Electric power shovels

Abstract

The present application provides an electric working machine. The electric working machine is provided with a brushless motor and a controller configured to control the brushless motor. The electric working machine is also provided with a setter configured to set a limit value of a line current. The controller controls the brushless motor in such a manner that the line current input to the brushless motor is below the limit value set by the setter. The setter changes the limit value according to a state of the electric working machine.

Description

Technical Field

[0001] This invention relates to an electric work machine. Background Technology

[0002] Japanese Patent Application Publication No. 10-328952 discloses a screw fastening method and a screw fastening device for controlling a permanent magnet synchronous motor by vector control. The screw fastening device is configured to independently perform speed-priority control and torque-priority control.

[0003] In speed-priority control, the screw tightening device prioritizes speed control over torque control. In torque-priority control, the screw tightening device prioritizes torque control over speed control. Initially, screw tightening is performed at high speed using speed-priority control. Later, screw tightening is performed with appropriate torque using torque-priority control. Summary of the Invention

[0004] Theoretically, there are limits to the current and voltage that can be used in a permanent magnet motor driven by an inverter. In conventional technology, the motor was controlled in a way that did not exceed these limits. However, electric work machines are used in a wide variety of conditions. Depending on these conditions, the limits change.

[0005] When the upper limit of the usable current is set low due to a hypothetical change in conditions, the motor will be driven for a longer time with an unnecessarily low current because of the constraint of the set upper limit. On the other hand, if the upper limit is set high, the actual limit may be lower than the set upper limit, resulting in unstable operation of the electric work machine.

[0006] Therefore, according to one aspect of the present invention, it is desirable to provide a technique that can appropriately set the limit value of the motor's line current according to the state of the electric work machine.

[0007] According to one aspect of the present invention, an electric work machine is provided. The electric work machine includes: a brushless motor, a controller, and a setting device. The brushless motor is configured to drive the working part.

[0008] The controller is configured to control the brushless motor. The setter is configured to set the limit value of the line current.

[0009] According to one aspect of the invention, the controller is configured to control the brushless motor by inputting a line current below a limit value set by a setter to the brushless motor. According to another aspect of the invention, the setter is configured to change the limit value according to the state of the electric work machine.

[0010] With this configuration, the limit value of the motor's line current can be appropriately set according to the state of the electric work machine. Attached Figure Description

[0011] Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

[0012] Figure 1 It is a 3D diagram of an electric work machine.

[0013] Figure 2 This is a diagram used to illustrate the electrical configuration of an electric work machine.

[0014] Figure 3 It is a functional block diagram used to illustrate the structure of the control circuit.

[0015] Figure 4 This is a functional block diagram used to illustrate the structure of the speed control unit.

[0016] Figure 5 This is a function block diagram used to explain the structure of the limit value setting unit.

[0017] Figure 6 It is a diagram used to illustrate N-T characteristics.

[0018] Figure 7 It is a flowchart representing the main process executed by the control circuit (e.g., a processor).

[0019] Figure 8 It is a flowchart representing the state discrimination process performed by the control circuit.

[0020] Figure 9 It is a flowchart representing the limit value setting process performed by the control circuit.

[0021] Figure 10 This is a flowchart representing the interrupt handling performed by the control circuit.

[0022] Figure 11A as well as Figure 11B This is a diagram used to illustrate the N-T characteristics of the first variation.

[0023] Figure 12 This is a flowchart illustrating the switching process performed by the control circuit of the first variant.

[0024] Figure 13 This is a function block diagram used to explain a part of the limit value setting section in the second variation. Detailed Implementation

[0025] 1. Overview of Implementation Methods

[0026] One embodiment provides an electric work machine. The electric work machine may have at least one of the following features.

[0027] Feature 1: The electric work machine is equipped with a motor.

[0028] Feature 2: The motor is a brushless motor.

[0029] Feature 3: The motor is used to drive the working part.

[0030] Feature 4: The electric work machine is equipped with a controller.

[0031] Feature 5: The controller is configured to control the motor.

[0032] Feature 6: The electric work machine is equipped with a setting device.

[0033] Feature 7: The setting device is configured to set the limit value of the line current.

[0034] Feature 8: The controller is configured to control the motor based on the limit values ​​set by the setter.

[0035] Feature 9: The controller is configured to control the motor by inputting a line current to the motor at a limit value set by the setter.

[0036] Feature 10: The setter is configured to change the limit value.

[0037] According to an electric work machine having at least feature 10, the limit value of the line current can be changed.

[0038] According to one embodiment, the electric work machine may have the following features in addition to having at least one of features 1 to 10, or alternatively.

[0039] Feature 11: The setting device is configured to change the limit value according to the status of the electric work machine.

[0040] According to the electric work machine having at least feature 11, the limit value of the motor's line current can be appropriately set according to the state of the electric work machine. Therefore, it is possible to suppress the problem of the motor's capacity not being effectively utilized due to the limit value being lower than the actual limit. Furthermore, it is possible to effectively utilize the motor's capacity while ensuring safety. As a result, the product performance as an electric work machine can be improved.

[0041] According to one embodiment, the electric work machine may have at least one of the following features in addition to having at least one of features 1 to 11, or alternatively, at least one of the following features.

[0042] Feature 12: The setting device is configured to set the value corresponding to the battery mounted on the electric work machine as a limit value.

[0043] Feature 13: The setting device is configured to set a limit value corresponding to the state of the battery mounted on the electric work machine.

[0044] According to an electric work machine having at least feature 12 or feature 13, the limit value of the motor's line current can be appropriately set according to the battery or according to the state of the battery.

[0045] According to one embodiment, the electric work machine may have at least one of the following features in addition to having at least one of features 1 to 13, or alternatively, at least one of the following features.

[0046] Feature 14: The setting device is configured to set a limit value corresponding to the type of battery installed in the electric work machine.

[0047] Feature 15: The setting device is configured to set the value corresponding to the electrical parameters of the battery mounted on the electric work machine as a limit value.

[0048] Feature 16: The battery status includes a status based on the battery category.

[0049] Feature 17: The state of the battery includes the state based on electrical parameters of the battery, such as internal impedance.

[0050] According to one embodiment, the electric work machine may have at least one of the following features in addition to having at least one of features 1 to 17, or alternatively.

[0051] Feature 18: The setting device is configured to set a limit value corresponding to the upper limit of the battery current.

[0052] Feature 19: The setting device is configured to set a limit value corresponding to the upper limit of the battery current in the power supply system for the motor.

[0053] Feature 20: The setter is configured to set the value corresponding to the upper limit of the input as the limit value.

[0054] Feature 21: The setter is configured to set the value corresponding to the upper limit of the input for the motor as the limit value.

[0055] According to the electric work machine having feature 18 or feature 19, the limit value of the motor's line current can be appropriately set according to the upper limit of the battery current. The battery current can be the current supplied from the battery. The upper limit of the battery current can be changed by replacing the battery installed in the electric work machine. Setting a limit value corresponding to the upper limit of the battery current helps to effectively utilize the motor's capacity under possible constraints on input energy.

[0056] According to the electric work machine having feature 20 or feature 21, the limit value of the motor's line current can be appropriately set according to the upper limit of the input. The upper limit of the input can correspond to the upper limit of the battery current. The upper limit of the input can be changed by replacing the battery installed in the electric work machine. Setting a limit value corresponding to the upper limit of the input helps to effectively utilize the motor's capacity under possible constraints on input energy.

[0057] According to one embodiment, the electric work machine may have at least one of the following features in addition to having at least one of features 1 to 21, or alternatively, at least one of the following features.

[0058] Feature 22: The setter is configured to set the value corresponding to the upper limit of the output as the limit value.

[0059] Feature 23: The setting device is configured to set the value corresponding to the upper limit of the motor's output as the limit value.

[0060] According to the electric work machine having feature 22 or feature 23, the limit value of the motor's line current can be appropriately set according to the upper limit of the output. The upper limit of the line current corresponding to the upper limit of the output can be changed, for example, by changing the rotational speed of the motor. Setting the limit value corresponding to the upper limit of the output helps to effectively utilize the motor's capacity under the constraints of possible output energy.

[0061] According to one embodiment, in addition to having at least one of the features 1 to 23 described above, or alternatively, the electric work machine may also have at least one of the following features.

[0062] Feature 24: The setting device is configured to set the value corresponding to the upper limit of torque as the limit value.

[0063] Feature 25: The setting device is configured to set a limit value corresponding to the upper limit of the motor torque.

[0064] According to the electric work machine having feature 24 or feature 25, the limit value of the motor's line current can be appropriately set according to the upper limit of torque. The upper limit of line current corresponding to the upper limit of torque can be changed, for example, by changing the rotational speed of the motor. Setting the limit value corresponding to the upper limit of torque helps to effectively utilize the motor's capacity under possible torque constraints.

[0065] According to one embodiment, the electric work machine may have at least one of the following features in addition to having at least one of features 1 to 25, or alternatively.

[0066] Feature 26: The setting device is configured to set the value corresponding to the temperature as a limit value.

[0067] Feature 27: The setting device is configured to set a limit value corresponding to the temperature of the motor.

[0068] The actual limit of the line current can vary, for example, due to changes in the motor's temperature. According to an electric work machine with feature 26 or feature 27, the limit value of the motor's line current can be appropriately set in accordance with changes in the motor's temperature. An electric work machine with feature 26 or feature 27 helps to effectively utilize the motor's capabilities under temperature variations.

[0069] According to one embodiment, the electric work machine may have at least one of the following features in addition to having at least one of features 1 to 27, or alternatively, having at least one of the following features.

[0070] Feature 28: The electric work machine is equipped with an inverter.

[0071] Feature 29: The setter is configured to set a limit value corresponding to the temperature of the inverter.

[0072] The inverter can be configured to input line current to the motor. The allowable current value of the inverter can vary, for example, by changes in the inverter's temperature. According to the electric motor with feature 29, the limit value can be appropriately set in accordance with changes in the inverter's temperature.

[0073] According to one embodiment, the electric work machine may have at least one of the following features in addition to having at least one of features 1 to 29, or alternatively, at least one of the following features.

[0074] Feature 30: The setting device is configured to estimate power loss.

[0075] Feature 31: The setting device is configured to estimate the power loss input to the motor.

[0076] Feature 32: The setter is configured to set limit values ​​based on power loss.

[0077] Feature 33: The setter is configured to estimate the power loss input to the motor and set a limit value based on the estimated loss.

[0078] An electric work machine having at least one of features 30 to 33 combines power loss to set a limit value, thereby helping to effectively utilize the motor's capacity.

[0079] According to one embodiment, the electric work machine may have the following features in addition to having at least one of features 1 to 33, or alternatively.

[0080] Feature 34: The setting device is configured to estimate power loss based on the motor's resistance.

[0081] According to one embodiment, the electric work machine may have the following features in addition to having at least one of features 1 to 34, or alternatively.

[0082] Feature 35: The setter is configured to estimate the motor resistance based on the motor temperature.

[0083] The magnitude of power loss can vary depending on the motor resistance. According to an electric work machine with feature 34 or feature 35, the line current limit value can be appropriately set corresponding to the change in motor resistance. An electric work machine with feature 34 or feature 35 helps to effectively utilize the motor's capacity despite variations in motor resistance.

[0084] According to one embodiment, the electric work machine may have the following features in addition to having at least one of features 1 to 35, or alternatively.

[0085] Feature 36: The setting device is configured to set a limit value based on the rotational speed of the motor.

[0086] The upper limit of the motor's line current can be changed in response to variations in the motor's rotational speed. Electric work machines with feature 36 set limits based on rotational speed, thereby facilitating the efficient use of the motor's capacity.

[0087] According to one embodiment, the electric work machine may have at least one of the following features in addition to having at least one of features 1 to 36, or alternatively, having at least one of the following features.

[0088] Feature 37: The setting device is configured to set one of the following as a limit value: a first limit value corresponding to the upper limit of the battery current, a second limit value corresponding to the upper limit of the output, and a third limit value corresponding to the upper limit of the torque.

