Electric power tool

Abstract

To enable controlling, in an electric work machine having a brushless motor, the revolution speed of the brushless motor to a target revolution speed while suppressing the heat generation of a motor drive system.SOLUTION: An electric work machine includes: a target revolution speed set unit which sets the target revolution speed of the brushless motor according to an operation target amount of a user interface; a target duty ratio set unit which sets a target duty ratio according to the operation target amount of the user interface; and a control unit which controls the brushless motor. The control unit simultaneously executes PWM control based on the target duty ratio and energization angle control which controls energization angle so that the brushless motor reaches the target revolution speed.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present disclosure relates to a power-operated work machine including a brushless motor.

Background Art

[0002] Patent Document 1 describes that in a backpack blower, the power supplied to a brushless motor serving as a power source is controlled using pulse width modulation (PWM) so that the rotational speed of the brushless motor becomes a target rotational speed (hereinafter referred to as PWM control).

[0003] In PWM control, a plurality of switches provided between the positive and negative sides of a DC power supply and a plurality of terminals of a brushless motor are turned on and off with a drive signal having a predetermined duty ratio, thereby controlling the power supplied to the brushless motor. And the conduction angle is set to a constant angle. For example, in the case of a three-phase brushless motor, the conduction angle is set to 120 degrees.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a power-operated work machine, when the rotational speed of a brushless motor is controlled to a target rotational speed by PWM control, there arises a problem that switching loss increases and the motor drive system tends to generate heat during high-load operation where the motor current becomes large.

[0006] One aspect of the present disclosure aims to enable control of the rotational speed of a brushless motor to a target rotational speed while suppressing heat generation in the motor drive system in a power-operated work machine including the brushless motor.

Means for Solving the Problems

[0007] In one aspect of the present disclosure, an electric working machine includes an output shaft, a brushless motor, a plurality of positive-side energization paths, a plurality of negative-side energization paths, a plurality of high-side switches, a plurality of low-side switches, and a user interface.

[0008] The output shaft is configured such that a driven object can be attached thereto. The brushless motor includes a plurality of terminals and is configured to rotate a driven object attached to the output shaft. The plurality of positive-side energization paths are configured to connect the plurality of terminals of the brushless motor to the positive electrode of a DC power source, and the plurality of negative-side energization paths are configured to connect the plurality of terminals of the brushless motor to the negative electrode of the DC power source.

[0009] The plurality of high-side switches are respectively provided on the plurality of positive-side energization paths, and the plurality of low-side switches are respectively provided on the plurality of negative-side energization paths. The user interface is configured to be operated by a user.

[0010] The above-described electric working machine further includes a target rotation speed setting unit, a target duty ratio setting unit, a rotation angle detection unit, a rotation speed detection unit, and a control unit.

[0011] The target rotation speed setting unit is configured to set a target rotation speed such that the target rotation speed of the brushless motor increases as the amount of operation of the user interface or the rotation command value input by the operation of the user interface increases.

[0012] The target duty ratio setting unit is configured to set a target duty ratio when performing PWM control of the brushless motor based on the amount of operation of the user interface or the rotation command value input by the operation of the user interface.

[0013] Specifically, when the manipulated amount or rotation command value of the user interface is less than the threshold value, the target duty ratio setting unit sets the target duty ratio so that the target duty ratio increases as the manipulated amount or rotation command value increases. Further, when the manipulated amount or rotation command value of the user interface is equal to or greater than the threshold value, the target duty ratio setting unit sets the target duty ratio to 100%.

[0014] The rotation angle detection unit is configured to detect the rotation angle of the brushless motor, and the rotation speed detection unit is configured to detect the rotation speed of the brushless motor. Then, the control unit controls the brushless motor.

[0015] That is, each time the rotation angle detection unit detects that the brushless motor has rotated by a predetermined rotation angle, the control unit is configured to select one of the plurality of high-side switches and one of the plurality of low-side switches as a pair of driven switches.

[0016] Further, the control unit simultaneously executes PWM control for turning on and off at least one of the pair of driven switches at a predetermined frequency based on the target duty ratio, and conduction angle control for controlling the conduction angle for implementing the PWM control so that the rotation speed of the brushless motor detected by the rotation speed detection unit becomes the target rotation speed.

[0017] Therefore, according to the above-described electric working machine, the rotation speed of the brushless motor is controlled to the target rotation speed by the conduction angle control, and the PWM control is performed only during the period in which energization of the brushless motor is permitted by the conduction angle control.

[0018] Thus, according to the above-described electric working machine, compared with the device described in Patent Document 1, the implementation period of the PWM control can be shortened, and the switching loss caused by turning on and off the driven switch by the PWM control can be reduced.

[0019] Therefore, according to the above-mentioned electric working machine, while suppressing heat generation in the drive system of the brushless motor, the rotational speed of the brushless motor can be controlled to the target rotational speed.

[0020] In addition, in PWM control, when the drive duty ratio at the time of actually turning on and off the driven switch becomes 100%, the driven switch is held in the on state. Therefore, when the target duty ratio is 100% and the drive duty ratio for actually turning on and off the driven switch also becomes 100%, the switching loss due to PWM control is further reduced, and heat generation in the drive system is more favorably suppressed.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Mode for Carrying Out the Invention

[0022] [Summary of Embodiment] The electric working machine in a certain embodiment may include a brushless motor having a plurality of terminals. The brushless motor may be configured to rotate a drive object. The drive object may be configured to be attached to the output shaft.

[0023] In addition / Alternatively, the electric working machine may include a plurality of positive-side energization paths configured to connect a plurality of terminals of the brushless motor to the positive electrode of the DC power supply. A plurality of high-side switches may be provided on each of the plurality of positive-side energization paths.

[0024] In addition / Alternatively, the electric working machine may include a plurality of negative-side energization paths configured to connect a plurality of terminals of the brushless motor to the negative electrode of the DC power supply. A plurality of low-side switches may be provided on each of the plurality of negative-side energization paths.

[0025] In addition / Alternatively, the electric working machine may include a user interface. The user interface may be configured to be operated by the user.

[0026] In addition / Alternatively, the electric working machine may include a target rotational speed setting unit. The target rotational speed setting unit may be configured to set the target rotational speed such that the target rotational speed of the brushless motor increases as the amount of operation of the user interface or the rotation command value input by the operation of the user interface increases.

