JP2005131770A - Battery pack, power tool and power tool system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive electric tool system having a simple configuration having both functions of current control of a motor of an electric tool and prevention of overdischarge of a battery pack, the battery pack and the electric tool.
An electric power tool according to the present invention provides a discharge stop command signal when any one of a power input terminal pair connected to a power output terminal pair of a battery pack and a voltage of each battery cell is lower than a first value. Motor control based on a discharge stop command signal input terminal for inputting a discharge stop command signal of the battery pack to be output, a motor and semiconductor switching element connected in series to the pair of power input terminals, an operation unit, and a command from the operation A controller that controls the semiconductor switching element by a motor control signal if a signal is generated and a discharge stop command signal is not input, and stops the semiconductor switching element if a discharge stop command signal is input.
[Selection] Figure 1

Description

  The present invention relates to a battery pack, a power tool, and a power tool system.

  Currently, nickel cadmium batteries and nickel metal hydride batteries are used for electric tools. Nickel cadmium batteries and nickel metal hydride batteries have a memory effect. The memory effect is that if the battery is charged without being used up, the charge level is stored, and the voltage drops at the stored level even though the capacity remains. In power tools that operate on nickel cadmium batteries and nickel metal hydride batteries, the memory effect has been eliminated by completely discharging the batteries.

  The energy density per unit weight of the lithium ion battery reaches approximately twice the energy density per unit weight of the nickel metal hydride battery. For this reason, lithium ion batteries are becoming mainstream in battery packs of recent mobile phones and portable personal computers. When a lithium ion battery is used as a battery pack for an electric tool, the battery pack can be reduced in size and weight, and the capacity can be increased, and an electric tool with good operability can be realized. However, unlike nickel cadmium batteries and nickel metal hydride batteries, the lithium ion battery becomes inactive when it is in an overdischarged state for a long period of time, and even if it is charged, it cannot be recovered to its initial charge capacity and its life is exhausted. End up. In order to prevent overdischarge of the lithium ion battery, the lithium ion battery needs to be provided with a protection circuit that forcibly cuts off the discharge when the battery voltage becomes lower than a set voltage.

  Patent Document 1 (Japanese Patent Application Laid-Open No. 2001-339867) discloses an electric device including a conventional lithium ion battery and a motor. The electric device of Patent Document 1 is mainly an electric razor or an electric toothbrush. FIG. 3 is a circuit block diagram showing the configuration of an electric device incorporating a conventional lithium ion battery and motor. In FIG. 3, 1 is a lithium ion secondary battery, 2 is a motor, 3 is a battery management circuit, 4 is a protection circuit, 10 is a battery pack, 11 is a charging circuit, 12 is a charging switch, 13 is a charging control circuit, and 14 is A power supply circuit, 15 is a power switch, 16 is a third voltage detection circuit, 17 is a power diode, 18 is a battery diode, 19 is an LED, 20 is an arithmetic circuit, 21 is a switching circuit, and 22 is an operation switch.

  The protection circuit 4 includes a main protection circuit 4A and a sub protection circuit 4B. The main protection circuit 4A includes a first protection circuit 4a and a second protection circuit 4b. The first protection circuit 4a includes a first voltage detection circuit 5a and a first switching element 6a. The first switching element 6 a is connected in series with the motor 2. When the voltage of the lithium ion secondary battery 1 becomes equal to or lower than the first set voltage, the first switching element 6 a blocks the current flowing through the motor 2. The second protection circuit 4b includes a second voltage detection circuit 5b and a second switching element 6b. The second switching element 6 b is connected in series with the lithium ion secondary battery 1. When the voltage of the lithium ion secondary battery 1 becomes equal to or lower than the second set voltage, the second switching element 6b cuts off the current flowing from the lithium ion secondary battery 1.

JP 2001-339867 A

  In an electric power tool, a current of about 20A to 30A and about 100A at the maximum normally flows through the motor. Inexpensive switching elements that are currently widely available can only handle a current of about 20A. A switching element that can handle a current of 100 A is expensive, and a power tool system that uses two of these switching elements is expensive.