[0089] Feature 38: The setting device is configured to set one of the following as a limit value: a first limit value corresponding to the upper limit of the battery current, a second limit value corresponding to the upper limit of the output, and a third limit value corresponding to the upper limit of the torque, which meets the specified conditions.

[0090] Feature 39: The setting device is configured to set the minimum value among the first limit value corresponding to the upper limit of the battery current, the second limit value corresponding to the upper limit of the output, and the third limit value corresponding to the upper limit of the torque as the limit value.

[0091] Feature 40: The upper limit of the battery current is: the upper limit of the battery current in the power supply system for the motor.

[0092] Feature 41: The output limit is the motor's output limit.

[0093] Feature 42: The upper limit of torque is the upper limit of the motor torque.

[0094] An electric work machine having at least one of features 37 to 39 sets limit values ​​by considering multiple constraints, thus enabling the setting of appropriate limit values ​​corresponding to the situation. Therefore, this electric work machine helps to effectively utilize the motor's capabilities.

[0095] According to one embodiment, the electric work machine may have at least one of the following features in addition to having at least one of features 1 to 42, or alternatively.

[0096] Feature 43: The controller is configured to switch the control of the motor.

[0097] Feature 44: The controller is configured to perform constant output control for the motor.

[0098] Feature 45: The controller is configured to perform torque limiting for the motor.

[0099] Feature 46: The controller is configured to switch and execute multiple controls, including constant output control for the motor and torque limiting.

[0100] Feature 47: The controller is configured to switch control of the motor in response to an increase in the load acting on the motor.

[0101] Feature 48: The controller is configured to switch and execute multiple controls, including constant output control for the motor and torque limiting, in response to an increase in the load acting on the motor.

[0102] Feature 49: The controller is configured such that, in response to an increase in the load acting on the motor, (i) in the first stage, constant output control for the motor is performed, and (ii) in the second stage, torque limiting for the motor is performed.

[0103] Feature 50: The controller is configured to perform constant output control for the motor in a first stage such that the motor speed changes inversely with respect to the motor torque.

[0104] Feature 51: The controller is configured to perform torque limiting for the motor in a second stage in such a way that the torque of the motor does not depend on the speed of the motor and does not exceed a constant value.

[0105] Feature 52: The controller is configured to perform torque limiting for the motor in a second stage in such a way that the torque of the motor varies monotonically with respect to the speed of the motor.

[0106] Monotonic changes can include both monotonic increases and monotonic decreases in a broad sense. An electric work machine having at least one of features 43-52 can perform appropriate motor control based on the state of the electric work machine. That is, the performance of the electric work machine can be improved according to at least one of features 43-52.

[0107] According to one embodiment, the electric work machine may have at least one of the following features in addition to having at least one of features 1 to 52, or alternatively.

[0108] Feature 53: The controller is configured to switch the mode of motor control according to the user's instructions.

[0109] Feature 54: The controller is configured to switch the torque limiting mode for the motor according to the user's instructions.

[0110] The electric work machine having at least one of features 53 to 54 is capable of: motor control that provides a user-preferred operating feel.

[0111] According to one embodiment, the electric work machine may have at least one of the following features in addition to having at least one of features 1 to 54, or alternatively, at least one of the following features.

[0112] Feature 55: When a limit value corresponding to the upper limit of torque is set by the setter, the motor is controlled by inputting a line current corresponding to the limit value into the motor, thereby achieving torque limitation.

[0113] Feature 56: When a limit value corresponding to the upper limit of the motor torque is set by the setter, the motor is controlled by inputting a line current corresponding to the limit value into the motor, thereby achieving torque limitation.

[0114] Electric work machines with feature 55 or feature 56 can achieve appropriate torque limiting for the motor by setting limit values.

[0115] According to one embodiment, the electric work machine may have at least one of the following features in addition to having at least one of features 1 to 56, or alternatively.

[0116] Feature 57: The motor is controlled under conditions where a limit value corresponding to the upper limit of the battery current is set by the setter, thereby achieving constant output control.

[0117] Feature 58: When a limit value corresponding to the upper limit of the battery current is set by the setter, the motor is controlled by inputting a line current corresponding to the limit value into the motor, thereby achieving constant output control.

[0118] Feature 59: The motor is controlled under conditions where a limit value corresponding to the upper limit of the output is set by the setter, thereby achieving constant output control.

[0119] • Feature 60: When a limit value corresponding to the upper limit of the output is set by the setter, the motor is controlled by inputting a line current corresponding to the limit value into the motor, thereby achieving constant output control.

[0120] • Feature 61: When the motor is controlled by a setting device with a limit value corresponding to the upper limit of the battery current in the power supply system for the motor or the upper limit of the motor output, constant output control is achieved.

[0121] • Feature 62: When a limit value corresponding to the upper limit of the battery current in the power supply system for the motor or the upper limit of the motor output is set by the setter, the motor is controlled by inputting a line current corresponding to the limit value into the motor, thereby achieving constant output control.

[0122] An electric work machine having at least one of features 57 to 62 can achieve appropriate constant output control for the motor by setting a limit value.

[0123] According to one embodiment, the electric work machine may have at least one of the following features in addition to having at least one of features 1 to 62, or alternatively.

[0124] Feature 63: The controller is configured to perform constant rotation control of the motor in a manner that causes the motor to rotate at a constant speed.

[0125] Feature 64: The controller is configured to perform constant rotation control of the motor in such a way that the motor rotates at a constant speed, and to perform constant output control in response to an increase in the load acting on the motor.

[0126] Feature 65: The controller is configured to: (i) perform constant rotation control of the motor in such a way that the motor rotates at a constant speed, and (ii) perform torque limiting in response to an increase in the load acting on the motor.

[0127] Feature 66: The controller is configured to: (i) perform constant rotation control of the motor in such a way that the motor rotates at a constant speed, and (ii) perform constant output control and torque limiting in response to an increase in the load acting on the motor.

[0128] An electric work machine having at least one of features 64 to 66 switches motor control from constant rotation control to constant output control and / or torque limiting in response to load increases. Therefore, it is possible to drive the motor while effectively utilizing its capacity under various constraints, including energy constraints and / or torque constraints.

[0129] According to one embodiment, the electric work machine may have at least one of the following features in addition to having at least one of features 1 to 66, or alternatively.

[0130] Feature 67: The controller is configured to drive the motor via vector control.

[0131] Feature 68: The controller is configured to drive the motor by controlling the inverter.

[0132] Electric work machines with feature 67 or feature 68 can drive the motor effectively while utilizing its capacity through vector control under various constraints.

[0133] In one embodiment, the electric work machine may have one or more features from features 1 to 68. In another embodiment, the electric work machine may also have features corresponding to any combination of two or more features from features 1 to 68. In yet another embodiment, the electric work machine may also have one or more features from features 1 to 68.

[0134] [2. Specific exemplary implementation methods]

[0135] The following provides several specific exemplary implementation methods.

[0136] [2-1. Main Implementation Method]

[0137] This embodiment illustrates an electric chainsaw 1. Hereinafter, the electric chainsaw 1 will be simply referred to as "saw 1". The saw 1 in this embodiment is an electric chainsaw. However, the electric chainsaw 1 is merely one example, and the present invention can be applied to all types of electric chainsaws.

[0138] Figure 1 Although directions such as "up," "down," "front," "back," "left," and "right" are shown, these directions are merely for the purpose of facilitating a better understanding of the structure of the work machine 1 and are not intended to limit the orientation of the electric work machine 1. The work machine 1 can be configured in all orientations.

[0139] [2-1-1. Mechanical Structure of Electric Working Machines]

[0140] Figure 1 The machine shown 1 has a housing 2. The motor 6, the power transmission unit 7, and the controller 13 are housed inside the housing 2.

[0141] The working machine 1 includes a guide rod 8. The guide rod 8 is a plate-shaped component. The guide rod 8 protrudes from the housing 2 toward the front of the working machine 1. The working machine 1 includes a saw chain 9. The saw chain 9 includes multiple interconnected blades. The saw chain 9 is detachably mounted to the periphery of the guide rod 8.

[0142] The power transmission unit 7 is directly or indirectly connected to the motor 6 (specifically, the rotor 19). See reference. Figure 2 The power transmission unit 7 includes a sprocket (not shown) configured for mounting the saw chain 9. The power transmission unit 7 transmits the rotational force of the motor 6 (or the rotation of the rotor 19) to the saw chain 9, thereby driving the saw chain 9.

[0143] When the motor 6 is driven, the saw chain 9 moves along the periphery of the guide bar 8. Accordingly, the saw chain 9 can perform work on the workpiece. Specifically, the saw chain 9 can cut workpieces such as wood, metal, and resin. The saw chain 9 is one example of the working unit. The motor 6 is a motor used to drive the saw chain 9.

[0144] The housing 2 has a battery assembly 3 at its rear. The battery pack 15 is detachably mounted in the battery assembly 3. Various battery packs 15, such as those with different capacities and / or outputs, can be replaced and mounted in the battery assembly 3. Figure 1 This shows the state in which the battery pack 15 is assembled in the battery assembly section 3.

[0145] Battery pack 15 houses a rechargeable battery 15a (see reference). Figure 2The battery 15a includes, for example, a lithium-ion battery. While the battery pack 15 is assembled in the battery assembly section 3, the power from the battery 15a can be supplied to various parts of the machine 1.

[0146] The work machine 1 has a front handle 4 on the upper part of the housing 2. The front handle 4 is held by the user of the work machine 1. The work machine 1 has a rear handle 5 on the rear part of the housing 2. The rear handle 5 is held by the user. The user can use the work machine 1, for example, by holding the front handle 4 with one hand (e.g., the left hand) and the rear handle 5 with the other hand (e.g., the right hand).

[0147] The machine 1 is equipped with a trigger 10. The trigger 10 is manually operated by the user. Specifically, the trigger 10 is pulled upwards manually. Once the trigger 10 is manually operated (i.e. pulled), the motor 6 is driven. In this embodiment, the trigger 10 is located on the rear handle 5. Thus, the user can manually operate the trigger 10 while holding the rear handle 5.

[0148] The workpiece 1 has an unlocking stop 11 next to the trigger 10. The unlocking stop 11 is manually operated by the user (e.g., by pressing downwards). When the unlocking stop 11 is not manually operated by the user, it restricts the movement of the trigger 10. When the unlocking stop 11 is manually operated by the user, the restriction on the trigger 10 is released, and the user can manually operate the trigger 10. In this embodiment, the unlocking stop 11 is located on the rear handle 5. Thus, the user can manually operate the trigger 10 while holding the rear handle 5 and manually operating the unlocking stop 11.

[0149] The workpiece 1 includes an operation panel 12. In this embodiment, the operation panel 12 is disposed on the upper surface of the rear end side of the housing 2. The operation panel 12 includes a power switch 12a and a display 12b.

[0150] The power switch 12a in this embodiment is a momentary switch. While the power switch 12a is pressed, it outputs an operation signal. While the power switch 12a is not pressed, it does not output an operation signal.

[0151] The display 12b visually informs the user of the status of the machine 1. The display 12b of this embodiment includes an LED (not shown). In the following description, "on" and "off" for the display 12b mean "on" and "off" of the LED.

[0152] [2-1-2. Electrical Configuration of the Working Machine]

[0153] Reference Figure 2The electrical configuration of the work machine 1 is explained below. The work machine 1 includes the motor 6 and the controller 13 described above.

[0154] In this embodiment, motor 6 is an internal rotor type brushless motor (specifically a three-phase brushless DC motor). In other embodiments, motor 6 can also be any other type of brushless motor (e.g., an external rotor type brushless motor).

[0155] The motor 6 includes a first coil 20a, a second coil 20b, and a third coil 20c. The first to third coils 20a, 20b, and 20c are connected in a delta configuration. However, the first to third coils 20a, 20b, and 20c can also be connected in a different configuration than the delta configuration. For example, the first to third coils 20a, 20b, and 20c can be connected in a star configuration.

[0156] The motor 6 has a stator (not shown), which includes first to third coils 20a, 20b, and 20c. The stator has multiple teeth (not shown), and the first to third coils 20a, 20b, and 20c are wound around the aforementioned multiple teeth.