[0027] In addition to and / or, the electric working machine may include a target duty ratio setting unit. When the manipulated amount or rotation command value of the user interface is less than the threshold value, the target duty ratio setting unit may be configured to set the target duty ratio such that the target duty ratio increases as the manipulated amount or rotation command value increases. Further, when the manipulated amount or rotation command value of the user interface is equal to or greater than the threshold value, the target duty ratio setting unit may be configured to set the target duty ratio to 100%.

[0028] In addition to and / or, the electric working machine may include a rotation angle detection unit. The rotation angle detection unit may be configured to detect the rotation angle of the brushless motor.

[0029] In addition to and / or, the electric working machine may include a rotation speed detection unit. The rotation speed detection unit may be configured to detect the rotation speed of the brushless motor.

[0030] In addition to and / or, the electric working machine may include a control unit configured to control the brushless motor.

[0031] Each time the rotation angle detection unit detects that the brushless motor has rotated by a predetermined rotation angle, the control unit may be configured to select one of the plurality of high-side switches and one of the plurality of low-side switches as a pair of driven switches.

[0032] Further, the control unit may be configured to simultaneously execute PWM control for turning on and off at a predetermined frequency at least one of the pair of driven switches based on the target duty ratio, and conduction angle control for controlling the conduction angle for implementing the PWM control such that the rotation speed of the brushless motor detected by the rotation speed detection unit becomes the target rotation speed.

[0033] If an electric power tool in a certain embodiment includes the above brushless motor, output shaft, plurality of positive electrode side energization paths, plurality of negative electrode side energization paths, plurality of high-side switches, plurality of low-side switches, user interface, target rotation speed setting unit, target duty ratio setting unit, rotation angle detection unit, rotation speed detection unit, and control unit, such an electric power tool can control the rotation speed of the brushless motor to the target rotation speed while suppressing heat generation in the drive system of the brushless motor.

[0034] In addition / Or, the electric power tool includes a three-phase brushless motor, and the control unit switches a pair of driven switches that perform PWM control every time the rotation angle detection unit detects that the three-phase brushless motor has rotated 60 degrees as a predetermined rotation angle, and in the energization angle control, it may be configured to control the rotation angle at which PWM control is performed while the three-phase brushless motor rotates 60 degrees.

[0035] In addition / Or, in the PWM control, the control unit may be configured to gradually increase the drive duty ratio by a predetermined change amount until the drive duty ratio for driving at least one of the pair of driven switches reaches the target duty ratio after the start of driving the brushless motor.

[0036] According to the electric power tool configured as described above by the control unit, since a so-called soft start can be realized in which the power supplied to the brushless motor is gradually increased after starting the drive of the brushless motor, the inrush current at startup can be suppressed.

[0037] In addition / Or, in the energization angle control, the control unit controls the energization angle so that the energization angle becomes the preset maximum angle until the rotation speed of the brushless motor reaches the target rotation speed after the start of driving the brushless motor, and when the rotation speed of the brushless motor reaches the target rotation speed, the energization angle is decreased from the maximum angle to maintain the rotation speed of the brushless motor at the target rotation speed, and may be configured as such.

[0038] According to the electric working machine configured as described above by the control unit, during the period until the rotational speed of the brushless motor reaches the target rotational speed by means of the soft start or the like described above, it is possible to suppress the suppression of the increase in the rotation of the brushless motor by the energization angle control. That is, it is possible to cause the rotational speed of the brushless motor to reach the target rotational speed more quickly.

[0039] In addition / Alternatively, the target duty ratio setting unit may be configured to set the target duty ratio to 100% regardless of the manipulated amount or the rotation command value when the user interface is operated.

[0040] According to the electric working machine configured as described above by the target duty ratio setting unit, it is possible to suppress the periodic switching operation of the driven switch by PWM control and better suppress the heat generation of the motor drive system.

[0041] In addition / Alternatively, the user interface may include a trigger configured to be pulled by the user and a rotary dial configured to be rotated by the user.

[0042] In addition / Alternatively, the target rotational speed setting unit may be configured to set the target rotational speed based on the amount of pulling of the trigger and the rotational position of the rotary dial.

[0043] In addition / Alternatively, the target duty ratio setting unit may be configured to set the target duty ratio based on the amount of pulling of the trigger and the rotational position of the rotary dial.

[0044] In a certain embodiment, the above-described features may be combined in any manner. In a certain embodiment, any of the above-described features may be excluded. [Specific exemplary embodiments] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings.

[0045] [First Embodiment] In the present embodiment, as the electric working machine, a backpack blower will be described as an example.

[0046] As shown in FIG. 1, the backpack blower 2 of the present embodiment includes a blower main body 6 mounted on a backpack 4, and a pipe 8 that guides the air discharged from the blower main body 6 to the discharge port 9 at the tip and discharges it from the discharge port 9.

[0047] The blower main body 6 houses a blower fan 10 shown in FIG. 2 and a brushless motor (hereinafter, also simply referred to as a motor) 30 that rotates the fan 10. The fan 10 is attached to the output shaft 12, and the motor 30 rotates the fan 10 by rotating the output shaft 12 directly or indirectly via a gear mechanism. As shown in FIG. 2, the motor 30 is a three-phase brushless motor and includes a U-phase terminal, a V-phase terminal, and a W-phase terminal.

[0048] The blower main body 6 is provided with a pipe attachment portion 7 for collecting the air supplied from the fan 10 and discharging it to the pipe 8. The blower main body 6 is fixed to the backpack 4 via a vibration-absorbing spring. The backpack 4 is provided with a shoulder pad 4a and a belt 4b for the user to put on the shoulder. The pipe attachment portion 7 is provided on the blower main body 6 so as to be located on the right side of the user when the user carries the blower main body 6 via the backpack 4.

[0049] The pipe 8 includes a first partial pipe 8a to a fifth partial pipe 8e divided along the central axis of the pipe 8. The first partial pipe 8a is detachably attachable to the pipe attachment portion 7 and is formed in an L shape so that the air discharge direction from the blower main body 6 can be changed from the lateral direction of the user to the forward direction.

[0050] Further, the second partial pipe 8b is connected to the pipe 8a and is formed in a bellows shape so that the orientation of the discharge port 9 can be arbitrarily changed. Also, the third partial pipe 8c is connected to the second partial pipe 8b. The third partial pipe 8c is a straight pipe, and a handle portion 20 is provided on its outer periphery so that the user can grip it to adjust the orientation of the discharge port 9. Note that the handle portion 20 is slidable in the central axis direction of the third partial pipe 8c and can be fixed at an arbitrary position for use.