  The present invention has been made in view of such problems, and uses only one large-current (for example, having a current capacity of 100 A) semiconductor switching element to control the current of the motor of the electric tool. An object of the present invention is to provide an inexpensive electric tool system having a simple configuration that performs both functions of preventing overdischarge of a battery pack, and the battery pack and the electric tool.

  In order to solve the above problems, the present invention has the following configuration. According to the first aspect of the present invention, a battery cell serial body in which a plurality of battery cells are connected in series and the voltage of each battery cell are detected, and any one of the voltages of each battery cell is lower than the first value. A control unit that outputs a discharge stop command signal when continued for a certain period of time, a pair of power output terminals connected directly or via a fuse to both terminals of the battery cell series body, and a discharge stop that outputs the discharge stop command signal A battery pack comprising: a command signal output terminal; and a connection connector detachably connected to a power tool as a load.

  In the present invention, the battery pack is not provided with a switching element, a discharge stop command signal output terminal is provided, and the switching element of the electric tool is shut off by the discharge stop command signal. Thereby, the switching element of the power tool plays two roles of current control of the motor of the power tool and prevention of overdischarge of the battery pack. Using the battery pack of the present invention, only one large current (for example, having a current capacity of 100 A) semiconductor switching element is used, and both the current control of the motor of the electric tool and the overdischarge prevention of the battery pack are performed. An inexpensive power tool system can be realized with a simple configuration.

Generally, the time constant delay is provided for the purpose of preventing malfunction due to noise or the like. The inrush current when starting the motor of the electric tool is very large, and a large voltage drop occurs due to the internal resistance of the battery. The present invention can realize a power tool system that does not react to this voltage drop by providing a time constant delay.
“Electric tool” includes, for example, a drilling machine (including a hammer drill and an electric hammer), a tightening machine (including an impact driver, an electric wrench, and a screw driver), a cutting machine, a cutting machine, a polishing machine, a kneading machine such as cement, Ink brush and mower are included. Includes applications such as metalwork, masonry, and woodwork.

According to a second aspect of the present invention, the control unit outputs a charge stop command signal when the voltage of each battery cell is higher than a second value higher than the first value. 2. The battery pack according to claim 1, wherein the battery pack outputs from a terminal or another terminal of the connection connector.
The battery pack of the present invention is not provided with a semiconductor switching element, but the battery pack outputs a charge stop command signal, and the semiconductor switching element of the charger is shut off by the charge stop command signal. Thereby, this semiconductor switching element plays two roles of current control of the charger and prevention of overcharge of the battery pack. Using the battery pack of the present invention, an inexpensive electric tool with a simple configuration that performs both functions of charger current control and battery pack overcharge prevention using only one large-current semiconductor switching element A system can be realized.

The invention according to claim 3 further includes a temperature detector that detects a surface temperature of the battery cell and outputs a discharge stop command signal when the surface temperature of the battery cell becomes a predetermined value or more. The battery pack according to claim 1, wherein the battery pack is a battery pack.
Lithium ion batteries are characterized in that the internal resistance is large, so heat is generated during discharge, and the performance is significantly degraded at high temperatures. The present invention can realize a highly reliable battery pack by stopping discharge and cooling when the surface temperature of the battery cell reaches a certain value or more.

  According to a fourth aspect of the present invention, any one of a pair of power input terminals connected to a power output terminal pair of a battery pack having a plurality of battery cells connected in series and receiving power from the battery pack, and a voltage of each battery cell A discharge stop command signal input terminal connected to a discharge stop command signal output terminal of the battery pack that outputs a discharge stop command signal when one is lower than the first value, and is detachable from the battery pack A connection connector to be connected, a motor connected in series to the power input terminal pair, a semiconductor switching element for controlling the current of the motor, an operation unit for inputting an operation command from a user, and a motor based on the operation command If the control signal is generated and the discharge stop command signal is not input from the discharge stop command signal input terminal, the semiconductor switching is performed by the motor control signal. Controls child, entering the discharge stop command signal from said discharge stop command signal input terminal, a power tool and having a control unit for stopping the semiconductor switching element.

