Electric power shovel, and control method of brushless motor in electric power shovel

Abstract

One aspect of the present application provides an electric power tool including a brushless motor, a drive circuit, and a control circuit. The control circuit sets an operation mode of the electric power tool to either of a first mode and a second mode. The control circuit controls the brushless motor in the first mode according to a first control method. The control circuit controls the brushless motor in the second mode according to a second control method. The first control method (i) is a control method other than a vector control or (ii) includes a first vector control. The second control method includes a second vector control. The first vector control is different from the second vector control.

Description

Technical Field

[0001] This invention relates to a technology for controlling the brushless motor of an electric work machine. Background Technology

[0002] Japanese Patent Application Publication No. 2023-31617 discloses an electric work machine equipped with a brushless motor. The electric work mechanism involves applying a rectangular wave voltage to the brushless motor, thereby driving the brushless motor. Summary of the Invention

[0003] According to this electric work machine, since the brushless motor is driven by a rectangular wave voltage, high rotational speeds are possible. However, from the viewpoint of control performance (e.g., control stability and / or control accuracy), there may be situations where it is necessary to reduce the possible range of motion (e.g., the maximum output torque in the low-speed range). In such cases, the output torque of the brushless motor may be insufficient in practical operation. For example, when the brushless motor rotates at low speeds, insufficient output torque may impair the ease of use for the user of the electric work machine.

[0004] One objective of this invention is to provide a technique for controlling the brushless motor of an electric work machine in a manner that appropriately corresponds to conditions requiring high-speed rotation and conditions requiring high output torque, respectively.

[0005] In this invention, the terms "first," "second," etc., are merely intended to distinguish elements from each other, and are not intended to limit the order or number of elements. Therefore, the first element can be called the second element, and similarly, the second element can be called the first element. In addition, the first element can be present without the second element, and similarly, the second element can be present without the first element.

[0006] One aspect of the present invention provides an electric work machine comprising: a brushless motor, a drive circuit, and a control circuit.

[0007] The brushless motor drives the front-end tool. The drive circuit (i) receives DC power from a DC power source, (ii) generates three-phase power from the received DC power, and (iii) supplies the generated three-phase power to the brushless motor to drive the brushless motor.

[0008] The control circuit selectively sets its operating mode to either mode 1 or mode 2. Based on the operating mode being set to mode 1, the control circuit controls the brushless motor via the drive circuit according to the first control method. The first control method (i) is a control method other than vector control, or (ii) includes first vector control.

[0009] The control circuit is set to mode 2 based on the operating mode, and controls the brushless motor using the drive circuit according to the second control method. The second control method (i) differs from the first control method and (ii) includes second vector control. The first vector control differs from the second vector control.

[0010] This configuration of the electric work machine allows it to appropriately respond to situations requiring high-speed rotation and situations requiring high output torque, respectively. Another aspect of the invention provides a control method for a brushless motor in an electric work machine. The method includes: selectively setting the operating mode of the electric work machine equipped with the brushless motor to either a first mode or a second mode; during the period when the operating mode is set to the first mode, controlling the drive of the brushless motor according to a control method other than vector control or through first vector control; and during the period when the operating mode is set to the second mode, controlling the drive of the brushless motor through second vector control. The first vector control and the second vector control are different.

[0011] According to this method, the brushless motor can be controlled in a way that appropriately corresponds to the conditions where high-speed rotation is desired and the conditions where high output torque is desired. Attached Figure Description

[0012] Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

[0013] Figure 1 This is a perspective view of the electric work machine according to the first embodiment.

[0014] Figure 2 This is an explanatory diagram showing the electrical configuration of the electric work machine according to the first embodiment.

[0015] Figure 3 This is a block diagram illustrating the function of the control circuit in the second mode of the first embodiment.

[0016] Figure 4 This is a block diagram illustrating the function of the control circuit in the first mode of the first embodiment.

[0017] Figure 5 It is an illustrative diagram that simulates the differences between mode 1 and mode 2.