[0051] Also, the third partial pipe 8c is configured to be connectable to either a straight fourth partial pipe 8d or a fifth partial pipe 8e having a small diameter at its tip as the discharge port 9. When the fourth partial pipe 8d is connected to the third partial pipe 8c, the tip of the fourth partial pipe 8d can be connected to the fifth partial pipe 8e.

[0052] Next, the handle portion 20 is provided with a trigger 22, a rotary dial 24, and a lock button 26 so that the user can operate them with fingertips while gripping the handle portion 20. Note that the trigger 22 and the rotary dial 24 correspond to an example of the user interface of the present disclosure.

[0053] The trigger 22 is for adjusting the discharge amount of air from the discharge port 9 when the user pulls it. Inside the handle portion 20, a trigger switch 22A that becomes on when the trigger 22 is pulled and a pull amount detection portion 22B that detects the pull amount of the trigger 22 are provided (see FIG. 2). The pull amount detection portion 22B includes, for example, a variable resistor whose resistance value changes according to the pull amount of the trigger 22.

[0054] The rotary dial 24 is rotated by the user and outputs a detection signal corresponding to its rotation position. The rotary dial 24 includes, for example, a variable resistor whose resistance value changes according to the rotation position of the dial, and is used to set the maximum discharge amount adjustable by the operation of the trigger 22.

[0055] The lock button 26 is a button for holding the trigger 22 at the maximum operation position where the pulling amount is maximum. The lock button 26 can be operated to the lock side when the trigger 22 is at the maximum operation position. When operated to the lock side, it engages with the trigger 22 and holds it at the maximum operation position. Also, when the lock button 26 is operated to the non-lock side, the engagement with the trigger 22 is released, and the user can then pull the trigger 22 between the non-operation position with a pulling amount of 0 and the maximum operation position.

[0056] The handle portion 20 is also provided with a main power switch 28 shown in FIG. 2. The main power switch 28 is, for example, a momentary type switch (normally off), and when turned on by the user's operation, it switches the on / off state of the controller 40 shown in FIG. 2 (in other words, the operation / stop of the controller 40).

[0057] The trigger switch 22A, the pulling amount detection unit 22B, the rotary dial 24, and the main power switch 28 are connected to the controller 40 via a cable 29. The controller 40 is fixed to the backpack 4 together with the blower main body 6 and the battery pack 60. The battery pack 60 houses a battery and is used to supply DC power to the controller 40. That is, the battery pack 60 functions as the DC power source of the present disclosure.

[0058] The controller 40 is configured to receive power supply from the battery pack 60 and drive and control the motor 30. That is, as shown in FIG. 2, the controller 40 includes a bridge circuit 42, a gate circuit 44, a regulator 48, and a control circuit 50.

[0059] The bridge circuit 42 receives power supply from the battery pack 60 and supplies current to each phase winding of the motor 30. In the present embodiment, the bridge circuit 42 is in the form of a three-phase full bridge circuit including first to sixth switching elements Q1 to Q6.

[0060] In the bridge circuit 42, the first to third switching elements Q1 to Q3 are provided as so-called high-side switches on the positive-side energization paths L1, L2, and L3 between the first terminal U, the second terminal V, and the third terminal W of the motor 30 and the power line connected to the positive electrode side of the battery pack 60. The first terminal U, the second terminal V, and the third terminal W respectively correspond to the U-phase, V-phase, and W-phase of the motor 30.

[0061] Also, the fourth to sixth switching elements Q4 to Q6 are provided as so-called low-side switches on the negative-side energization paths L4, L5, and L4 between the first terminal U, the second terminal V, and the third terminal W of the motor 30 and the ground line connected to the negative electrode side of the battery pack 60.

[0062] In this embodiment, the first to sixth switching elements Q1 to Q6 are in the form of n-channel metal-oxide semiconductor field-effect transistors (MOSFETs). Therefore, first to sixth diodes D1 to D6 (so-called parasitic diodes) that are in the forward direction from the source to the drain are respectively connected in parallel between the drain and source of each of the first to sixth switching elements Q1 to Q6.

[0063] Therefore, each of the first to sixth diodes D1 to D6 can conduct current in the direction opposite to the forward direction from the positive electrode side to the negative electrode side of the battery pack 60 when the corresponding one of the first to sixth switching elements Q1 to Q6 is in the off state.

[0064] The gate circuit 44 causes current to flow through each phase winding of the motor 30 and rotates the motor 30 by individually turning on and off the first to sixth switching elements Q1 to Q6 in the bridge circuit 42 according to the control signal output from the control circuit 50.

[0065] The regulator 48 receives power supply from the battery pack 60 and generates the operating power supply voltage (DC constant voltage) for each part in the controller 40. Each part in the controller 40, including the control circuit 50, operates using the operating power supply voltage from the regulator 48 as the power source.

[0066] The control circuit 50 drives and controls the motor 30 via the gate circuit 44. The control circuit 50 in this embodiment is in the form of an MCU (Micro Control Unit) including a CPU, a ROM, and a RAM. The control circuit 50 of this embodiment is provided with a non-volatile memory 51 for storing the states (such as abnormalities) of the motor 30 and the controller 40 to be controlled. In other embodiments, the control circuit 50 may include, instead of or in addition to the MCU, a combination of electronic components such as discrete elements, may include an application-specific integrated circuit (ASIC), may include an application-specific standard product (ASSP), may include a programmable logic device such as a field programmable gate array (FPGA), or may include a combination thereof.

[0067] The control circuit 50 receives a trigger switch signal, a draw amount detection signal, a dial position signal, and a main power switch signal from the trigger switch 22A, the draw amount detection unit 22B, the rotary dial 24, and the main power switch 28 provided on the handle unit 20.

[0068] In addition, a voltage detection unit 52, a current detection unit 46, a motor temperature detection unit 34, a rotation angle detection unit 36, a FET temperature detection unit 54, and a battery communication unit 58 are connected to the control circuit 50.

[0069] The voltage detection unit 52 is a circuit that detects the battery voltage input from the battery pack 60 to the controller 40. The current detection unit 46 is provided on the current path to the motor 30 from the bridge circuit 42 to the ground line and is a circuit that detects the current flowing through the motor 30. The motor temperature detection unit 34 is a temperature sensor provided on the motor 30 and detects the temperature of the motor 30, and is, for example, in the form of a thermistor.