[0157] Motor 6 includes a rotor 19. The rotor 19 is configured to extend through the stator and is rotatably supported by bearings (not shown). The rotor 19 has multiple magnetic poles along the direction of rotation. Specifically, in the rotor 19, N poles and S poles are arranged alternately along the direction of rotation. Figure 2 The rotor 19, "N" schematically represents the N pole and "S" schematically represents the S pole.

[0158] Figure 2 For the sake of simplicity, the motor 6 is simply shown as a brushless motor with a 2-pole, 3-slot (i.e., 3-tooth) configuration. However, the motor 6 of the present invention actually has 4 or more magnetic poles and 6 or more slots (i.e., 6 or more teeth). Of course, the motor 6 can also actually be in a 2-pole, 3-slot configuration.

[0159] The motor 6 includes a first terminal 6a, a second terminal 6b, and a third terminal 6c. The first terminal 6a is connected to the first end of the first coil 20a and the first end of the third coil 20c. The second terminal 6b is connected to the second end of the first coil 20a and the first end of the second coil 20b. The third terminal 6c is connected to the second end of the second coil 20b and the second end of the third coil 20c.

[0160] The workpiece 1 includes a position signal output circuit 21. The position signal output circuit 21 is located next to the motor 6 (specifically next to the rotor 19). The position signal output circuit 21 includes a first rotation sensor 21a, a second rotation sensor 21b, and a third rotation sensor 21c. In this embodiment, the first to third rotation sensors 21a to 21c are Hall sensors, but are not limited to Hall sensors.

[0161] The first to third rotation sensors 21a to 21c are configured to move away from the rotor 19 by a predetermined distance in the direction along the rotation axis of the rotor 19. The first to third rotation sensors 21a to 21c are configured to be electrically separated from each other by 120 degrees along the rotation direction of the rotor 19.

[0162] The first rotation sensor 21a outputs the first Hall signal Hu, the second rotation sensor 21b outputs the second Hall signal Hv, and the third rotation sensor 21c outputs the third Hall signal Hw. The first to third Hall signals Hv, Hu, and Hw are digital signals (i.e., binary signals). Whenever the rotor 19 rotates 180 degrees, the logic values ​​of the first to third Hall signals Hu, Hv, and Hw are reversed. The phases of the first to third Hall signals Hu, Hv, and Hw are offset by 120 degrees.

[0163] The working machine 1 includes a power line Lp. The power line Lp extends from the positive terminal of the battery pack 15 mounted in the battery assembly 3 toward the controller 13. The working machine 1 also includes a grounding wire Ln. The grounding wire Ln extends from the negative terminal of the battery pack 15 mounted in the battery assembly 3 toward the controller 13. The battery pack 15 applies a voltage from the battery 15a (hereinafter referred to as "battery voltage") between the power line Lp and the grounding wire Ln.

[0164] The controller 13 includes a power supply circuit 32. The power supply circuit 32 is connected to the power supply line Lp and receives the battery voltage Vbat via the power supply line Lp. The power supply circuit 32 generates a DC voltage (hereinafter referred to as the "power supply voltage") Vc based on the battery voltage Vbat.

[0165] The controller 13 includes a control circuit 30. The control circuit 30 operates upon receiving a power supply voltage Vc. The control circuit 30 is a microcomputer equipped with a processor 30a and a memory 30b.

[0166] The memory 30b is in the form of a semiconductor memory. The memory 30b includes ROM, RAM, and rewritable non-volatile memory. Examples of non-volatile memory include EEPROM, flash memory, ReRAM, and FeRAM. The various functions of the control circuit 30 are implemented by the processor 30a executing computer programs stored in the memory 30b.

[0167] In other embodiments, the control circuit 30 may include an additional microcomputer. Furthermore, in other embodiments, some or all of the functions performed by the processor 30a may be implemented using one or more electronic devices (e.g., integrated circuits). Furthermore, in other embodiments, the control circuit 30 may also be a logic circuit (or hardwired logic connection) including two or more electronic devices. Furthermore, in other embodiments, the control circuit 30 may also include an ASIC and / or an ASSP. Furthermore, in other embodiments, the control circuit 30 may also include a programmable logic device capable of constructing reconfigurable logic circuits. Examples of programmable logic devices include FPGAs.

[0168] The controller 13 includes a drive circuit 31. The drive circuit 31 is electrically connected to the power supply line Lp and the ground line Ln, and receives the battery voltage Vbat via the power supply line Lp and the ground line Ln.

[0169] The drive circuit 31 is electrically connected to the motor 6 via a first lead 26, a second lead 27, and a third lead 28. Specifically, the first lead 26 is connected to the first terminal 6a of the motor 6. The second lead 27 is connected to the second terminal 6b of the motor 6. The third lead 28 is connected to the third terminal 6c of the motor 6.

[0170] The drive circuit 31 functions as an inverter. The drive circuit 31 generates three-phase voltage (i.e., generates three-phase power) based on the battery voltage Vbat. The drive circuit 31 supplies the generated three-phase voltage to the motor 6 via leads 1 to 3, 26 to 28.

[0171] In the following description, the current flowing through the first lead 26 is referred to as the U-phase line current, the current flowing through the second lead 27 is referred to as the V-phase line current, and the current flowing through the third lead 28 is referred to as the W-phase line current. The U-phase line current, V-phase line current, and W-phase line current supplied to the motor 6 from the drive circuit 31 correspond to the line currents input to the motor 6, respectively.

[0172] The drive circuit 31 in this embodiment is a three-phase bridge circuit, but it is not limited to a three-phase bridge circuit. The drive circuit 31 has first to third current paths Lp1 to Lp3 as the so-called upper bridge arm. The first to third current paths Lp1 to Lp3 electrically connect the power line Lp to the first to third terminals 6a, 6b, and 6c of the motor 6, respectively.

[0173] The drive circuit 31 has 4 to 6 current paths Lp4 to Lp6 as the so-called lower bridge arm. The 4 to 6 current paths Lp4 to Lp6 electrically connect the ground wire Ln to the 1 to 3 terminals 6a, 6b, and 6c of the motor 6, respectively.

[0174] The drive circuit 31 includes: a first switch Q1 on the first current path Lp1, a second switch Q2 on the second current path Lp2, a third switch Q3 on the third current path Lp3, a fourth switch Q4 on the fourth current path Lp4, a fifth switch Q5 on the fifth current path Lp5, and a sixth switch Q6 on the sixth current path Lp6.

[0175] Switches Q1 to Q3 (numbers 1-3) function as high-side switches. Switches Q4 to Q6 (numbers 4-6) function as low-side switches. Current paths Lp1 to Lp3 (numbers 1-3) are either turned on or off by switches Q1 to Q3. Current paths Lp4 to Lp6 (numbers 4-6) are either turned on or off by switches Q4 to Q6.

[0176] Switches Q1 to Q6 are semiconductor switches. In this embodiment, switches Q1 to Q6 are n-channel metal-oxide-semiconductor field-effect transistors (MOSFETs). However, switches Q1 to Q6 can also be other types of semiconductor switches, such as bipolar transistors, insulated-gate bipolar transistors (IGBTs), etc.

[0177] Switch Q1 receives a first drive signal UH from control circuit 30 and switches on or off according to UH. Switch Q2 receives a second drive signal VH from control circuit 30 and switches on or off according to VH. Switch Q3 receives a third drive signal WH from control circuit 30 and switches on or off according to WH. Switch Q4 receives a fourth drive signal UL from control circuit 30 and switches on or off according to UL. Switch Q5 receives a fifth drive signal VL from control circuit 30 and switches on or off according to VL. Switch Q6 receives a sixth drive signal WL from control circuit 30 and switches on or off according to WL. In this embodiment, the first to sixth drive signals UH, VH, WH, UL, VL, and WL can each be a pulse width modulation signal.

[0178] When motor 6 is driven, in principle, any one high-side switch and any one low-side switch are turned on. Accordingly, current flows from the positive terminal of battery pack 15 through the high-side switch, motor 6, and the low-side switch to the negative terminal of battery pack 15, thereby causing motor 6 to rotate. This current corresponds to the battery current Ibat.

[0179] The drive circuit 31 includes a first current detection circuit 36 ​​on the first lead 26. The first current detection circuit 36 ​​detects the U-phase line current flowing through the first lead 26. Specifically, the first current detection circuit 36 ​​outputs a U-phase line current detection signal Siu corresponding to the magnitude of the U-phase line current. The U-phase line current detection signal Siu is input to the control circuit 30.

[0180] The drive circuit 31 includes a second current detection circuit 37 on the second lead 27. The second current detection circuit 37 detects the V-phase line current flowing through the second lead 27. Specifically, the second current detection circuit 37 outputs a V-phase line current detection signal Siv corresponding to the magnitude of the V-phase line current. The V-phase line current detection signal Siv is input to the control circuit 30.

[0181] The drive circuit 31 includes a third current detection circuit 38 on the third lead 28. The third current detection circuit 38 detects the W-phase line current flowing through the third lead 28. Specifically, the third current detection circuit 38 outputs a W-phase line current detection signal Siw corresponding to the magnitude of the W-phase line current. The W-phase line current detection signal Siw is input to the control circuit 30.

[0182] The controller 13 includes a battery current detection circuit 33. The battery current detection circuit 33 is located on the current path through which the battery current Ibat flows. In this embodiment, the battery current detection circuit 33 is located on the grounding wire Ln within the controller 13, and more specifically, on the current path between the drive circuit 31 and the grounding part.

[0183] The battery current detection circuit 33 detects the battery current Ibat. Specifically, the battery current detection circuit 33 outputs a battery current detection signal Sib corresponding to the magnitude of the battery current Ibat. The battery current detection signal Sib is input to the control circuit 30.

[0184] According to this embodiment, the battery current detection circuit 33 is located between the drive circuit 31 (inverter) and the grounding portion; in other words, it is located between the drive circuit 31 (inverter) and the negative terminal of the battery 15a, and measures the battery current Ibat returning to the battery 15a. Therefore, as another example, the battery current detection circuit 33 can also be located between the negative terminal of the battery 15a and the grounding portion. The battery current Ibat detected here does not include the capacitor current flowing between the capacitor (not shown) on the inverter and the motor 6, but the term "battery current" is not limited to a current that does not include capacitor current. That is, the term "battery current" can be understood broadly as a term that allows the inclusion of capacitor current in its components.

[0185] The controller 13 also includes a battery voltage detection circuit 34. The battery voltage detection circuit 34 detects the battery voltage Vbat, which is the potential difference generated across the terminals of the battery 15a. The battery voltage detection circuit 34 inputs the detected battery voltage Vbat to the control circuit 30.

[0186] The controller 13 includes a first temperature detection circuit 39. The first temperature detection circuit 39 is located within or next to the drive circuit 31. The first temperature detection circuit 39 includes a first temperature sensor (not shown). The first temperature sensor is, for example, a thermistor. The first temperature sensor outputs a first temperature detection signal Std corresponding to the temperature around the sensor. The first temperature detection signal Std is input to the control circuit 30. The first temperature detection signal Std directly or indirectly represents the temperature of switches Q1 to Q6 (in other words, the temperature of the drive circuit 31). The first temperature detection circuit 39 is provided for detecting the temperature of the drive circuit 31, i.e., the inverter.

[0187] The workpiece 1 includes a second temperature detection circuit 23. The second temperature detection circuit 23 is located inside or beside the motor 6. The second temperature detection circuit 23 includes a second temperature sensor (not shown). The second temperature sensor is, for example, a thermistor. The second temperature sensor outputs a second temperature detection signal Stm corresponding to the temperature around the sensor. The second temperature detection signal Stm is input to the control circuit 30. The second temperature detection signal Stm directly or indirectly represents the temperature of the motor 6. The second temperature detection circuit 23 is provided for detecting the temperature of the motor 6. However, temperature, as described later, is a parameter that can be estimated. Therefore, the temperature detection circuit can be arbitrarily set. For example, the second temperature detection circuit 23 may not be provided.