  The battery pack is not provided with a switching element, and a discharge stop command signal output terminal is provided to output a discharge stop command signal. When the electric power stop tool of the present invention receives a discharge stop command signal, it normally shuts off the semiconductor switching element controlled by the motor control signal. As a result, the semiconductor switching element of the power tool plays two roles of current control of the motor of the power tool and prevention of overdischarge of the battery pack. The present invention can realize an inexpensive electric tool system with a simple configuration that uses only one large-current semiconductor switching element to perform both functions of electric current control of the electric tool motor and prevention of overdischarge of the battery pack. .

  According to a fifth aspect of the present invention, the semiconductor switching element is a field effect transistor (FET), and the motor control signal is a pulse width modulation (PWM) signal. It is a power tool. With this configuration, both functions of motor rotation speed and / or torque control and battery pack overdischarge prevention can be performed using a single semiconductor switching element.

  A sixth aspect of the present invention includes the battery pack according to any one of the first to third aspects and the electric power tool according to the fourth or fifth aspect. It is a power tool system. The present invention realizes an inexpensive electric tool system with a simple configuration that performs both functions of electric current control of the electric tool motor and prevention of over-discharge of the battery pack using only one large-current semiconductor switching element. Has the effect of being able to.

  The invention according to claim 7 is a battery cell serial body in which a plurality of battery cells are connected in series, a semiconductor switching element connected in series with the battery cell serial body and controlling the current, and the battery cell serial body. And a pair of power supply output terminals connected to both terminals of the series body of the semiconductor switching element and supplying power to the power tool as a load, and a motor control signal input for inputting a motor control signal for controlling the motor from the power tool A connection connector that is detachably connected to the electric tool, and detects a voltage of each battery cell, and a state in which any one of the voltages of each battery cell is lower than the first value is a certain time If the discharge stop command signal is not generated, the semiconductor switching element is controlled by the motor control signal, and the discharge stop command is generated. If it generates No., a battery pack and having a control unit for stopping the semiconductor switching element.

The battery pack of the present invention is provided with a motor control signal input terminal, and controls a built-in semiconductor switching element using a motor control signal input therefrom. Since the semiconductor switching element of the battery pack performs both functions of current control of the motor of the electric tool and prevention of overdischarge of the battery pack, the electric current tool connected to the battery pack of the present invention has a semiconductor switching element for current control of the motor. There is no need to provide it. Using the battery pack of the present invention, an electric motor with a simple configuration that performs both functions of current control of the motor of the electric tool and prevention of overdischarge of the battery pack using only one large-current semiconductor switching element. A tool system can be realized.
The present invention can realize a power tool system that does not react to this voltage drop by providing a time constant delay.

The invention according to claim 8 is the battery pack according to claim 7, wherein the battery is a lithium ion battery.
The present invention prevents overdischarge of a lithium ion battery and prevents its performance from being significantly reduced. The present invention has the effect of using a lithium ion battery to realize a battery pack having high reliability, light weight, small size and large capacity.

  According to a ninth aspect of the present invention, there is provided an operation unit for inputting an operation command from a user, a motor connected to a pair of power input terminals directly or via a fuse, and motor control for controlling the motor based on the operation command. A control unit that generates a signal, a power output terminal pair of a battery pack having a plurality of battery cells connected in series, and the power input terminal pair that receives supply of power from the battery pack, and outputs the motor control signal A power tool comprising: a motor control signal output terminal; and a connection connector detachably connected to the battery pack.

  The electric power tool of the present invention is provided with a motor control signal output terminal, and controls a semiconductor switching element built in the battery pack using a motor control signal output therefrom. Since the semiconductor switching element of the battery pack performs both functions of current control of the motor of the electric tool and prevention of overdischarge of the battery pack, the electric tool of the present invention does not need to be provided with a semiconductor switching element for current control of the motor. Using the electric power tool of the present invention, the electric tool is inexpensive and has a simple configuration that performs both the current control of the electric tool motor and the overdischarge prevention function of the battery pack using only one large-current semiconductor switching element. A tool system can be realized.