[0070] Next, the rotation angle detection unit 36 is a circuit that detects the rotational position of the motor based on a detection signal from the rotation sensor 32 provided in the motor 30. That is, the rotation sensor 32 includes three hall sensors (not shown) arranged around the rotor of the motor 30. From these three hall sensors, hall signals corresponding to the U-phase, V-phase, and W-phase of the motor 30 are output, and the increase / decrease direction of the hall signals reverses every time the rotor rotates by an electrical angle of 180 degrees.

[0071] The rotation angle detection unit 36 includes a waveform shaping circuit that generates a pulsed hall signal (see FIGS. 4 and 5) whose positive and negative reverse every 180 degrees of the electrical angle of the rotor by shaping the hall signals of each phase U, V, and W.

[0072] Then, the rotation angle detection unit 36 outputs a detection signal representing the rotational position of the rotor of the motor 30 (in other words, the rotation angle of the motor 30) at intervals of 60 degrees of electrical angle from the edges of the respective hall signals to the control circuit 50.

[0073] For this reason, the control circuit 50 can detect the rotation angle of the motor 30 based on the detection signal input from the rotation angle detection unit 36. Further, the control circuit 50 can detect the number of rotations per unit time (in other words, the rotation speed) of the motor 30 based on the detection signal input from the rotation angle detection unit 36.

[0074] The FET temperature detection unit 54 is a temperature sensor provided in the bridge circuit 42 that detects the temperatures of the first to sixth switching elements Q1 to Q6 (in other words, the temperature of the bridge circuit 42), and is, for example, in the form of a thermistor.

[0075] The battery communication unit 58 communicates with the communication unit provided in the battery pack 60 to acquire information such as the amount of electric power stored in the battery in the battery pack 60 (hereinafter referred to as the remaining capacity) and the deterioration state of the battery. Then, the control circuit 50 determines whether the motor 30 can be driven with the supply power from the battery pack 60 based on the information acquired via the battery communication unit 58.

[0076] Next, the control process executed by the control circuit 50 to drive and control the motor 30 will be described. This control process is executed as a main routine in the control circuit 50 when it is determined that the battery pack 60 is normal and the motor 30 can be driven by the power supplied from the battery pack 60.

[0077] As shown in FIG. 3, the control circuit 50 first obtains the pulling amount of the trigger 22 from the pulling amount detection unit 22B at S110 (S represents a step), and then obtains the dial position from the rotary dial 24 at S120.

[0078] At S130, based on the pulling amount of the trigger 22 and the dial position of the rotary dial 24 obtained at S110 and S120, the target rotational speed of the motor 30 is set. The process of S130 corresponds to an example of the target rotational speed setting unit of the present disclosure.

[0079] In S130, for example, the pulling amount Ptgr of the trigger 22 is defined by the operation ratio with respect to the maximum pulling amount, and the dial position Pdial of the rotary dial 24 is defined by the operation ratio with respect to the maximum operation position, so that the target rotational speed Rtgt is calculated based on the following formula.

[0080] Rtgt = Rmax × Ptgr × Pdial However, Rmax is the allowable maximum rotational speed of the motor 30.

[0081] Therefore, the target rotational speed Rtgt is set so as to approach the allowable maximum rotational speed Rmax as the pulling amount (in other words, the amount to be operated) of the trigger 22 and the dial position (in other words, the amount to be operated) of the rotary dial 24 are larger.

[0082] Next, in S140, based on the pulling amount of the trigger 22 and the dial position of the rotary dial 24 acquired in S110 and S120, the target duty ratio (hereinafter, the duty ratio is referred to as DUTY) when performing PWM control on the power supplied to the motor 30 is set. Note that the process of S140 corresponds to an example of the target duty ratio setting unit of the present disclosure.

[0083] In S140, for example, the pulling amount Ptgr of the trigger 22 is defined as the operation ratio with respect to the maximum pulling amount, and the dial position Pdial of the rotary dial 24 is defined as the operation ratio with respect to the maximum operation position, so that the target DUTY is calculated based on the following formula.

[0084] Target DUTY = 100% × Ptgr × Pdial × K However, K is a coefficient for correcting the target DUTY so that the target DUTY becomes 100% when "Ptgr × Pdial", which is the amount of operation of the trigger 22 and the rotary dial 24, is equal to or greater than a preset threshold value.

[0085] Therefore, the target DUTY is set to approach 100% as the pulling amount of the trigger 22 is larger and the dial position of the rotary dial 24 is larger when the amount of operation "Ptgr × Pdial" of the trigger 22 and the rotary dial 24 is less than the threshold value. Also, when the amount of operation "Ptgr × Pdial" of the trigger 22 and the rotary dial 24 is equal to or greater than the threshold value, the target DUTY is set to 100%.

[0086] When the target rotation speed and the target DUTY of the motor 30 are set in S130 and S140, the control circuit 50 proceeds to S150 and drives and controls the motor 30 based on the target rotation speed and the target DUTY.

[0087] In S150, the motor control process for controlling the rotation of the motor 30 is executed by simultaneously performing the PWM control shown in FIG. 4 and the energization angle control shown in FIG. 5. Note that this motor control process corresponds to an example of the control unit of the present disclosure.

[0088] In the PWM control shown in FIG. 4, based on the hall signal, every time the motor 30 rotates by an electrical angle of 60 degrees, the energization path to the motor 30 is switched, and the current flowing through the energization path is controlled by a PWM signal set to a predetermined duty ratio at a constant frequency.

[0089] That is, in the PWM control, every time the motor 30 rotates by an electrical angle of 60 degrees, as a pair of driven switches that form the energization path to the motor 30 in the bridge circuit 42, the sixth switching element Q6 and the first switching element Q1, the first switching element Q1 and the fifth switching element Q5, the fifth switching element Q5 and the third switching element Q3, the third switching element Q3 and the fourth switching element Q4, the fourth switching element Q4 and the second switching element Q2, the second switching element Q2 and the sixth switching element Q6, are sequentially selected.

[0090] Then, among the combinations of the selected first to third switching elements Q1 to Q3 (high-side switches) and the fourth to sixth switching elements Q4 to Q6 (low-side switches), one is turned on, and the other is periodically turned on and off with a PWM signal having a predetermined duty ratio to control the energization current to the motor 30.