[0188] The work machine 1 also includes a trigger detection circuit 22. The trigger detection circuit 22 is mechanically connected to the trigger 10 and outputs a first trigger signal TR1 and a second trigger signal TR2 corresponding to the state of the trigger 10. The first trigger signal TR1 is a binary signal indicating whether the trigger 10 is manually operated. For example, when the trigger 10 is not manually operated, the first trigger signal TR1 is a low-level signal; when the trigger 10 is manually operated, the first trigger signal TR1 is a high-level signal. The second trigger signal TR2 is an analog signal corresponding to the amount of movement (in other words, the amount of pulling) by which the trigger 10 has moved from its initial position.

[0189] The first and second trigger signals TR1 and TR2 are input to the control circuit 30. Based on the first and second trigger signals TR1 and TR2, the control circuit 30 can obtain information indicating whether the trigger 10 is turned on (i.e., manually operated), and the pull amount of the trigger 10 when the trigger 10 is manually operated.

[0190] The power switch 12a and display 12b are electrically connected to the control circuit 30. The control circuit 30 receives an operation signal from the power switch 12a. Based on the presence or absence of the operation signal, the control circuit 30 can identify whether the power switch 12a has been pressed.

[0191] In this embodiment, even if the battery pack 15 is assembled into the battery assembly section 3, the power supply voltage Vc will not be generated immediately. After the battery pack 15 is assembled, the power supply voltage Vc is generated corresponding to the power switch 12a being pressed and held, thereby activating the control circuit 30. A "press and hold" means, for example, that the power switch 12a has been continuously pressed for a first predetermined time (e.g., 2 to 3 seconds) or more.

[0192] The control circuit 30 controls the display 12b (specifically, an LED in this embodiment) according to the state of the work machine 1. For example, during startup, the control circuit 30 illuminates the display 12b in a first mode. The first mode may be, for example, illuminating the LED with a first color (e.g., green).

[0193] The control circuit 30 receives the first to third Hall signals Hu, Hv, and Hw from the position signal output circuit 21. As described above, the phases of the first to third Hall signals Hu, Hv, and Hw are offset from each other by an electrical angle of 120 degrees. Therefore, whenever the rotor 19 rotates by an electrical angle of 60 degrees, one of the logic values ​​of the first to third Hall signals Hu, Hv, and Hw changes. Based on the change in logic value every 60 degrees, the control circuit 30 detects the rotational position (in other words, the rotation angle) and rotational speed of the motor 6.

[0194] The control circuit 30 also receives the first temperature detection signal Std and the second temperature detection signal Stm mentioned above.

[0195] The control circuit 30 also receives the aforementioned U-phase line current detection signal Siu, V-phase line current detection signal Siv, and W-phase line current detection signal Siw.

[0196] The control circuit 30 controls the rotation of the motor 6 based on various input signals, as described later. The control circuit 30 is configured to drive the motor 6 via vector control.

[0197] [2-1-3. Functions of the control circuit]

[0198] like Figure 3 As shown, the control circuit 30 has the functions of a position and speed calculation unit 41, a current conversion unit 42, a speed command unit 43, a speed control unit 44, a limit value setting unit 45, a current control unit 47, and a voltage conversion unit 49. These functions are not limited, but can be implemented, for example, by the processor 30a executing a computer program stored in the memory 30b.

[0199] As another example, the function of at least one of the position-speed calculation unit 41, current conversion unit 42, speed command unit 43, speed control unit 44, limit value setting unit 45, current control unit 47, and voltage conversion unit 49 can also be implemented by hardware (e.g., dedicated electronic circuitry) rather than software. That is, the corresponding hardware can also be assembled into the control circuit 30.

[0200] Hall signals Hu, Hv, and Hw, from the first to the third position signal output circuit 21 (see reference) Figure 2 The value is input to the position and speed calculation unit 41. The position and speed calculation unit 41 calculates the rotation angle θ of the rotor 19 and the speedometer measurement value ω_m based on the first to third Hall signals Hu, Hv, and Hw. The speedometer measurement value ω_m is the measured value of the rotation speed of the rotor 19.

[0201] The method for calculating the rotation angle θ and the speedometer measurement value ω_m based on the first to third Hall signals Hu, Hv, and Hw is not limited to a specific method; for example, a known method can be used. The position-velocity calculation unit 41 inputs the calculated rotation angle θ to the current conversion unit 42 and the voltage conversion unit 49, and inputs the calculated speedometer measurement value ω_m to the speed control unit 44 and the limit value setting unit 45.

[0202] The detection signals of the three-phase line currents of phases U, V, and W are input to the current conversion unit 42. The three-phase line current detection signals input to the current conversion unit 42 are: the U, V, and W phase line current detection signals Siu, Siv, and Siw from the first to third current detection circuits 36, 37, and 38. The U, V, and W phase line current detection signals Siu, Siv, and Siw represent the magnitudes of the U, V, and W phase line currents detected by the first to third current detection circuits 36, 37, and 38, that is, the measured values ​​of the U, V, and W phase line currents.

[0203] The current conversion unit 42 converts the measured values ​​of the three-phase line currents of phases U, V, and W into d-q axis currents (Id_m, Iq_m) in the d-q coordinate system. The d-q axis currents (Id_m, Iq_m) are two-dimensional current vectors that include the d-axis current Id_m and the q-axis current Iq_m in the element. The current conversion unit 42 can convert the measured values ​​of the three-phase line currents into the d-axis current Id_m and the q-axis current Iq_m, for example, through Clarke transformation and Park transformation.

[0204] The d-q coordinate system is a well-known rotating coordinate system consisting of orthogonal d-axis and q-axis. The d-axis represents the direction of magnetic flux of the magnetic body of the rotor 19 inside the motor 6. The q-axis represents the direction of torque generated in the rotor 19. The d-axis current Id_m is the d-axis component of the current vector. The q-axis current Iq_m is the q-axis component of the current vector.

[0205] The current conversion unit 42 inputs the converted d-axis current Id_m and q-axis current Iq_m to the limit value setting unit 45 and the current control unit 47, respectively. Hereinafter, the d-axis current Id_m and q-axis current Iq_m output from the current conversion unit 42 will be described as the d-axis current meter measured value Id_m and the q-axis current meter measured value Iq_m, respectively.

[0206] The first trigger signal TR1 and the second trigger signal TR2 of trigger 10 are input to the speed command unit 43. The speed command unit 43 calculates the speed command value ω_r based on the first trigger signal TR1 and the second trigger signal TR2.

[0207] The speed command value ω_r is a command value for the rotational speed of rotor 19. When the first trigger signal TR1 indicates that trigger 10 is not manually operated, the speed command unit 43 calculates the speed command value ω_r = 0. When the first trigger signal TR1 indicates that trigger 10 is manually operated, the speed command unit 43 calculates the speed command value ω_r in such a way that the larger the pull amount of trigger 10 indicated by the second trigger signal TR2, the larger the value. The speed command unit 43 outputs the calculated speed command value ω_r to the speed control unit 44.

[0208] The speed command value ω_r and the speedometer measurement value ω_m are input to the speed control unit 44. The d-axis current limit value, Id_limit, set by the limit value setting unit 45, is also input to the speed control unit 44. The q-axis current limit value, Iq_limit, set by the limit value setting unit 45, is also input to the speed control unit 44.

[0209] The speed control unit 44 calculates the d-axis current command value Id_r and the q-axis current command value Iq_r based on the speed command value ω_r and the speedometer measurement value ω_m. Specifically, the speed control unit 44 calculates the d-axis current command value Id_r within a range not exceeding the d-axis current limit value Id_limit, and calculates the q-axis current command value Iq_r within a range not exceeding the q-axis current limit value Iq_limit. The speed control unit 44 inputs the calculated d-axis current command value Id_r and q-axis current command value Iq_r to the current control unit 47.

[0210] Figure 4 The detailed configuration of the speed control unit 44 is shown. The speed control unit 44 includes: a deviation calculation unit 441, a PI controller 443, a dq converter 445, and a limiter 447. The deviation calculation unit 441 calculates the speed deviation E = ω_r - ω_m. The speed deviation E is the deviation between the speed command value ω_r and the speedometer measurement value ω_m. The speed deviation E is input to the PI controller 443.

[0211] The PI controller 443 is configured to output a q-axis current command value Iq_pi corresponding to the speed deviation E through PI (Proportional-Integral control). The q-axis current command value Iq_pi output from the PI controller 443 is input to the dq converter 445.

[0212] The dq conversion unit 445 converts the q-axis current command value Iq_pi into the d-axis current command value Id_tp and the q-axis current command value Iq_tp. For example, the dq conversion unit 445 calculates the d-axis current command value Id_tp and the q-axis current command value Iq_tp in a manner that implements MTPA (Maximum Torque Per Ampere) control. For example, the dq conversion unit 445 calculates the d-axis current command value Id_tp and the q-axis current command value Iq_tp in a manner that implements weak excitation control. For example, the dq conversion unit 445 calculates the d-axis current command value Id_tp and the q-axis current command value Iq_tp in a manner that implements zero d-axis current control.

[0213] The dq conversion unit 445 can operate in multiple control modes, including at least one of the MTPA control mode, weak excitation control mode, and d-axis current zero control mode. Based on the q-axis current command value Iq_pi, the dq conversion unit 445 can calculate the d-axis current command value Id_tp and the q-axis current command value Iq_tp corresponding to the control mode. The dq conversion unit 445 can treat the q-axis current command value Iq_pi as a torque command value and calculate the d-axis current command value Id_tp and the q-axis current command value Iq_tp in a manner that achieves the corresponding torque.

[0214] The d-axis current command value Id_tp and the q-axis current command value Iq_tp calculated by the dq conversion unit 445 are input to the limiter 447.

[0215] When the d-axis current command value Id_tp input from the dq conversion unit 445 is below the d-axis current limit value Id_limit, the limiter 447 outputs the d-axis current command value Id_tp as the output of the speed control unit 44. That is, the limiter 447 outputs the d-axis current command value Id_tp as the aforementioned d-axis current command value Id_r.

[0216] When the d-axis current command value Id_tp input from the dq conversion unit 445 exceeds the d-axis current limit value Id_limit, the limiter 447 outputs the d-axis current limit value Id_limit as the d-axis current command value Id_r.

[0217] Similarly, when the q-axis current command value Iq_tp input from the dq conversion unit 445 is below the q-axis current limit value Iq_limit, the limiter 447 outputs the q-axis current command value Iq_tp as the aforementioned q-axis current command value Iq_r.

[0218] When the q-axis current command value Iq_tp input from the dq conversion unit 445 exceeds the q-axis current limit value Iq_limit, the limiter 447 outputs the q-axis current limit value Iq_limit as the q-axis current command value Iq_r.

[0219] The d-axis current command value Id_r and the q-axis current command value Iq_r output from the limiter 447 are input to the current control unit 47 as described above. The d-axis current meter readings Id_m and Iq_m are also input to the current control unit 47.

[0220] The current control unit 47 is configured to convert the d-axis current command value Id_r and the q-axis current command value Iq_r input from the speed control unit 44 into the d-axis voltage command value Vd_r and the q-axis voltage command value Vq_r. This conversion is not limited and can be performed using known techniques.

[0221] Specifically, the current control unit 47 calculates the d-axis voltage command value Vd_r and the q-axis voltage command value Vq_r based on the q-axis current command value Iq_r, the q-axis current meter reading Iq_m, the d-axis current command value Id_r, and the d-axis current meter reading Id_m. The current control unit 47 then inputs the calculated d-axis voltage command value Vd_r and the q-axis voltage command value Vq_r to the voltage conversion unit 49.

[0222] The d-axis voltage command value Vd_r, the q-axis voltage command value Vq_r, the battery voltage Vbat, and the rotation angle θ are input to the voltage conversion unit 49. The voltage conversion unit 49 calculates the three-phase voltage command values ​​based on the d-axis voltage command value Vd_r, the q-axis voltage command value Vq_r, the battery voltage Vbat, and the rotation angle θ.

[0223] The voltage conversion unit 49 converts the d-axis voltage command value Vd_r and the q-axis voltage command value Vq_r into three-phase voltage command values, for example, through inverse Clarke transformation and inverse Park transformation. The voltage conversion unit 49 outputs the calculated three-phase voltage command values ​​as the first to sixth drive signals UH, VH, WH, UL, VL, and WL to the drive circuit 31 (see reference). Figure 2 The three-phase line current is supplied to the motor 6 through the drive circuit 31.