  A tenth aspect of the present invention is an electric power tool system including the battery pack according to the seventh or eighth aspect and the electric power tool according to the ninth aspect. The present invention can realize an inexpensive electric tool system with a simple configuration that uses only one large-current semiconductor switching element to perform both functions of electric current control of the electric tool motor and prevention of overdischarge of the battery pack. .

  The invention according to claim 11 is characterized in that the semiconductor switching element is a field effect transistor (FET), and the motor control signal is a pulse width modulation (PWM) signal. It is a power tool system. With this configuration, both functions of motor rotation speed and / or torque control and battery pack overdischarge prevention can be performed using a single semiconductor switching element.

  According to the present invention, only one large-current (for example, having a current capacity of 100 A) semiconductor switching element is used to perform both the current control of the electric tool motor and the prevention of overdischarge of the battery pack. An advantageous effect of realizing an inexpensive electric tool system, a battery pack, and an electric tool with a simple structure can be obtained.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments that specifically show the best mode for carrying out the present invention will be described below with reference to the drawings.

Embodiment 1
The power tool system (including a battery pack and a power tool) of the first embodiment will be described with reference to FIG. FIG. 1 is a circuit block diagram showing the configuration of the electric power tool system according to Embodiment 1 of the present invention. In FIG. 1, 101 is a battery pack, and 102 is a power tool.

  The battery pack 101 includes a battery cell series body in which six battery cells 111 to 116 are connected in series, a battery protection IC 117, a time constant capacitor 118, a temperature detector 119, a connection connector, and a fuse (current fuse and / or temperature). Fuse). The temperature detector 119 includes a positive temperature coefficient thermistor 131 and a comparator 132. The connection connector has a pair of power output terminals 121 and 122 connected to both terminals of the battery cell series body via a fuse, and a discharge stop command signal output terminal 120 that outputs a discharge stop command signal. A power tool 102 is detachably connected. In the present embodiment, battery cells 111 to 116 are lithium ion batteries. The battery pack 101 of Embodiment 1 does not have a semiconductor switching element for preventing overdischarge.

  The electric tool 102 includes an AND gate (cutoff circuit) 131, a semiconductor switching element (FET) 132, a motor 133, an ON / OFF switch 134, a variable resistor 135, a pulse generator 136, and a connection connector. The connection connector includes a pair of power input terminals 141 and 142 that receive power from the battery pack 101 and a discharge stop command signal input terminal 140 that inputs a discharge stop command signal, and is detachably connected to the battery pack 101. Is done. The power input terminal pair 141, 142 is connected to the power output terminal pair 121, 122, respectively. Discharge stop command signal input terminal 140 is connected to discharge stop command signal output terminal 120. The motor 133 and the FET 132 that controls the motor current are connected in series to the power input terminal pair 141 and 142.

In the battery pack 101, the battery protection IC 117 detects the voltage across the battery cells 111 to 116.
When the battery pack 101 supplies (discharges) power to the electric tool 102, the battery protection IC 117 determines that the voltage across the battery cell is lower than the first predetermined value (lower limit value). A discharge stop command signal is generated so that the battery cell is not overdischarged, and is output to the electric tool 102 through the discharge stop command signal output terminal 120. According to the discharge stop command signal, the FET 132 of the electric tool 102 is turned off, and the discharge of the battery pack 101 is stopped. By providing hysteresis to the first predetermined value, the battery protection IC 117 continues to output the discharge stop command signal even when the discharge of the battery pack 101 stops and the voltage across the battery cell rises. By providing hysteresis at the first predetermined value, the electric tool 102 can be prevented from chattering.

