric device, and the cell portion. A battery pack including a protection circuit unit including a control unit that operates by supplying power from the cell unit and controls discharge or charging of the cell unit. The protection circuit unit is the cell unit to the cell unit. The control unit includes a switch element that turns on and off an electrical connection for supplying power to the control unit, and the control unit is electrically connected to the cell unit and the electric device by the terminal when the switch element is off. Then, the cell unit receives power from the cell unit via the electric device to start the operation and controls the switch element to be turned on. It is characterized in that the switch element is controlled to be turned off when the electrical connection between the cell portion and the electric device by the terminal is cut during the operation.

According to the battery pack of the present invention, when the battery pack is removed from the electric device, it is determined whether or not the connection between the cell portion and the electric device is disconnected, and it is determined that the connection is disconnected. , The electrical connection between the cell part and the protection circuit part is cut off by the cutoff part. As a result, it is possible to prevent a minute leakage current from flowing from the cell portion to the protection circuit portion. Therefore, it is possible to prevent the leakage current from flowing from the cell portion to the protection circuit portion even at a high temperature of about 135 ° C. in the high temperature sterilization process, and to prevent problems such as shortening the life of the battery pack and liquid leakage. In addition, even when the battery pack is stored for a long period of time, the flow of current from the cell portion to the protection circuit portion is blocked and only self-discharge is performed, so that the decrease in the amount of stored electricity can be suppressed for a long period of time, and as a result, Over-discharge can be prevented.

It is a figure which shows the circuit structure of the battery pack to which this invention is applied. It is a flowchart which shows the operation at the time of starting of the battery pack of FIG. It is a circuit diagram which shows the state which the battery pack of FIG. 1 and the surgical drill of an electric device are connected. It is a flowchart which shows the operation of the removal determination routine of the battery pack of FIG.

Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a battery pack 10 to which the present invention is applied. The battery pack 10 includes a cell unit 11 and a protection circuit unit 21. The cell portion 11 has four batteries 12a to 12d, and the batteries 12a to 12d are connected in series in that order. Each of the batteries 12a to 12d is, for example, a lithium ion battery. Connection point 13a connected to the positive terminal of the battery 12a, connection point 13b between the negative terminal of the battery 12a and the positive terminal of the battery 12b, connection point 13c between the negative terminal of the battery 12b and the positive terminal of the battery 12c, negative of the battery 12c The connection point 13d between the terminal and the positive terminal of the battery 12d and the connection point 13e connected to the negative terminal of the battery 12d are connected to the protection circuit unit 21. In this embodiment, the cell unit 11 includes a plurality of batteries 12a to 12d, but the number of the batteries is not limited to four, and for example, five or more batteries may be connected in series. Further, it may be provided only with a single battery instead of a plurality of batteries.

The protection circuit unit 21 includes a control device 22, FETs (field effect transistors) 23a to 23e, a discharge switch 24, a charge switch 25, and a current measurement resistor 26. These elements of the protection circuit unit 21 are formed on the same substrate 30.

The board 30 is provided with device connection terminals 31a to 31f for connecting to the electric device 40 which is an external device. Each of the device connection terminals 31a to 31f is arranged at a predetermined position, and is electrically and mechanically connectable to the electric device 40 using the battery pack 10 as a power source. The electric device 40 is provided with connection terminals 41a to 41f corresponding to the device connection terminals 31a to 31f, respectively. For example, if the battery pack 10 and the electric device 40 are connected by a connector, the device connection terminals 31a to 31a to 31f is formed as the male side or the female side of the connector.

The device connection terminal 31a is for discharging on the positive power supply side for supplying the discharge current to the electric device 40 in the discharge mode of the battery pack 10, and 31b is for positive for receiving the charging current in the charging mode when the electric device 40 is a charger. Power supply side charging, 31c for activation to detect that an electric device is connected, 31d for communication to communicate with an electric device, 31e for energy mode selection to select between normal mode and energy saving mode 31f is a terminal for a common power supply on the negative power supply side of the electric device. The device connection terminals 31b to 31f are individually connected to the control device 22, and the device connection terminals 31b, 31c, and 31f are connected to the power input terminals INA, INB, and INC of the control device 22, respectively.