[0091] The target DUTY set at S140 is used to generate the PWM signal. Then, the control circuit 50 outputs a control signal to the gate circuit 44 to turn on one of the selected pair of switching elements and turn on and off the other switching element with the PWM signal.

[0092] In the above-mentioned Patent Document 1, the rotation speed of the motor 30 is controlled to the target rotation speed by such PWM control, and the period in which each of the first to sixth switching elements Q1 to Q6 is selected to form the energization path is fixed at a maximum electrical angle of 120 degrees as the so-called energization angle.

[0093] Therefore, the first to sixth switching elements Q1 to Q6 are sequentially and continuously turned on and off while the motor 30 rotates 360 degrees in electrical angle, resulting in increased switching losses and heat generation in the bridge circuit 42.

[0094] Therefore, in this embodiment, as illustrated in FIG. 5 for the energization angle control, for every 60-degree rotation of the electrical angle of the motor 30, the period during which the first to sixth switching elements Q1 to Q6 are turned on and off by PWM control is shortened to suppress heat generation in the bridge circuit 42.

[0095] That is, in the energization angle control, the energization angle is set such that the period during which each of the first to sixth switching elements Q1 to Q6 is selected to form an energization path is shorter than 120 degrees of electrical angle, which is the maximum angle. Then, at the OFF timing when the set energization angle has elapsed, the first to sixth switching elements Q1 to Q6 are forcibly turned off.

[0096] Therefore, in this embodiment, by combining and simultaneously implementing this energization angle control and PWM control, while suppressing heat generation of the first to sixth switching elements Q1 to Q6 by PWM control, the rotational speed of the motor 30 is controlled to the target rotational speed by the energization angle control.

[0097] Also, in the PWM control, after starting the drive of the motor 30, the drive DUTY for actually turning on the first to sixth switching elements Q1 to Q6 is gradually increased to the target DUTY to soft-start the motor 30 and suppress the inrush current.

[0098] That is, in the motor control process of S150, as shown in FIG. 6, in S200, for the energization angle control, an energization angle setting process is performed to update the energization angle so that the rotational speed of the motor 30 becomes the target rotational speed.

[0099] Also, in S300, for the PWM control, a DUTY setting process is performed to update the drive DUTY so that the drive DUTY of the first to sixth switching elements Q1 to Q6 selected as described above becomes the target DUTY.

[0100] Note that since the energization angle setting process of S200 and the DUTY setting process of S300 may be carried out almost simultaneously, the execution order of these processes may be changed. That is, as shown in FIG. 6, the DUTY setting process of S300 may be carried out after the energization angle setting process of S200, or may be carried out before the energization angle setting process of S200.

[0101] As shown in FIG. 6, in the energization angle setting process of S200, at S210, based on the detection signal input from the rotation angle detection unit 36, the current motor rotation speed Rnow is obtained. Note that the process of S210 corresponds to an example of the rotation speed detection unit of the present disclosure.

[0102] Next, at S220, the current motor rotation speed Rnow obtained at S210 is compared with the target rotation speed Rtgt set at S130. When the motor rotation speed Rnow is lower than the target rotation speed Rtgt, the process proceeds to S230, and the energization angle is updated by adding a certain update value to the currently set energization angle, and the process proceeds to the DUTY setting process of S300.

[0103] Note that since the maximum angle of the energization angle is 120 electrical degrees, at S230, the energization angle is updated with 120 electrical degrees as the upper limit value. Also, the initial value of the energization angle when starting the drive of the motor 30 is set to the maximum angle. Therefore, as shown in FIG. 7, after starting the drive of the motor 30, until the motor rotation speed Rnow reaches the target rotation speed Rtgt, the energization angle is held at 120 electrical degrees.

[0104] On the other hand, when it is determined at S220 that the motor rotation speed Rnow is equal to or higher than the target rotation speed Rtgt, the process proceeds to S240, and the energization angle is updated by subtracting a certain update value from the currently set energization angle, and the process proceeds to the DUTY setting process of S300. In the present embodiment, the minimum value of the energization angle is set to 70 electrical degrees, and at S240, the energization angle is updated with 70 electrical degrees as the lower limit value. However, the minimum value of the energization angle may be set as appropriate, and may be 70 degrees or more, or may be 70 degrees or less.

[0105] Next, in the DUTY setting process of S300, at S310, the current drive DUTY (Dnow) in the PWM control is acquired. At S320, the current drive DUTY (Dnow) acquired at S310 is compared with the target DUTY (Dtgt) set at S140.

[0106] And when the current drive DUTY (Dnow) is lower than the target DUTY (Dtgt), the process proceeds to S330, and the drive DUTY is updated by adding a certain update value to the currently set drive DUTY (Dnow), and the motor control process of S150 is terminated.

[0107] Note that the maximum value of the drive DUTY is 100%, and at S330, the drive DUTY is updated with 100% as the upper limit value. Also, the initial value of the drive DUTY when starting the drive of the motor 30 is set to the minimum value of 0%.

[0108] Therefore, as shown in FIG. 7, the drive DUTY gradually increases (increases gradually) from 0% after the start of the drive of the motor 30, and when the drive DUTY reaches the target DUTY, it is held at that target DUTY.

[0109] Also, after the motor control process of S150 ends, the process proceeds to S110, and the control circuit 50 executes the processes after S110 again.

[0110] As described above, in the backpack blower 2 of the present embodiment, according to the manipulated amounts of the trigger 22 and the rotary dial 24, the target rotation speed of the motor 30 and the target DUTY of the PWM control are set, and the motor 30 is driven by executing the conduction angle control and the PWM control.

[0111] After the drive of the motor 30 starts, the drive duty of the first to sixth switching elements Q1 to Q6 by PWM control is gradually increased from 0% toward the target duty. Also, the conduction angle for turning on the first to sixth switching elements Q1 to Q6 is set to the maximum angle of 120 electrical degrees until the motor speed reaches the target speed.

[0112] Therefore, as shown in FIG. 7, after the drive of the motor starts, the motor speed increases with a substantially constant slope as the drive duty increases. Then, when the motor speed reaches the target speed, the conduction angle is controlled by conduction angle control in order to maintain the motor speed at the target speed.