[0224] [2-1-4. Structure of the Limit Value Setting Unit]

[0225] The limit setting unit 45 is configured to: (i) set a line current limit value Ia_limit corresponding to the operating state of the machine 1; (ii) convert the line current limit value Ia_limit into a d-axis current limit value Id_limit and a q-axis current limit value Iq_limit; and (iii) output the limit value.

[0226] The line current limit value Ia_limit is the limit value for the line current flowing through motor 6. The line current corresponds to the current flowing through each of the three phases of motor 6. The line current limit value Ia_limit can correspond to the upper limit value of the line current amplitude.

[0227] Specifically, the limit setting unit 45 is configured to set a line current limit value Ia_limit that takes into account the input limit Pin_limit, the output limit Pout_limit, and the torque limit Trq_limit. The limit setting unit 45 is configured to consider factors such as the rotational speed of the motor 6, temperature Tm, battery current Ibat, and battery voltage Vbat when setting the line current limit value Ia_limit.

[0228] The input limit Pin_limit, output limit Pout_limit, and torque limit Trq_limit correspond to the constraint parameters. The input limit Pin_limit is the constraint on the input energy from battery 15a. The input limit Pin_limit corresponds to the upper limit of the input energy from battery 15a to motor 6. The input limit Pin_limit can be expressed using the battery voltage Vbat and the upper limit of the battery current Ibat_limit, and is represented by the formula Pin_limit = Vbat · Ibat_limit.

[0229] The upper limit of the battery current, Ibat_limit, can correspond to the maximum allowable current of the battery 15A. The input limit, Pin_limit, can vary depending on the battery 15A installed in the work machine 1. That is, the input limit, Pin_limit, varies depending on the state of the work machine 1.

[0230] The output limit Pout_limit is the constraint on the output energy produced by the capability of motor 6. The output limit Pout_limit corresponds to the upper limit of the output energy. The torque limit Trq_limit is the constraint on the output torque produced by the capability of motor 6. The torque limit Trq_limit corresponds to the upper limit of the output torque. Both the output limit Pout_limit and the torque limit Trq_limit are determined based on the performance of motor 6 mounted on the work machine 1.

[0231] Figure 5 The detailed configuration of the limit setting unit 45 is shown below. The limit setting unit 45 includes: an input limit input unit 51 for inputting the upper limit of the battery current Ibat_limit for calculating the input limit Pin_limit, an output limit input unit 53 for inputting the output limit Pout_limit, and a torque limit input unit 55 for inputting the torque limit Trq_limit.

[0232] The limit setting unit 45 also includes an inverter efficiency input unit 57 for inputting inverter efficiency η_inv and a mechanical conversion efficiency input unit 59 for inputting mechanical conversion efficiency η_mech. Inverter efficiency η_inv represents the ratio of output energy Pmtr to input energy Pin supplied to the inverter (drive circuit 31), where η_inv = Pmtr / Pin. For example, the inverter efficiency η_inv is set to a fixed value relative to the inverter (drive circuit 31).

[0233] The mechanical conversion efficiency η_mech represents the ratio of output energy Pout to input energy Pmtr supplied to motor 6, where η_mech = Pout / Pmtr. Output energy Pout can be calculated, for example, using torque × angular velocity. The mechanical conversion efficiency input unit 59 can calculate the mechanical conversion efficiency η_mech based on the speedometer measurement value ω_m input from the position-speed calculation unit 41.

[0234] The limit setting unit 45 also includes: a loss calculation unit 60, an input limit calculation unit 71, a torque limit calculation unit 73, an output limit calculation unit 75, a first selection unit 77, and a limit conversion unit 80.

[0235] The loss calculation unit 60 is configured to calculate the energy lost from the input to the motor 6 that is not converted into mechanical output. The lost energy includes copper loss and iron loss. The loss calculation unit 60 includes: a line current amplitude calculation unit 61, a temperature estimation unit 63, a resistance estimation unit 65, a copper loss estimation unit 67, an iron loss estimation unit 68, and a motor loss estimation unit 69.

[0236] The line current amplitude calculation unit 61 is configured to calculate the line current amplitude Ia_m based on the d-axis galvanometer measurement value Id_m and the q-axis galvanometer measurement value Iq_m input from the current conversion unit 42. The line current amplitude Ia_m can be understood as the magnitude of the current vector (Id_m, Iq_m). The line current amplitude calculation unit 61 inputs the calculated line current amplitude Ia_m to the temperature estimation unit 63.

[0237] The temperature estimation unit 63 is configured to estimate the temperature Tm of the motor 6. Specifically, the temperature estimation unit 63 (i) estimates the temperature Tm of the motor 6 based on the linear current amplitude Ia_m and the speedometer measurement value ω_m input from the position speed calculation unit 41, and (ii) inputs the estimated temperature Tm of the motor 6 as the motor temperature Tm to the resistance estimation unit 65. The temperature estimation unit 63 can (i) receive a second temperature detection signal Stm representing the temperature of the motor 6 detected by the second temperature detection circuit 23 from the second temperature detection circuit 23, and (ii) input the temperature represented by the second temperature detection signal Stm as the motor temperature Tm to the resistance estimation unit 65.

[0238] The resistance estimation unit 65 estimates the resistance Ra of the motor 6 based on the motor temperature Tm input from the temperature estimation unit 63. The resistance estimation unit 65 inputs the estimated resistance Ra of the motor 6 as the motor resistance Ra to the copper loss estimation unit 67.

[0239] The copper loss estimation unit 67 estimates the copper loss in the motor 6, that is, the power loss generated by the motor resistance Ra, based on the motor resistance estimation unit 65 and the line current amplitude Ia_m, which is input from the line current amplitude calculation unit 61. The copper loss estimation unit 67 inputs the estimated copper loss as loss Lc to the motor loss estimation unit 69.

[0240] The iron loss estimation unit 68 estimates the iron loss in the motor 6, that is, the power loss generated by the change of the magnetic field, based on the line current amplitude Ia_m input from the line current amplitude calculation unit 61 and the speedometer measurement value ω_m input from the position speed calculation unit 41. The iron loss estimation unit 68 inputs the estimated iron loss as loss Li to the motor loss estimation unit 69.

[0241] The iron loss estimation unit 68 includes a table (not shown) that associates each combination of loss Li with the line current amplitude Ia_m and the speedometer measurement value ω_m. The iron loss estimation unit 68 can refer to this table to input the loss Li based on the line current amplitude Ia_m and the speedometer measurement value ω_m into the motor loss estimation unit 69.

[0242] The motor loss estimation unit 69 is configured to output the sum of the input loss Lc and loss Li (Lc + Li) as the energy loss of the motor 6, i.e., the motor loss P_loss. The motor loss P_loss output by the motor loss estimation unit 69 is input to the input limit value calculation unit 71.

[0243] The upper limit of the battery current Ibat_limit is input from the input limit input unit 51 to the input limit value calculation unit 71, the inverter efficiency η_inv is input from the inverter efficiency input unit 57 to the input limit value calculation unit 71, the battery voltage Vbat is input from the battery voltage detection circuit 34 to the input limit value calculation unit 71, the motor loss P_loss is input from the loss calculation unit 60 to the input limit value calculation unit 71, and the speedometer measurement ω_m is input from the position speed calculation unit 41 to the input limit value calculation unit 71.

[0244] The input limit calculation unit 71 calculates the upper limit of the line current Ia caused by the constraint of input energy, namely the input limit Pin_limit = Vbat·Ibat_limit, based on the upper limit of battery current Ibat_limit, inverter efficiency η_inv, battery voltage Vbat, motor loss P_loss, and speedometer measurement ω_m, which is also the first limit value LM1.

[0245] As is well known, the output energy Pout of motor 6 is calculated using the product of torque τ and angular velocity ω of motor 6, Pout = τ·ω. Torque τ is expressed by the formula τ = pn·Ia·Ψa, using the line current Ia, induced voltage constant Ψa, and stator pole pair number pn of motor 6.

[0246] If we use the inverter efficiency η_inv, the motor efficiency η_mtr, and the input energy Pin for motor 6, then the mechanical output of motor 6 is represented by Pin·η_inv·η_mtr = Pin·η_inv - P_loss. That is: Pin·η_inv - P_loss = pn·Ia·Ψa·ω.

[0247] In the above formula, when the input energy Pin is replaced by the input limit = Pin_limit = Vbat·Ibat_limit, and the line current Ia is replaced by the upper limit of the line current (LM1), the upper limit of the line current (LM1) can be calculated by the following formula.

[0248] LM1={Vbat·Ibat_limit·η_inv-P_loss} / (pn·Ψa·ω_m)

[0249] ω_m, as described above, is the measured speed value of motor 6, and also the measured value of angular velocity ω. The input limit value calculation unit 71 calculates the first limit value LM1 according to this formula. The input limit value calculation unit 71 inputs the calculated first limit value LM1 to the first selection unit 77. In the above formula, the stator pole pair number pn and the induced voltage constant Ψa are constants corresponding to motor 6.

[0250] The torque limit calculation unit 73 calculates the upper limit of the line current Ia, i.e., the second limit value LM2, based on the torque limit Trq_limit and the speedometer measurement value ω_m. The torque limit Trq_limit is input to the torque limit calculation unit 73 from the torque limit input unit 55, and the speedometer measurement value ω_m is input to the torque limit calculation unit 73 from the position speed calculation unit 41.

[0251] As mentioned above, the torque τ is represented by the formula τ = pn·Ia·Ψa. In this formula, when the torque τ is replaced by the torque limit Trq_limit and the line current Ia is replaced by the upper limit of the line current (LM2), the upper limit of the line current (LM2) corresponding to the torque limit Trq_limit can be calculated by the following formula.

[0252] LM2=Trq_limit / (pn·Ψa)

[0253] The torque limit calculation unit 73 calculates the second limit value LM2 according to the formula. The torque limit calculation unit 73 inputs the calculated second limit value LM2 to the first selection unit 77. The second limit value LM2 is the upper limit of the line current that may cause the coil of the motor 6 to burn out or the switching element (MOSFET) to be thermally damaged when the line current exceeds the second limit value LM2.

[0254] The output limit calculation unit 75 calculates the upper limit of the line current Ia, i.e., the third limit value LM3, based on the output limit Pout_limit and the speedometer measurement value ω_m. The output limit Pout_limit is input to the output limit calculation unit 75 from the output limit input unit 53, and the speedometer measurement value ω_m is input to the output limit calculation unit 75 from the position and speed calculation unit 41.

[0255] The output energy Pout of motor 6 can be calculated using the formula Pout=τ·ω=pn·Ia·Ψa·ω. In this formula, when the output energy Pout is replaced with the output limit Pout_limit and the line current Ia is replaced with the upper limit of the line current (LM3), the upper limit of the line current (LM3) corresponding to the output limit Pout_limit can be calculated by the following formula.

[0256] LM3=Pout_limit / (pn·Ψa·ω_m)

[0257] The output limit value calculation unit 75 calculates the third limit value LM3 according to the calculation formula. The output limit value calculation unit 75 inputs the calculated third limit value LM3 into the first selection unit 77.

[0258] According to another example, the mechanical conversion efficiency η_mech can also be input from the mechanical conversion efficiency input unit 59 to the output limit value calculation unit 75. Taking the mechanical conversion efficiency η_mech into account, the output energy Pout of the motor 6 is represented by the formula Pout=η_mech·pn·Ia·Ψa·ω.

[0259] The output limit calculation unit 75 can take into account the mechanical conversion efficiency η_mech and calculate the upper limit of the line current (LM3) corresponding to the output limit Pout_limit using the following formula.

[0260] LM3=Pout_limit / (η_mech·pn·Ψa·ω_m)

[0261] According to another example, the output limit calculation unit 75 can calculate the third limit value LM3, which takes into account the mechanical conversion efficiency η_mech, according to the calculation formula, and input it into the first selection unit 77.

