WO2014119216A1 - Electric equipment and body thereof - Google Patents

Abstract

The electric equipment in one aspect of the present invention is provided with a motor, multiple battery packs, a voltage-raising unit, a battery pack-selecting unit, and a pathway-forming unit. The voltage-raising unit raises the voltage of each of the multiple battery packs and generates a drive voltage for driving the motor. The battery pack-selecting unit selects at least one of the multiple battery packs on the basis of a previously established selection procedure. The pathway-forming unit forms an electric power supply pathway from the at least one battery pack, selected from the multiple battery packs by the battery pack-selecting unit, to the motor via the voltage-raising unit.

Description

Electric machine tool and main body thereof Cross-reference of related applications

This international application claims priority based on Japanese Patent Application No. 2013-018653 filed with the Japan Patent Office on February 1, 2013, and is based on Japanese Patent Application No. 2013-018653. The entire contents are incorporated into this international application.

The present invention relates to an electric machine instrument.

The electric power tool disclosed in the following Patent Document 1 is configured so that two battery packs can be attached to the main body of the electric power tool. In this electric power tool, two battery packs mounted on the main body of the electric power tool are connected in series to obtain a voltage necessary for appropriately driving the electric power tool.

JP 2011-161602 A

In the power tool described above, when the voltage of one of the two battery packs is significantly reduced due to a decrease in the remaining amount of power in one of the two battery packs, the power tool is appropriately driven. Therefore, there is a possibility that the voltage required for the power tool cannot be obtained and the electric tool cannot be driven properly.

Accordingly, one aspect of the present invention is to appropriately drive an electric machine instrument that is appropriately driven by a voltage higher than a voltage that can be output by one battery pack even if the voltage of one battery pack is significantly reduced. It would be desirable to be able to provide possible technology.

An electric machine instrument according to one aspect of the present invention includes a motor, a plurality of battery packs, a boosting unit, a battery pack selecting unit, and a path forming unit.
The boosting unit boosts the voltage of each of the plurality of battery packs to generate a driving voltage for driving the motor. The battery pack selection unit selects at least one of the plurality of battery packs based on a preset selection procedure. The path forming unit forms a power supply path from at least one of the plurality of battery packs selected by the battery pack selecting unit to the motor via the boosting unit.

That is, in the electric machine instrument configured as described above, the drive voltage is applied to the motor through the power supply path from at least one battery pack selected based on the selection procedure to the motor via the booster.

Therefore, in this electric machine instrument, even if the voltage of one of the plurality of battery packs is significantly reduced, the motor can be driven by the drive voltage generated using the voltages of the remaining battery packs.

Note that the selection procedure may be set in any way. For example, the selection procedure may be set to select only one of the plurality of battery packs. Alternatively, it may be set to select all of the plurality of battery packs. When it is set to select a plurality of battery packs, the motor can be appropriately driven when it is necessary to drive the motor with electric power larger than the electric power that can be output by one battery pack.

The electric machine apparatus may include a motor state detection unit that detects a state of the motor, and the battery pack selection unit is based on at least one of the plurality of battery packs based on the motor state detected by the motor state detection unit. It may be configured to select one.

In the electric machine instrument configured as described above, at least one battery pack can be selected based on the state of the motor.
The motor state detection unit may detect any state of the motor in any way.

For example, the motor state detection unit may be configured to detect a load applied to the motor. In this case, the battery pack selection unit selects at least two of the plurality of battery packs if the load detected by the motor state detection unit is equal to or greater than a preset threshold, and the load detected by the motor state detection unit. May be configured to select one of a plurality of battery packs.

In the electric machine apparatus configured as described above, when a large load is applied to the motor and a large amount of electric power is required to drive the motor, power can be supplied to the motor from at least two battery packs. If the applied load is small, power can be supplied from one battery pack to the motor.

The motor state detection unit may detect the load applied to the motor in any way. For example, the motor state detection unit may detect a load applied to the motor based on at least one of a current flowing through the motor, a rotation speed of the motor, and a temperature of the motor.

The electric machine instrument may include a battery pack state detection unit that detects the state of each of the plurality of battery packs. In this case, the battery pack selection unit may be configured to select at least one of the plurality of battery packs based on each state of the plurality of battery packs detected by the battery pack state detection unit.

In the electric machine instrument configured as described above, at least one battery pack can be selected based on the state of each of the plurality of battery packs.
The battery pack state detection unit may detect any state of the plurality of battery packs.

For example, the battery pack state detection unit may be configured to detect the remaining amount of power in each of the plurality of battery packs. In this case, the battery pack selection unit is configured to select at least one of the plurality of battery packs based on the remaining amount of power in each of the plurality of battery packs detected by the battery pack state detection unit. Also good.

In the electric machine instrument configured as described above, at least one battery pack can be selected based on the remaining amount of electric power in each of the plurality of battery packs.
In this case, the battery pack selection unit may select at least one battery pack based on the remaining amount of power in each of the plurality of battery packs. For example, the battery pack selection unit may be configured to select a battery pack with the smallest remaining amount of power detected by the battery pack state detection unit from a plurality of battery packs.

In this case, a battery pack with sufficient remaining power is selected first, the power is consumed first, and all the remaining battery pack power is consumed while this battery pack is replaced or charged. Thus, it is possible to prevent the use of the electric machine tool from being interrupted.

The boosting unit may boost the voltage of each of the plurality of battery packs.
For example, the boosting unit may be configured to be able to change the magnitude of the drive voltage in accordance with a command. In this case, the electric machine instrument may further include a command unit that commands the boosting unit to specify the magnitude of the drive voltage.

In the electric machine instrument configured as described above, the magnitude of the drive voltage can be appropriately changed.
The electric machine instrument may further include a pulse width modulation unit that performs pulse width modulation on the drive voltage applied to the motor.

It is not necessary to separately provide a configuration for adjusting the current flowing through the motor, such as a resistor, in the electric machine instrument configured as described above, and the current flowing through the motor can be appropriately adjusted with a simple configuration.

The boosting unit may include a plurality of boosting circuits connected to each of the plurality of battery packs, and the number of the plurality of boosting circuits may be the same as the number of the plurality of battery packs.
In this case, since it is not necessary to directly connect a plurality of battery packs, it is possible to suppress a current from flowing from one battery pack to the other battery pack.

Alternatively, the number of the plurality of booster circuits may be smaller than the number of the plurality of battery packs.
In this case, the configuration of the boosting unit can be simplified as compared to providing the same number of boosting circuits as the number of battery packs.

