Electric working machine and method for controlling brushless motor of electric working machine

Abstract

The invention provides an electric work machine and a method for controlling a brushless motor of the electric work machine. One aspect of the present invention relates to an electric work machine including a brushless motor, a plurality of positive electrode-side conduction paths, a plurality of negative electrode-side conduction paths, a plurality of high-side switches, a plurality of low-side switches, and a control circuit. The control circuit performs energization control and energization restriction. The energization control includes turning on the drive pair according to the first energization mode each time the update time arrives. The energization limitation includes limiting or stopping the supply of power to the brushless motor by temporarily stopping the energization control on the basis of a limitation time elapsed since the next update time has not arrived after the update time arrives.

Description

TECHNICAL FIELD

[0001] The present application relates to an electric working machine including a brushless motor. BACKGROUND

[0002] An electric working machine including a brushless motor is disclosed in Japanese Patent Application Publication No. 2023-31617. In the electric working machine, control of the brushless motor uses PWM control and conduction angle control.

[0003] With regard to the PWM control, a switching element (hereinafter referred to as a "drive switch") is selected each time the brushless motor rotates a prescribed rotation angle, and a duty ratio is set. The duty ratio is set so that the brushless motor rotates at a target rotational speed. The drive switch is driven (i.e., turned on or turned off) in accordance with the duty ratio.

[0004] With regard to the conduction angle control, the on period of the drive switch is set in such a manner that the brushless motor rotates at the target rotational speed. The on period corresponds to a rotation angle at which the brushless motor should be turned on (i.e., a conduction angle). The drive switch is turned on in accordance with its conduction angle (i.e., continuously during the on period). SUMMARY

[0005] With regard to the conduction angle control, periodic turning on and off of the switching element as performed in the PWM control is not required. As a result, the number of times of turning on and off of the switching element in the conduction angle control is smaller than the number of times of turning on and off in the PWM control. As a result, according to the conduction angle control, it is possible to reduce the turning on and off loss, and accordingly, it is possible to suppress heating of the switching element (and further, heating of the motor drive system).

[0006] However, when a heavy load is performed, (i) the rotational speed of the brushless motor decreases, (ii) accordingly, the time required for the brushless motor to rotate a prescribed rotation angle becomes longer, (iii) accordingly, the on time of the drive switch also becomes longer. When the on time of the drive switch becomes longer, the peak value of the current flowing through the brushless motor increases. The increase in the peak value can cause failure of the switching element, and / or demagnetization of the magnet of the brushless motor.

[0007] The electric working machine of one aspect of the present application aims to suppress the situation in which the peak value of the current flowing through the brushless motor increases when the rotational speed of the brushless motor decreases due to a heavy load.

[0008] In the present application, the terms "first", "second", and the like are merely intended to distinguish elements from one another, and are not intended to limit the order or the number of the elements. Therefore, the first element can be referred to as the second element, and similarly, the second element can be referred to as the first element. In addition, the first element can be provided without the second element, and similarly, the second element can be provided without the first element.

[0009] One aspect of the present application provides an electric power machine including: a brushless motor, a plurality of positive electrode-side current paths, a plurality of negative electrode-side current paths, a plurality of high-side switches, a plurality of low-side switches, and a control circuit.

[0010] The brushless motor is configured to (i) include a plurality of terminals, and (ii) drive a driven appliance. The driven appliance is configured to be fixed to the electric power machine, or to be attached to the electric power machine in a detachable manner.

[0011] The plurality of positive electrode-side current paths electrically connect the plurality of terminals to a positive electrode of a direct-current power source, respectively. The plurality of negative electrode-side current paths electrically connect the plurality of terminals to a negative electrode of the direct-current power source, respectively.

[0012] The plurality of high-side switches are configured to (i) be present on the plurality of positive electrode-side current paths, respectively, and (ii) turn on or off the plurality of positive electrode-side current paths, respectively. The plurality of low-side switches are configured to (i) be present on the plurality of negative electrode-side current paths, respectively, and (ii) turn on or off the plurality of negative electrode-side current paths, respectively.

[0013] The control circuit is configured to perform current supply control and current supply limitation.

[0014] The current supply control includes: each time an update timing comes, turning on a drive pair corresponding to a rotation angle of the brushless motor in accordance with a first current supply mode, whereby a first electric power is supplied from the direct-current power source to the brushless motor via the drive pair. The update timing comes each time the brushless motor rotates a reference rotation angle. The drive pair includes one of the plurality of high-side switches and one of the plurality of low-side switches.

[0015] The current supply limitation includes: based on a first abnormality occurring during the execution of the current supply control, temporarily stopping the current supply control, whereby the supply of the first electric power to the brushless motor is limited or stopped. The first abnormality includes: after the update timing comes, a next update timing does not come, and a limitation time elapses.

[0016] Thus, each time the brushless motor rotates the reference rotation angle, the control circuit selects the drive pair. The control circuit supplies the first electric power to the brushless motor by turning on the selected drive pair in accordance with the first current supply mode. When the rotational speed of the brushless motor decreases, the time required for the brushless motor to rotate the reference rotation angle (hereinafter referred to as "reference rotation time" (or current supply control time)) becomes longer.

[0017] In contrast, the control circuit performs the current supply limitation based on the limitation time elapsing after the update timing comes and a next update timing does not come.

[0018] Therefore, according to the electric power machine of the present application, even if the rotational speed of the brushless motor is reduced and the reference rotation time is lengthened during heavy load work, the peak value of the current flowing through the brushless motor can be suppressed from increasing. Accordingly, during heavy load work, the occurrence of a failure of the drive pair or the demagnetization of the magnet of the brushless motor is suppressed.

[0019] Another aspect of the present application provides a method of controlling a brushless motor of an electric power machine, the method comprising the steps of:

[0020] driving a drive pair corresponding to a rotation angle of the brushless motor in a conduction pattern each time an update timing arrives, the drive pair being two of a plurality of switches corresponding to the rotation angle, the plurality of switches being respectively on a plurality of conduction paths electrically connecting the brushless motor and a direct current power source; and

[0021] temporarily stopping the driving of the drive pair in the conduction pattern based on a limited time elapsing after the update timing arrives until a next update timing arrives.

[0022] If the brushless motor is controlled by such a method, even if the rotational speed of the brushless motor is reduced due to heavy load work or the like, the peak value of the current flowing through the brushless motor can be suppressed from increasing. Accordingly, during heavy load work, the occurrence of a failure of the drive pair or the demagnetization of the magnet of the brushless motor is suppressed. BRIEF DESCRIPTION OF DRAWINGS

[0023] Hereinafter, exemplary embodiments of the present application will be described with reference to the accompanying drawings.

[0024] Figure 1 is a perspective view of an electric power machine of Embodiment 1.

[0025] Figure 2 is a block diagram showing an electrical configuration of the electric power machine.

[0026] Figure 3 is a timing chart showing the operation of the control circuit during no-load operation.

[0027] Figure 4 is a timing chart showing the operation of the control circuit during heavy load operation.

[0028] Figure 5 is a timing chart showing the operation of the control circuit during lock detection.

[0029] Figure 6 is a flowchart of a main control process executed by the control circuit.

[0030] Figure 7 is a flowchart of the main loop timing interrupt processing executed by the control circuit.

[0031] Figure 8 is a flowchart of the commutation timing interrupt processing executed by the control circuit.

[0032] Figure 9 is a flowchart of the rotation detection processing executed by the control circuit.

[0033] Figure 10 is a flowchart of the switch operation detection processing executed by the control circuit.

[0034] Figure 11 is a flowchart of the motor lock detection processing executed by the control circuit.

[0035] Figure 12 is a flowchart of the motor control processing executed by the control circuit.

[0036] Figure 13 is a flowchart of the display processing executed by the control circuit.

[0037] Figure 14 is a timing chart showing the operation of the control circuit during the heavy load operation in the second embodiment.

[0038] Figure 15 is a flowchart of the main loop timing interrupt processing of the second embodiment.

[0039] Figure 16 is a timing chart showing the operation of the control circuit during the heavy load operation in the third embodiment.

[0040] Figure 17 is a flowchart of the main loop timing interrupt processing of the third embodiment.

[0041] Figure 18 is a timing chart showing the operation of the control circuit during the heavy load operation in the fourth embodiment.

[0042] Figure 19 is a flowchart of the main loop timing interrupt processing of the fourth embodiment.

[0043] Figure 20 is a timing chart of the control action of the control circuit during the heavy load of the fifth embodiment. DETAILED DESCRIPTION

[0044] [1. SUMMARY OF EMBODIMENTS]

[0045] An embodiment can provide an electric power shovel having at least any one of the following features.

[0046] • Feature 1: A brushless motor (or a brushless DC motor).

[0047] • Feature 2: The brushless motor has a plurality of terminals.

[0048] • Feature 3: The brushless motor is configured to drive (e.g., rotate) a driven implement (or a driving target object).

[0049] • Feature 4: The driven implement is configured to be fixed to the electric power tool or to be detachably attached to the electric power tool.

[0050] • Feature 5: A plurality of positive-side current paths.

[0051] • Feature 6: The plurality of positive-side current paths respectively electrically connect the plurality of terminals to a positive terminal of a DC power source.

[0052] • Feature 7: A plurality of negative-side current paths.

[0053] • Feature 8: The plurality of negative-side current paths respectively electrically connect the plurality of terminals to a negative terminal of the DC power source.

[0054] • Feature 9: A plurality of high-side switches.

[0055] • Feature 10: The plurality of high-side switches are respectively provided in the plurality of positive-side current paths.

[0056] • Feature 11: The plurality of high-side switches are configured to respectively turn on or turn off the plurality of positive-side current paths.

[0057] • Feature 12: A plurality of low-side switches.

[0058] • Feature 13: The plurality of low-side switches are respectively provided in the plurality of negative-side current paths.

[0059] • Feature 14: The plurality of low-side switches are configured to respectively turn on or turn off the plurality of negative-side current paths.

[0060] • Feature 15: A control circuit (or a control unit).

[0061] • Feature 16: The control circuit is configured to perform current conduction control.

[0062] • Feature 17: The energization control includes: whenever an update timing comes, turning on a drive pair (or a pair of driven switches) corresponding to a rotation angle of the brushless motor in a 1st energization pattern, whereby a 1st electric power is supplied from the DC power supply to the brushless motor via the drive pair. The brushless motor can also be configured to be driven (i.e., rotated) by accepting the 1st electric power. The 1st energization pattern can also be predetermined.

[0063] • Feature 18: The update timing comes whenever the brushless motor rotates a reference rotation angle.

[0064] • Feature 19: The drive pair includes: one of the plurality of high-side switches and one of the plurality of low-side switches.

[0065] • Feature 20: The control circuit is configured to perform energization restriction.

[0066] • Feature 21: The energization restriction includes: temporarily stopping the energization control based on a 1st abnormality occurring during execution of the energization control, whereby the supply of the 1st electric power to the brushless motor is restricted or stopped.

[0067] • Feature 22: The 1st abnormality includes: a limited time elapses without the next update timing coming after the update timing comes.

[0068] According to the electric power tool having at least features 1 to 22, even when the rotation speed of the brushless motor decreases to make the reference rotation time longer during heavy load work, the peak value of the current flowing to the brushless motor can be suppressed from increasing. The reference rotation time corresponds to a time required for the brushless motor to rotate the reference rotation angle.

[0069] Therefore, during heavy load work, the drive pair from malfunctioning, or the magnet of the brushless motor from being demagnetized, is suppressed.

[0070] The brushless motor can also be in the form of a three-phase brushless DC motor. The plurality of terminals can also have 3 terminals.