  When charging the battery pack 101 with the charger, the battery protection IC 117 causes the voltage across one of the battery cells to be higher than the second predetermined value (the upper limit value, which is higher than the first predetermined value). When it becomes, it generates a charge stop command signal and outputs it to the charger through the discharge stop command signal output terminal 120. In accordance with the charge stop command signal, the charging current control element (typically FET) of the charger is turned OFF, and charging to the battery pack 101 is stopped. By providing hysteresis to the second predetermined value, the battery protection IC 117 continues to output the charge stop command signal even if the charging of the charger stops and the voltage across the battery cell drops. By providing hysteresis at the second predetermined value, the charger can be prevented from chattering. The output terminal for the charge stop command signal and the output terminal for the discharge stop command signal may be separate terminals.

  The time constant capacitor 118 delays the response of the battery protection IC 117 by a predetermined time. The battery protection IC 117 does not react to an instantaneous voltage drop due to an inrush current or the like at the start of the motor 133 (does not output a discharge stop command signal if it is an instantaneous voltage drop). That is, the battery protection IC 117 outputs a discharge stop command signal from the discharge stop command signal output terminal 120 when the voltage across one of the battery cells is lower than the first predetermined value and the state continues for a certain time. To do. Even when the discharge stop command signal is canceled, the response of the battery protection IC 117 is delayed for a predetermined time. When the voltage across both battery cells is higher than the first predetermined value by a predetermined value (hysteresis voltage) or longer, the battery protection IC 117 stops the discharge stop command signal.

  A lithium ion battery is characterized in that it self-heats during discharge, and its performance is significantly reduced when it is in a high temperature state. For this reason, the temperature detector 119 detects the surface temperature of the battery cells 111 to 116, and generates a discharge stop command signal when the surface temperature exceeds a predetermined temperature (upper limit value), and the discharge stop command signal output terminal. The power is output to the power tool 102 through 120. According to the discharge stop command signal, the FET 132 of the electric tool 102 is turned off, the discharge of the battery pack 101 is stopped, and the surface temperatures of the battery cells 111 to 116 begin to decrease.

  In the electric tool 102, the user operates an ON / OFF switch 134 and a variable resistor 135 (which constitutes an operation unit) and inputs operation commands such as power-on, high-speed drive, low-speed drive, and power-off of the motor 133. . When the user operates the throttle, the voltage value (one of the operation command signals) output from the variable resistor 135 to the pulse generator 136 changes. The pulse generator 136 generates a pulse signal (PWM signal) in which the pulse duty is changed according to the voltage value. The pulse signal is a motor control signal. The discharge stop command signal output from the discharge stop command signal output terminal 120 of the battery pack 101 is input to the discharge stop command signal input terminal 140 of the electric tool 102.

  The AND gate 131 inputs the pulse signal generated by the pulse generator 136 and the discharge stop command signal input from the discharge stop command signal input terminal 140. If the discharge stop command signal is not input from the discharge stop command signal input terminal 140, the AND gate 131 controls the FET 132 by a pulse signal (PWM signal). The motor 133 outputs, for example, a predetermined torque or rotates at a predetermined rotation speed. The AND gate 131 stops the FET 140 when a discharge stop command signal is input from the discharge stop command signal input terminal 140. The pulse generator 136 and the AND gate 131 constitute a control unit of the motor 133.

The power output terminal pair 121 may be directly connected to both terminals of the battery cell series body without using a fuse.
In the present embodiment, six battery cells are connected in series, but the number is arbitrary. The present invention realizes an inexpensive power tool system with a simple configuration by performing both functions of controlling the motor current of the power tool and preventing overdischarge of the battery pack by the FET incorporated in the power tool.

<< Embodiment 2 >>
A power tool system (including a battery pack and a power tool) according to the second embodiment will be described with reference to FIG. FIG. 2 is a circuit block diagram showing the configuration of the power tool system according to the second embodiment of the present invention. In FIG. 2, 201 is a battery pack and 202 is an electric tool.

  The battery pack 201 includes a battery cell serial body in which six battery cells 111 to 116 are connected in series, a battery protection IC 117, a time constant capacitor 118, a temperature detector 119, an AND gate 221, a semiconductor switching element (embodiment). 2 includes an FET) 222, a connector, and a fuse (current fuse and / or thermal fuse). The connector has a power output terminal pair 121, 122 connected to a series body of a fuse, a battery cell series body, and an FET 222, and a motor control signal input terminal 220 for inputting a motor control signal, and is a load. The power tool 202 is detachably connected. In the present embodiment, battery cells 111 to 116 are lithium ion batteries.