Alternatively, the booster unit may include a single booster circuit.
In this case, the configuration of the booster can be simplified most.
Furthermore, in this case, a backflow suppression unit that suppresses the backflow of current to each of the plurality of battery packs may be provided.

In the electric machine instrument configured as described above, it is possible to suppress the occurrence of a problem in each of the plurality of battery packs due to the current flowing back to each of the plurality of battery packs.
The electric machine instrument may be configured such that each of the plurality of battery packs cannot be detached.

Alternatively, the electric machine instrument may include a mounting portion that detachably mounts each of the plurality of battery packs.
In the electric machine instrument configured as described above, the battery pack whose voltage is remarkably lowered can be easily replaced, and as a result, the use of the electric machine instrument can be easily continued.

The electric machine instrument according to the present invention may be, for example, an electric tool or an electric work machine.
According to another aspect of the present invention, the main body of the electric machine instrument includes a motor, a mounting portion, a boosting portion, a battery pack selecting portion, and a path forming portion.

* A plurality of battery packs are mounted on the mounting part. The boosting unit boosts the voltage of each of the plurality of battery packs mounted on the mounting unit to generate a driving voltage for driving the motor. The battery pack selection unit selects at least one of the plurality of battery packs based on a preset selection procedure. The path forming unit forms a power supply path from at least one of the plurality of battery packs selected by the battery pack selecting unit to the motor via the boosting unit.

In the main body configured in this way, a drive voltage is applied to the motor through a power supply path from at least one battery pack selected based on the selection procedure to the motor via the booster.

That is, another aspect of the present invention can exhibit the same effect as the above-described one aspect of the present invention.

It is a perspective view of the electrically-driven machine instrument of 1st Embodiment to which this invention was applied. It is a circuit diagram which shows a part of circuit structure in the electric machine instrument of 1st Embodiment. It is a circuit diagram which shows the remaining part of the circuit structure in the electric machine instrument of 1st Embodiment. It is a flowchart which shows the flow of the main routine which the main control unit of 1st Embodiment performs. It is a flowchart which shows the flow of the priority setting process which the main control unit of 1st Embodiment performs. It is a circuit diagram which shows a part of circuit structure in the electric machine instrument of 2nd Embodiment. It is a circuit diagram which shows the remaining part of the circuit structure in the electric machine instrument of 2nd Embodiment. It is a flowchart which shows the flow of the main routine which the main control unit of 2nd Embodiment performs. It is a circuit diagram which shows a part of circuit structure in the electric machine instrument of 3rd Embodiment. It is a circuit diagram which shows a part of circuit structure in the electric machine instrument of 4th Embodiment. It is a perspective view which shows an example of the electric tool which can apply this invention.

DESCRIPTION OF SYMBOLS 1 ... Apparatus, 2 ... Main body, 3 ... Motor unit, 4a ... 1st battery pack, 4b ... 2nd battery pack, 4c ... 3rd battery pack, 5 ... Shaft pipe, 6 ... Indicator, 6a ... 1st LED, 6b 2nd LED, 7 ... Battery pack mounting part, 8 ... Cutter, 9 ... Cutter mounting part, 10 ... Handle, 11 ... Right hand grip, 12 ... Trigger switch, 13 ... Left hand grip, 41a, 41b ... Battery, 42a, 42b ... Positive terminal, 43a, 43b ... Negative terminal, 45a, 45b ... Output circuit, 46a, 46b ... Signal terminal, 81 ... Blade, 100 ... Drive circuit, 101 ... First positive terminal, 102 ... First negative terminal, 103 ... First 1 signal terminal, 104 ... second positive terminal, 105 ... second negative terminal, 106 ... second signal terminal, 110 ... MCU, 111 ... power supply circuit, 112a ... first voltage division 112b, second voltage divider, 112c, third voltage divider, 113a, first display circuit, 113b, second display circuit, 113c, third display circuit, 114a, first current detection circuit, 114b, second current detection. Circuit 114c Third current detection circuit 115a First boost circuit 115b Second boost circuit 116 Boost voltage setting circuit 117 Overcurrent detection circuit 118a First operation circuit 118b Second operation Circuits, 119a, 119b ... FET, 120a, 120b ... overcurrent detection circuit, 121 ... operation detection circuit, 122 ... voltage divider, 123 ... error amplifier, 124 ... triangular wave generator, 125 ... comparator, 200 ... drive circuit, 211a ... 1st FET, 211b ... 2nd FET, 212 ... Power supply circuit, 300 ... Drive circuit, 301 ... FET, 302 ... PWM signal generator, 316 ... Boosting power Setting circuit, 400 ... driving circuit, 401 ... third positive terminal, 402 ... third negative terminal, 403 ... third signal terminal, 500 ... power tool, 501 ... main body, 502 ... battery pack attachment portion

Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
<Overall configuration of electric machinery / equipment>
As shown in FIG. 1, the electric machine instrument (hereinafter abbreviated as instrument) 1 of the first embodiment is configured as an electric working machine, and more specifically, cuts grass and small-diameter trees. It is configured as a brush cutter.

The main body 2 of the instrument 1 includes a motor unit 3 and a shaft pipe 5 connected to one end of the motor unit 3.
The motor unit 3 houses a drive circuit 100 (described later) including a motor M1 (described later) inside the motor unit 3. Further, the motor unit 3 is provided with a battery pack mounting portion 7 on the other end of the motor unit 3 for detachably mounting the first battery pack 4a and the second battery pack 4b. More specifically, the battery pack mounting part 7 slides the first battery pack 4a and the second battery pack 4b on the battery pack mounting part 7 in the directions indicated by the arrows in the drawing, respectively. 4a and the 2nd battery pack 4b are comprised so that attachment or detachment is possible respectively. The battery pack mounting portion 7 is provided with a pair of hooks that engage with the first battery pack 4a and the second battery pack 4b mounted on the battery pack mounting portion 7, and the pair of hooks is used to The first battery pack 4 a and the second battery pack 4 b are fixed to the battery pack mounting portion 7.

Furthermore, the motor unit 3 is provided with an indicator 6 on one side of the motor unit 3 for notifying the user of the appliance 1 of the state of each of the first battery pack 4a and the second battery pack 4b. ing. The display device 6 may be any type of display device, and the display device 6 in the first embodiment is a display device including two LEDs. More specifically, the display device 6 includes a first LED 6a and a second LED 6b. The first LED 6a is an LED for notifying the user of the state of the first battery pack 4a, and the second LED 6b is an LED for notifying the user of the state of the second battery pack 4b.