[0071] The rotation speed (i) means the number of rotations per unit time, and (i) is the same as the rotation speed. Therefore, the rotation speed can be referred to as the rotation speed.

[0072] The plurality of positive electrode side current paths can also include three positive electrode side current paths. The plurality of negative electrode side current paths can also include three negative electrode side current paths. The direct current power source can include a storage battery. The storage battery can be a secondary battery that can be repeatedly charged. The electric power tool can have the storage battery built in, or can be configured such that the storage battery is attached in a detachable manner. The "current path" can be referred to as a "current flow path".

[0073] Each of the plurality of high-side switches and each of the plurality of low-side switches can be a semiconductor switch. Examples of the semiconductor switch include a field effect transistor (FET), a bipolar transistor, and an insulated gate bipolar transistor (IGBT).

[0074] The plurality of high-side switches can include three high-side switches. The plurality of low-side switches can include three low-side switches. That is, the electric power tool can include a full-bridge circuit. The full-bridge circuit includes the three high-side switches and the three low-side switches.

[0075] The first current supply mode can include causing the drive pair to be continuously turned on for a constant time until the brushless motor rotates by a certain angle. The certain angle can be the same as the reference rotation angle, or can be smaller than the reference rotation angle. The first current supply mode can include causing at least one of the drive pair to be periodically repeatedly turned on and off until the brushless motor rotates by the certain angle.

[0076] The reference rotation angle can be, for example, 60 degrees in electrical angle.

[0077] The first electric power can be equal to the maximum electric power that the direct current power source can supply, or can be smaller than the maximum electric power.

[0078] The current supply restriction can include supplying electric power smaller than the first electric power to the brushless motor, or stopping supply of electric power from the direct current power source to the brushless motor.

[0079] The control circuit can be configured to detect that the brushless motor has rotated by the reference rotation angle. The control circuit can detect (or determine) that the update timing has come based on the detection that the brushless motor has rotated by the reference rotation angle.

[0080] The drive pair can be set in advance in correspondence with the rotation angle of the brushless motor.

[0081] Examples of the driven tool include various tool bits, cutters (for example, rotary knives, cutting knives, saw blades, and planer knives), and grinding wheels.

[0082] The embodiment can have the following feature in addition to having at least any one of features 1 to 22 or instead of having at least any one of features 1 to 22.

[0083] • Feature 23: The control circuit is configured to restart the power supply control based on the update timing having come during execution of the power supply restriction.

[0084] The electric power working machine having at least features 1 to 23 can restart the power supply control based on the next update timing even when the power supply restriction is executed during heavy load work.

[0085] Therefore, even during heavy load work, it is possible to suppress the situation where the peak value of the current flowing through the brushless motor increases and to continue driving the brushless motor.

[0086] The embodiment can have the following feature in addition to having at least any one of features 1 to 23 or instead of having at least any one of features 1 to 23.

[0087] • Feature 24: The control circuit is configured to restart the power supply control based on a waiting time elapsing from the start of the power supply restriction.

[0088] The waiting time can be set in advance.

[0089] In the electric power working machine having at least features 1 to 22 and 24, the power supply control can be restarted as long as the waiting time elapses even when the power supply restriction is executed during heavy load work.

[0090] Therefore, even during heavy load work, it is possible to suppress the situation where the peak value of the current flowing through the brushless motor increases and to continue driving the brushless motor.

[0091] The embodiment can have the following feature in addition to having at least any one of features 1 to 24 or instead of having at least any one of features 1 to 24.

[0092] • Feature 25: The control circuit is configured to restart the power supply control based on the waiting time elapsing without the update timing coming from the start of the power supply restriction.

[0093] The embodiment can have the following feature in addition to having at least any one of features 1 to 25 or instead of having at least any one of features 1 to 25.

[0094] • Feature 26: The power supply restriction includes turning off the plurality of high-side switches and the plurality of low-side switches, thereby stopping supply of the electric power of the direct-current power supply to the brushless motor.

[0095] In the electric power tool having at least features 1 to 22 and 26, when the elapsed time from the update time reaches the limit time, the current supply to the brushless motor is cut off by the current supply restriction. Thus, the occurrence of a failure of the drive pair or the demagnetization of the magnet of the brushless motor is further suppressed by the current flowing through the brushless motor.

[0096] The embodiment can have at least any one of the following features in addition to having at least any one of features 1 to 26, or instead of having at least any one of features 1 to 26.

[0097] • Feature 27: The current supply restriction includes supplying second electric power to the brushless motor from the direct-current power supply via the drive pair.

[0098] • Feature 28: The second electric power is smaller than the first electric power.

[0099] The embodiment can have at least any one of the following features in addition to having at least any one of features 1 to 28, or instead of having at least any one of features 1 to 28.

[0100] • Feature 29: The current supply restriction includes driving the drive pair in a second current supply mode, by which the second electric power is supplied to the brushless motor.

[0101] • Feature 30: The second current supply mode is different from the first current supply mode.

[0102] • Feature 31: The second current supply mode includes periodically repeating turning on and off of at least one of the drive pair.

[0103] In the electric power tool having at least features 1 to 22 and 27 to 31, the second electric power is supplied to the brushless motor even in the current supply restriction. Thus, the occurrence of a failure of the drive pair or the demagnetization of the magnet of the brushless motor is suppressed by the current flowing through the brushless motor. In addition, the rotation of the brushless motor is suppressed from being stopped until the current control is restarted.

[0104] The embodiment can have at least any one of the following features in addition to having at least any one of features 1 to 31, or instead of having at least any one of features 1 to 31.

[0105] • Feature 32: A drive circuit (or a drive system of the brushless motor).

[0106] • Feature 33: The drive circuit includes the plurality of high-side switches and the plurality of low-side switches.

[0107] • Feature 34: The drive circuit is configured to supply the brushless motor with electric power of the direct-current power supply.

[0108] • Feature 35: An amount of heat generated from the drive circuit corresponding to the supply of the second electric power to the brushless motor is smaller than an amount of heat generated from the drive circuit corresponding to the supply of the first electric power to the brushless motor.

[0109] In the electric power tool having at least features 1 to 22, 27, 28, 32 to 35, the increase in the amount of heat of the drive circuit at the time of execution of the current supply restriction is thereby suppressed, and the occurrence of a failure of the drive circuit is thereby suppressed.

[0110] The embodiment can have at least any one of features 1 to 35, or can have the following feature instead of at least any one of features 1 to 35.

[0111] • Feature 36: The control circuit is configured to perform first notification based on the start of the current supply restriction.

[0112] The first notification can correspond to notification of the execution of the current supply restriction and / or the occurrence of the first abnormality.

[0113] The embodiment can have at least any one of features 1 to 36, or can have the following feature instead of at least any one of features 1 to 36.

[0114] • Feature 37: The control circuit is configured to continue the first notification until the current supply control is restarted based on the start of the current supply restriction.

[0115] In the electric power tool having at least features 1 to 22, 36, and 37, the user of the electric power tool can be notified of the occurrence of the first abnormality and / or the execution of the current supply restriction. The user can recognize that the protection function of the electric power tool is activated (that is, the current supply restriction is executed) based on the first notification.

[0116] The embodiment can have at least any one of features 1 to 37, or can have at least any one of the following features instead of at least any one of features 1 to 37.

[0117] • Feature 38: The control circuit is configured to stop the supply of electric power of the direct-current power supply to the brushless motor based on the occurrence of a second abnormality in the electric power tool.

[0118] • Feature 39: The second abnormality is different from the first abnormality.

[0119] • Feature 40: The control circuit is configured to perform a second notification based on the second abnormality occurring in the electric power working machine.

[0120] • Feature 41: The second notification is different from the first notification.

[0121] In the electric power working machine having at least features 1 to 22 and 36 to 41, the user can recognize the second abnormality in addition to the first abnormality. Thus, the user can grasp the cause of the abnormality of the electric power working machine.

[0122] The embodiment can have at least any one of the following features in addition to at least any one of features 1 to 41 or instead of them.

[0123] • Feature 42: The second abnormality includes that a protection determination time elapses without the update time coming since the power supply restriction starts.

[0124] • Feature 43: The protection determination time is longer than the waiting time.

[0125] • Feature 44: The second abnormality includes that the rotation of the driven tool is forcibly stopped by another object different from the electric power working machine, and the brushless motor is locked (i.e., the rotation is stopped) accordingly.

[0126] The brushless motor can be locked based on the driven tool abutting against the other object (e.g., an obstacle).

[0127] The embodiment can have at least any one of the following features in addition to at least any one of features 1 to 44 or instead of them.

[0128] • Feature 45: The power supply control includes power supply angle control. The turning on of the drive pair in the first power supply mode can include the power supply angle control.

[0129] • Feature 46: The power supply angle control includes setting (or controlling) a power supply angle in such a manner that the rotation speed of the brushless motor coincides with a target rotation speed.

[0130] • Feature 47: The power supply angle control includes continuously turning on the drive pair from the start of the power supply control until the brushless motor rotates by a rotation angle corresponding to the power supply angle.

[0131] The embodiment can have at least any one of the following features in addition to at least any one of features 1 to 47 or instead of them.

[0132] • Feature 48: The energization control includes PWM control.

[0133] • Feature 49: The PWM control includes setting a duty ratio in such a manner that a rotational speed of the brushless motor coincides with a target rotational speed. The turning on of the drive pair in accordance with the first energization mode can also include the PWM control.

[0134] • Feature 50: The PWM control includes periodically repeating turning on and off of at least one of the drive pair in accordance with the duty ratio.

[0135] In the electric power work machine provided with at least any one of features 1 to 22 and 45 to 47, and / or the electric power work machine provided with at least any one of features 1 to 22 and 48 to 50, the energization restriction is executed based on the elapse of the restriction time from the update time. Thus, the above-described effects can be obtained.

[0136] In certain embodiments, in addition to being provided with at least any one of features 1 to 50, or instead of being provided with at least any one of features 1 to 50, the following features can also be provided:

[0137] • Feature 51: The rotation angle detection section is configured to output a position detection signal corresponding to the rotation angle of the brushless motor.

[0138] • Feature 52: The update time comes based on the position detection signal indicating that the brushless motor has rotated a reference rotation angle.

[0139] In certain embodiments, the control circuit can also be integrated in a single electronic unit or a single electronic device or a single circuit board.

[0140] In certain embodiments, the control circuit can also be a combination of two or more electronic circuits or two or more electronic units or two or more electronic devices provided on the electric power work machine or respectively provided in the electric power work machine.

[0141] In certain embodiments, the control circuit can also be provided with a microcomputer (or microcontroller, or microprocessor), a wired logic, an application specific integrated circuit (ASIC), an application specific system (ASSP), a programmable logic device (such as a field programmable gate array (FPGA)), a discrete electronic element, and / or a combination thereof.

[0142] Certain embodiments can also provide a method of controlling a brushless motor of an electric power work machine provided with at least any one of the following features.

[0143] • Feature 53: whenever the update timing comes, driving the drive pair corresponding to the rotation angle of the brushless motor in the energization pattern.

[0144] The update timing can also come whenever the brushless motor rotates by a reference rotation angle. The drive pair can also be two of the plurality of switches corresponding to the rotation angle. The plurality of switches can also be on a plurality of energization paths electrically connecting the brushless motor to a direct-current power source, respectively.

[0145] • Feature 54: based on the fact that a next update timing does not come after the update timing comes, causing the driving of the drive pair in the energization pattern to be temporarily stopped for a limited time.