[0113] Also, as shown in FIG. 7, when the target duty is 100% and the drive duty does not reach the target duty even when the motor speed reaches the target speed, the drive duty continues to increase, and the drive power of the motor 30 increases by PWM control. On the other hand, in conduction angle control, the increase in the drive power of the motor 30 is suppressed by decreasing the conduction angle.

[0114] Therefore, after the motor speed reaches the target speed, the motor speed is controlled to the target speed by conduction angle control, and the period for turning on and off the first to sixth switching elements Q1 to Q6 by PWM control becomes shorter than the maximum period of 60 electrical degrees for each of the first to sixth switching elements Q1 to Q6.

[0115] In particular, when the manipulated variable determined by the amount of pulling of the trigger 22 and the dial position of the rotary dial 24 is equal to or greater than the threshold value and the motor 30 is operated under high load, the target duty is set to 100%. For this reason, it is possible to suppress the on / off operation of the first to sixth switching elements Q1 to Q6 by PWM control during high-load operation of the motor 30.

[0116] Therefore, according to the backpack blower 2 of the present embodiment, compared with the one described in Patent Document 1, the switching losses generated in the first to sixth switching elements Q1 to Q6 can be suppressed, and the heat generation of the bridge circuit 42 due to the switching losses can be suppressed.

[0117] That is, in the one described in Patent Document 1, as shown in FIG. 8, the motor speed is controlled to the target speed by PWM control, and the conduction angle is fixed at 120 degrees, which is the maximum angle. Therefore, each of the first to sixth switching elements Q1 to Q6 is sequentially and continuously turned on and off. Accordingly, the switching losses generated in the first to sixth switching elements Q1 to Q6 are large, and the bridge circuit 42 is likely to generate heat. However, according to the present embodiment, such problems can be suppressed.

[0118] [Second Embodiment] In the first embodiment, it has been described that when the manipulated amount of the user interface determined by the pulling amount of the trigger 22 and the dial position of the rotary dial 24 is less than the threshold value, the target DUTY is set to a value less than 100% according to the manipulated amount.

[0119] In contrast, in the present embodiment, the target DUTY is set to 100% regardless of the manipulated amount of the user interface.

[0120] Then, in the motor control process of S150, instead of the DUTY setting process of S300 shown in FIG. 6, the DUTY setting process of S400 shown in FIG. 9 is executed.

[0121] That is, in the DUTY setting process of S400, first, in S410, it is determined whether or not the target rotation speed Rtgt of the motor 30 is greater than 0, in other words, whether or not the driving condition of the motor 30 is satisfied.

[0122] If the target rotation speed Rtgt of the motor 30 is greater than 0 and the driving condition of the motor 30 is satisfied, the process proceeds to S420. If the driving condition of the motor 30 is not satisfied, the process proceeds to S450.

[0123] In S420, the current drive duty (Dnow) in PWM control is obtained, and in subsequent S430, it is determined whether the current drive duty (Dnow) obtained in S420 is smaller than the target duty (100%).

[0124] And when the current drive duty (Dnow) is smaller than the target duty (100%), the process proceeds to S440, where a certain update value is added to the currently set drive duty (Dnow) to update the drive duty, and the duty setting process ends.

[0125] On the other hand, if it is determined in S430 that the current drive duty (Dnow) has reached the target duty (100%), the duty setting process ends.

[0126] Also, in S450, since the driving condition of the motor 30 is not satisfied, the drive duty (Dnow) is set to 0%, and the duty setting process ends.

[0127] Thus, in this embodiment, the target duty is set to 100% regardless of the manipulated amount of the user interface, but the drive duty when performing PWM control gradually increases with a certain update value until it reaches 100% after the start of driving the motor 30.

[0128] Therefore, also in this embodiment, similar to the first embodiment, after the start of driving the motor 30, the motor 30 can be soft-started to suppress the inrush current. Also, the first to sixth switching elements Q1 to Q6 are turned on and off by PWM control until the drive duty reaches 100% after the start of driving the motor 30, but are not turned on and off by PWM control after the drive duty reaches 100%.

[0129] Therefore, according to this embodiment, the switching losses generated by turning on and off the first to sixth switching elements Q1 to Q6 can be better suppressed, and the heat generation of the bridge circuit 42 can be suppressed.

[0130] [Embodiment 3] In the second embodiment, regardless of the amount of operation of the user interface, by setting the target DUTY to 100%, the switching loss can be suppressed more favorably.

[0131] In contrast, in this embodiment, in PWM control, the drive DUTY is controlled so that the rotation speed of the motor 30 becomes the target rotation speed, and by setting the target rotation speed to a value larger than the target rotation speed in the conduction angle control, the target DUTY becomes 100%.

[0132] That is, in this embodiment, the control circuit 50 executes the control process shown in FIG. 10 instead of the control process shown in FIG. 3. And in the control process shown in FIG. 10, instead of the processes of S130 to S150 shown in FIG. 3, the processes of S135 to S155 are executed.

[0133] In S135, in the same procedure as S130, the target rotation speed RtgtA of the conduction angle control is set according to the amount of operation of the user interface. In S145, the target rotation speed RtgtB of the PWM control is set by adding a predetermined offset value (for example, 500 rpm) to the target rotation speed RtgtA set in S135. And in S155, the motor control process is executed in the procedure shown in FIG. 11.

[0134] As shown in FIG. 11, in the motor control process of S155, in S200, for the conduction angle control, a conduction angle setting process is executed to update the conduction angle so that the rotation speed of the motor 30 becomes the target rotation speed RtgtA. Note that the process of S200 is executed in the same procedure as that of the first embodiment shown in FIG. 6.

[0135] Also, in the motor control process of S155, instead of the DUTY setting process described in S300 of FIG. 6 or S400 of FIG. 9, the DUTY setting process of S500 is executed.

[0136] In this duty setting process, at S510, the current motor rotation speed Rnow is obtained based on the detection signal input from the rotation angle detection unit 36. Next, at S520, the current motor rotation speed Rnow obtained at S510 is compared with the target rotation speed RtgtB of the PWM control set at S145.

[0137] When the motor rotation speed Rnow is lower than the target rotation speed RtgtB, the process proceeds to S530, where a certain update value is added to the currently set drive duty (Dnow) to update the drive duty and end the duty setting process. Note that the maximum value of the drive duty updated at S530 is 100%, and at S530, the drive duty is updated with 100% as the upper limit.