The shaft pipe 5 is formed in a hollow rod shape, and a cutter mounting portion 9 for detachably mounting the cutter 8 is provided at the end of the shaft pipe 5 opposite to the motor unit 3. The cutter 8 is formed in a substantially disc shape as a whole. More specifically, the center portion of the cutter 8 is formed of a material having a rigidity equal to or higher than a predetermined value (for example, a metal material or a high hardness synthetic resin), and is formed into a disk shape or a cylindrical shape. Has been. A plurality of blades 81 are provided on the periphery of the cutter 8.

Further, a handle 10 is provided in the vicinity of an intermediate position in the axial direction of the shaft pipe 5. The handle 10 is provided with a right hand grip 11 for the user to hold with the right hand and a left hand grip 13 for the user to hold with the left hand. The right hand grip 11 is provided with a trigger switch 12 for the user to operate the rotation of the cutter 8.

A transmission shaft (not shown) is accommodated in the shaft pipe 5. One end of the transmission shaft is connected to the rotor of a motor M1 (described later) housed in the motor unit 3, while the other end of the transmission shaft is connected to the cutter via a plurality of gears (not shown) provided in the cutter mounting portion 9. 8 is connected. For this reason, the rotational driving force of the motor M1 is transmitted to the cutter 8 through the transmission shaft and the plurality of gears.
<Electrical configuration of appliance>
The instrument 1 has a circuit configuration shown in FIGS. This circuit configuration is formed when the first battery pack 4a and the second battery pack 4b are mounted on the main body 2.

As shown in FIG. 2, the instrument 1 includes the drive circuit 100 described above, and the first battery pack 4 a and the second battery pack 4 b are electrically connected to the drive circuit 100.
Each of the first battery pack 4a and the second battery pack 4b includes a battery 41a or a battery 41b, and each of the batteries 41a and 41b includes a plurality of battery cells connected in series. The number of battery cells included in each of the batteries 41a and 41b and the voltage generated by each battery cell may be set in any manner. For example, in the first embodiment, each of the batteries 41a and 41b includes five battery cells, and each of these battery cells generates a voltage of 3.6 VDC. That is, the batteries 41a and 41b in the first embodiment are configured to generate voltages VB1 and VB2 of 18 VDC, respectively. Each battery cell in the first embodiment is configured as a secondary battery (for example, a lithium ion secondary battery). That is, the first battery pack 4a and the second battery pack 4b in the first embodiment are each configured as a rechargeable battery pack.

In the first battery pack 4a, the positive electrode of the battery 41a is connected to the positive terminal 42a provided in the first battery pack 4a, and the voltage VB1 generated in the battery 41a is supplied to the drive circuit 100 via the positive terminal 42a. Is output. On the other hand, the negative electrode of the battery 41a is connected to a negative electrode terminal 43a provided in the first battery pack 4a.

In the second battery pack 4b, the positive electrode of the battery 41b is connected to the positive terminal 42b provided in the second battery pack 4b, and the voltage VB2 generated in the battery 41b is supplied to the drive circuit 100 via the positive terminal 42b. Is output. On the other hand, the negative electrode of the battery 41b is connected to a negative electrode terminal 43b provided in the second battery pack 4b.

Further, each of the first battery pack 4a and the second battery pack 4b includes a battery management unit (BMU) 44a or a BMU 44b. Each of the BMUs 44a and 44b detects overcharge and overdischarge of each battery cell based on the voltage between the positive electrode and the negative electrode of each battery cell in the battery 41a or the battery 41b. Each of the BMUs 44a and 44b outputs an overcharge detection signal indicating that overcharge has been detected and an overdischarge detection signal indicating that overdischarge has been detected. More specifically, the BMU 44a outputs an overdischarge detection signal to the drive circuit 100 via the output circuit 45a and the signal terminal 46a provided in the first battery pack 4a. The BMU 44b outputs an overdischarge detection signal to the drive circuit 100 via the output circuit 45b and the signal terminal 46b provided in the second battery pack 4b.

The drive circuit 100 includes a first positive terminal 101, a first negative terminal 102, a first signal terminal 103, a second positive terminal 104, a second negative terminal 105, and a second signal terminal 106. The terminals are connected to the positive terminal 42a, the negative terminal 43a, the signal terminal 46a, the positive terminal 42b, the negative terminal 43b, and the signal terminal 46b, respectively.

The drive circuit 100 further includes a main control unit (MCU) 110, a power supply circuit 111, a first voltage divider 112a, a second voltage divider 112b, a first display circuit 113a, a second display circuit 113b, A first current detection circuit 114a and a second current detection circuit 114b are provided.

The MCU 110 controls various operations of the appliance 1. The MCU 110 in the first embodiment is a microcomputer including at least a CPU, a memory (eg, ROM, RAM, etc.), an I / O, and the like.

The power supply circuit 111 is connected to the first positive electrode terminal 101 via the diode D1, and receives the voltage VB1 output from the first battery pack 4a. The power supply circuit 111 is further connected to the second positive electrode terminal 104 via the diode D2, and receives the voltage VB2 output from the second battery pack 4b. The power circuit 111 generates a control voltage Vcc for driving various circuits in the drive circuit 100 including the MCU 110 from one of the voltages VB1 and VB2 output from the first battery pack 4a and the second battery pack 4b. The controlled voltage Vcc is supplied to these various circuits. The diode D1 is provided to suppress a current from flowing from the second battery pack 4b to the first battery pack 4a via the power supply circuit 111, while the diode D2 is provided from the first battery pack 4a. It is provided to suppress the current from flowing into the second battery pack 4b via 111. With such a circuit configuration, when the remaining amount of power in one battery pack of the first battery pack 4a and the second battery pack 4b is low, the other battery pack of the first battery pack 4a and the second battery pack 4b It is possible to suppress the occurrence of current flowing into one battery pack due to electric power and damage to one battery pack.

The first voltage divider 112a divides the voltage VB1 input from the first battery pack 4a via the first positive electrode terminal 101, and outputs the divided voltage to the MCU 110.
The second voltage divider 112b divides the voltage VB2 input from the second battery pack 4b via the second positive terminal 104 and outputs the divided voltage to the MCU 110.