[0146] According to the method having at least features 53 and 54, even if the reference rotation time becomes longer due to the decrease in the rotation speed of the brushless motor during heavy load work, the peak value of the current flowing to the brushless motor can be suppressed from increasing.

[0147] Examples of the electric working machine include various site working machines used in construction, manufacturing, civil engineering, construction, agriculture, gardening, cleaning, amateur woodworking, and the like, and configured to receive electric power to cause a brushless motor to operate. The electric working machine can also be configured to receive alternating current. In this case, the direct-current power source can be configured to (i) receive the alternating current, (ii) generate direct current from the alternating current, and (iii) supply the direct current.

[0148] More specific examples of the electric working machine include electric power tools for masonry, metalworking, and woodworking, working machines for gardening, devices for modifying the environment of a working site, and more specifically, include electric blower, electric hammer, electric hammer drill, electric drill, electric screwdriver, electric wrench, electric sander, electric circular saw, electric jigsaw, electric wire saw, electric cutter, electric chain saw, electric planer, electric nailer (including riveter), electric hedge trimmer, electric grass trimmer, electric lawn mower, electric cleaner, electric sprayer, electric spreader, electric dust collector, electric trowel, electric vibrator, electric tamper, electric compactor, electric pump, electric pile driver, electric concrete saw, electric screed, electric cutoff saw, robot vacuum cleaner, battery-driven handcart, battery-driven bicycle, air-conditioning jacket.

[0149] In some embodiments, the features 1 to 54 described above can be combined in any combination. In some embodiments, any one of the features 1 to 54 described above can be excluded.

[0150] [2. Specific exemplary embodiments]

[0151] Hereinafter, with reference to the drawings, exemplary embodiments of the present application will be described.

[0152] [2-1. First Embodiment]

[0153] [2-1-1. Mechanical configuration of electric working machine]

[0154] The following exemplary embodiments provide Figure 1 The electric working machine 1 shown in the first embodiment is in the form of a lawn mower.

[0155] As Figure 1 shown, the electric working machine 1 is provided with a main pipe 2, a control unit 3, a drive unit 4, and a lever 7. The main pipe 2 has a long and hollow rod shape. The control unit 3 is provided on the rear end side of the main pipe 2, and the drive unit 4 is provided on the front end side of the main pipe 2.

[0156] The drive unit 4 is provided with an output shaft (not shown). A rotary blade 5 is attached to the output shaft in a detachable and rotatable manner. The rotary blade 5 is used to cut the cutting target. Examples of the cutting target include grass and small diameter wood. Figure 1 The rotary blade 5 shown is in the form of a so-called cutting saw. The rotary blade 5 is an example of a driven device in the generalization of the embodiment.

[0157] The rotary blade 5 of the first embodiment (i) is made of metal, (ii) has a circular plate shape, and (iii) has serrated teeth formed all over the outer periphery of the rotary blade 5. A hard blade is attached to the tip of each tooth.

[0158] The electric working machine 1 is provided with a cover 6 on the front end side of the main pipe 2. The cover 6 is used to suppress the grass and the like cut by the rotary blade 5 from flying toward the user (or operator) side of the electric working machine 1.

[0159] The drive unit 4 houses a motor 30 (see Figure 2 ) and a gear mechanism (not shown). The motor 30 is a drive source for rotating and driving the rotary blade 5. The gear mechanism is directly or indirectly connected to the motor 30 and the output shaft, respectively. The gear mechanism transmits the rotation of the motor 30 to the output shaft.

[0160] The motor 30 is in the form of an IPM (Interior Permanent Magnet) type 3-phase brushless motor (in detail, a 3-phase brushless DC motor). The control unit 3 houses a controller 40 (see Figure 2 ). The motor 30 is driven and controlled by the controller 40.

[0161] The lever 7 is attached to the main pipe 2 near the middle of the length direction of the main pipe 2. The user can use the electric power tool 1 while holding the lever 7. In the first embodiment, the lever 7 is in the form of a so-called U-shaped lever, and has a grip at each end. The lever 7 can also be in a form other than the U-shaped lever (for example, a ring-shaped lever).

[0162] The lever 7 is provided with an operation / display unit 8 at one grip (or near the one grip). The operation / display unit 8 can also be provided at any position on the lever 7, or at a position different from the lever 7. The operation / display unit 8 is operated by the user's finger. Further, the user can confirm the operation state of the electric power tool 1 by means of the operation / display unit 8. The operation / display unit 8 has a trigger switch 10, a lock release switch 12, and a display panel 14.

[0163] The display panel 14 displays (i) the rotation state of the motor 30, (ii) the remaining amount of power of the battery pack 18 (more specifically, the remaining amount of power of the batteries built in the battery pack 18), and the like. The display panel 14 also has an operation switch. The user can set the rotation direction of the motor 30 (in other words, the rotary blade 5) and the like by means of the operation switch.

[0164] The battery pack 18 is detachably attached to the rear end of the control unit 3. The battery pack 18 supplies direct-current electric power to the control unit 3. The trigger switch 10 inputs a drive command of the motor 30 to the controller 40. The lock release switch 12 restricts the operation of the trigger switch 10. The user can operate the trigger switch 10 (specifically, pull or move) while pressing the lock release switch 12. The trigger switch 10 outputs a trigger signal during the trigger switch 10 is operated. The trigger signal is input to the control circuit 50.

[0165] The trigger switch 10 and the display panel 14 are electrically connected to the controller 40 via a cable 19. The controller 40 corresponds to the operation of the trigger switch 10 and / or the display panel 14 performed by the user, and (i) causes the motor 30 to be driven, and / or (ii) switches the rotation direction of the motor 30, and / or (iii) displays various information on the display panel 14.

[0166] [2-1-2. Electric configuration of electric power tool]

[0167] Reference Signs List Figure 2The electrical configuration of the electric working machine 1 is described below. The electric working machine 1 includes a controller 40 within the control unit 3. The controller 40 includes a control circuit 50. The main power switch 20, the trigger switch 10 described above, and the display panel 14 are electrically connected to the controller 40 (more specifically, the control circuit 50). The controller 40 may also be located in a location separate from the control unit 3.

[0168] The main power switch 20 is operated by the user and issues a start or stop instruction to the controller 40. In the first embodiment, the main power switch 20 is a momentary switch and is normally open. Whenever the main power switch 20 is manually operated by the user (for example, pressed), (i) a main power signal is input from the main power switch 20 to the control circuit 50, and (ii) in response to the main power signal, the control circuit 50 switches the controller 40 from the on state (or operating state) to the off state (or operating stop state), or vice versa. The "on state" corresponds to a state in which normal operation is performed. The "off state" corresponds to a state in which no operation is performed, or corresponds to a state in which the function is limited compared to the "on state". The "on state" and "off state" of the controller 40 can also be referred to as the "on state" and "off state" of the main power state, or the "on state" and "off state" of the main power switch 20.

[0169] The display panel 14 includes a plurality of LEDs for displaying various states of the electric working machine 1. The plurality of LEDs includes a main power display LED (not shown). The main power display LED lights up when the controller 40 is turned on.

[0170] like Figure 2 As shown, the plurality of LEDs include an error detection notification LED 15 and a power-limit notification LED 16. The error detection notification LED 15 illuminates when a second abnormality of the electric working machine 1 (e.g., locking of the motor 30) is detected. The power-limit notification LED 16 illuminates when a first abnormality occurs in the electric working machine 1. The occurrence of the first abnormality includes the implementation of power-limitation, as described later. Lighting of the power-limit notification LED 16 is an example of the first notification in the summary of the embodiment. Lighting of the error detection notification LED 15 is an example of the second notification in the summary of the embodiment.

[0171] The motor 30 has first to third windings 30a to 30c, a rotor 30r, and first to third terminals 30u to 30w. The first to third terminals 30u to 30w correspond to U, V, and W phases of the motor 30, respectively. The first to third windings 30a to 30c are connected to each other in a delta configuration. The rotor 30r includes a permanent magnet, not shown, in its interior. The first terminal 30u is connected to a first end of the first winding 30a and a first end of the third winding 30c. The second terminal 30v is connected to a second end of the first winding 30a and a first end of the second winding 30b. The third terminal 30w is connected to a second end of the second winding 30b and a second end of the third winding 30c. In other embodiments, the motor 30 can be a single-phase brushless DC motor, a two-phase brushless DC motor, a four-phase or more brushless DC motor, or any other configuration of brushless DC motor. In other embodiments, the first to third windings 30a to 30c can be connected to each other in a star configuration (or Y configuration).

[0172] The electric power tool 1 has a rotation sensor 32 around the rotor 30r. The rotation sensor 32 has three Hall sensors, not shown, disposed at an electrical angle of 120 degrees apart from each other in a circumferential direction of the rotor 30r. The Hall sensors output first to third Hall signals. The first to third Hall signals correspond to the U, V, and W phases of the motor 30, respectively. The first to third Hall signals are (i) analog signals, and (ii) have their logic values inverted every time the rotor 30r rotates an electrical angle of 180 degrees. The first to third Hall signals are out of phase with each other by an electrical angle of 120 degrees.

[0173] The controller 40 is operated by receiving direct-current electric power (hereinafter referred to as "battery electric power") from the battery pack 18, and drives and controls the motor 30.

[0174] The controller 40 has a positive-side current path Lp. The positive-side current path Lp is connected to a positive electrode of the battery pack 18 (and further to a positive electrode of a battery). The controller 40 has a negative-side current path Ln. The negative-side current path Ln is connected to a negative electrode of the battery pack 18 (and further to a negative electrode of a battery).

[0175] The controller 40 has a drive circuit (or bridge circuit) 42, a gate circuit 44, a regulator 46, and a power supply control circuit 48.

[0176] The drive circuit 42 (i) receives the battery power from the battery pack 18, (ii) generates drive power for rotating the motor 30 (in detail, the rotor 30r) from the battery power, and (iii) supplies the drive power to the motor 30. In this first embodiment, the drive circuit 42 is in the form of a 3-phase full-bridge circuit. In other embodiments, the drive circuit 42 can be in any bridge circuit other than a 3-phase full-bridge circuit. In other embodiments, the drive circuit 42 can be provided separately from the controller 40.

[0177] The drive circuit 42 includes first to third positive-side current paths Lp1 to Lp3 as so-called upper arms. The first to third positive-side current paths Lp1 to Lp3 are configured to electrically connect the positive-side current path Lp to the first to third terminals 30u to 30w of the motor 30, respectively, and transmit the drive current (or the power source current) from the positive-side current path Lp to any one of the first to third terminals 30u to 30w. The first to third positive-side current paths Lp1 to Lp3 each have a first to third switch Q1 to Q3 as so-called high-side switches thereon. The first to third positive-side current paths Lp1 to Lp3 are turned on or off by the first to third switches Q1 to Q3.

[0178] The drive circuit 42 includes first to third negative-side current paths Ln1 to Ln3 as so-called lower arms. The first to third negative-side current paths Ln1 to Ln3 are configured to electrically connect the negative-side current path Ln to the first to third terminals 30u to 30w of the motor 30, respectively, and transmit the drive current from any one or both of the first to third terminals 30u to 30w to the negative-side current path Ln. The first to third negative-side current paths Ln1 to Ln3 each have a fourth to sixth switch Q4 to Q6 as so-called low-side switches thereon. The first to third negative-side current paths Ln1 to Ln3 are turned on or off by the fourth to sixth switches Q4 to Q6. The "switch" in the first to sixth switches Q1 to Q6 can also be referred to as a "switching element" or a "opening-and-closing element".