  The electric tool 202 includes a motor 133, an ON / OFF switch 134, a variable resistor 135, a pulse generator 136, and a connection connector. The connection connector has a pair of power input terminals 141 and 142 that receive power supply from the battery pack 201 and a motor control signal output terminal 240 that outputs a motor control signal, and is detachably connected to the battery pack 201. . The power input terminal pair 141, 142 is connected to the power output terminal pair 121, 122, respectively. The motor control signal output terminal 240 is connected to the motor control signal input terminal 220. The motor 133 is connected in series to the power input terminal pair 141, 142 directly or via a fuse. 2, the same blocks and elements as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. The electric power tool 202 of the second embodiment does not have a semiconductor switching element for controlling the motor current.

In the battery pack 201, the six battery cells 111 to 116 are connected in series. The battery protection IC 117 detects the battery voltage of each battery cell 111 to 116.
When the battery pack 201 supplies (discharges) power to the electric power tool 202, the battery protection IC 117 determines that the voltage across the battery cell is lower than the first predetermined value (lower limit). A discharge stop command signal is generated so as to prevent the battery cell from being overdischarged and output to the AND gate 221. In accordance with the discharge stop command signal, the AND gate 221 turns off the FET 222, and the discharge of the battery pack 201 is stopped. By providing hysteresis to the first predetermined value, the battery protection IC 117 continues to output the discharge stop command signal even when the discharge of the battery pack 201 stops and the voltage across the battery cells 111 to 116 rises. To do. By providing hysteresis at the first predetermined value, the electric tool 202 can be prevented from chattering.

  When charging the battery pack 201 with the charger, the battery protection IC 117 is configured such that the voltage across one of the battery cells is higher than a second predetermined value (an upper limit value that is higher than the first predetermined value). If it is, a charge stop command signal is generated and output to the FET 222. The FET 222 is turned OFF in accordance with the charge stop command signal, and the charging of the battery pack 201 is stopped. By providing hysteresis to the second predetermined value, the battery protection IC 117 continues to output the charge stop command signal even when charging from the charger stops and the voltage across the battery cells 111 to 116 drops. To do. By providing hysteresis at the second predetermined value, the charger can be prevented from chattering. The time constant capacitor 118 and the temperature detector 119 play the same role as in the first embodiment.

  In the electric tool 202, the user operates the ON / OFF switch 134 and the variable resistor 135 (which constitutes an operation unit), and inputs operation commands such as power-on, high-speed drive, low-speed beating, and power-off of the motor 133. . When the user operates the throttle, the voltage value (one of the operation command signals) output from the variable resistor 135 to the pulse generator 136 changes. The pulse generator 136 generates a pulse signal (PWM signal) in which the pulse duty is changed according to the voltage value. The pulse signal is a motor control signal. The pulse signal is input to the AND gate 221 of the battery pack 201 through the motor control signal output terminal 240 and the motor control signal input terminal 220.

  The AND gate 221 inputs the pulse signal (PWM signal) generated by the pulse generator 136 and the discharge stop command signal output by the battery protection IC 117. If no discharge stop command signal is input, the AND gate 221 controls the FET 222 by a pulse signal (PWM signal). The motor 133 outputs, for example, a predetermined torque or rotates at a predetermined rotation speed. The AND gate 221 stops the FET 222 when a discharge stop command signal is input. The battery protection IC 117 and the AND gate 221 constitute a control unit.

  In the present embodiment, six battery cells are connected in series, but the number is arbitrary. The present invention realizes an inexpensive electric tool system with a simple configuration by performing both functions of controlling the electric current of the electric tool motor and preventing overdischarge of the battery pack by the FET incorporated in the battery pack.

  The battery pack, power tool, and power tool system of the present invention are useful for industrial and household applications.