The control device 22 is a control unit, and includes, for example, a CPU (Central Processing Unit). The FETs 23a to 23e are switch elements of the blocking unit, and are connected between the control device 22 and each of the connection points 13a to 13e. That is, the drain of the FET 23a is connected to the connection point 13a, the drain of the FET 23b is connected to the connection point 13b, the drain of the FET 23c is connected to the connection point 13c, the drain of the FET 23d is connected to the connection point 13d, and the drain of the FET 23e is connected. It is connected to the connection point 13e. The gates of the FETs 23a to 23e are individually connected to the control device 22. The gates of the FETs 23a to 23e are commonly connected to the control device 22. FETs 23a to 23e are normally off. Needless to say, the switch element of the cutoff portion is not limited to a semiconductor switch such as an FET, and a mechanical switch may be used.

The discharge switch 24 is a switch element that is turned on when the battery pack 10 is discharged, and the charging switch 25 is a switch element that is turned on when the battery pack 10 is charged. One end of each of the discharge switch 24 and the charge switch 25 is connected to the connection point 13a via the connection line 14a. The other end of the discharge switch 24 is connected to the device connection terminal 31a, and the other end of the charge switch 25 is connected to the device connection terminal 31b. Each control end of the discharge switch 24 and the charge switch 25 is connected to the control device 22, and their on / off control is performed by the control device 22. The discharge switch 24 is normally off and is controlled to be off during charging, and the charge switch 25 is normally off and is controlled to be on during charging.

The current measurement resistor 26 is a resistor for measuring the discharge current in the discharge mode and the charge current in the charge mode of the battery pack 10. One end of the current measurement resistor 26 is connected to the device connection terminal 31f, and the other end is connected to the connection point 13e via the connection line 14b. Further, both ends of the current measurement resistor 26 are connected to the control device 22, whereby a voltage level corresponding to the discharge current or the charge current is supplied to the control device 22.

In the battery pack 10 according to the present invention having such a configuration, when the connection terminals 41a to 41f of the electric device 40 are not connected to the device connection terminals 31a to 31f, the FETs 23a to 23e are in the off state. Further, the power supply voltage is not supplied to the control device 22, and the control device 22 is stopped. In this state, the path from the batteries 12a to 12d of the cell unit 11 to the control device 22 is blocked. Therefore, it is possible to prevent the inflow of a minute current from the batteries 12a to 12d to the control device 22.

Next, the operation of the battery pack 10 when the charger is connected to the device connection terminals 31a to 31f as the electric device 40 will be described with reference to FIG. When the charger is connected, a voltage is applied between the connection terminals 41b and 41f of the charger and the device connection terminals 31b and 31f. This applied voltage is further applied from the device connection terminals 31b and 31f to the power input terminals INA and INC of the control device 22, and activates the control device 22. In the case of a charger, it is not necessary to provide the connection terminal 41a.

When the control device 22 is activated, as shown in FIG. 2, it first determines whether it is in the charge mode or the discharge mode (step S101). The control device 22 can be determined to be in the charging mode if, for example, a positive potential is applied to the power input terminal INA connected to the device connection terminal 31b. When it is determined that the charging mode is determined, the discharge switch 24 is controlled to be off, the charging switch 25 is controlled to be on (step S102), and the FETs 23a to 23e are controlled to be on (step S103). When the charging switch 25 is turned on, a charging current flows from the device connection terminal 31b to the batteries 12a to 12d via the charging switch 25, and the charging current flows through the current measurement resistor 26 and reaches the device connection terminal 31f. As a result, the batteries 12a to 12d are charged. By turning on the FETs 23a to 23e, the control device 22 can measure the voltage of each of the batteries 12a to 12d, and the control device 22 reads the voltage across the current measuring resistor 26 and measures the charging current from the read voltage. Can be done (step S104).