[0018] Figure 6 This is an explanatory diagram showing an example of the operation of the second mode in the first embodiment.

[0019] Figure 7 This is an explanatory diagram showing the first operation example of the first mode in the first embodiment.

[0020] Figure 8This is an explanatory diagram showing a second operation example of the first mode in the first embodiment.

[0021] Figure 9 This is a flowchart of the motor control process in the first embodiment.

[0022] Figure 10 This is a flowchart of the motion information acquisition and processing in the first embodiment.

[0023] Figure 11 This is a flowchart of the operation mode switching process in the first embodiment.

[0024] Figure 12 This is an explanatory diagram showing the first action example of the second mode in the second embodiment.

[0025] Figure 13 This is an explanatory diagram showing a second operation example of the second mode in the second embodiment.

[0026] Figure 14 This is an explanatory diagram used to illustrate the overmodulation control in the third embodiment.

[0027] Figure 15 This is a flowchart of the motor control process in the fourth embodiment.

[0028] Figure 16 This is a flowchart of the motor control process in the fifth embodiment.

[0029] Figure 17 This is a flowchart of the specific mode monitoring process in the fifth embodiment.

[0030] Figure 18 This is a flowchart of the motor control process in the sixth embodiment.

[0031] Figure 19 This is a flowchart of the specific mode monitoring process in the sixth embodiment. Detailed Implementation

[0032] 1. Overview of Implementation Methods

[0033] One embodiment may provide an electric work machine having at least one of the following features.

[0034] • Feature 1: Brushless motor (or brushless DC motor).

[0035] • Feature 2: The brushless motor is configured to drive a front-end tool (or work tool, or driven tool, or front-end accessory).

[0036] • Feature 3: Drive circuit.

[0037] • Feature 4: The drive circuit is configured to receive DC power from a DC power source.

[0038] • Feature 5: The drive circuit is configured to generate three-phase power from the received DC power.

[0039] • Feature 6: The drive circuit is configured to supply the generated three-phase power to the brushless motor, thereby driving the brushless motor.

[0040] • Feature 7: Control circuit.

[0041] • Feature 8: The control circuit is configured to selectively set the operating mode of the control circuit to either mode 1 or mode 2.

[0042] • Feature 9: The control circuit is configured to control the brushless motor by means of the drive circuit based on the first mode of operation and the first control method.

[0043] • Feature 10: The first control mode (i) is a control mode other than vector control (or a control mode different from vector control, or a control mode that does not use vector control, or a non-vector control mode), or (ii) includes the first vector control.

[0044] • Feature 11: The control circuit is configured to be set to the second mode based on the operating mode, and the brushless motor is controlled by the drive circuit according to the second control method.

[0045] • Feature 12: The second control method is different from the first control method.

[0046] • Feature 13: The second control method includes a second vector control that is different from the first vector control.

[0047] According to an electric work machine having at least features 1 to 13, it is possible to provide an electric work machine equipped with a brushless motor that can appropriately correspond to a high-speed priority state and a high-torque priority state respectively. The high-speed priority state corresponds to a state where high-speed rotation is desired. The high-torque priority state corresponds to a state where high output torque is desired. For example, a first control method can be used in the high-speed priority state (or a state where high output torque is not desired). For example, a second control method can be used in the high-torque priority state (or a state where high-speed rotation is not desired).

[0048] Mode 1 can be understood as an operating mode that prioritizes rotational speed over output torque. In other words, Mode 1 can be understood as an operating mode that prioritizes rotating the brushless motor at a higher speed rather than at a higher output torque.

[0049] The second mode can be understood as an operation mode that prioritizes output torque over rotational speed. In other words, the second mode can be understood as an operation mode that prioritizes rotating the brushless motor with greater output torque rather than rotating it at a higher speed.

[0050] Brushless motors can be classified as permanent magnet synchronous motors. Brushless motors can also be called brushless DC motors. A brushless motor typically consists of a stator and a rotor. The rotor typically includes a shaft that rotates together with it.