[0179] The first to sixth switches Q1 to Q6 are semiconductor switches. In this first embodiment, the first to sixth switches Q1 to Q6 are in the form of n-channel metal oxide semiconductor field effect transistors (MOSFETs). Thus, the first to sixth switches Q1 to Q6 are assembled with the first to sixth diodes D1 to D6 (so-called parasitic diodes or body diodes). More specifically, the first to sixth diodes D1 to D6 have cathodes connected to the drains of the first to sixth switches Q1 to Q6, respectively. The first to sixth diodes D1 to D6 have anodes connected to the sources of the first to sixth switches Q1 to Q6, respectively. In other embodiments, the first to sixth diodes D1 to D6 can be provided in addition to or instead of the parasitic diodes or body diodes.

[0180] Each of the first to sixth diodes D1 to D6 is capable of bypassing the drive current in the direction from the negative-side current path Ln toward the positive-side current path Lp when the corresponding switch is off. In other embodiments, the first to sixth switches Q1 to Q6 can be other semiconductor elements such as bipolar transistors and insulated gate bipolar transistors (IGBTs).

[0181] The gate circuit 44 is electrically connected to the positive electrode of the battery pack 18. The gate circuit 44 receives a battery voltage (hereinafter referred to as "battery voltage") from the battery pack 18 and drives the first to sixth switches Q1 to Q6.

[0182] The regulator 46 receives the battery power via the power supply control circuit 48. The regulator 46 generates an operating voltage Vcc from the battery power. In other words, the regulator 46 receives the battery voltage and converts (e.g., steps down) the battery voltage to the operating voltage Vcc. The operating voltage Vcc is a fixed direct current voltage. Each part in the controller 40 operates using the operating voltage Vcc.

[0183] The power supply control circuit 48 is electrically connected to the positive electrode of the battery pack 18 and receives the battery power. The power supply control circuit 48 supplies the battery power to the regulator 46 when the controller 40 is in the on state. As a result, the operating voltage Vcc is generated in the regulator 46. The power supply control circuit 48 can have a power path (not shown) that outputs the battery power to the regulator 46. The power supply control circuit 48 can be configured to supply the battery power to the regulator 46 by turning on the power path.

[0184] The power supply control circuit 48 is configured to receive the first power supply cutoff signal from the battery pack 18 and / or the second power supply cutoff signal from the control circuit 50. The power supply control circuit 48 stops supply of the battery power to the regulator 46 based on the reception of the first power supply cutoff signal and / or the second power supply cutoff signal. Accordingly, the generation of the operating voltage Vcc by the regulator 46 is stopped. The power supply control circuit 48 can also be configured to stop supply of the battery power to the regulator 46 by cutting off the power supply path.

[0185] The first power supply cutoff signal is output from the battery pack 18 in a case where an abnormality of the battery pack 18 (for example, a decrease in the battery voltage) is detected in the battery pack 18. The second power supply cutoff signal is output from the control circuit 50 in a case where an abnormality of the electric power tool 1 is detected in the control circuit 50.

[0186] The control circuit 50 outputs the first to sixth control signals UH, VH, WH, UL, VL, WL to the gate circuit 44, and drives and controls the motor 30 via the gate circuit 44 and the drive circuit 42. The first to sixth control signals UH, VH, WH, UL, VL, WL correspond to the first to sixth switches Q1 to Q6, respectively. The gate circuit 44 turns on or off the first to sixth switches Q1 to Q6 in accordance with the first to sixth control signals UH, VH, WH, UL, VL, WL. The first to third control signals UH, VH, WH can be pulse width modulation (PWM) signals, and the fourth to sixth control signals UL, VL, WL can be non-PWM signals, or vice versa. Alternatively, all of the first to sixth control signals UH, VH, WH, UL, VL, WL can be PWM signals. The motor 30 is supplied with a drive current based on one of the first to third switches Q1 to Q3 and one of the fourth to sixth switches Q4 to Q6 being turned on, and accordingly rotates.

[0187] The control circuit 50 in the first embodiment is in the form of a micro controller unit (MCU) or microcomputer including a CPU, a ROM, and a RAM, which are not shown. In the first embodiment, the control circuit 50 is provided with a memory 51. The memory 51 stores a state (abnormality, etc.) of the motor 30 and / or the controller 40. The memory 51 of the first embodiment is in the form of a nonvolatile memory in which the stored contents can be electrically rewritten.

[0188] In other embodiments, the control circuit 50 can be provided with, instead of or in addition to the MCU, discrete components, wired logic, an application specific integrated circuit (ASIC), an application specific standard product (ASSP), a programmable logic device (such as a field programmable gate array (FPGA)), and / or combinations thereof.

[0189] The controller 40 is provided with a voltage detection circuit (or voltage detection section) 52, a current detection circuit (or current detection section) 54, a rotational angle detection circuit (or rotational angle detection section) 56, and a temperature detection circuit (or temperature detection section) 58. The voltage detection circuit 52, the current detection circuit 54, the rotational angle detection circuit 56, and the temperature detection circuit 58 are electrically connected to the control circuit 50. At least one of the voltage detection circuit 52, the current detection circuit 54, and the temperature detection circuit 58 can be omitted.

[0190] The voltage detection circuit 52 detects the magnitude of the battery voltage. The voltage detection circuit 52 outputs a voltage detection signal to the control circuit 50. The voltage detection signal has a variable voltage corresponding to the magnitude of the battery voltage.

[0191] The current detection circuit 54 is present on the negative-side current path Ln. The current detection circuit 54 detects the magnitude of the drive current ibat flowing through the motor 30. The current detection circuit 54 outputs a drive current detection signal to the control circuit 50. The drive current detection signal has a variable voltage corresponding to the magnitude of the drive current ibat. The drive current ibat corresponds to any one of the U-phase current iu, the V-phase current iv, and the W-phase current iw. The U-phase current iu corresponds to the current flowing between the drive circuit 42 and the first terminal 30u. The V-phase current iv corresponds to the current flowing between the drive circuit 42 and the second terminal 30v. The W-phase current iw corresponds to the current flowing between the drive circuit 42 and the third terminal 30w. For example, in the case where the first switch Ql and the fifth switch Q5 are turned on, the U-phase current iu and the V-phase current iv correspond to the drive current ibat.

[0192] The rotational angle detection circuit 56 receives the first to third Hall signals from the rotational sensor 32 described above. The rotational angle detection circuit 56 detects the rotational angle (or rotational position; hereinafter referred to as rotor angle) of the rotor 30r on the basis of the first to third Hall signals.

[0193] The rotational angle detection circuit 56 is provided with a waveform shaping circuit, not shown. The waveform shaping circuit shapes the first to third Hall signals into pulse-shaped first to third position detection signals (see FIG. 6). The first to third position detection signals are output to the control circuit 50. Figures 3-5). Each of the first to third position detection signals also inverts its logic value each time the rotor 30r rotates an electrical angle of 180 degrees. In addition, the first to third position detection signals are also 120 degrees out of phase with each other. The first position detection signal corresponds to the U phase, the second position detection signal corresponds to the V phase, and the third position detection signal corresponds to the W phase. The rotation angle detection circuit 56 outputs the first to third position detection signals. The first to third position detection signals are input to the control circuit 50.

[0194] The control circuit 50 detects the rotor angle on the basis of the first to third position detection signals. The control circuit 50 is capable of detecting the rotor angle with a resolution of 60 degrees in electrical angle. The control circuit 50 also detects the actual number of rotations per unit time (in other words, the actual rotational frequency or the actual rotational speed) of the motor 30 on the basis of the first to third position detection signals.

[0195] The rotation angle detection circuit 56 can also output the rotation angle detection signal each time a rising edge or a falling edge occurs in any one of the first to third position detection signals (that is, every 60 degrees in electrical angle). In this case, the control circuit 50 can also detect (or recognize) that the rotor 30r has rotated an electrical angle of 60 degrees (and the rotor angle) each time the rotation angle detection signal is received.

[0196] The temperature detection circuit 58 outputs a temperature detection signal to the control circuit 50. The temperature detection circuit 58 includes a temperature sensor (for example, a thermistor) provided at the drive circuit 42. The temperature detection signal directly or indirectly indicates the temperature of the first to sixth switches Q1 to Q6 (in other words, the temperature of the drive circuit 42). The temperature detection signal has a variable voltage corresponding to the temperature of the first to sixth switches Q1 to Q6.

[0197] [2-1-3. Operation of the Control Circuit]

[0198] Next, the control of the motor 30 by the control circuit 50 will be described using Figures 3-5

[0199] As described above, the control circuit 50 is capable of detecting the rotor angle with a resolution of 60 degrees in electrical angle. In addition, the control circuit 50 is capable of detecting the actual number of rotations per unit time of the motor 30. Furthermore, the control circuit 50 is capable of detecting the temperature of the drive circuit 42. Figure 3 ​As shown, the control circuit 50 basically drives the motor 30 by supplying the first electric power to the motor 30 through conduction control. The conduction control includes driving the first to sixth switches Q1 to Q6 in pairs every time the rotor 30r rotates an electric angle of 60 degrees (e.g., forward rotation). In the first embodiment, the control circuit 50 drives the first to sixth pairs described below in order via the gate circuit 44 every time the rotor 30r rotates an electric angle of 60 degrees.

[0200] • The first pair: the first switch Q1 and the sixth switch Q6

[0201] • The second pair: the first switch Q1 and the fifth switch Q5

[0202] • The third pair: the third switch Q3 and the fifth switch Q5

[0203] • The fourth pair: the third switch Q3 and the fourth switch Q4

[0204] • The fifth pair: the second switch Q2 and the fourth switch Q4

[0205] • The sixth pair: the second switch Q2 and the sixth switch Q6

[0206] Any one of the first to sixth pairs (hereinafter referred to as "driven pair") is driven in the first conduction pattern. The driving in the first conduction pattern can be any one of the first to third driving forms.

[0207] The first driving form corresponds to fixing (or maintaining) both of the two switches in the driven pair to be on. In the conduction angle control described later, the driven pair is driven in the first driving form.

[0208] The second driving form corresponds to fixing one of the two switches in the driven pair (hereinafter referred to as "non-PWM driving switch") to be on and repeatedly (i.e., periodically) turning on and off the other switch (hereinafter referred to as "PWM driving switch") at a constant interval. The PWM driving switch is driven by a PWM signal, and the non-PWM driving switch is driven by a non-PWM signal. In the first driving form described above, both of the two switches in the driven pair are non-PWM driving switches.

[0209] The third driving form corresponds to periodically turning on both of the two switches in the driven pair, i.e., driving both of the two switches by a PWM signal. In the third driving form, both of the two switches in the driven pair are PWM driving switches.

[0210] In the PWM control described later, the drive pair is driven in the 2nd drive form. In the PWM control, the drive pair can also be driven in the 3rd drive form. The 1st switch Ql being driven means that the 1st switch Ql is fixed to be on, or the 1st switch Ql is periodically turned on and off. The same applies to the 2nd to 6th switches Q2 to Q6.

[0211] The electrical angle of 60 degrees is an example of a reference rotation angle in the generalization of the embodiments. In the following description, the electrical angle of 60 degrees is sometimes referred to as the reference rotation angle.

[0212] The control circuit 50 switches the drive pair each time the update timing to of the 1st to 3rd position detection signals. Specifically, the drive pair is switched in order from the 1st pair to the 6th pair described above. The 1st pair is driven after the 6th pair.