The circuit block diagram which shows the structure of the electric tool system of Embodiment 1 of this invention The circuit block diagram which shows the structure of the electric tool system of Embodiment 2 of this invention Circuit block diagram showing the configuration of a conventional lithium-ion battery and an electric device incorporating a motor

Explanation of symbols

101, 201 Battery pack 102, 202 Electric tool 111-116 Battery cell 117 Battery protection IC
118 Capacitor for time constant 119 Temperature detector 120-122, 140-142, 220, 240 Connection terminal 121, 221 AND gate 122, 222 FET
135 Variable Resistor 136 Pulse Generator 133 Motor

Claims (11)

A battery cell series body in which a plurality of battery cells are connected in series;
A controller that detects a voltage of each battery cell and outputs a discharge stop command signal when any one of the voltages of each battery cell is lower than a first value for a certain period of time;
A power output terminal pair that is connected to both terminals of the battery cell series body directly or via a fuse, and a discharge stop command signal output terminal that outputs the discharge stop command signal; A connector that is detachably connected;
A battery pack comprising:   The control unit outputs a charge stop command signal to the discharge stop command signal output terminal or another terminal of the connection connector when any one of the voltages of the battery cells is higher than a second value higher than the first value. The battery pack according to claim 1, wherein the battery pack is output from the battery pack. A temperature detector that detects a surface temperature of the battery cell and outputs a discharge stop command signal when the surface temperature of the battery cell reaches a predetermined value;
The battery pack according to claim 1, further comprising: Any one of a pair of power input terminals connected to a power output terminal pair of a battery pack having a plurality of battery cells connected in series and receiving power from the battery pack, and a voltage of each battery cell is lower than the first value A discharge stop command signal input terminal connected to a discharge stop command signal output terminal of the battery pack for outputting a discharge stop command signal, and a connection connector detachably connected to the battery pack;
A motor connected in series to the power input terminal pair and a semiconductor switching element for controlling the current of the motor;
An operation unit for inputting an operation command from a user;
A motor control signal is generated based on the operation command, and if the discharge stop command signal is not input from the discharge stop command signal input terminal, the semiconductor switching element is controlled by the motor control signal, and the discharge stop command If the discharge stop command signal is input from a signal input terminal, a control unit that stops the semiconductor switching element;
A power tool characterized by comprising:   The electric tool according to claim 4, wherein the semiconductor switching element is a field effect transistor (FET), and the motor control signal is a pulse width modulation (PWM) signal.   An electric power tool system comprising: the battery pack according to any one of claims 1 to 3; and the electric power tool according to claim 4 or 5. A battery cell series body in which a plurality of battery cells are connected in series;
A semiconductor switching element connected in series with the battery cell serial body and controlling the current;
A pair of power supply output terminals connected to both terminals of the series body of the battery cell series body and the semiconductor switching element and supplying power to a power tool as a load, and a motor control signal for controlling the motor from the power tool are input. A motor control signal input terminal, and a connection connector detachably connected to the power tool,
The voltage of each battery cell is detected, and when any one of the voltage of each battery cell is lower than the first value for a certain period of time, a discharge stop command signal is generated, and the discharge stop command signal is generated. Otherwise, the semiconductor switching element is controlled by the motor control signal, and if the discharge stop command signal is generated, a control unit that stops the semiconductor switching element;
A battery pack comprising:   The battery pack according to claim 7, wherein the battery is a lithium ion battery. An operation unit for inputting an operation command from a user;
A motor connected to the power input terminal pair directly or via a fuse;
A control unit that generates a motor control signal for controlling the motor based on the operation command;
A pair of power supply output terminals connected to a pair of power supply output terminals of a battery pack having a plurality of battery cells connected in series to receive power from the battery pack; and a motor control signal output terminal for outputting the motor control signal. A connection connector detachably connected to the battery pack;
A power tool characterized by comprising:   An electric tool system comprising: the battery pack according to claim 7 or claim 8; and the electric tool according to claim 9.   9. The electric tool system according to claim 8, wherein the semiconductor switching element is a field effect transistor (FET), and the motor control signal is a pulse width modulation (PWM) signal.

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