[0051] The rotor and shaft can penetrate the stator. That is, the brushless motor can be of the inner rotor type. The rotor can be configured to rotate on the outer periphery of the stator, and the shaft can be configured to penetrate the stator. That is, the brushless motor can also be of the outer rotor type.

[0052] The rotor may have a plurality of permanent magnets arranged circumferentially on the rotor. The plurality of permanent magnets may be configured such that multiple magnetic poles are arranged circumferentially on the outer circumferential surface of the rotor (e.g., N poles and S poles are alternately generated circumferentially). The plurality of magnetic poles may have 2N (N is a natural number) magnetic poles.

[0053] The stator may have: multiple teeth, and armature coils wound around those teeth. The armature coils may have: one or more sets of three-phase coils. Each set of three-phase coils comprises: three coils interconnected. The three coils are arranged circumferentially spaced at intervals equivalent to an electrical angle of 120°. The three coils are wound around corresponding three teeth. The three coils can be connected in a star configuration or a delta configuration. The aforementioned set of three-phase coils may have M sets (M being a natural number). In other words, the aforementioned set of three-phase coils may have 3M coils. In this case, the stator may have 3M teeth, and the 3M coils are wound around the 3M teeth respectively.

[0054] A brushless motor may have terminals 1, 2, and 3, as described below. One or more three-phase coils may be connected to terminals 1, 2, and / or 3. Three-phase power (or three-phase AC power) may be input to terminals 1, 2, and 3. Supplying three-phase power to the brushless motor includes applying a three-phase voltage to the brushless motor and / or supplying a three-phase current to the brushless motor. The three-phase voltage includes the first-phase voltage, the second-phase voltage, and the third-phase voltage applied to terminals 1 through 3, respectively. The three-phase current includes the first-phase current, the second-phase current, and the third-phase current supplied to terminals 1 through 3, respectively.

[0055] Brushless motors can be in the form of an interior permanent magnetic synchronous motor (IPMSM). Brushless motors can also be in the form of a surface permanent magnetic synchronous motor (SPMSM).

[0056] Front-end tools can include any tools or implements that can directly or indirectly perform the desired function on the exterior (or working object) of the power work machine. Examples of front-end tools include: various tool heads (such as drill bits and screwdriver bits), various rotary cutters (including chainsaws), various cutters other than rotary cutters (including whetstones), and various fans (specifically, blades). Various fans can be used in any power work machine configured to draw in or expel air. Examples of such power work machines include: electric vacuum cleaners, electric dust collectors, and electric blowers. Front-end tools can be exposed on the exterior of the power work machine or housed inside it.

[0057] The front-end tool (i) can be mounted (fixed) to the power work machine, or (ii) can be configured to be detachably mounted to the power work machine. The power work machine may have a power transmission unit (or output shaft) configured to transmit the rotational force of the brushless motor to the front-end tool. The front-end tool (i) can be mounted (fixed) to the power transmission unit, or (ii) can be configured to be detachably mounted to the power transmission unit.

[0058] The drive circuit may have a configuration capable of generating three-phase power from DC power, or similar configuration. The drive circuit may include a three-phase bridge circuit as described later. The three-phase bridge circuit may have three positive-side energizing paths, and / or three negative-side energizing paths, and / or three high-side switches (i.e., switch 1, switch 2, and switch 3), and / or three low-side switches (i.e., switch 4, switch 5, and switch 6).

[0059] The three positive-side power paths connect the first to third terminals of the brushless motor to the positive terminal of the DC power supply, respectively. The three negative-side power paths connect the first to third terminals to the negative terminal of the DC power supply, respectively. The three high-side switches are configured such that (i) they are respectively on the three positive-side power paths, and (ii) they enable or disable the three positive-side power paths, respectively. The three low-side switches are configured such that (i) they are respectively on the three negative-side power paths, and (ii) they enable or disable the three negative-side power paths, respectively.