[0213] The update timing arrives each time the motor 30 rotates the reference rotation angle. The update timing specifically corresponds to the timing at which a rising edge or a falling edge occurs in any one of the 1st to 3rd position detection signals. In the case where the rotation angle detection circuit 56 is configured to output the rotation angle detection signal, the update timing corresponds to the timing at which the rotation angle detection signal is output. That is, the update timing arrives each time the motor 30 rotates the electrical angle of 60 degrees. In the example of Fig. 6, at the update timing to, the 1st pair is set as the drive pair, and at the update timing ti, the 2nd pair is set as the drive pair. Figure 3

[0214] At the time of reverse rotation of the motor 30, for example, the 1st to 6th pairs described above are driven in order in a different order from that at the time of forward rotation. That is, the 1st to 6th pairs, and / or the driving order of these pairs are respectively set in advance in correspondence with the rotation direction of the motor 30.

[0215] By the drive pair being switched in order from the 1st to 6th pairs, the drive current ibat can be supplied to the motor 30. Accordingly, the motor 30 generates a rotation torque in the forward rotation direction.

[0216] ​The rotational torque of the motor 30 changes in accordance with the drive current ibat (that is, in accordance with the U-phase to W-phase currents iu, iv, iw. In other words, in accordance with the power supplied to the motor 30). Thus, the control circuit 50 implements the conduction angle control as the above-mentioned conduction control. In the conduction angle control, basically, the drive pair is driven in the first drive form. However, in the conduction angle control of this first embodiment, the time during which the drive pair is driven is controlled within the reference control period (or the conduction control period). The reference control period is the period during which the motor 30 rotates the reference rotation angle (that is, the electrical angle of 60 degrees). The length of the conduction control period, that is, the time required for the motor 30 to rotate the reference rotation angle (hereinafter referred to as the "reference rotation time") changes in accordance with the actual rotation speed of the motor 30.

[0217] Specifically, in conduction angle control, if Figure 3 As shown, during each reference control period, the drive current ibat is stopped at the disconnection time tc within the reference control period. Specifically, after the drive of the drive pair corresponding to the start of the reference control period (that is, the update time) is started, at the disconnection time tc, any one switch in the drive pair will be disconnected. The disconnection time tc arrives before the next update time arrives (that is, before the end of the reference control period of the drive pair). The period from the start of the reference control period to the disconnection time tc corresponds to the conduction angle. In the conduction angle control, the conduction angle is calculated. Moreover, when the motor 30 rotates by the rotation angle corresponding to its conduction angle from the start of the reference control period, the drive current ibat is stopped.

[0218] The control circuit 50 sets the off timing tc (that is, sets the conduction angle) according to the rotation state of the motor 30 in each reference control period, thereby controlling the motor 30 to a desired rotation state.

[0219] The conduction angle control can be appropriately performed when the motor 30 is in no-load operation or normal operation. On the other hand, when the motor 30 is in heavy-load operation, the rotation speed of the motor 30 decreases. Figure 4 An example is shown in which the motor 30 is operated under heavy load.

[0220] like Figure 4 As shown (particularly during update times t1 to t3), as the rotation speed of motor 30 decreases, the reference rotation time increases, and the actual drive time (or energization time, actual energization time, or energization control time) of motor 30 during the reference control period also increases. The actual drive time is the time during which drive current ibat is supplied to motor 30; in other words, the time during which the driving current ibat is driven.

[0221] When the actual drive time in the reference control period becomes longer, the drive current ibat rises (i.e., the absolute values of the U-phase ~ W-phase currents iu, iv, iw rise), and the peak value of the drive current ibat becomes higher. As a result, failure of the first to sixth switches Q1 to Q6 and / or demagnetization of the permanent magnet of the motor 30 can occur.

[0222] Therefore, in the first embodiment, the control circuit 50 measures the elapsed time from each update time (i.e., the actual drive time) at each update time. Specifically, as shown in Figure 3 and Figure 4 , the control circuit 50 starts counting using the time counter at each update time. Specifically, the count value of the time counter (hereinafter referred to as "first count value") is periodically increased. The first count value corresponds to (i.e., is equivalent to) the actual drive time.

[0223] The control circuit 50 determines whether the first count value has reached a limit threshold. In other words, the control circuit 50 determines whether the actual drive time has reached a limit time. The limit time corresponds to (i.e., is equivalent to) the limit threshold. The first count value reaching the limit threshold means the same as the actual drive time reaching the limit time. The limit threshold can also be set in advance.

[0224] The control circuit 50, in the case where the first count value does not reach the limit threshold, maintains the energization limit flag in the reset state and continues the energization angle control (see Figure 3 ).

[0225] On the other hand, as shown in Figure 4 , when the motor 30, for example, performs a heavy load operation, the reference rotation time becomes longer, and the first count value can reach the limit threshold. In Figure 4 , the first count value reaches the limit threshold at a time t2x after the update time t2 and before the disconnection time tc arrives. The control circuit 50, in correspondence with the first count value reaching the limit threshold, (i) sets the energization limit flag and (ii) thereby disconnects all of the first to sixth switches Q1 to Q6. That is, the control circuit 50 temporarily stops the energization angle control and performs the energization limitation. The energization limitation of the first embodiment includes disconnecting the drive pair and thereby stopping the supply of electric power to the motor 30. As a result, the rise of the drive current ibat is suppressed, and the failure of the first to sixth switches Q1 to Q6 and the deterioration of the motor 30 are suppressed. The first count value reaching the limit threshold is an example of the first abnormality in the generalization of the embodiment.

[0226] The control circuit 50, after the first count value reaches the limit threshold, when the next update time t3 arrives, resets the energization limit flag (i.e., stops the energization limitation) and restarts the energization angle control.

[0227] Even if power to motor 30 is stopped when the first count value reaches the limit threshold, motor 30 continues to rotate due to inertia. This causes update time t3 to arrive again, resuming conduction angle control. Therefore, driving motor 30 under conduction angle control continues.

[0228] When the power-limit flag is set, thereby stopping power to the motor 30, the control circuit 50 illuminates the power-limit notification LED 16. This notifies the user that power to the motor 30 is being limited due to a decrease in the actual speed of the motor 30. This allows the user to recognize that the electric working machine 1 is operating under heavy loads. This recognition allows the user to operate the electric working machine 1 to reduce the load.

[0229] On the other hand, situations may arise, such as grass becoming entangled in the rotary blade 5, preventing it from rotating. When this occurs, the motor 30 is forcibly stopped. In other words, the motor 30 is locked. In this case, after the power-on limit flag is set, the conduction angle control will not resume until the next update time arrives. Motor 30 can also be locked by objects other than grass and other than the electric working machine 1.

[0230] In contrast, Figure 5 As shown, the control circuit 50 uses the motor lock detection counter to measure the elapsed time (hereinafter referred to as the "stop duration" (or deenergization time)) from the moment the first count value reaches the limit threshold (specifically, the moment all the first to sixth switches Q1 to Q6 are turned off). Specifically, the control circuit 50 periodically increments the count value of the motor lock detection counter (hereinafter referred to as the "second count value"). The second count value corresponds to (i.e., is equivalent to) the stop duration.

[0231] The control circuit 50 determines whether the second count value has reached the protection threshold (or protection detection threshold). The second count value reaching the protection threshold corresponds to the fact that the protection determination time has passed since the start of the power-on restriction and the update time has not yet arrived. In other words, the protection threshold is equivalent to the protection determination time. The protection threshold can also be pre-set. Figure 5 At time te, the second count value reaches the protection threshold. When the second count value reaches the protection threshold, the control circuit 50 determines that the motor 30 is locked. Specifically, the control circuit 50 (i) sets the motor lock detection flag, (ii) turns on the error detection notification LED 15, (iii) clears the power limit flag and the motor lock detection counter, and (iv) turns off the power limit notification LED 16.

[0232] The user can recognize that the motor 30 is locked based on the lighting of the error detection notification LED 15. This allows the user to perform an operation to unlock the motor 30. Specifically, the user can remove grass entangled in the rotary blade 5, for example.

[0233] As described above, when the second count value reaches the protection threshold, the energization restriction flag and the motor lock detection counter are cleared, thereby enabling the conduction angle control to be resumed after the motor 30 is unlocked.

[0234] [2-1-4. Flowchart]

[0235] Reference Figure 6 , Description: Main control processing performed by the control circuit 50 to control the motor 30.

[0236] In the first embodiment, when the control circuit 50 determines that the battery pack 18 is normal and has a charge level greater than the minimum charge level, the control circuit 50 executes Figure 6 The main control process shown in FIG. 1 is used as the main loop. The minimum amount of electricity can be any amount, for example, it can be the minimum amount required to start the motor 30.

[0237] like Figure 6 As shown, the control circuit 50 determines in S10 (S represents step): whether the main timing flag has been set. Figure 7 The main cycle is set during the timer interrupt process. When it is determined that the main timer counter has reached the threshold, the main timer flag is set. In other words, the main timer flag is set every specified control cycle.

[0238] If the master timer flag is not set in S10, the constant time corresponding to the control cycle has not yet elapsed since the previous processing from S20 onwards was started. Therefore, in this case, the control circuit 50 executes the determination process of S10 again. In other words, the control circuit 50 waits for the constant time to elapse.

[0239] If the main timer flag is set in S10, and a fixed time has elapsed since the previous processing of S20 and subsequent steps was started, the control circuit 50 clears the main timer flag, executes the processing of S20 to S80, and then moves to S10.

[0240] In S20, the control circuit 50 executes a rotation detection process (or a Hall signal detection process). Specifically, the control circuit 50 determines whether or not any of the 1st to 3rd position detection signals has generated a rising edge or a falling edge during a period from the immediately preceding S20 to the present S20. Further, in the case where a rising edge or a falling edge has been generated, a position update flag is set. That is, the position update flag is set each time the motor 30 rotates a reference rotation angle.

[0241] In S30, the control circuit 50 executes a switch operation detection process. Specifically, the control circuit 50 detects the operation state of various manual switches (for example, the trigger switch 10) provided in the operation / display unit 8.

[0242] In S40, the control circuit 50 executes an A / D conversion process. Specifically, the control circuit 50 A / D-converts various analog signals input to the control circuit 50. The various analog signals include: a voltage detection signal from the voltage detection circuit 52, a drive current detection signal from the current detection circuit 54, and a temperature detection signal from the temperature detection circuit 58. Thereby, the control circuit 50 acquires: the magnitude of the battery voltage, the magnitude of the drive current ibat, the temperature of the drive circuit 42, and the like.

[0243] In S50, the control circuit 50 executes an error detection process. Specifically, the control circuit 50 determines whether or not the operation state of the electric power tool 1 is normal. In the case where the operation state is abnormal, the control circuit 50 activates a protection function. The protection function can also be determined in advance. The error detection process includes a motor lock detection process (refer to S60 described later) to be described later. Figure 11 ).

[0244] In S60, the control circuit 50 executes a motor control process. Specifically, the control circuit 50 drives and controls the motor 30 by the conduction angle control, and calculates a conduction angle for each reference control period. The control circuit 50 outputs the 1st to 6th control signals UH, VH, WH, UL, VL, and WL to the gate circuit 44 on the basis of the conduction angle. The control circuit 50 thus controls the conduction to the motor 30.

[0245] In S70, the control circuit 50 executes a display process. Specifically, the control circuit 50 causes the plurality of LEDs provided in the display panel 14 to be turned on or off, thereby displaying the state of the electric power tool 1.

[0246] At S80, the control circuit 50 executes power management processing. Specifically, if (i) the trigger switch 10 has not been operated for a predetermined period of time or longer, and (ii) the conditions for transitioning to power saving mode are met, the control circuit 50 is placed in a sleep state. After S80, the process proceeds to S10. The process from S10 onwards is repeated in this manner.