The first display circuit 113a is a circuit for lighting the first LED 6a described above, and lights the first LED 6a in accordance with a command output from the MCU 110.
The second display circuit 113b is a circuit for lighting the above-described second LED 6b, and lights the second LED 6b in accordance with a command output from the MCU 110.

The first current detection circuit 114a is provided between the downstream side of the motor M1 and the first negative terminal 102, detects the magnitude of current flowing from the motor M1 to the first negative terminal 102, and detects the magnitude of the detected current. A signal indicating this is output to the MCU 110. Since the first negative electrode terminal 102 is connected to the ground of the drive circuit 100, when the first battery pack 4a is attached to the appliance 1, the potential of the negative electrode of the battery 41a in the first battery pack 4a (the first battery pack). 4a is the same potential as the ground of the drive circuit 100.

The second current detection circuit 114b is provided between the downstream side of the motor M1 and the second negative terminal 105, detects the magnitude of the current flowing from the motor M1 to the second negative terminal 105, and detects the magnitude of the detected current. A signal indicating this is output to the MCU 110. Since the second negative electrode terminal 105 is connected to the ground of the drive circuit 100, when the second battery pack 4b is attached to the appliance 1, the potential of the negative electrode of the battery 41b in the second battery pack 4b (second battery pack). 4b) is at the same potential as the ground of the drive circuit 100.

The above-described discharge stop signal input from the first battery pack 4a to the drive circuit 100 via the first signal terminal 103 and the above-described input from the second battery pack 4b to the drive circuit 100 via the second signal terminal 106. Each of the discharge stop signals is input to the MCU 110 via an interface circuit (not shown). Each of the discharge stop signals in the first embodiment is a binary signal. The logical value of each of these binary signals is high when discharging is continued, and is high impedance when discharging is stopped.

As shown in FIG. 3, the drive circuit 100 further includes a first booster circuit 115a, a second booster circuit 115b, a boosted voltage setting circuit 116, the motor M1, the overcurrent detection circuit 117, and the first booster circuit 115b. An operation circuit 118a and a second operation circuit 118b are provided.

The first booster circuit 115a has the input side of the first booster circuit 115a connected to the first positive terminal 101, boosts the voltage VB1 input from the first battery pack 4a via the first positive terminal 101, and the motor M1. A drive voltage for driving is generated. The first booster circuit 115a in the first embodiment is a known step-up converter.

More specifically, the first booster circuit 115a includes a capacitor C1a, a transformer Ta, an N-channel FET 119a, an overcurrent detection circuit 120a, a diode D3a, and a capacitor C2a.

The capacitor C1a is connected between the first positive terminal 101 and the ground of the drive circuit 100, and is set so as to store electric charge by the drive voltage VB1.
The transformer Ta includes a primary side coil and a secondary side coil. One end of the primary coil is connected to the first positive terminal 101, while the other end of the primary coil is connected to the drain of the FET 119a. One end of the secondary side coil of the transformer Ta is connected to the upstream side of the motor M1 via the diode D3a and the boost voltage setting circuit 116, while the other end of the secondary side coil is connected to the ground of the drive circuit 100. ing.

The FET 119a has a source connected to the ground of the drive circuit 100 via the overcurrent detection circuit 120a, and the FET 119a is turned on / off by a voltage input to the gate of the FET 119a. It is set to switch the flowing current.

The overcurrent detection circuit 120a monitors the current flowing from the primary coil of the transformer Ta to the ground of the drive circuit 100 via the FET 119a, and outputs a binary signal indicating whether or not an overcurrent has been detected. The logical value of the binary signal is Low when an overcurrent is detected, and High when no overcurrent is detected.

The diode D3a half-rectifies the AC voltage generated in the secondary coil of the transformer Ta, and the capacitor C2a generates a smoothed drive voltage by smoothing the voltage half-wave rectified by the diode D3a. To do.

The second booster circuit 115b has the input side of the second booster circuit 115b connected to the second positive terminal 104, boosts the voltage VB2 input from the second battery pack 4b via the second positive terminal 104, and the motor M1. A drive voltage for driving is generated. The second booster circuit 115b in the first embodiment is configured similarly to the first booster circuit 115a.

That is, the second booster circuit 115b includes a capacitor C1b, a transformer Tb, an N-channel FET 119b, an overcurrent detection circuit 120b, a diode D3b, and a capacitor C2b.

The capacitor C1b is connected between the second positive terminal 104 and the ground of the drive circuit 100, and is set to store electric charge by the drive voltage VB2.
The transformer Tb includes a primary side coil and a secondary side coil. One end of the primary side coil is connected to the second positive terminal 104, while the other end of the primary side coil is connected to the drain of the FET 119b. One end of the secondary side coil of the transformer Tb is connected to the upstream side of the motor M1 via the diode D3b and the boost voltage setting circuit 116, while the other end of the secondary side coil is connected to the ground of the drive circuit 100. ing.

The source of the FET 119b is connected to the ground of the drive circuit 100 via the overcurrent detection circuit 120b, and the FET 119b is turned on / off by a voltage input to the gate of the FET 119b. It is set to switch the flowing current.

The overcurrent detection circuit 120b monitors the current flowing from the primary coil of the transformer Tb to the ground of the drive circuit 100 via the FET 119b, and outputs a binary signal indicating whether or not an overcurrent has been detected. The logical value of the binary signal is Low when an overcurrent is detected, and High when no overcurrent is detected.

The diode D3b rectifies the AC voltage generated in the secondary coil of the transformer Tb by half-wave rectification, and the capacitor C2b generates the smoothed drive voltage by smoothing the voltage rectified by the diode D3b by half-wave. To do.

The boost voltage setting circuit 116 includes a main switch SW1, a variable resistor R1, a switch (SW) operation detection circuit 121, a voltage divider 122, an error amplifier 123, a triangular wave generator 124, and a comparator 125. ing.

The main switch SW1 has one contact of the main switch SW1 connected to the diodes D3a and D3b, and the other contact of the main switch SW1 connected to the upstream side of the motor M1. The main switch SW1 is configured to be interlocked with the above-described trigger switch 12. When the trigger switch 12 is operated, the main switch SW1 is turned on, and the diodes D3a and D3b are connected to the motor M1 via the main switch SW1. Connected upstream. On the other hand, when the trigger switch 12 is not operated, the main switch SW1 is turned off, and the diodes D3a and D3b are disconnected from the upstream side of the motor M1.