Next, the operation of the battery pack 10 when, for example, the surgical drill 40a is connected to the battery pack 10 as the electric device 40 will be described with reference to FIGS. 2 and 3. As shown in FIG. 3, the drill 40a is provided with connection terminals 41a to 41f corresponding to the device connection terminals 31a to 31f, respectively. When the battery pack 10 is attached to the drill 40a, the device connection terminals 31a to 31f are provided. And the connection terminals 41a to 41f are mechanically and electrically connected to each other. When connected in this way, the positive potential of the cell portion 11 is applied to the connection terminal 41a via the connection point 13a, the discharge switch 24, and the device connection terminal 31a, while the negative potential of the cell portion 11 is the connection point 13e. It is applied to the connection terminal 41f via the connection line 14b, the current measurement resistor 26, and the device connection terminal 31f. As a result, the drill 40a can operate because the stored voltage of the cell portion 11 is applied between the connection terminals 41a and 41f.

Further, in the drill 40a, a connection line 42 which is a current path connecting the connection terminals 41a and 41c so as to short-circuit is formed. As a result, when the device connection terminals 31a to 31f and the connection terminals 41a to 41f are mechanically and electrically connected, the positive potential applied to the connection terminal 41a connects the connection line 42, the connection terminal 41c, and the device connection terminal 31c. It is applied to the power input terminal INB of the control device 22 via. The negative potential of the cell portion 11 is applied from the connection point 13e to the power input terminal INC of the control device 22 via the connection line 14b and the current measurement resistor 26. Therefore, since the stored voltage of the cell unit 11 is applied between the power input terminals INB and INC of the control device 22, the control device 22 is activated.

As shown in FIG. 2, when the control device 22 is activated, it determines whether it is in the charge mode or the discharge mode (step S101). The control device 22 can be determined to be in the discharge mode if, for example, a positive potential is applied to the power input terminal INB connected to the device connection terminal 31c. When it is determined that the discharge mode is determined, the discharge switch 24 is controlled to be on, the charge switch 25 is controlled to be off (step S105), and the FETs 23a to 23e are controlled to be on (step S106). Since the discharge switch 24 remains on, the stored voltage of the cell portion 11 is continuously applied to the drill 40a. By turning on each of the FETs 23a to 23e, the control device 22 can measure the voltage of each of the batteries 12a to 12d, and the control device 22 reads the voltage across the current measurement resistor 26 and discharges the current from the read voltage. Can be measured (step S107).

In the state where the electric device 40 and the battery pack 10 are connected as described above, the control device 22 inputs the stored voltage of the cell unit 11 obtained via the FETs 23a and 23e by turning on the FETs 23a to 23e. It can operate continuously using the stored voltage as the power supply voltage.

As shown in FIG. 4, the control device 22 repeatedly executes the removal determination routine, for example, at a predetermined timing in a state where the electric device 40 and the battery pack 10 are connected. In the removal determination routine, it is determined whether or not the battery pack 10 has been removed from the electric device 40 (step S111). When the battery pack 10 is removed, the positive potential is not applied to the power input terminal INA in the charge mode, and the positive potential is not applied to the power input terminal INB in the discharge mode. Therefore, when the positive potential is no longer applied to the power input terminal INA or INB, it can be determined that the battery pack 10 has been removed from the electric device 40. When the control device 22 determines that the battery pack 10 has been removed, the control device 22 stops the control of the discharge switch 24 and the charge switch 25 (step S112), and controls the FETs 23a to 23e to be off (step S113).

In step S112, the discharge switch 24 is turned on and the charging switch 25 is turned off. Further, since the FETs 23a to 23e are turned off by step S113, the operation of the control device 22 is stopped because the power supply voltage is not applied to the control device 22.