[0262] The first selection unit 77 is configured to select the minimum limit value among the first limit value LM1 input from the input limit value calculation unit 71, the second limit value LM2 input from the torque limit value calculation unit 73, and the third limit value LM3 input from the output limit value calculation unit 75, and output it as the line current limit value Ia_limit. The line current limit value Ia_limit output from the first selection unit 77 is input to the limit value conversion unit 80.

[0263] The limit value conversion unit 80 is configured to convert the line current limit value Ia_limit input from the first selection unit 77 into the d-axis current limit value Id_limit and the q-axis current limit value Iq_limit, and then output them.

[0264] like Figure 5 As shown, the limit value conversion unit 80 includes: an MTPA conversion unit 81, a battery current limiter 83, and a second selection unit 85. The MTPA conversion unit 81 includes an MTPA table (not shown) that describes the d-axis current and q-axis current for achieving maximum torque relative to the line current. It is configured such that, according to the MTPA table, the values ​​of the d-axis current and q-axis current for achieving maximum torque are output as upper limits for the d-axis current and q-axis current relative to the line current limit value Ia_limit. The upper limits for the d-axis current and q-axis current output by the MTPA conversion unit 81 are input to the second selection unit 85.

[0265] The battery current limiter 83 is configured to output upper limits of the d-axis current and q-axis current, taking into account the battery current Ibat, the d-axis current meter reading Id_m, and the q-axis current meter reading Iq_m.

[0266] The second selection unit 85 outputs the smaller of the upper limit value input from the MTPA conversion unit 81 and the upper limit value input from the battery current limiter 83 as the d-axis current limit value Id_limit and the q-axis current limit value Iq_limit, respectively, for the d-axis current and q-axis current. The d-axis current limit value Id_limit and the q-axis current limit value Iq_limit output from the second selection unit 85 are input to the speed control unit 44.

[0267] The speed control unit 44 controls the motor 6 based on the d-axis current limit value Id_limit and the q-axis current limit value Iq_limit set as follows. As a result, the speed and torque of the motor 6 are as follows: Figure 6 It changes as shown.

[0268] Figure 6In the graph with torque τ on the horizontal axis and speed N on the vertical axis, the N-T characteristic curve, showing the relationship between torque τ and speed N achieved through the control of motor 6, is shown by a thick solid line. The N-T characteristic curve referred to here means: a characteristic curve representing the relationship between the speed N of motor 6 and torque τ (in other words, torque T).

[0269] Figure 6 The N-T characteristic curve shown represents the relationship between torque τ and rotational speed N when the pull amount of trigger 10 is constant (e.g., maximum pull amount) and a constant speed command value ω_r corresponding to the pull amount is input from the speed command unit 43. In this case, under conditions of relatively small load on motor 6, the rotational speed N of motor 6 is maintained constant. Figure 6 The region R1 shown is shown.

[0270] Subsequently, as the load increases, and the torque τ achieved by motor 6 increases, the voltage corresponding to the current command values ​​(Id_r, Iq_r) reaches the upper limit of the inverter's (drive circuit 31) output voltage. Motor 6 then reduces its speed N while achieving the required torque corresponding to the load. Figure 6 (See region R2). In this region, the torque τ and the rotational speed N are proportional. That is, relative to the increase in torque τ, the rotational speed N decreases at a constant slope.

[0271] When the load on motor 6 increases, and the required torque increases, the speed control unit 44 will be constrained by the input energy or output energy to perform constant output control on motor 6. Figure 6 (As shown in region R3). The d-axis current limit value Id_limit and the q-axis current limit value Iq_limit corresponding to the first limit value LM1 or the third limit value LM3 are input to the speed control unit 44. Accordingly, the d-axis current command value Id_r and the q-axis current command value Iq_r output from the speed control unit 44 are set as the d-axis current limit value Id_limit and the q-axis current limit value Iq_limit, thereby realizing the constant output control.

[0272] At this point, it means that the rotational speed N is inversely proportional to the torque τ. This is because the output energy corresponds to the product of the torque τ and the rotational speed N (in other words, the angular velocity ω).

[0273] When the load on motor 6 increases further, and the required torque increases, the speed control unit 44 is constrained by the motor torque and performs a process to control motor 6 in a way that ensures the torque of motor 6 does not exceed a constant value, that is, to limit the torque. Figure 6(See location R4). The d-axis current limit value Id_limit and the q-axis current limit value Iq_limit, corresponding to the second limit value LM2, are input to the speed control unit 44. Accordingly, the d-axis current command value Id_r and the q-axis current command value Iq_r output from the speed control unit 44 are set as the d-axis current limit value Id_limit and the q-axis current limit value Iq_limit, thereby achieving torque limiting.

[0274] In this embodiment, the machine 1 sets the minimum value among the energy-constrained limit values ​​LM1, LM3, and the torque-constrained limit value LM2 as the line current limit value Ia_limit. The machine 1 outputs the d-axis current command value Id_r and the q-axis current command value Iq_r based on the d-axis current limit value Id_limit and the q-axis current limit value Iq_limit, ensuring that the line current Ia flowing through the motor 6 does not exceed the line current limit value Ia_limit. Therefore, the machine 1 can operate stably under increasing load while maximizing the utilization of the motor 6's capacity.

[0275] That is, it can suppress the following situation: when motor control is executed based on d-axis current command values ​​Id_r and q-axis current command values ​​Iq_r that do not conform to the state of machine 1, errors caused by overcurrent or overload will occur, causing machine 1 to stop suddenly and reducing availability. In addition, it can suppress thermal damage such as coil burnout.

[0276] The above describes the operation of the control circuit 30 using functional modules. The following flowchart will be used to illustrate the operation of the control circuit 30.

[0277] [2-1-5. Control Circuit Processing]

[0278] The processor 30a of the control circuit 30 executes Figure 7 The main processing unit is shown. The loops within the main processing unit (processing steps S130–S170 described later) are executed with a first cycle, for example, 1 kHz. Processor 30a executes separately from this main processing unit. Figure 10 The interrupt handling is shown. The interrupt handling is executed in a second cycle, which is shorter than the first cycle, for example, a cycle of 20 kHz.

[0279] [2-1-5-1. Main Processing]

[0280] Processor 30a begins main processing along with the startup of workstation 1. When main processing begins, processor 30a communicates with battery pack 15 to obtain battery information (S110). The battery information includes: internal impedance, overcurrent threshold, overload threshold, and battery type information. The battery type information may include the battery model and capacity. The battery information may also include remaining capacity, battery temperature, battery voltage, and battery current.

[0281] In the following S120, the processor 30a sets the upper limit of battery current Ibat_limit, the torque limit Trq_limit, the output limit Pout_limit, and the inverter conversion efficiency η_inv as parameters for setting the line current limit value Ia_limit.

[0282] Settings are made based on the device information of the work machine 1 stored in the memory 30b. As described above, the work machine 1 is configured to be able to replace the battery pack 15. That is, by replacement, the work machine 1 can be equipped with multiple types of battery packs 15.

[0283] Therefore, the processor 30a sets a battery current limit Ibat_limit corresponding to the battery current that the battery pack 15 mounted on the work unit 1 can supply, based on information about the battery type obtained through communication with the battery pack 15. The battery current limit Ibat_limit can be set taking into account the battery temperature.

[0284] In the following S130, the processor 30a determines whether the drive conditions are met. The processor 30a can determine that the drive conditions are met when the protection circuit issues a drive permission, and the trigger switch (not shown) is switched on by pulling the trigger 10.

[0285] When it is determined that the driving condition is not met (No in S130), the processor 30a stops the motor 6 or maintains the stopped state of the motor 6 (S135). After that, the process proceeds to S170.

[0286] When it is determined that the driving condition has been met (Yes in S130), the processor 30a commands the speed control unit 44 to drive the motor 6 (S140). The processor 30a can command the speed control unit 44 to drive the motor 6 by generating and outputting a speed command value ω_r corresponding to the pull amount of the trigger 10. The generation and output of the speed command value ω_r correspond to the processing implemented by the speed command unit 43 described above.

[0287] In the following S150, processor 30a performs state determination processing. Details of the state determination processing are as follows... Figure 8 As shown. When the state determination process begins, the processor 30a determines the battery current Ibat and the battery voltage Vbat (S210). In the following S220, the processor 30a calculates the line current amplitude Ia_m. The calculation of the line current amplitude Ia_m corresponds to the processing performed by the line current amplitude calculation unit 61 described above.

[0288] In the following S230, the processor 30a performs speed determination processing. As speed determination processing, the processor 30a can perform processing to calculate the rotational speed N, that is, the speed measurement value ω_m of the motor 6. The processing to calculate the speed measurement value ω_m corresponds to the processing performed by the position speed calculation unit 41 described above.

[0289] In the following S240, processor 30a performs temperature determination processing. In this temperature determination processing, processor 30a can determine the battery temperature, motor temperature, and inverter temperature.

[0290] Processor 30a can determine the battery temperature based on battery information. Processor 30a can estimate the motor temperature Tm based on the line current amplitude Ia_m and the speedometer measurement ω_m. That is, processor 30a can determine the motor temperature Tm by estimation. Processor 30a can determine the motor temperature Tm based on the second temperature detection signal Stm. Processor 30a can determine the inverter temperature based on the first temperature detection signal Std. The estimation of the motor temperature corresponds to the processing performed by the temperature estimation unit 63 described above.

[0291] In the following S250, processor 30a performs motor resistance calculation processing. Processor 30a can estimate the motor resistance Ra based on the motor temperature Tm. That is, processor 30a can determine the motor resistance Ra by estimation. The estimation of motor resistance Ra corresponds to the processing performed by the resistance estimation unit 65 described above.

[0292] In the following S260, processor 30a performs loss calculation processing. Processor 30a can calculate motor loss P_loss based on motor resistance Ra, line current amplitude Ia_m, and speedometer measurement ω_m. The calculation of motor loss P_loss corresponds to the processing performed by the copper loss estimation unit 67, iron loss estimation unit 68, and motor loss estimation unit 69 mentioned above.

[0293] In the following S270, processor 30a performs efficiency determination processing. In the efficiency determination processing, processor 30a can calculate the mechanical conversion efficiency η_mech based on the speedometer measurement value ω_m, and thus determine the mechanical conversion efficiency η_mech.

[0294] Processor 30a can determine the inverter efficiency η_inv by reading the inverter efficiency η_inv stored in memory 30b. The calculation of the mechanical conversion efficiency η_mech corresponds to the processing implemented by the mechanical conversion efficiency input unit 59. Thus, processor 30a executes the state determination process (S150), and once the state determination process ends, it executes the processing of S160.

[0295] In S160, processor 30a performs limit value setting processing. The limit value setting processing is as follows: Figure 9 As shown. When the limit value setting process begins, processor 30a calculates the limit value of the line current based on the input energy constraint, i.e., the first limit value LM1, in S310. As described above, the first limit value LM1 is calculated based on the upper limit of the battery current Ibat_limit, the inverter efficiency η_inv, the battery voltage Vbat, the motor loss P_loss, and the speedometer measurement ω_m. The calculation of the first limit value LM1 corresponds to the processing implemented by the input limit value calculation unit 71 described above.

[0296] In the following S320, the processor 30a calculates the limit value of the line current based on the torque constraint, namely the second limit value LM2. As described above, the second limit value LM2 is calculated based on the torque limit Trq_limit and the speedometer measurement value ω_m. The calculation of the second limit value LM2 corresponds to the processing performed by the torque limit value calculation unit 73 described above.

[0297] In the following S330, processor 30a calculates the limit value of the line current based on the output energy constraint, namely the third limit value LM3. As described above, the third limit value LM3 is calculated based on the output limit Pout_limit and the speedometer measurement value ω_m. Here, the mechanical conversion efficiency η_mech can also be arbitrarily considered in the calculation of the third limit value LM3. The calculation of the third limit value LM3 corresponds to the processing implemented by the output limit value calculation unit 75 described above.

[0298] In the following S340, the processor 30a sets the minimum value among the first limit value LM1, the second limit value LM2, and the third limit value LM3 as the line current limit value Ia_limit. The setting of the line current limit value Ia_limit corresponds to the processing implemented by the first selection unit 77 described above.