[0247] Next, refer to Figure 7 , which indicates that the main loop uses timer interrupt processing. The main loop uses timer interrupt processing to repeatedly execute at a specified execution interval. The specified execution interval is sufficiently shorter than the control period of the main loop.

[0248] When the main loop timer interrupt processing begins, the control circuit 50 executes a main timer counter increment process at S100. Specifically, the control circuit 50 increments the count value of the main timer counter (hereinafter referred to as the "third count value") by "1." At S110, the control circuit 50 determines whether the current third count value is greater than or equal to the cycle threshold. The cycle threshold corresponds to the control period of the main loop.

[0249] If the third count value exceeds the period threshold in S110, the process proceeds to S120. At S120, the control circuit 50 sets the master timer flag. At S130, the control circuit 50 resets the master timer counter. If the third count value does not exceed the period threshold in S110, the process proceeds to S140.

[0250] In S140, the control circuit 50 determines whether the motor program has been set to "drive". The motor program is described later in the motor control process (see Figure 12 ) is set to "drive" or "stop". If the motor program is not set to "drive" in S140, there is no need to drive the motor 30. Accordingly, in this case, the process is transferred to S150. In S150, the control circuit 50 clears the power-on limit flag. In S160, the control circuit 50 resets the time counter to end the main loop timing interrupt processing. Resetting the time counter includes: setting the first count value to an initial value (for example, zero).

[0251] If the motor program is set to "drive" in S140, it is necessary to drive the motor 30. In this case, the process proceeds to S170. In S170, the control circuit 50 determines whether the energization restriction flag has been cleared.

[0252] In the case where the power-on restriction flag is not cleared (in other words, is set) in S170, the process shifts to S180. In S180, the control circuit 50 executes power-on restriction, whereby the drive current ibat is reduced or stopped. The power-on restriction of the first embodiment includes a first restriction process (or output stop process). The first restriction process includes stopping the supply of the drive current ibat to the motor 30. That is, the control circuit 50 turns off all of the first to sixth switches Q1 to Q6 by means of the gate circuit 44. After the process in S180, the main loop timing interrupt process is ended.

[0253] In the case where the power-on restriction flag is cleared in S170, the process shifts to S190. In S190, the control circuit 50 executes a time counter addition process. Specifically, the control circuit 50 increases the first count value of the time counter by "1".

[0254] In S200, the control circuit 50 determines whether the first count value reaches or exceeds the restriction threshold. In the case where the first count value is less than the restriction threshold, the main loop timing interrupt process is ended.

[0255] In the case where the first count value reaches or exceeds the restriction threshold in S200, the process shifts to S210. In S210, the control circuit 50 sets the power-on restriction flag.

[0256] In S220, the control circuit 50 executes the same power-on restriction (that is, the first restriction process) as in S180.

[0257] In S230, the control circuit 50 resets the time counter, to end the main loop timing interrupt process.

[0258] Next, the commutation timing interrupt process will be described with reference to Figure 8 The commutation timing interrupt process is executed every time when a rising edge or a falling edge occurs in any one of the first to third position detection signals, that is, every time when the motor 30 rotates a reference rotation angle.

[0259] The control circuit 50 clears the power-on restriction flag in S410 when starting the commutation timing interrupt process. In S420, the control circuit 50 resets the time counter. In S430, the control circuit 50 executes a motor drive commutation process. Specifically, the control circuit 50 switches the drive pair in correspondence with the switch pattern (that is, the order from the first pair to the sixth pair) set in advance.

[0260] The motor drive commutation process will be specifically described with reference to Figure 9 Figure 6 ​the rotation detection process of S20. The control circuit 50 acquires position update information at S510 at the time of transition to the rotation detection process. The position update information indicates whether or not the first to third position detection signals have been updated, that is, whether or not a rising edge or a falling edge has occurred in any one of the first to third position detection signals. The control circuit 50 can acquire the position update information, for example, based on the execution state of the commutation timing interrupt process.

[0261] The control circuit 50 judges whether or not the first to third position detection signals have been updated based on the position update information at S520.

[0262] In a case where it is judged at S520 that the first to third position detection signals have been updated, the process transitions to S530. The control circuit 50 sets a position update flag (or an update flag of the Hall signal) at S530 to end the rotation detection process.

[0263] In a case where it is judged at S520 that the first to third position detection signals have not been updated, the process transitions to S540. The control circuit 50 clears the position update flag at S540 to end the rotation detection process.

[0264] Next, the switch operation detection process of S30 will be described with reference to Figure 10 The control circuit 50 acquires the operation states of the various manual switches at S610 at the time of transition to the switch operation detection process. Specifically, the control circuit 50 acquires the signal output from the trigger switch 10 and the signal output from the main power supply switch 20, respectively.

[0265] The control circuit 50 performs filter processing on the signals from the various manual switches at S620, respectively, whereby noise is removed from the signals from the various manual switches. The trigger signal received from the trigger switch 10 is also subjected to the filter processing in a case where the trigger signal is received from the trigger switch 10.

[0266] The control circuit 50 monitors the state changes of the various manual switches based on the signals that have been subjected to the filter processing at S630. The state changes include switching from off to on and switching from on to off. A change flag corresponding to the manual switch is set in a case where a state change has occurred in any one of the various manual switches.

[0267] The control circuit 50 measures the on time or the off time of the manual switch for which the change flag is set at S640.

[0268] The on-time and the off-time are calculated, for example, based on a time difference between the time at which the change flag was set last time and the time at which the change flag is set this time. In a case where the change flag is set based on the manual switch being switched from on to off, the on-time is calculated. In a case where the change flag is set based on the manual switch being switched from off to on, the off-time is calculated.

[0269] At S640, the control circuit 50 also clears the change flag. Thus, in the switch operation detection processing, the operation time (i.e., the on-time or the off-time) is detected in addition to the operation state of each manual switch.

[0270] Next, the motor lock detection processing included in the error detection processing of S50 will be described with reference to Figure 11

[0271] The control circuit 50 determines at S710 whether or not the current motor lock detection flag has been reset at the start of the motor lock detection processing. The motor lock detection flag having been reset corresponds to the motor lock protection not being set.

[0272] In a case where the motor lock detection flag has been reset at S710, the processing is transferred to S720. At S720, the control circuit 50 determines whether or not the power-on restriction flag has been set. In a case where the power-on restriction flag has been set, the power-on to the motor 30 is restricted (specifically, cut off) by the 1st restriction processing of S220. Thus, in this case, the processing is transferred to S730. At S730, the control circuit 50 increases the 2nd count value of the motor lock detection counter by "1". That is, the aforementioned stop duration is measured.

[0273] At S740, the control circuit 50 determines whether or not the current 2nd count value reaches or exceeds the protection threshold. In a case where the 2nd count value reaches or exceeds the protection threshold, the control circuit 50 determines that the motor 30 has locked, and the processing is transferred to S750. At S750, the control circuit 50 (i) sets the error state to the motor lock protection, and (ii) sets the motor lock detection flag. After the execution of the processing of S750, the control circuit 50 ends the motor lock detection processing.

[0274] In a case where the 2nd count value does not reach the protection threshold at S740, the control circuit 50 ends the motor lock detection processing.

[0275] ​In a case where the energization restriction flag is not set in S720, the motor 30 is normally driven by the energization angle control. Accordingly, in this case, the present processing shifts to S770. In S770, the control circuit 50 resets the motor lock detection counter to end the motor lock detection processing. The resetting of the motor lock detection counter includes setting the 2nd count value to an initial value (for example, zero).

[0276] In a case where the motor lock detection flag is set in S710, that is, in a case where the error state is set to the motor lock protection, the present processing shifts to S760. In S760, the control circuit 50 determines whether or not the motor lock protection can be released. For example, the user performs an operation for releasing the lock of the motor 30, whereby the motor lock protection can be released.

[0277] In S760, the control circuit 50 releases (i) the setting of the motor lock protection and (ii) the motor lock detection flag when it is determined that the motor lock protection can be released.

[0278] Next, the motor control processing of S60 will be described with reference to Figure 12 .

[0279] The control circuit 50 determines whether or not the controller 40 (that is, the main power state) is in the on state in S810 when starting the motor control processing. In a case where the controller 40 is in the on state, the present processing shifts to S820.

[0280] In S820, the control circuit 50 determines whether or not protection of the electric working machine 1 (specifically, for example, the motor 30 and / or the controller 40) is required in the error state. The control circuit 50 makes the determination of S820 on the basis of the results of various error detection processing. The various error detection processing includes the aforementioned motor lock detection processing (refer to Figure 11 ). The error state being set to the aforementioned motor lock protection corresponds to one of the conditions in which protection of the electric working machine 1 is required in the error state. In a case where protection of the electric working machine 1 is not required in the error state, the present processing shifts to S830.

[0281] In S830, the control circuit 50 determines whether or not the trigger switch 10 is in the on state (that is, has been operated). The control circuit 50 can determine that the trigger switch 10 is in the on state on the basis of the reception of the trigger signal that has been subjected to the filtering processing. If the trigger switch 10 is in the on state, the present processing shifts to S840. In S840, the control circuit 50 sets the motor program to “drive”. That is, the drive of the motor 30 is permitted.

[0282] In a case where it is determined in S810 that the controller 40 is in the off state, or in a case where it is determined in S820 that the electric power actuator 1 needs to be protected in the error state, or in a case where it is determined in S830 that the trigger switch 10 is in the off state (i.e., is not operated), the present processing shifts to S870. In S870, the control circuit 50 sets the motor program to "stop". That is, the drive of the motor 30 is prohibited.

[0283] In S850, the control circuit 50 sets the target rotational speed (in other words, the target rotational velocity) of the motor 30. Specifically, the control circuit 50 sets the target rotational speed on the basis of the operation state of the trigger switch 10 and / or the current rotational state of the motor 30.

[0284] In S860, the control circuit 50 calculates the drive ratio (or the motor output duty ratio). The drive ratio is the time ratio (generalized duty ratio) of the period during which the drive pair is driven with respect to the reference control period. The drive ratio is calculated in such a manner that the actual rotational speed of the motor 30 coincides with the target rotational speed set in S850.

[0285] The control circuit 50 sets the energization angle time corresponding to the energization angle on the basis of the drive ratio. The control circuit 50 sets the set energization angle time in the energization angle timer and causes the energization angle timer to operate.

[0286] Furthermore, while the energization angle time is timed with the energization angle timer, the control circuit 50 turns off one or both of the two switches in the drive pair (one in the first embodiment). That is, the above-described energization angle control is implemented.

[0287] In S880, the control circuit 50 executes the motor stop processing. The motor stop processing is processing for stopping the drive of the motor 30.

[0288] In the motor stop processing, the motor 30 can also be stopped in an arbitrary method. For example, the motor 30 can be stopped by cutting off the drive current ibat flowing to the motor 30. Alternatively, for example, the motor 30 can be braked by causing two or more of the first to third terminals 30u to 30w to be short-circuited to each other via the drive circuit 42. That is, the motor 30 can be braked or stopped by so-called short-circuit braking.

[0289] In S890, the control circuit 50 initializes the drive ratio. Specifically, the control circuit 50 sets the drive ratio to an initial value (for example, 0%).

[0290] Next, the display processing of S70 will be described with reference to Figure 13

[0291] ​The control circuit 50 judges whether or not the motor lock detection flag has been cleared at the start of the display processing in S910. In the case where the motor lock detection flag has been cleared, the processing shifts to S920. In S920, the control circuit 50 sets (i.e., turns off) the error detection notification LED 15 to the off state, and shifts to S940. In S910, if the motor lock detection flag has not been cleared (i.e., if it has been set), the processing shifts to S930. In S930, the control circuit 50 sets (i.e., turns on) the error detection notification LED 15 to the on state, and shifts to S940.