[0138] On the other hand, when it is determined at S520 that the motor rotation speed Rnow is equal to or higher than the target rotation speed RtgtB, the process proceeds to S540, where a certain update value is subtracted from the currently set drive duty (Dnow) to update the drive duty and end the duty setting process. Note that the minimum value of the drive duty updated at S530 is, for example, 1%, and at S530, the drive duty is updated with that minimum value as the lower limit.

[0139] Thus, in this embodiment, the target rotation speed RtgtA of the energization angle control and the target rotation speed RtgtB of the PWM control are set. Then, in the energization angle control and the PWM control, the energization angle and the drive duty are controlled so that the motor rotation speed Rnow becomes the target rotation speeds RtgtA and RtgtB, respectively.

[0140] As shown in FIG. 12, the target rotation speed RtgtB of the PWM control is larger than the target rotation speed RtgtA of the energization angle control by a predetermined rotation speed defined by an offset value. Therefore, after the drive of the motor 30 starts, the motor rotation speed reaches the target rotation speed RtgtA and is controlled to the target rotation speed RtgtA by the energization angle control.

[0141] Therefore, in PWM control, even when the motor speed reaches the target speed RtgtA, the drive duty is gradually increased until it reaches 100% so that the motor speed further increases.

[0142] Thus, according to this embodiment, PWM control is performed in the same manner as when the target duty of PWM control is set to 100% as in the second embodiment, and the same effects as those of the second embodiment can be obtained.

[0143] Note that in this embodiment, the process of S145 for setting the target rotation speed RtgtB of PWM control and the duty setting process of S500 correspond to an example of the target duty ratio setting unit of the present disclosure.

[0144] [Modification Example] As described above, one embodiment of the present disclosure has been described. However, the present disclosure is not limited to the above embodiment and can be implemented in various modifications.

[0145] For example, in the above embodiment, as the user interface, the trigger 22 and the rotary dial 24 are provided, and it has been described that the target rotation speed and the target duty of the motor 30 are set based on the manipulated amounts of these respective parts. However, as the user interface, only the trigger 22 or the rotary dial 24 may be sufficient, or it may be another manipulated part operated by the user.

[0146] Also, in the above embodiment, it has been described that the target rotation speed and the target duty are set based on the manipulated amount of the user interface. However, the target rotation speed and the target duty may be set based on the rotation command value input by operating the user interface.

[0147] Further, in the above embodiment, the backpack blower has been described as the electric working machine. However, the technology of the present disclosure can be applied in the same manner as in the above embodiment even to an electric working machine in which a drive object (so-called tool) different from the fan 10, such as a tool bit, is attached to the output shaft.

[0148] Also, in the above-described embodiment, the motor 30 has been described as a three-phase brushless motor provided with a rotation sensor 32. However, the motor 30 may be a brushless motor other than three-phase, for example, a single-phase brushless motor, and may not be provided with the rotation sensor 32.

[0149] In addition, when the brushless motor does not include the rotation sensor 32, for example, the rotation angle detection unit 36 may be configured to detect the rotor position (rotation angle) from the induced voltage generated in the motor coil as a so-called sensorless method.

[0150] Also, in the above-described embodiment, in the energization angle control, as shown in FIG. 5, it has been described that the energization angle is made shorter than 120 degrees, which is the maximum angle, by advancing the OFF timing for forcibly turning off the first to sixth switching elements Q1 to Q6.

[0151] However, in the energization angle control, it is only necessary to control the energization angle so that the period in which each of the first to sixth switching elements Q1 to Q6 is selected to form an energization path is shorter than 120 degrees, which is the maximum angle.

[0152] Therefore, for example, the energization angle may be controlled by delaying the ON timing for turning on the first to sixth switching elements Q1 to Q6. Also, for example, the energization angle may be controlled by adjusting both the ON timing and the OFF timing of the first to sixth switching elements Q1 to Q6. Also, for example, the energization angle may be controlled by providing a non-energization period during which the first to sixth switching elements Q1 to Q6 are turned off within 120 degrees, which is the maximum angle.

[0153] The plurality of functions of one component in the above-described embodiment may be realized by a plurality of components, or one function of one component may be realized by a plurality of components. Also, the plurality of functions of a plurality of components may be realized by one component, or one function realized by a plurality of components may be realized by one component. Further, a part of the configuration of the above-described embodiment may be omitted. Still further, at least a part of the configuration of the above-described embodiment may be added to or replaced with the configuration of another of the above-described embodiments.

[0154] In addition to the electric working machine, the present disclosure can also be realized in various forms such as a system including the electric working machine as a component, a program for causing a computer to function as the electric working machine, a non-transitory tangible recording medium such as a semiconductor memory recording this program, and a control method.

Description of Reference Numerals

[0155] 2... backpack blower, 10... fan, 12... output shaft, 22... trigger, 24... rotation dial, 30... brushless motor, 32... rotation sensor, 36... rotation angle detection unit, 40... controller, 42... bridge circuit, 50... control circuit, 60... battery pack, L1 to L3... positive electrode side energization paths, L4 to L6... negative electrode side energization paths, Q1 to Q6... switching elements.

Claims

1. An output shaft configured to attach a driven object thereto, A brushless motor having a plurality of terminals and configured to rotate the driven object, A plurality of positive-side energization paths configured to connect the plurality of terminals to the positive electrode of a DC power supply, A plurality of negative-side energization paths configured to connect the plurality of terminals to the negative electrode of the DC power supply, A plurality of high-side switches respectively provided on the plurality of positive-side energization paths, A plurality of low-side switches respectively provided on the plurality of negative-side energization paths, A user interface configured to be operated by a user, A target rotation speed setting unit configured to set the target rotation speed of the brushless motor such that the target rotation speed increases as the manipulated amount of the user interface or a rotation command value input by the operation of the user interface increases, A target duty ratio setting unit configured to set the target duty ratio such that the target duty ratio increases as the manipulated amount or the rotation command value increases when the manipulated amount or the rotation command value is less than a threshold value, and to set the target duty ratio to 100% when the manipulated amount or the rotation command value is greater than or equal to the threshold value, A rotation angle detection unit configured to detect the rotation angle of the brushless motor, A rotation speed detection unit configured to detect the rotation speed of the brushless motor, A control unit configured to control the brushless motor and The control unit is configured to select, as a pair of driven switches, one of the plurality of high-side switches and one of the plurality of low-side switches each time the rotation angle detection unit detects that the brushless motor has rotated by a predetermined rotation angle, The control unit simultaneously executes PWM control for turning on and off at least one of the pair of driven switches at a predetermined frequency based on the target duty ratio, and energization angle control for controlling the energization angle for implementing the PWM control such that the rotational speed of the brushless motor detected by the rotational speed detection unit becomes the target rotational speed. Moreover, the brushless motor is a three-phase brushless motor. The control unit switches the pair of driven switches for performing the PWM control every time the rotation angle detection unit detects that the three-phase brushless motor has rotated by 60 degrees as the predetermined rotation angle, and in the energization angle control, is configured to control the rotation angle for implementing the PWM control while the three-phase brushless motor rotates by 60 degrees. An electric working machine.