[0299] In the following S350, the processor 30a sets the d-axis current limit value Id_limit and the q-axis current limit value Iq_limit corresponding to the line current limit value Ia_limit by converting the line current limit value Ia_limit into the d-axis current limit value Id_limit and the q-axis current limit value Iq_limit. This conversion corresponds to the processing performed by the limit value conversion unit 80 described above. Thus, the processor 30a executes the limit value setting process (S160).

[0300] When the processor 30a finishes the limit value setting process in S160, it executes the process in S170. In S170, the processor 30a determines whether the end condition of the main process has been met. For example, the end condition of the main process is met when the work machine 1 is disconnected via the power switch 12a.

[0301] If the processor determines that the termination condition of the main process (No in S170) has not been met, the processor 30a transfers to the processing in S130. The processor 30a repeatedly executes the processing of S130 to S170 in the first cycle until the termination condition is met. When the termination condition (Yes in S170) is met, the processor 30a terminates the main process.

[0302] [2-1-5-2. Interruption Handling]

[0303] Processor 30a begins Figure 10 During the interrupt handling shown, in S410, position and speed calculation processing related to motor 6 is performed. In the position and speed calculation processing, processor 30a calculates the rotation angle θ of motor 6 and the speedometer measurement value ω_m. The position and speed calculation processing corresponds to the processing implemented by the position and speed calculation unit 41 described above.

[0304] In the following S420, processor 30a performs current conversion processing related to motor 6. In this current conversion processing, processor 30a acquires the measured values ​​of the three-phase line currents of motor 6 (U, V, W phases) by sampling the U, V, W phase line current detection signals Siu, Siv, and Siw input from the first to third current detection circuits 36, 37, and 38. Processor 30a converts the acquired measured values ​​of the three-phase line currents into d-q axis currents (Id_m, Iq_m). This current conversion processing corresponds to the processing performed by the current conversion unit 42 described above.

[0305] In the following S430, processor 30a executes speed control processing related to motor 6. In the speed control processing, processor 30a generates a torque command value (q-axis current command value Iq_pi) corresponding to the deviation E = ω_r - ω_m between the speed command value ω_r and the speedometer measurement value ω_m via PI control.

[0306] The processor 30a converts the torque command value (Iq_pi) into the d-axis current command value Id_r and the q-axis current command value Iq_r. At this time, the processor 30a converts the torque command value (Iq_pi) into the d-axis current command value Id_r and the q-axis current command value Iq_r within the set d-axis current limit value Id_limit and the q-axis current limit value Iq_limit. The speed control processing corresponds to the processing implemented by the speed control unit 44 described above.

[0307] In the following S440, processor 30a performs current control processing. In this current control processing, processor 30a converts the d-axis current command value Id_r and the q-axis current command value Iq_r into the d-axis voltage command value Vd_r and the q-axis voltage command value Vq_r. This current control processing corresponds to the processing implemented by the current control unit 47 described above.

[0308] In the following S450, processor 30a performs voltage conversion processing. In this processing, processor 30a converts the d-axis voltage command value Vd_r and the q-axis voltage command value Vq_r into three-phase voltage command values. The three-phase voltage command values ​​calculated by processor 30a are then input to drive circuit 31 (see reference 1) as the first to sixth drive signals UH, VH, WH, UL, VL, and WL. Figure 2 Accordingly, the three-phase line current is supplied to the motor 6 through the drive circuit 31.

[0309] In this way, processor 30a controls motor 6 through interrupt handling. Specifically, processor 30a drives motor 6 through vector control, according to the d-axis current limit value Id_limit and the q-axis current limit value Iq_limit, to ensure that the line current of motor 6 does not exceed the line current limit value Ia_limit. Accordingly, processor 30a achieves... Figure 6 The speed N and torque τ are controlled using the N-T characteristic curve shown. Accordingly, the motor 6 is driven in a way that safely maximizes its capacity in response to load increases.

[0310] By controlling the motor based on the d-axis current limit value Id_limit and the q-axis current limit value Iq_limit, the processor 30a can operate under low load conditions ( Figure 6 In region R1, constant rotational control is performed corresponding to the pull amount of trigger 10, and in medium load (region R2), motor 6 is controlled in such a way that the rotational speed N decreases proportionally to the increase of torque τ.

[0311] The processor 30a performs constant output control on the motor 6 under the first high load (region R3) and performs torque limiting on the motor 6 under the second high load (location R4).

[0312] [2-1-6. Functions and Effects]

[0313] The speed control unit 44 corresponds to an example of a controller configured to control the brushless motor (specifically, motor 6), and the limit setting unit 45 corresponds to an example of a setter configured to set the limit value Ia_limit of the line current input to the brushless motor (specifically, motor 6).

[0314] According to this embodiment, the speed control unit 44 drives the motor 6 by outputting current command values ​​Id_r and Iq_r that do not exceed the limit values ​​Id_limit and Iq_limit set by the limiter 447, so that the line current below the limit value Ia_limit set by the limit value setting unit 45 is input to the motor 6 through vector control.

[0315] The limit setting unit 45 sets a first limit value LM1, which is based on the upper limit of the battery current Ibat_limit corresponding to the battery 15a mounted on the work machine 1, and specifically, the type of battery 15a, as the state of the work machine 1.

[0316] The limit setting unit 45 sets a third limit value LM3 corresponding to the upper limit of the output of the motor 6, that is, the output limit Pout_limit, to determine the state of the work machine 1. The limit setting unit 45 sets a second limit value LM2 corresponding to the upper limit of the torque of the motor 6, that is, the torque limit Trq_limit, to determine the state of the work machine 1.

[0317] The limit setting unit 45 estimates the temperature Tm of the motor 6 and sets a first limit value LM1 corresponding to the motor temperature Tm as the state of the work machine 1. The limit setting unit 45 estimates the power loss (P_loss) input to the motor 6 and sets the first limit value LM1 in combination with the power loss (P_loss). The limit setting unit 45 estimates the motor resistance Ra based on the motor temperature Tm and estimates the power loss (P_loss) based on the motor resistance Ra.

[0318] The limit setting unit 45 sets first, second, and third limit values ​​LM1, LM2, and LM3 based on the rotational speed (ω_m) of the motor 6 to determine the state of the work machine 1.

[0319] The limit setting unit 45 sets the smallest value among the first, second, and third limit values ​​LM1, LM2, and LM3 as the limit value Ia_limit.

[0320] In this way, the limit setting unit 45 appropriately sets the limit value Ia_limit of the line current of the motor 6 according to the state of the machine 1. Therefore, according to this embodiment, the machine 1 can suppress the problem of the motor 6's ability not being effectively utilized because the limit value Ia_limit is lower than the actual limit, thereby enabling the motor 6 to be driven to its maximum capacity while ensuring safety. Therefore, according to this embodiment, a high-performance machine 1 that can operate safely and stably with high output even under high load can be provided.

[0321] In particular, the speed control unit 44, through the setting of the aforementioned limit value Ia_limit, corresponds to the pulling operation of the trigger 10, and performs constant rotation control for the motor 6 in a manner that causes the motor 6 to rotate at a constant speed. Figure 6 In area R1, corresponding to the increase in load acting on motor 6, constant output control (area R3) and torque limiting (location R4) are performed.

[0322] When the limit value LM2, which corresponds to the torque upper limit Trq_limit, is set as the line current limit value Ia_limit by the limit value setting unit 45, the motor 6 is driven by inputting the line current corresponding to the limit value Ia_limit, thereby achieving torque limitation. Through torque limitation, the torque of the motor 6 is limited to a constant torque.

[0323] When the limit value setting unit 45 sets the limit value LM1 corresponding to the upper limit of the battery current Ibat_limit or the limit value LM3 corresponding to the upper limit of the output Pout_limit to the line current limit value Ia_limit, the motor 6 is driven by inputting the line current corresponding to the limit value Ia_limit to the motor 6, thereby achieving constant output control.

[0324] In response to the increase in load acting on the motor 6, the speed control unit 44 performs constant output control for the motor 6 in a first stage (region R3) in such a way that the rotational speed N of the motor 6 changes inversely with the torque τ of the motor 6. In a second stage, it performs torque limiting for the motor 6 in such a way that the torque τ of the motor 6 does not exceed a constant value regardless of the rotational speed N of the motor 6 (location R4).

[0325] Therefore, in this embodiment, as the load acting on the motor 6 increases, the machine 1 can maximize the capacity of the motor 6 while ensuring safety and stability, thereby enabling operation on an object (e.g., a workpiece) (e.g., a cutting operation). The safety mentioned here includes the ability of the machine 1 to stop in an emergency due to overcurrent, or the ability of the machine 1 to operate in a way that prevents thermal damage to the components within the machine 1.

[0326] [2-2. First variation]

[0327] According to the main implementation, the control circuit 30 sets the second limit value LM2 based on a constant torque limit Trq_limit that is independent of the rotational speed (ω_m) of the motor 6 (processing and torque limit value calculation unit 73 of S320).

[0328] However, the control circuit 30 can be configured to set a limit value LM2 corresponding to the torque limit Trq_limit_w that depends on the rotational speed of the motor 6, instead of a constant torque limit Trq_limit. That is, the control circuit 30 can be configured to perform torque limiting for the motor 6 in a manner that causes the torque of the motor 6 to change relative to the rotational speed of the motor 6 under high load.

[0329] For example, the control circuit 30 can be configured to perform torque limiting on the motor 6 in a manner that causes the torque of the motor 6 to change monotonically relative to the rotational speed of the motor 6 under high load.

[0330] For example, the control circuit 30 can be configured to limit the torque of the motor 6 under high load by monotonically increasing or monotonically decreasing the torque of the motor 6 relative to the speed of the motor 6. The terms "monotonically increasing" and "monotonically decreasing" can be interpreted broadly. "Monotonically increasing" and "monotonically decreasing" can also be interpreted as "monotonically non-decreasing" and "monotonically non-increasing."

[0331] For example, the control circuit 30 can be configured to limit the torque of the motor 6 under high load by causing the torque of the motor 6 to change relative to the rotational speed of the motor 6 according to a quadratic curve or an approximate curve. The approximate curve includes an approximate curve of a quadratic curve having multiple linear intervals.

[0332] For example, the control circuit 30 can be configured to perform torque limiting on the motor 6 in a manner that causes the torque of the motor 6 to vary linearly relative to the rotational speed of the motor 6 under high load.

[0333] For example, in the processing of S320 or in the torque limit calculation unit 73, the control circuit 30 can use the torque limit Trq_limit_w = Trq_limit - k·(ω0 - ω_m), obtained by adding the correction term k·(ω0 - ω_m) to the torque limit Trq_limit which is independent of the rotational speed of the motor 6, instead of the torque limit Trq_limit, to set the second limit value LM2. Here, ω0 corresponds to the rotational speed of the motor 6 at the time point (location R4) when the constant output control ends.

[0334] In this case, such as Figure 11A as well as Figure 11B As shown, when the control circuit 30 is in the second high load following the first high load (region R3), instead of limiting the torque of the motor 6 to a constant value, it performs a torque limit that causes the torque τ to vary according to the rotational speed N. Figure 11A In the figure, the trajectories of torque τ and rotational speed N are shown, especially when the coefficient k is positive, using thick solid lines. Figure 11B In the diagram, the trajectories of torque τ and rotational speed N, especially when the coefficient k is negative, are shown by thick solid lines. By adjusting the coefficient k, the user's perception of the machine's handling under high loads can be adjusted. As in the main embodiment, the coefficient k can also be set to zero.

[0335] The control circuit 30 can be configured to set the value of the coefficient k corresponding to the user-specified operation mode by receiving a selection operation of the coefficient k from the user, for example, an operation mode selection operation. The work machine 1 can be configured to receive an operation mode selection operation from the user via a power switch 12a.

[0336] That is, the power switch 12a can also function as a mode selection switch. For example, when the power switch 12a is pressed for a long time, the control circuit 30 can identify the operation as a power on / off operation, and when the power switch 12a is pressed for a short time, the operation can be identified as a mode switching operation.