[0292] In S940, the control circuit 50 judges whether or not the power-on limit flag has been set. If the power-on limit flag has been set, the processing shifts to S950. In S950, the control circuit 50 sets the power-on limit notification LED 16 to the on state (i.e., turns on), and ends the display processing. If the power-on limit flag has not been set (i.e., if it has been cleared), the processing shifts to S960. In S960, the control circuit 50 sets (i.e., turns off) the power-on limit notification LED 16 to the off state, and ends the display processing.

[0293] [2-1-5. Effects]

[0294] As explained above, in the electric power tool 1 of this first embodiment, the motor 30 is driven by the power-on angle control. During the driving of the motor 30, the actual driving time is measured at each update timing (i.e., the first count value is counted up). When the actual driving time reaches the limit time (i.e., when the first count value reaches the limit threshold), the power-on to the motor 30 is cut off by the first limit processing (S220).

[0295] Thus, at the time when the actual rotational speed of the motor 30 decreases due to heavy load work or the like, it is possible to suppress the situation where the peak value of the driving current ibat and the peak values of the U-phase to W-phase currents iu, iv, iw each increase. Accordingly, it is possible to suppress the failure of the first to sixth switches Q1 to Q6 and / or the demagnetization of the permanent magnet of the motor 30.

[0296] The control circuit 50, after executing the first limit processing of S220, causes the power-on to the motor 30 based on the power-on angle control to restart when the update timing comes (i.e., when the aforementioned rising edge or falling edge occurs). Thus, it is possible to continuously perform the driving of the motor 30 based on the power-on angle control.

[0297] The control circuit 50 causes the energization restriction notification LED 16 to be lit during the period from after the start of the first restriction processing S220 to the restart of the energization of the motor 30, and thereby the occurrence of the first abnormality (or the first energization abnormality) of the electric power tool 1 can be notified.

[0298] The control circuit 50 causes the error detection notification LED 15 to be lit in the case where the second abnormality (or the second energization abnormality) that requires the stop of the drive of the motor 30 has occurred, and thereby the occurrence of the second abnormality is notified. The second abnormality includes the lock of the motor 30, that is, the setting of the motor lock detection flag.

[0299] The user can recognize that the protection function of the electric power tool 1 is acting by the lighting of the energization restriction notification LED 16. Further specifically, the user can recognize that the load of the motor 30 is increasing and / or the drive current ibat and the U-phase to W-phase currents iu, iv, iw are increasing because of the increase of the load. In addition, the user can recognize that the motor 30 has been locked and further the error that requires the stop of the drive of the motor 30 has occurred by the lighting of the error detection notification LED 15 when the error that requires the stop of the drive of the motor 30 has occurred because of the occurrence of the motor lock or the like.

[0300] The user can grasp the occurrence of the abnormality of the motor 30 and the content of the abnormality by the lighting of the energization restriction notification LED 16 and / or the error detection notification LED 15. Thereby, it is expected that the user operates the electric power tool 1 so that the abnormality can be suppressed or eliminated.

[0301] In the first embodiment, the first and second abnormalities are notified by the energization restriction notification LED 16 and the error detection notification LED 15, respectively. However, the first and second abnormalities can be notified by one LED. Even if the first abnormality has occurred, the normal control can be restarted at the next update time. Thus, the occurrence of the first abnormality can not be notified.

[0302] [2-2. Second Embodiment]

[0303] In the first embodiment, after the energization to the motor 30 is cut off when the actual drive time reaches the restriction time, the first to sixth switches Q1 to Q6 are kept in the off state until the update time comes, that is, until the energization to the motor 30 is restarted. That is, the first restriction processing is executed as the energization restriction.

[0304] On the contrary, in the second embodiment, the second restriction processing (or PWM output processing) is executed as the energization restriction. Specifically, as shown in FIG. 6, the PWM output processing is executed in the case where the actual drive time reaches the restriction time. Figure 14As shown, during the period from when the actual driving time reaches the limit time until the update time comes, the drive pair is driven in accordance with the 2nd conduction pattern. Further specifically, the drive pair is driven in the 2nd drive form. That is, one of the 2 switches of the drive pair is kept in the on state, and the other is periodically turned on / off. That is, the switch of one side is set as the non-PWM drive switch, and the switch of the other side is set as the PWM drive switch. Accordingly, the drive current ibat is lower than that of the usual conduction angle control. In other words, the 2nd electric power is supplied to the motor 30. The 2nd electric power is smaller than the 1st electric power (i.e., the electric power supplied to the motor 30 by the conduction angle control).

[0305] When the drive pair is driven in accordance with the 2nd conduction pattern, the PWM drive switch is driven by the 1st PWM signal as shown by the single-dot chain line. The 1st PWM signal has a 1st duty ratio set in advance. The 1st duty ratio is set in such a manner that the amount of heat generated in the drive system of the motor 30 is smaller than that when the usual conduction angle control is executed. The drive system of the motor 30 includes the drive circuit 42. Figure 14

[0306] In this 2nd embodiment, the driving of the drive pair is continued even after the actual driving time reaches the limit time. However, after the actual driving time reaches the limit time, the drive pair is driven in the 2nd conduction pattern which is different from the usual conduction angle control (i.e., the 1st conduction pattern). The 2nd conduction pattern is set so that the drive current ibat is lower than that of the usual conduction angle control. Thus, as in the 1st embodiment, the failure of the 1st to 6th switches Q1 to Q6 and the demagnetization of the permanent magnet of the motor 30 can be suppressed.

[0307] In order to achieve such control of the motor 30, in this 2nd embodiment, the control circuit 50 executes the main loop timing interrupt processing shown in FIG. 27 instead of the main loop timing interrupt processing shown in FIG. 25. Figure 15 Figure 7 In the main loop timing interrupt processing shown in FIG. 27, the processing of S225, S185 is executed instead of the processing of S220, S180. In S225, S185, the control circuit 50 executes the conduction limitation (i.e., the 2nd limitation processing). The 2nd limitation processing includes outputting the 1st PWM signal as the control signal corresponding to the PWM drive switch. The 1st duty ratio can be fixed or can be variably set in correspondence with the driving conditions of the motor 30 (e.g., the battery voltage).

[0308] In the main loop timing interrupt processing shown in FIG. 27, the processing of S225, S185 is executed instead of the processing of S220, S180. In S225, S185, the control circuit 50 executes the conduction limitation (i.e., the 2nd limitation processing). The 2nd limitation processing includes outputting the 1st PWM signal as the control signal corresponding to the PWM drive switch. The 1st duty ratio can be fixed or can be variably set in correspondence with the driving conditions of the motor 30 (e.g., the battery voltage). Figure 15 Figure 7 In the main loop timing interrupt processing shown in FIG. 27, the processing of S225, S185 is executed instead of the processing of S220, S180. In S225, S185, the control circuit 50 executes the conduction limitation (i.e., the 2nd limitation processing). The 2nd limitation processing includes outputting the 1st PWM signal as the control signal corresponding to the PWM drive switch. The 1st duty ratio can be fixed or can be variably set in correspondence with the driving conditions of the motor 30 (e.g., the battery voltage).

[0309] ​​​In the second embodiment, even after the actual driving time reaches the limit time, the drive pair is driven in the second energization pattern, and accordingly, the energization to the motor 30 is continued.

[0310] [2-3. Third Embodiment]

[0311] In the first embodiment, after the actual driving time reaches the limit time, the energization to the motor 30 is cut off until the next update time comes.

[0312] In contrast, in the third embodiment, as shown in Figure 16 , during a period from when the actual driving time reaches the limit time until a certain waiting time elapses, the energization to the motor 30 is cut off. Further, after the waiting time elapses, the energization to the motor 30 is restarted.

[0313] Even with such a control method, as with the first embodiment, the failure of the first to sixth switches Q1 to Q6 and the demagnetization of the permanent magnet of the motor 30 can be suppressed.

[0314] Further, the energization is cut off during the waiting time, and after the waiting time elapses, the energization is restarted. Thereby, for example, even if a state in which the update time does not come continues due to sudden deceleration of the motor 30 or the like, the peak values of the drive current ibat and the U-phase to W-phase currents iu, iv, iw can be limited, and the drive current ibat can be intermittently supplied to the motor 30 to drive the motor 30.

[0315] To realize such control of the motor 30, in the third embodiment, instead of the main loop timer interrupt processing of Figure 7 , the control circuit 50 executes the main loop timer interrupt processing shown in Figure 17 .

[0316] In Figure 17 , the processing of S100 to S130 is executed as with the main loop timer interrupt processing of Figure 7 , which is omitted from illustration. Figure 17 , for the main loop timer interrupt processing of Figure 7 , S300 to S350 are added.

[0317] S300 is executed after S160. In S300, the control circuit 50 resets the count value of the energization restart counter (hereinafter referred to as "fourth count value"), and ends the main loop timer interrupt processing.

[0318] The power-on restart counter is a counter for counting the time elapsed from the time when the actual drive time reaches the limit time, that is, the time when the power-on to the motor 30 is stopped. When it is determined in S170 that the power-on limit flag has not been cleared, S310 is executed. In S310, the control circuit 50 performs power-on restart counter addition processing. Specifically, the control circuit 50 increases the fourth count value by "1". During the period in which the power-on limit flag is set, that is, during the period in which the power-on to the motor 30 is stopped, S310 is repeatedly executed, whereby the time during which the power-on to the motor 30 is stopped is measured.

[0319] After the processing in S310, the present processing branches to S320. In S320, the control circuit 50 determines whether or not the fourth count value has reached or exceeded the power-on restart threshold. The power-on restart threshold corresponds to the waiting time. In the case where the fourth count value has not reached or exceeded the power-on restart threshold in S320, the present processing branches to S180. The processing after S180 is the same as that in the first embodiment. Figure 7

[0320] In the case where the fourth count value has reached or exceeded the power-on restart threshold in S320, the present processing branches to S330. In S330, the control circuit 50 clears the power-on limit flag. In S340, the control circuit 50 resets the power-on restart counter, and branches to S350.

[0321] In S350, the control circuit 50 performs output restart processing. Specifically, the control circuit 50 turns on the drive pair that was turned off in S220 again, whereby the power-on angle control is restarted. After the processing in S350 is executed, the control circuit 50 ends the main loop timing interrupt processing.

[0322] In the case where it is determined in S170 that the power-on limit flag has been cleared, the processing in S190 to S230 is executed as well. Figure 7

[0323] Even in this third embodiment, the motor lock detection processing of Figure 11 is executed as well as in the first embodiment. However, in this third embodiment, in S720, instead of determining whether or not the power-on limit flag has been set, it is determined whether or not the position update flag has been cleared. This is because, in this third embodiment, the power-on limit flag has been cleared by S330 at the time when the output restart processing of S350 is started.

[0324] As for the position update flag, it is set in the rotation detection processing Figure 9 in correspondence with the fact that the first to third position detection signals have been updated, and is cleared in the case where the first to third position detection signals have not been updated. ​​

[0325] Thus, in the third embodiment, the control circuit 50, in the case where the position update flag has been cleared in S720, shifts to S730, and increases the second count value by "1". By this, it is possible to measure the stop duration of the motor 30, and it is possible to detect the lock of the motor 30 based on the stop duration.

[0326] [2-4. Fourth Embodiment]

[0327] In the fourth embodiment, as shown in Figure 18 the PWM output period of the second embodiment shown in Figure 14 is limited to a certain wait time as in the third embodiment, and after the wait time has elapsed, the normal conduction angle control is restarted.