When the battery pack 10 is removed from the electric device 40 in this way, all the FETs 23a to 23e are turned off, so that the current flow from each of the batteries 12a to 12d to the control device 22 is cut off. Become. That is, it is prevented that a minute leakage current flows from the cell portion 11 to the protection circuit portion 21. Therefore, it is possible to prevent the leakage current from flowing from the cell portion 11 to the protection circuit portion 21 even at a high temperature of about 135 ° C. in the high temperature sterilization treatment, and it is possible to prevent problems such as shortening the life of the battery pack and liquid leakage. Further, even when the battery pack is stored for a long period of time, the flow of current from the cell portion to the protection circuit portion is blocked and only self-discharge is performed, so that the decrease in the amount of stored electricity can be suppressed for a long period of time, and as a result. , Over-discharge can be prevented.

Further, in the above-described embodiment, whether or not the battery pack 10 is connected to the electric device 40 is determined from the presence or absence of a positive potential applied to the device connection terminals 31b or 31c, but the battery pack is connected to the electric device 40. It may be mechanically detected that 10 is connected. For example, when the battery pack 10 described above is installed in the electric device 40, the stored voltage of the battery pack 10 is supplied to the control device 22 by a switch that is mechanically turned on, whereby the control device 22 starts the operation described above. Can be configured to: Further, it is also possible to determine whether or not the electric device 40 is a charger by individually arranging the switches that are mechanically turned on at different positions between the charger and the other devices.

Further, in the above embodiment, the case where the battery pack 10 is a battery pack that is attached to an electric device such as a surgical drill to supply power to the electric device has been described as an example, but the battery pack 10 is a battery pack. It may be used for a moving body or a fixing device such as an electric vehicle (HV (Hybrid Vehicle), PHV (Plug-in Hybrid Vehicle), EV (Electric Vehicle)) that operates by using 10 as a power source.

For example, when the battery pack 10 is mounted on an electric vehicle, the battery pack 10 and the power supply terminal of the electric vehicle can be removed during storage or transportation of the vehicle after assembly to increase the amount of electricity stored in the battery pack 10. The decrease can be suppressed for a long period of time, and as a result, over-discharge can be prevented.

10 Battery pack 11 Cell unit 12a to 12d Battery 14a, 14b Connection line 21 Protection circuit unit 22 Control device 23a to 23e FET
24 Discharge switch 25 Charge switch 26 Current measurement resistor 30 Substrate 31a to 31f Equipment connection terminal 40 Electrical equipment 40a Surgical drill 41a to 41f Connection terminal 42 Connection line

Claims (4)

A cell unit containing a single or multiple batteries that can be charged and discharged,
Terminals for electrical connection between the cell and electrical equipment,
A battery pack including a protection circuit unit that is electrically connected to the cell unit, operates by supplying power from the cell unit, and includes a control unit that controls discharge or charging of the cell unit.
The protection circuit unit
Includes a switch element that turns on and off the electrical connection for power supply from the cell unit to the control unit.
The control unit
When the switch element is off, when the cell portion and the electric device are electrically connected by the terminal, power is received from the cell portion via the electric device to start operation and the switch element. Control to turn on,
When the switch element is on and the control unit receives power from the cell unit to perform the operation, the switch is disconnected from the electrical connection between the cell unit and the electric device by the terminal. A battery pack characterized by controlling the element off. The plurality of batteries are connected in series and
The switch element is between a positive terminal at one end of the plurality of batteries and the control unit, between a connection point between the plurality of batteries and the control unit, and a negative terminal at the other end of the plurality of batteries. The battery pack according to claim 1, wherein each of the batteries and the control unit includes a switch element. The battery pack according to claim 2, wherein the switch element comprises a normally-off field effect transistor. When the electric device is a device that receives a discharge current from the cell unit, the connection between the cell unit and the electric device via the terminal to the control unit via a current path in the electric device. The battery pack according to claim 1, wherein a power supply path is formed.