[0337] Processor 30a can execute repeatedly Figure 12 The process shown accepts a user's operation mode switching operation. Processor 30a can determine whether an operation mode switching operation has been performed (S610). When it is determined that an operation mode switching operation has been performed (Yes in S610), the value of coefficient k is set to a value defined for the switched operation mode (S620). Memory 30b can store a table describing the values ​​of coefficient k that should be set for each operation mode. Processor 30a can refer to this table to set the value of coefficient k.

[0338] In this way, by switching the value of the coefficient k corresponding to the mode selection operation, the operability of the work machine 1 under high load can be adjusted according to the user's preferences. It can be understood that the work machine 1 of the first modified example described above is constructed in the same way as the main embodiment, except for the point mentioned above.

[0339] [2-3. Second variation]

[0340] The control circuit 30 can be configured to set the line current limit value Ia_limit considering the inverter temperature. The machine 1 in the second modification described below is configured such that the limit setting unit 45 of the control circuit 30 sets the line current limit value Ia_limit considering the inverter temperature. Apart from this, the machine 1 in the second modification is configured similarly to that in the main embodiment.

[0341] In this modified example, the temperature represented by the first temperature detection signal Std is input to the limit setting unit 45 as the inverter temperature T_inv (see reference). Figure 13 ).

[0342] According to this modified example, a first limiting unit 71R is provided in the limiting value setting unit 45, between the input limiting value calculation unit 71 and the first selection unit 77. A second limiting unit 73R is provided between the torque limiting value calculation unit 73 and the first selection unit 77. A third limiting unit 75R is provided between the output limiting value calculation unit 75 and the first selection unit 77.

[0343] The first limiting unit 71R is configured to limit the first limiting value LM1 input to the first selection unit 77 based on the inverter temperature T_inv. Specifically, the first limiting unit 71R is configured to set a first current threshold LM1_H corresponding to the inverter temperature T_inv.

[0344] The first limiting unit 71R is configured such that when the first limiting value LM1 input from the input limiting value calculation unit 71 is less than the first current threshold LM1_H, the first limiting value LM1 is input to the first selection unit 77; when the first limiting value LM1 is greater than or equal to the first current threshold LM1_H, the first limiting value LM1 is changed to the first current threshold LM1_H, and the first current threshold LM1_H is input to the first selection unit 77 as the new first limiting value LM1.

[0345] The first limiting unit 71R may include a table illustrating the relationship between the inverter temperature T_inv and the first current threshold LM1_H that should be set. The first limiting unit 71R can refer to this table to set the first current threshold LM1_H corresponding to the inverter temperature T_inv. For example, the higher the inverter temperature T_inv, the lower the first current threshold LM1_H should be set.

[0346] The first limiting unit 71R can be configured such that the first current threshold LM1_H is set only when the inverter temperature T_inv is above a predetermined threshold temperature, and the first current threshold LM1_H is not set when the inverter temperature T_inv is below the threshold temperature. The first current threshold LM1_H can also be set to a constant value when the inverter temperature T_inv is above the threshold temperature. The first limiting unit 71R can also be configured such that when the inverter temperature T_inv is below the threshold temperature, the first limiting value LM1 input from the input limiting value calculation unit 71 is not changed, but is instead input to the first selection unit 77 unchanged.

[0347] The second limiting unit 73R is configured similarly to the first limiting unit 71R: it limits the second limiting value LM2 input to the first selection unit 77 based on the inverter temperature T_inv. Specifically, the second limiting unit 73R is configured to set a second current threshold LM2_H corresponding to the input inverter temperature T_inv. For example, the second current threshold LM2_H is set to be lower as the inverter temperature T_inv increases.

[0348] The second limiting unit 73R is configured such that when the second limiting value LM2 input from the torque limiting value calculation unit 73 is less than the second current threshold LM2_H, the second limiting value LM2 is input to the first selection unit 77; when the second limiting value LM2 is greater than or equal to the second current threshold LM2_H, the second limiting value LM2 is changed to the second current threshold LM2_H, and the second current threshold LM2_H is input to the first selection unit 77 as the new second limiting value LM2. The second limiting unit 73R can also be configured such that, similar to the first limiting unit 71R, the second current threshold LM2_H is set only when the inverter temperature T_inv is above the threshold temperature. The second current threshold LM2_H can also be set to a constant value when the threshold temperature is above the threshold temperature.

[0349] The third limiting unit 75R, like the first limiting unit 71R, is configured to limit the third limiting value LM3 input to the first selection unit 77 based on the inverter temperature T_inv. Specifically, the third limiting unit 75R is configured to set a third current threshold LM3_H corresponding to the input inverter temperature T_inv. For example, the third current threshold LM3_H is set to be lower as the inverter temperature T_inv increases.

[0350] The third limiting unit 75R is configured such that when the third limiting value LM3 input from the output limiting value calculation unit 75 is less than the third current threshold LM3_H, the third limiting value LM3 is input to the first selection unit 77; when the third limiting value LM3 is greater than or equal to the third current threshold LM3_H, the third limiting value LM3 is changed to the third current threshold LM3_H, and the third current threshold LM3_H is input to the first selection unit 77 as the new third limiting value LM3. The third limiting unit 75R can also be configured such that, similar to the first limiting unit 71R, the third current threshold LM3_H is set only when the inverter temperature T_inv is above the threshold temperature, thus limiting the third limiting value LM3 to a value not exceeding the third current threshold LM3_H. The third current threshold LM3_H can also be set to a constant value when the threshold temperature is above the threshold temperature.

[0351] As in this variant, by setting the current thresholds LM1_H, LM2_H, and LM3_H corresponding to the inverter temperature T_inv, it is possible to further set an appropriate line current limit value Ia_limit corresponding to the state of the machine 1, thereby effectively utilizing the capabilities of the motor 6.

[0352] [2-4. Other implementation methods]

[0353] This invention is not limited to the embodiments described above, and various methods can be employed. For example, in the above embodiments, an example of applying the technology of this invention to an electric chainsaw was described as machine 1. However, this invention is not limited thereto, and can also be applied to various electric machines.

[0354] Examples of electric work machines to which the technology of this invention can be applied include various types of field electrical equipment used in amateur woodworking, manufacturing, gardening, construction, and other work sites and configured to be battery-powered. Specifically, these include: power tools for stonemasonry, metalworking, and woodworking; gardening work machines; and devices for preparing the work site environment. More specifically, these include: electric blowers, electric hammers, electric hammer drills, electric drills, electric screwdrivers, electric wrenches, electric grinders, electric circular saws, electric reciprocating saws, electric wire saws, electric cutting tools, electric chainsaws, and electric... Electric planers, electric nailing machines (including riveting machines), electric hedge trimmers, electric lawn trimmers, electric lawn mowers, electric lawn mowers, electric vacuum cleaners, electric sprayers, electric spreaders, electric dust collectors, laser rangefinders, laser line markers, laser line marker receivers, wall detectors, radios, televisions, speakers, electronic hot and cold cabinets, electric kettles, coffee machines (coffee makers or coffee distillers), microwave ovens, robot vacuum cleaners, battery-powered handcarts, battery-powered bicycles, fan vests, heated vests, etc.

[0355] The present invention can be implemented in various ways, not limited to the work machine 1 and the control circuit 30 described above. For example, the present invention can be implemented in the form of a system comprising the control circuit 30, a computer program for enabling a computer to function as the control circuit 30, a non-transferable physical storage medium such as a semiconductor memory storing the computer program, and a control method.

[0356] This invention is applicable to electric work machines that perform vector control of motor 6 without using a Hall sensor (position signal output circuit 21). In other words, this invention is applicable to electric work machines that perform sensorless vector control of motor 6.

[0357] The positions of the first current detection circuit 36, the second current detection circuit 37, and the third current detection circuit 38 are not limited to the first lead 26, the second lead 27, and the third lead 28. The first current detection circuit 36, the second current detection circuit 37, and the third current detection circuit 38 can also be respectively arranged between the fourth switch Q4, the fifth switch Q5, and the sixth switch Q6 and the grounding part.

[0358] To perform vector control of motor 6, it is not necessary to detect all three-phase line currents (i.e., U-phase line current, V-phase line current, and W-phase line current), or only two of the U-phase line current, V-phase line current, and W-phase line current need to be detected. Alternatively, a single shunt current detection method can be used, employing a signal from the drive circuit 31 that only contains the path of the bus current.

[0359] The function of one component in the above embodiments can be distributed among multiple components. The functions of multiple components can be summarized in one component. A part of the structure of the above embodiments can be omitted. At least a part of the structure of the above embodiments can be added to or replaced with the structure of other above embodiments. All modes included by the technical concept defined by the statements in the claims are embodiments of the present invention.

Claims

1. An electric work machine, characterized in that, The electric work machine has the following features: A brushless motor is used to drive the workpiece; A controller configured to control the brushless motor; and The setting device is configured to set the limit value of the line current. The controller controls the brushless motor in such a way that a line current below the limit value set by the setter is input to the brushless motor. The setting device changes the limit value according to the state of the electric work machine.

2. The electric work machine according to claim 1, characterized in that, The setting device is configured to set the value corresponding to the battery mounted on the electric work machine as the limit value.

3. The electric work machine according to claim 2, characterized in that, The setting device is configured to set the limit value as a value corresponding to the upper limit of the battery current.

4. The electric work machine according to any one of claims 1 to 3, characterized in that, The setting device is configured to set the value corresponding to the upper limit of the output of the brushless motor as the limit value.

5. The electric work machine according to any one of claims 1 to 4, characterized in that, The setting device is configured to set the limit value as the value corresponding to the upper limit of the torque of the brushless motor.

6. The electric work machine according to any one of claims 1 to 5, characterized in that, The setting device is configured to set the limit value as a value corresponding to the temperature of the brushless motor.

7. The electric work machine according to any one of claims 1 to 6, characterized in that, The electric work machine is equipped with an inverter. The setting device is configured to set the limit value as a value corresponding to the temperature of the inverter.

8. The electric work machine according to any one of claims 1 to 7, characterized in that, The setting device is configured to estimate the power loss input to the brushless motor and set the limit value in conjunction with the power loss.

9. The electric work machine according to claim 8, characterized in that, The setting device is configured to estimate the loss based on the resistance of the brushless motor.

10. The electric work machine according to claim 9, characterized in that, The setting device is configured to estimate the resistance based on the temperature of the brushless motor.

11. The electric work machine according to any one of claims 1 to 10, characterized in that, The setting device is configured to set the limit value based on the rotational speed of the brushless motor.

12. The electric work machine according to claim 1, characterized in that, The setting device is configured to set the minimum value among a first limit value corresponding to the upper limit of the battery current, a second limit value corresponding to the upper limit of the output of the brushless motor, and a third limit value corresponding to the upper limit of the torque of the brushless motor as the limit value.

13. The electric work machine according to claim 1, characterized in that, The controller is configured to: in a first stage, in response to an increase in the load acting on the brushless motor, perform constant output control for the brushless motor in such a way that the rotational speed of the brushless motor changes inversely with respect to the torque of the brushless motor; and in a second stage, perform torque limiting for the brushless motor in such a way that the torque of the brushless motor does not exceed a constant value regardless of the rotational speed of the brushless motor, or in a way that changes monotonically with respect to the rotational speed.

14. The electric work machine according to claim 13, characterized in that, In an environment where the limit value corresponding to the upper limit of the torque of the brushless motor is set by the setter, the brushless motor is controlled by inputting a line current corresponding to the limit value into the brushless motor, thereby achieving the torque limit.

15. The electric work machine according to claim 13, characterized in that, Under the condition that the limit value corresponding to the upper limit of the battery current or the upper limit of the output of the brushless motor is set by the setter, the brushless motor is controlled by inputting a line current corresponding to the limit value into the brushless motor, thereby achieving constant output control.

16. The electric work machine according to any one of claims 13 to 15, characterized in that, The controller is configured to perform constant rotation control for the brushless motor in such a way that the brushless motor rotates at a constant speed, and to perform constant output control and torque limiting in response to an increase in the load acting on the brushless motor.

17. The electric work machine according to any one of claims 1 to 16, characterized in that, The controller is configured to drive the brushless motor via vector control.

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