2. The control unit In the PWM control, after the start of driving of the brushless motor, the drive duty ratio for driving at least one of the pair of driven switches is gradually increased by a predetermined change amount until the drive duty ratio reaches the target duty ratio. The electric working machine according to claim 1.

3. An output shaft configured to be attached with a drive object, A brushless motor having a plurality of terminals and configured to rotate the drive object, A plurality of positive electrode side energization paths configured to connect the plurality of terminals and the positive electrode of a DC power supply, A plurality of negative electrode side energization paths configured to connect the plurality of terminals and the negative electrode of the DC power supply, A plurality of high-side switches respectively provided on the plurality of positive electrode side energization paths, A plurality of low-side switches respectively provided on the plurality of negative electrode side energization paths, A user interface configured to be operated by a user, A target rotation speed setting unit configured to set the target rotation speed of the brushless motor such that the target rotation speed increases as the amount of operation of the user interface or the rotation command value input by the operation of the user interface increases; A target duty ratio setting unit configured to set the target duty ratio such that the target duty ratio increases as the amount of operation or the rotation command value increases when the amount of operation or the rotation command value is less than a threshold value, and to set the target duty ratio to 100% when the amount of operation or the rotation command value is greater than or equal to the threshold value; A rotation angle detection unit configured to detect the rotation angle of the brushless motor; A rotation speed detection unit configured to detect the rotation speed of the brushless motor; A control unit configured to control the brushless motor and comprising: The control unit is configured such that: each time the rotation angle detection unit detects that the brushless motor has rotated by a predetermined rotation angle, one of the plurality of high-side switches and one of the plurality of low-side switches are selected as a pair of driven switches, and simultaneously executes PWM control for turning on and off at least one of the pair of driven switches at a predetermined frequency based on the target duty ratio, and energization angle control for controlling the energization angle for executing the PWM control such that the rotation speed of the brushless motor detected by the rotation speed detection unit becomes the target rotation speed. Moreover, in the PWM control, after the start of driving of the brushless motor, the driving duty ratio for driving at least one of the pair of driven switches is gradually increased by a predetermined change amount until the driving duty ratio reaches the target duty ratio. In the energization angle control, after the start of driving of the brushless motor, the energization angle is controlled so as to be a preset maximum angle until the rotational speed of the brushless motor reaches the target rotational speed. When the rotational speed of the brushless motor reaches the target rotational speed, the energization angle is decreased from the maximum angle to hold the rotational speed of the brushless motor at the target rotational speed. An electric working machine configured as described above.

4. The electric working machine according to claim 3, wherein the target duty ratio setting unit is configured to set the target duty ratio to 100% when the user interface is operated, regardless of the amount of operation or the rotation command value.

5. An output shaft configured to be attached with a driving object; A brushless motor having a plurality of terminals and configured to rotate the driving object; A plurality of positive electrode side energization paths configured to connect the plurality of terminals and the positive electrode of a DC power source; A plurality of negative electrode side energization paths configured to connect the plurality of terminals and the negative electrode of the DC power source; A plurality of high-side switches respectively provided on the plurality of positive electrode side energization paths; A plurality of low-side switches respectively provided on the plurality of negative electrode side energization paths; A user interface configured to be operated by a user; A target rotational speed setting unit configured to set the target rotational speed such that the target rotational speed of the brushless motor increases as the amount of operation of the user interface or the rotation command value input by the operation of the user interface increases. When the manipulated variable or the rotation command value is less than the threshold value, the target duty ratio is set so that the target duty ratio increases as the manipulated variable or the rotation command value increases, and when the manipulated variable or the rotation command value is equal to or greater than the threshold value, the target duty ratio is set to 100%. A target duty ratio setting unit configured as described above; A rotation angle detection unit configured to detect the rotation angle of the brushless motor; A rotation speed detection unit configured to detect the rotation speed of the brushless motor; A control unit configured to control the brushless motor; Comprising: The control unit: Each time the rotation angle detection unit detects that the brushless motor has rotated by a predetermined rotation angle, one of the plurality of high-side switches and one of the plurality of low-side switches are selected as a pair of driven switches. Configured as follows: At least one of the pair of driven switches is subjected to PWM control in which it is turned on and off at a predetermined frequency based on the target duty ratio, and the energization angle for controlling the PWM control is set so that the rotation speed of the brushless motor detected by the rotation speed detection unit becomes the target rotation speed. It is configured to simultaneously execute the energization angle control; In the PWM control, after the driving of the brushless motor starts, the driving duty ratio for driving at least one of the pair of driven switches is gradually increased by a predetermined change amount until the driving duty ratio reaches the target duty ratio. The target duty ratio setting unit is configured to set the target duty ratio to 100% regardless of the manipulated variable or the rotation command value when the user interface is operated. An electric working machine.

6. The brushless motor is a three-phase brushless motor; The control unit switches the pair of driven switches that perform the PWM control every time the rotation angle detection unit detects that the three-phase brushless motor has rotated by 60 degrees as the predetermined rotation angle. In the energization angle control, it is configured to control the rotation angle at which the PWM control is performed while the three-phase brushless motor rotates by 60 degrees. The electric working machine according to any one of claims 3 to 5.

7. The user interface A trigger configured to be pulled by the user, A rotary dial configured to be rotated by the user, and is provided with The target rotation speed setting unit is configured to set the target rotation speed based on the amount of pulling of the trigger and the rotation position of the rotary dial. The electric working machine according to any one of claims 1 to 6.

8. The target duty ratio setting unit is configured to set the target duty ratio based on the amount of pulling of the trigger and the rotation position of the rotary dial. The electric working machine according to claim 7, which cites any one of claims 1 to 3.

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