[0328] Even so, as in the second embodiment, during the period from when the actual drive time reaches the limit time and the conduction to the motor 30 is cut off until the conduction control is restarted, the first PWM signal can be output to cause current to flow to the motor 30. Also, once the time during which the normal conduction angle control is suspended and the first PWM signal is output reaches the wait time specified by the conduction restart threshold, the conduction angle control can be restarted, so as in the third embodiment, the driving of the motor 30 can be realized.

[0329] Thus, the output period of the first PWM signal from when the actual drive time reaches the limit time until the conduction angle control is restarted is limited to a certain wait time. In order to realize such control, the control circuit 50 of the fourth embodiment executes the main loop timing interrupt processing in the order shown in Figure 19

[0330] Figure 19 The main loop timing interrupt processing shown in Figure 17 is substantially the same as the main loop timing interrupt processing of the third embodiment. Figure 19 The main loop timing interrupt processing of the fourth embodiment differs from the third embodiment in that the processing of S225, S185 is executed instead of the processing of S220, S180 described in Figure 17 S225, S185 are the same as S225, S185 of the second embodiment. That is, in S225, S185, as in the second embodiment, the control circuit 50 executes the conduction limitation (specifically, the second limitation processing). That is, the control circuit 50 outputs the first PWM signal as the control signal corresponding to the PWM drive switch.

[0331] Also, even in this fourth embodiment, the control circuit 50, in the case where the position update flag has been cleared in S720, shifts to S730, and increases the second count value by "1". Figure 11 ​In the motor lock detection process S720, the same process as in the third embodiment is performed. That is, instead of determining whether the power limit flag is set, it is determined whether the position update flag is cleared. If the position update flag is cleared, the process proceeds to S730.

[0332] [2-5. Fifth embodiment]

[0333] In the above-described first to fourth embodiments, the control circuit 50 controls the rotation of the motor 30 through conduction angle control.

[0334] In contrast, Figure 20 As shown, the control circuit 50 of the fifth embodiment controls the motor 30 through PWM control. Specifically, in the fifth embodiment, PWM control is performed as the aforementioned energization control, thereby supplying the first power to the motor 30. In PWM control, at least one of the two switches in the drive pair is driven based on a second PWM signal, that is, periodically switched on and off. The second PWM signal has a second duty cycle. The second duty cycle is set so that the actual rotational speed of the motor 30 matches the target rotational speed.

[0335] In the fifth embodiment, as in the first embodiment, when the actual drive time reaches the time limit, the power supply to the motor 30 is cut off. In other words, the PWM control is stopped. Thus, the fifth embodiment can also achieve the same effects as the first embodiment.

[0336] In this fifth embodiment, Figure 12 The "drive ratio" of S860 and S890 can be interpreted as "second duty cycle".

[0337] That is, in the fifth embodiment as well, the control circuit 50 calculates the drive ratio in S860 in the same manner as in the first embodiment, but uses the drive ratio as the second duty ratio.

[0338] Figure 20 In the example shown, the first limiting process is performed similarly to the first embodiment from the time the actual drive time reaches the limit until the update time arrives again (i.e., until normal PWM control resumes). However, the motor 30 may be controlled similarly to any of the second to fourth embodiments during this period.

[0339] [2-6. Modification]

[0340] The present invention is not limited to the first to fifth embodiments described above, and can be implemented in various modified forms.

[0341] In the above-described first to fifth embodiments, the actual driving time is measured using the time counter during the reference control period. Also, when the actual driving time reaches the limit time (i.e., when the first count value reaches the limit threshold), (i) the energization to the motor 30 is limited, and (ii) the energization limit notification LED 16 is lit.

[0342] However, the notification implemented by the lighting of the energization limit notification LED 16 is not necessarily essential. The notification implemented by the energization limit notification LED 16 can also be omitted, in which case, the desired object of the present application can also be achieved. In addition, the notification at the time of energization limitation or at the time of motor lock detection can also be performed in addition to the lighting of the LED, or instead, can also be performed by other methods. Specifically, for example, the notification can also be performed by performing information display on the display panel 14, or by emitting a notification sound, and the like.

[0343] The electric working machine 1 of the above-described first to fifth embodiments is in the form of a lawn mower. However, the technology of the present application can be applied to various electric working machines other than the lawn mower, and the same effects as the above-described first to fifth embodiments can be obtained. The various electric working machines can also be configured so that the rotational speed of the motor 30 is changed in correspondence with the working state.

[0344] The motor 30 in the above-described first to fifth embodiments is in the form of a 3-phase brushless motor provided with the rotation sensor 32. However, the motor 30 can also be a brushless motor other than 3-phase, such as a single-phase brushless motor. The motor 30 can also be controlled by the so-called sensorless method. Specifically, the motor 30 can also not be provided with the rotation sensor 32. Also, the rotation angle detection circuit 56 can also detect the rotor angle based on the induced voltage generated in the first to third windings 30a to 30c.

[0345] In the above-described first to fifth embodiments, the energization to the motor 30 is controlled by the energization angle control or the PWM control. However, the motor 30 can also be controlled by combining the energization angle control and the PWM control, similarly to the technology disclosed in Japanese Patent Application Publication No. 2023-31617.

[0346] [2-7. Supplement]

[0347] The plurality of functions possessed by one of the components in the first to fifth embodiments described above can be implemented by a plurality of components, or one function possessed by one component can be implemented by a plurality of components. In addition, a plurality of functions possessed by a plurality of components can be implemented by one component, or one function implemented by a plurality of components can be implemented by one component. In addition, a part of the configuration of the first to fifth embodiments described above can be omitted. In addition, at least a part of one of the configurations among the first to fifth embodiments described above can be added to or replaced with the configuration of the other of the first to fifth embodiments described above.

[0348] The present application is realized in various forms including the electric working machine, a system including the electric working machine, a program for causing a computer to function as the electric working machine, a non-transitory tangible recording medium such as a semiconductor memory in which the program is recorded, a control method of the electric working machine, and the like.

Claims

1. An electric power machine characterized by comprising: a brushless motor configured to (i) have a plurality of terminals and (ii) drive a driven appliance configured to be fixed to the electric power machine or attached to the electric power machine in a detachable manner; a plurality of positive electrode-side conduction paths that electrically connect the plurality of terminals to a positive electrode of a direct current power source, respectively; a plurality of negative electrode-side conduction paths that electrically connect the plurality of terminals to a negative electrode of the direct current power source, respectively; a plurality of high-side switches configured to (i) be present on the plurality of positive electrode-side conduction paths, respectively, and (ii) conduct or shut off the plurality of positive electrode-side conduction paths, respectively; a plurality of low-side switches configured to (i) be present on the plurality of negative electrode-side conduction paths, respectively, and (ii) conduct or shut off the plurality of negative electrode-side conduction paths, respectively; and a control circuit configured to perform conduction control and conduction limitation, the conduction control includes, every time an update timing comes, turning on a drive pair corresponding to a rotation angle of the brushless motor in a first conduction mode, whereby a first electric power is supplied from the direct current power source to the brushless motor via the drive pair, the drive pair includes one of the plurality of high-side switches and one of the plurality of low-side switches every time the update timing comes when the brushless motor rotates a reference rotation angle, the conduction limitation includes temporarily stopping the conduction control based on a first abnormality occurring during the execution of the conduction control, whereby the supply of the first electric power to the brushless motor is limited or stopped, the first abnormality includes that a limited time elapses without the next update timing coming after the update timing comes.

2. The electric power machine according to claim 1, characterized in that the control circuit is configured to restart the conduction control based on the update timing coming during the execution of the conduction limitation.

3. The electric power machine according to claim 1 or 2, characterized in that the control circuit is configured to restart the conduction control based on a waiting time elapsing from the start of the conduction limitation.

4. The electric power machine according to claim 3, characterized in that the control circuit is configured to restart the conduction control based on the waiting time elapsing without the update timing coming from the start of the conduction limitation.

5. The electric power machine according to any one of claims 1 to 4, characterized in that the conduction limitation includes turning off the plurality of high-side switches and the plurality of low-side switches, whereby the supply of the electric power of the direct current power source to the brushless motor is stopped.

6. The electric power machine according to any one of claims 1 to 4, characterized in that the conduction limitation includes supplying a second electric power from the direct current power source to the brushless motor via the drive pair, the second electric power is smaller than the first electric power.

7. The electric power machine according to claim 6, characterized in that ​ ​ The current supply restriction includes driving the drive pair in a second current supply mode in which the second electric power is supplied to the brushless motor. The second current supply mode (i) is different from the first current supply mode and (ii) includes periodically repeating turning on and off at least one of the drive pair.

8. The electric power tool according to claim 6 or 7, wherein The electric power tool further includes a drive circuit (i) including the plurality of high-side switches and the plurality of low-side switches and (ii) configured to supply the electric power of the direct-current power source to the brushless motor, An amount of heat generated from the drive circuit corresponding to the supply of the second electric power to the brushless motor is smaller than an amount of heat generated from the drive circuit corresponding to the supply of the first electric power to the brushless motor.

9. The electric power tool according to any one of claims 1 to 8, wherein The control circuit is configured to perform first notification based on the current supply restriction having started.

10. The electric power tool according to claim 9, wherein The control circuit is configured to continue the first notification until the current supply control restarts based on the current supply restriction having started.

11. The electric power tool according to claim 9 or 10, wherein The control circuit is configured to stop the supply of the electric power of the direct-current power source to the brushless motor and perform second notification based on a second abnormality having occurred in the electric power tool, The second abnormality is different from the first abnormality, The second notification is different from the first notification.

12. The electric power tool according to claim 11, wherein The second abnormality includes a protection determination time elapsing without the update time coming since the current supply restriction started.

13. The electric power tool according to claim 11 or 12, wherein The second abnormality includes the rotation of the driven appliance being forcibly stopped by an object other than the electric power tool, whereby the brushless motor is locked.

14. The electric power tool according to claim 3, wherein The control circuit is configured to perform second notification based on a protection determination time elapsing without the update time coming since the current supply restriction started, The protection determination time is longer than the waiting time.

15. The electric power tool according to any one of claims 1 to 14, wherein The current supply control includes current supply angle control, The current supply angle control includes (i) setting a current supply angle in such a manner that a rotational speed of the brushless motor coincides with a target rotational speed and (ii) continuously turning on the drive pair from the start of the current supply control until the brushless motor rotates a rotational angle corresponding to the current supply angle.

16. The electric power tool according to any one of claims 1 to 14, wherein The current supply control includes PWM control, The PWM control includes (i) setting a duty ratio in such a manner that the rotational speed of the brushless motor agrees with a target rotational speed, and (ii) periodically repeating turning on and off at least one of the drive pair in accordance with the duty ratio.

17. The electric power tool according to any one of claims 1 to 16, characterized in that The electric power tool further includes a rotation angle detection unit configured to output a position detection signal corresponding to the rotation angle of the brushless motor, The update timing comes based on the position detection signal indicating that the brushless motor has rotated a reference rotation angle.

18. A method of controlling a brushless motor of an electric power tool, characterized by comprising: The method includes the steps of: driving a drive pair corresponding to a rotation angle of the brushless motor in accordance with an energization pattern every time update timing comes, the update timing coming every time the brushless motor rotates a reference rotation angle, the drive pair being two of a plurality of switches on a plurality of energization paths electrically connecting the brushless motor to a direct-current power supply, and temporarily stopping the driving of the drive pair in accordance with the energization pattern based on a lapse of a limit time after the update timing comes until next update timing comes. ​

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