The variable resistor R1 is set to divide the control voltage Vcc and generate a divided voltage. The variable resistor R1 is configured to be interlocked with the trigger switch 12, and the resistance value of the variable resistor R1 changes according to the operation amount of the trigger switch 12. That is, the variable resistor R1 generates a voltage corresponding to the operation amount of the trigger switch 12.

The SW operation detection circuit 121 is a circuit that detects that the trigger switch 12 is operated. More specifically, the voltage between the contacts of the main switch SW1 is input to the SW operation detection circuit 121. The SW operation detection circuit 121 operates the trigger switch 12 based on the voltage between the contacts. A binary signal indicating whether or not it has been output is output to the MCU 110. The logical value of the binary signal becomes High when the trigger switch 12 is operated, and becomes Low when the trigger switch 12 is not operated.

The voltage divider 122 divides the drive voltage generated in the first booster circuit 115 a and the second booster circuit 115 b and outputs the divided voltage to the MCU 110 and the error amplifier 123.
The error amplifier 123 amplifies the difference between the voltage divided by the voltage divider 122 and the voltage generated in the variable resistor R1, and outputs the amplified voltage.

The triangular wave generator 124 repeatedly generates a preset triangular wave.
The comparator 125 compares the voltage of the output signal from the error amplifier 123 with the voltage of the triangular wave from the triangular wave generator 124, and outputs a pulse train signal whose duty ratio changes according to the comparison result.

The boost voltage setting circuit 116 is configured to output a pulse train signal having a larger duty ratio as the operation amount of the trigger switch 12 is larger, by the circuit configuration as described above.
In the first embodiment, the motor M1 is a DC motor with a brush. A diode D4 for absorbing a counter electromotive force generated in the coil is connected in parallel to the coil of the motor M1.

The overcurrent detection circuit 117 monitors the current flowing downstream of the motor M1 and outputs a binary signal indicating whether or not an overcurrent has been detected. The logical value of the binary signal is Low when an overcurrent is detected, and High when no overcurrent is detected.

The first actuating circuit 118a is configured as an AND gate, a binary signal output from the overcurrent detection circuit 120a, a binary signal indicating whether or not boosting is output from the MCU 110, and a boosting voltage setting circuit The pulse train signal output from 116 and the binary signal output from the overcurrent detection circuit 117 are input. In the first operating circuit 118a, the logic value of the output voltage of the first operating circuit 118a becomes High when the logic values of all these binary signals are High, and the first value when the logic value of at least one signal is Low. The logical value of the output voltage of the 1 operation circuit 118a becomes Low. That is, in the first operating circuit 118a, the boost voltage is detected only when the overcurrent is not detected by the overcurrent detection circuit 120a, the MCU 110 permits boosting, and the overcurrent detection circuit 117 detects no overcurrent. A pulse train signal synchronized with the pulse train signal output from the setting circuit 116 is output to the FET 119a. In the first booster circuit 115a, the FET 119a is switched by the pulse train signal output from the first operating circuit 118a. By switching the FET 119a, the voltage VB1 is boosted and a drive voltage is generated. The magnitude of the drive voltage is proportional to the magnitude of the duty ratio of the pulse train signal.

Similarly to the first operation circuit 118a, the second operation circuit 118b is configured as an AND gate. The second operating circuit 118b is output from the binary signal output from the overcurrent detection circuit 120b, the above-described binary signal indicating whether or not to allow boosting from the MCU 110, and the boosting voltage setting circuit 116. The pulse train signal and the binary signal output from the overcurrent detection circuit 117 are input. In the second operating circuit 118b, when the logic values of all these binary signals are High, the logic value of the output voltage of the second operating circuit 118b is High, and when the logic value of at least one signal is Low, the second operating circuit 118b 2 The logic value of the output voltage of the operating circuit 118b becomes Low. That is, in the second operating circuit 118b, the boost voltage is only detected when the overcurrent is not detected by the overcurrent detection circuit 120b, the MCU 110 permits the boosting, and the overcurrent detection circuit 117 does not detect the overcurrent. A pulse train signal synchronized with the pulse train signal output from the setting circuit 116 is output to the FET 119b. In the second booster circuit 115b, the FET 119b is switched by the pulse train signal output from the second operating circuit 118b. By switching the FET 119b, the voltage VB2 is boosted and a drive voltage is generated.

Hereinafter, the main routine according to the present invention executed by the MCU 110 will be described.
When at least one of the first battery pack 4a and the second battery pack 4b is mounted on the battery pack mounting portion 7 of the main body 2 and the control voltage Vcc is applied to the MCU 110 and the MCU 110 is activated, the MCU 110 is activated. The main routine shown in the above is repeatedly executed.

As shown in FIG. 4, in this main routine, first, based on the logical value of the binary signal input from the SW operation detection circuit 121, it is determined whether or not the main switch SW1 is turned on (S10). If it is determined that the main switch SW1 is turned off (S10: No), the process proceeds to S40 described later.

On the other hand, if it is determined that the main switch SW1 is turned on (S10: Yes), a preset priority setting process is executed (S20). This priority setting process is a process of setting a battery pack (main battery) to be discharged preferentially and a battery pack (sub-battery) to be discharged auxiliary, and will be described in detail later.

When the priority setting process is completed, it is determined whether or not there is a battery pack corresponding to the main battery (S30). When it is determined that there is no corresponding battery pack (S30: No), the value of the voltage VB1 of the first battery pack 4a is calculated based on the voltage input from the first voltage divider 112a, and the calculated value is used as the MCU 110. (S40). Subsequently, the value of the voltage VB2 of the second battery pack 4b is calculated based on the voltage input from the second voltage divider 112b, and the calculated value is stored in the memory (S50). Thereafter, a binary signal whose logic value is Low is output to the first operating circuit 118a, the first booster circuit 115a is stopped (S60), and a binary value whose logic value is Low is output to the second operating circuit 118b. A signal is output to stop the second booster circuit 115b (S70), and this main routine is terminated.

If it is determined in S30 that there is a battery pack corresponding to the main battery (S30: Yes), it corresponds to the battery pack set as the main battery among the first booster circuit 115a and the second booster circuit 115b. The booster circuit is activated to boost the voltage of the main battery (S80).

Then, based on the signal from the current detection circuit corresponding to the battery pack set to the main battery among the first current detection circuit 114a and the second current detection circuit 114b, the discharge from the battery pack set to the main battery. It is determined whether or not the current is greater than or equal to a preset threshold value (S90). If it is determined that the discharge current is equal to or greater than the threshold (S90: Yes), it is determined whether there is a battery pack corresponding to the sub-battery (S100). When it is determined that there is no battery pack corresponding to the sub-battery (S100: No), the process proceeds to S120 described later. On the other hand, when it is determined that there is a battery pack corresponding to the sub-battery (S100: Yes), of the first booster circuit 115a and the second booster circuit 115b, the booster circuit corresponding to the battery pack set as the sub-battery. To increase the voltage of the sub-battery (S110), and the main routine is terminated.

If it is determined in S90 that the discharge current is less than the threshold (S90: No), the booster circuit corresponding to the battery pack set in the sub-battery is stopped, and the boosting of the sub-battery voltage is stopped. (S120), this main routine is terminated.

Here, the priority setting process in S20 is executed as follows.
That is, in this process, first, it is set in the memory of the MCU 110 that there is no battery pack corresponding to the main battery and that there is no battery pack corresponding to the sub battery (S200). Then, it is determined whether or not the first battery pack 4a is connected to the drive circuit 100 (S210). This determination is made based on the voltage input from the voltage divider 112a.

When it is determined in S210 that the first battery pack 4a is not connected to the drive circuit 100 (S210: No), the process immediately proceeds to S240 described later. On the other hand, when it is determined that the first battery pack 4a is connected to the drive circuit 100 (S210: Yes), the discharge stop is performed based on the logical value of the discharge stop signal input from the first battery pack 4a. It is determined whether it is notified from the first battery pack 4a (S220). When it is determined that the discharge stop is notified (S220: Yes), the process immediately proceeds to S240 described later, whereas when it is determined that the discharge stop is not notified (S220: No), the first battery The pack 4a is set as the main battery (S230).

Subsequently, it is determined whether or not the second battery pack 4b is connected to the drive circuit 100 (S240). This determination is performed based on a signal input from the second battery pack 4b via a path not shown in FIG.

If it is determined in S240 that the second battery pack 4b is not connected to the drive circuit 100 (S240: No), this process is immediately terminated, while the second battery pack 4b is connected to the drive circuit 100. If it is determined that the discharge is stopped (S240: Yes), it is determined whether the discharge stop is notified from the second battery pack 4b based on the logical value of the discharge stop signal input from the second battery pack 4b. (S250). When it is determined that the discharge stop has been notified (S250: Yes), the process immediately proceeds, while when it is determined that the discharge stop has not been notified (S250: No), the first battery pack. It is determined whether 4a is set as the main battery (S260).

If it is determined that the first battery pack 4a is not set as the main battery (S260: No), the second battery pack 4b is set as the main battery (S270), and this process is terminated. On the other hand, when it is determined that the first battery pack 4a is set as the main battery (S260: Yes), the voltage is determined based on the values of the voltages VB1 and VB2 stored in the memory in S40 and 50 of the main routine. It is determined whether VB1 is equal to or higher than voltage VB2 (S280).

If it is determined that the voltage VB1 is less than the voltage VB2 (S280: No), the second battery pack 4b is set as a sub-battery (S290), and this process ends.
On the other hand, if it is determined that the voltage VB1 is equal to or higher than the voltage VB2 (S280: Yes), the second battery pack 4b is set as the main battery and the first battery pack 4a is set as the sub-battery (S300). finish.

In the appliance 1 according to the first embodiment configured as described above, the first booster circuit 115a and the first booster circuit 115a are selected from at least one of the first battery pack 4a and the second battery pack 4b selected by the MCU 110. A power supply path to the motor M1 is formed through at least one corresponding booster circuit of the two booster circuits 115b, and a drive voltage is applied to the motor M1.

Therefore, in this instrument 1, even if the voltage of one of the first battery pack 4a and the second battery pack 4b is significantly reduced, the motor M1 is driven by the drive voltage generated using the voltage of the other battery pack. can do.

Moreover, in this instrument 1, when the discharge current of one battery pack to be discharged preferentially reaches a threshold value, the current is also output from the other battery pack, and therefore, for example, the load on the motor M1 is large and the motor M1 When a large amount of electric power is required to drive the motor M1, a large amount of electric power can be supplied from the two battery packs to the motor M1. On the other hand, when the load applied to the motor is small and a large amount of electric power is not required, electric power can be supplied from one battery pack to the motor M1.

Moreover, in this instrument 1, based on both values of the voltages VB1 and VB2, of the first battery pack 4a and the second battery pack 4b, the battery pack with the smaller remaining power is set as the main battery. . For this reason, the power of the battery pack with the larger remaining power is consumed first, and the power of the battery pack with the smaller remaining power is consumed while the battery pack is replaced or charged. The use of the instrument 1 can be prevented from being interrupted.

Moreover, in this instrument 1, the magnitude | size of a drive voltage can be changed suitably according to the operation amount of the trigger switch 12. FIG.
In the first embodiment, the first booster circuit 115a and the second booster circuit 115b correspond to an example of the booster in the present invention, and execute S230 to S300 in the priority setting process and S90 to S120 of the main routine. The MCU 110 corresponds to an example of a battery pack selection unit in the present invention, and the MCU 110 that executes S80 to S110 in the main routine corresponds to an example of a path formation unit in the present invention.

In the first embodiment, the first current detection circuit 114a, the second current detection circuit 114b, and the MCU 110 that executes S90 of the main routine correspond to an example of the motor state detection unit in the present invention, and the first voltage divider 112a, the second voltage divider 112b, and the MCU 110 that executes S40 and 50 of the main routine correspond to an example of the battery pack state detection unit in the present invention, and the boost voltage setting circuit 116 corresponds to an example of the command unit in the present invention.
[Second Embodiment]
The instrument in the second embodiment is the same as the instrument of the first embodiment except for the configuration of a part of the drive circuit, which is different from the first embodiment.

Therefore, in the following description, the same components as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and only different portions are denoted by new symbols.
As shown in FIGS. 6 and 7, in the drive circuit 200 of the second embodiment, a diode D5a and a P-channel type first FET 211a are composed of a primary side coil of a transformer Ta in the first positive terminal 101 and the first booster circuit 115a. Connected between and. More specifically, the anode of the diode D5a is connected to the first positive terminal 101, and the cathode of the diode D5a is connected to the source of the first FET 211a. The drain of the first FET 211a is connected to one end of the primary coil of the transformer Ta, and a drive signal is input from the MCU 210 to the gate of the first FET 211a.

In the driving circuit 200 of the second embodiment, the diode D5b and the P-channel type second FET 211b are connected between the second positive terminal 104 and the primary coil of the transformer Ta. More specifically, the anode of the diode D5b is connected to the second positive terminal 104, and the cathode of the diode D5b is connected to the source of the second FET 211b. The drain of the second FET 211b is connected to one end of the primary side coil of the transformer Ta, and a drive signal is input from the MCU 210 to the gate of the second FET 211b.

In addition, the drain of the first FET 211a and the drain of the second FET 211b are connected to the input side of the power supply circuit 212 provided in the drive circuit 200 of the second embodiment, and the first battery pack is connected via these FETs. The voltage VB1 of 4a and the voltage VB2 of the second battery pack 4b are input, and the control voltage Vcc is generated based on these voltages.

In the driving circuit 200 of the second embodiment, the second operating circuit 118b and the second booster circuit 115b provided in the driving circuit 100 of the first embodiment are omitted.
Hereinafter, a main routine according to the present invention executed by the MCU 210 will be described.

When the control voltage Vcc is applied and the MCU 210 is activated, the MCU 210 repeatedly executes the main routine shown in FIG.
As shown in FIG. 8, in this main routine, first, based on the logical value of the binary signal input from the SW operation detection circuit 121, it is determined whether or not the main switch SW1 is turned on (S400). If it is determined that the main switch SW1 is turned off (S400: No), the process proceeds to S430 described later.

On the other hand, when it is determined that the main switch SW1 is turned on (S400: Yes), the same priority setting process as the priority setting process in the first embodiment is executed (S410).

When the priority setting process ends, it is determined whether there is a battery pack corresponding to the main battery (S420). When it is determined that there is no corresponding battery pack (S420: No), the value of the voltage VB1 of the first battery pack 4a is calculated based on the voltage input from the first voltage divider 112a, and the calculated value is used as the MCU 110. (S430). Subsequently, the value of the voltage VB2 of the second battery pack 4b is calculated based on the voltage input from the second voltage divider 112b, and the calculated value is stored in the memory (S440). Thereafter, a drive signal having a logical value of High is output to the gate of the first FET 211a, the first FET 211a is turned off (S450), and a drive signal having a logical value of High is output to the gate of the second FET 211b. The 2FET 211b is turned off (S70). When these FETs are turned off, a binary signal whose logic value is Low is output to the first operating circuit 118a, the first booster circuit 115a is stopped (S470), and this main routine is terminated.

If it is determined in S420 that there is a battery pack corresponding to the main battery (S420: Yes), a logical value is applied to the gate of the FET corresponding to the battery pack set to the main battery among the first FET 211a and the second FET 211b. A drive signal in which is low is output to turn on this FET (S480).

Then, based on the signal from the current detection circuit corresponding to the battery pack set to the main battery among the first current detection circuit 114a and the second current detection circuit 114b, the discharge from the battery pack set to the main battery. It is determined whether or not the current is greater than or equal to a threshold value (S490). If it is determined that the discharge current is equal to or greater than the threshold (S490: Yes), it is determined whether there is a battery pack corresponding to the sub-battery (S500). If it is determined that there is no battery pack corresponding to the sub-battery (S500: No), the process proceeds to S520 described later. On the other hand, if it is determined that there is a battery pack corresponding to the sub-battery (S500: Yes), the logic value is low at the gate of the FET corresponding to the battery pack set as the sub-battery among the first FET 211a and the second FET 211b. Is output, this FET is turned on (S510), and the process proceeds to S530 described later.

If it is determined in S490 that the discharge current is less than the threshold value (S490: No), a drive signal whose logic value is High is output to the gate of the FET corresponding to the battery pack set in the sub-battery. The FET is turned off (S520). Then, a binary signal whose logical value is High is output to the first operating circuit 118a, the first booster circuit 115a is operated (S530), and this main routine is terminated.

In the appliance of the second embodiment configured as described above, both the voltage VB1 of the first battery pack 4a and the voltage VB2 of the second battery pack 4b can be boosted only by the first booster circuit 115a. The configuration of the drive circuit 200 can be simplified.

Moreover, in the appliance of the second embodiment, the diodes D5a and D5b prevent the current from flowing back to the first battery pack 4a and the second battery pack 4b. For this reason, in the instrument of the second embodiment, it is possible to suppress the occurrence of problems in each of these battery packs due to the backflow of current to the first battery pack 4a and the second battery pack 4b.

In the second embodiment, the diodes D5a and D5b correspond to an example of the backflow suppressing unit in the present invention.
[Third Embodiment]
The instrument in the third embodiment is the same as the instrument of the first embodiment except for the configuration of a part of the drive circuit, which is different from the first embodiment.

Therefore, in the following description, the same components as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and only different portions are denoted by new symbols.
As shown in FIG. 9, the appliance drive circuit 300 in the third embodiment is partially different in the configuration of the boost voltage setting circuit 316 from the configuration of the boost voltage setting circuit 116 in the first embodiment.

That is, in the boosted voltage setting circuit 316, the preset reference voltage Vref is input to the error amplifier 123 instead of the voltage generated by the variable resistor R1.
The drive circuit 300 further includes an N-channel FET 301 and a PWM signal generator 302.

In the FET 301, the drain of the FET 301 is connected to the downstream side of the motor M <b> 1, and the source of the FET 301 is connected to the overcurrent detection circuit 117.
The PWM signal generator 302 is connected to the gate of the FET 301, and outputs a pulse train signal having a duty ratio corresponding to the magnitude of the voltage generated by the variable resistor R1 to the gate of the FET 301 to switch the FET 301. More specifically, the PWM signal generator 302 outputs a pulse train signal having a larger duty ratio as the operation amount of the trigger switch 12 is larger.

In the instrument according to the third embodiment configured as described above, it is not necessary to separately provide a configuration for adjusting the current flowing through the motor M1, such as a resistor, and the current flowing through the motor M1 can be appropriately set with a simple configuration. Can be adjusted.

In the third embodiment, the PWM signal generator 302 corresponds to an example of a pulse width modulation unit in the present invention.
[Fourth Embodiment]
The instrument according to the fourth embodiment is the same as the first embodiment and the second embodiment except for a part of the configuration of the instrument that differs from the first and second embodiments.

Accordingly, in the following description, the same components as those in the first embodiment and the second embodiment are denoted by the same reference numerals, the description thereof is omitted, and only different portions are denoted by new symbols.
As shown in FIG. 10, the instrument according to the third embodiment includes a third battery pack 4c in addition to the first battery pack 4a and the second battery pack 4b. The third battery pack 4c is configured in the same manner as the first battery pack 4a and the second battery pack 4b.

The drive circuit 400 according to the fourth embodiment is a combination of the drive circuit 100 in the first embodiment and the drive circuit 200 in the second embodiment.
That is, in the drive circuit 400, the booster circuit corresponding to the first battery pack 4a and the second battery pack 4b is the first booster circuit 115a, and the booster circuit corresponding to the third battery pack 4c is the second booster circuit 115b. It is comprised so that.

For this configuration, the drive circuit 400 is provided with a third positive terminal 401, a third negative terminal 402, and a third signal terminal 403. A third voltage divider 112c is provided for detecting the voltage of the third battery pack 4c, and a third display circuit 113c is provided for notifying the user of the instrument of the state of the third battery pack 4c. . Further, a third current detection circuit 114c is provided for detecting the discharge current of the third battery pack 4c.

The MCU 410 selects at least one of the first battery pack 4a, the second battery pack 4b, and the third battery pack 4c based on the procedure as disclosed in the first embodiment and the second embodiment, The voltage of at least one selected battery pack is boosted to generate a drive voltage.

In the appliance according to the third embodiment, the configuration of the drive circuit 400 can be simplified due to the provision of two booster circuits instead of three booster circuits for the three battery packs.

As mentioned above, although exemplary embodiment of this invention was described, this invention is not limited to the said embodiment, A various aspect can be taken in the range which does not deviate from the summary of this invention.

For example, in the first to fourth embodiments, the appliance to which the present invention is applied is configured as an electric working machine, but is configured as an electric tool 500 such as an impact driver shown in FIG. Also good. In the electric power tool 500, the first battery pack 4a and the second battery pack 4b are detachably attached to a battery pack attachment portion 502 provided in the main body 501 of the electric power tool 500.

In the first to fourth embodiments, the MCU is a microcomputer. However, the MCU may be configured by combining various individual electronic components, or may be an ASIC (Application Specific Integrated Circuit). For example, it may be a programmable logic device such as an FPGA (Field Programmable Gate Array), or a combination thereof.

In the first to fourth embodiments, the motor M1 is a DC motor with a brush. However, the present invention can be applied to any motor such as a brushless DC motor, an AC motor, a stepping motor, or a linear motor. It is.

In the first to fourth embodiments, the booster circuit is a step-up converter, but may be any form of booster circuit.
Further, the battery pack in the first to fourth embodiments is configured as a rechargeable secondary battery, but may be configured as a non-chargeable primary battery.

Claims (15)

1. A motor,
   Multiple battery packs;
   Boosting each voltage of the plurality of battery packs to generate a driving voltage for driving the motor; and
   A battery pack selector that selects at least one of the plurality of battery packs based on a preset selection procedure;
   And a path forming unit that forms a power supply path from at least one of the plurality of battery packs selected by the battery pack selecting unit to the motor via the boosting unit.
2. The electric machine instrument according to claim 1,
   further,
   A motor state detection unit for detecting the state of the motor;
   The electric machine instrument, wherein the battery pack selection unit is configured to select at least one of the plurality of battery packs based on the state of the motor detected by the motor state detection unit.
3. The electric machine instrument according to claim 2,
   The motor state detection unit is configured to detect a load applied to the motor,
   The battery pack selection unit selects at least two of the plurality of battery packs when the load detected by the motor state detection unit is greater than or equal to a preset threshold value, and is detected by the motor state detection unit. An electric machine instrument configured to select one of the plurality of battery packs if the load is less than the threshold.
4. The electric machine instrument according to any one of claims 1 to 3,
   further,
   A battery pack state detector for detecting the state of each of the plurality of battery packs;
   The battery pack selection unit is configured to select at least one of the plurality of battery packs based on the state of each of the plurality of battery packs detected by the battery pack state detection unit. Machinery.
5. The electric machine instrument according to claim 4,
   The battery pack state detection unit is configured to detect a remaining amount of power in each of the plurality of battery packs,
   The battery pack selection unit is configured to select at least one of the plurality of battery packs based on the remaining amount of power in each of the plurality of battery packs detected by the battery pack state detection unit. Electric machinery and equipment.
6. The electric machine instrument according to claim 5,
   The electric machine instrument, wherein the battery pack selection unit is configured to select a battery pack with the least remaining amount of power detected by the battery pack state detection unit from the plurality of battery packs.
7. The electric machine instrument according to any one of claims 1 to 6,
   The boosting unit is configured to be able to change the magnitude of the driving voltage according to a command,
   The electric machine instrument further includes:
   An electric machine instrument comprising a command unit for commanding the magnitude of the drive voltage to the boosting unit.
8. The electric machine instrument according to any one of claims 1 to 6,
   further,
   An electric machine instrument comprising a pulse width modulation unit that performs pulse width modulation on the drive voltage applied to the motor.
9. The electric machine instrument according to any one of claims 1 to 8,
   The booster unit is an electric machine instrument including a plurality of booster circuits connected to each of the plurality of battery packs.
10. The electric machine instrument according to claim 9,
    The number of the plurality of booster circuits is the same as the number of the plurality of battery packs.
11. The electric machine instrument according to claim 9,
    The number of the plurality of boosting circuits is less than the number of the plurality of battery packs.
12. The electric machine instrument according to any one of claims 1 to 8,
    The booster unit is an electric machine instrument including a single booster circuit.
13. The electric machine instrument according to claim 12,
    further,
    The electric machine instrument provided with the backflow suppression part which suppresses that an electric current flows back into each of these battery packs.
14. The electric machine instrument according to any one of claims 1 to 13,
    An electric machine instrument comprising a mounting portion for detachably mounting each of the plurality of battery packs.
15. A body of an electric machine instrument,
    A motor,
    A mounting portion on which a plurality of battery packs are mounted;
    Boosting each voltage of the plurality of battery packs mounted on the mounting unit to generate a driving voltage for driving the motor; and
    A battery pack selector that selects at least one of the plurality of battery packs based on a preset selection procedure;
    A path forming unit that forms a power supply path from at least one of the plurality of battery packs selected by the battery pack selecting unit to the motor via the boosting unit.

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