[0060] Examples of DC power sources include: batteries, which will be described later, and DC power supply circuits. A DC power supply circuit can be configured to: (i) receive alternating current (AC) and (ii) convert that AC current into DC current.

[0061] The 1st to 6th switches can be in the form of semiconductor switches, or they can be in a different form than semiconductor switches.

[0062] The control circuit controls the brushless motor via the drive circuit, which can also be described as the control circuit controlling the drive circuit, thereby indirectly controlling the brushless motor. This control circuit's control of the brushless motor via the drive circuit can include (or imply) the control circuit driving (i.e., turning on or off) switches 1 through 6 respectively.

[0063] Vector control, also known as vector control, is a control method that processes the three-phase current supplied to a brushless motor using a d-q coordinate system. The d-q coordinate system has mutually orthogonal d-axis and q-axis. Vector control involves converting the three-phase current into d-axis current and q-axis current. The d-axis current is the d-axis component of the three-phase current, and the q-axis current is the q-axis component of the three-phase current. Vector control is a control method that controls the d-axis current and q-axis current separately. The d-axis is (i) perpendicular to the rotor's rotation axis, (ii) radially outward from the rotation axis, and (iii) along the direction of the rotor's N-pole. The q-axis is along a direction rotated by an electrical angle of 90° relative to the d-axis.

[0064] Further explanation of d-axis and q-axis currents is provided. When three-phase current flows through the armature coil, it generates magnetic flux (in other words, a magnetic field) in the armature coil. This magnetic flux (magnetic field) rotates. This magnetic flux can be vector-decomposed into d-axis and q-axis magnetic flux. The d-axis magnetic flux is the component of the magnetic flux along the d-axis, and the q-axis magnetic flux is the component of the magnetic flux along the q-axis. Thus, given the definitions of d-axis and q-axis magnetic flux, the d-axis current can be understood as the current component that generates the d-axis magnetic flux within the overall three-phase current, and the q-axis current can be understood as the current component that generates the q-axis magnetic flux within the overall three-phase current.

[0065] Based on these definitions of d-axis and q-axis currents, it is clear that d-axis current does not contribute to the generation of rotor torque, while q-axis current does. The positive and negative directions of the q-axis can be defined arbitrarily. For example, the positive direction of the q-axis can be the direction of the torque applied to the rotor to accelerate the brushless motor, and the negative direction of the q-axis can be the direction opposite to that torque.

[0066] Vector control may include converting the first-phase current value, the second-phase current value, and the third-phase current value into actual d-axis current values ​​and actual q-axis current values. The first-phase current value, the second-phase current value, and the third-phase current value are the individual values ​​of the three-phase currents (i.e., the first-phase current, the second-phase current, and the third-phase current) actually flowing through the brushless motor. The actual d-axis current value is the d-axis component of the actual three-phase current, and the actual q-axis current value is the q-axis component of the actual three-phase current.

[0067] Vector control may include generating or setting d-axis current command values ​​and / or q-axis current command values. The d-axis current command value is a target value for the d-axis current, and the q-axis current command value is a target value for the q-axis current. The d-axis and q-axis current command values ​​may also be generated based on the difference between the target rotational speed and the actual rotational speed (e.g., with the difference close to zero).

[0068] Vector control may include calculating the d-axis difference and / or the q-axis difference. The d-axis difference is the difference between the d-axis current command value and the actual d-axis current value, and the q-axis difference is the difference between the q-axis current command value and the actual q-axis current value.

[0069] Vector control can include calculating d-axis voltage command values ​​based on d-axis differences and / or calculating q-axis voltage command values ​​based on q-axis differences. The d-axis voltage command value can be calculated with the d-axis difference approaching (or nearly approaching) zero. The q-axis voltage command value can also be calculated with the q-axis difference approaching (or nearly approaching) zero. The d-axis and q-axis voltage command values ​​can also be calculated arbitrarily based on the d-axis and q-axis differences, respectively. The d-axis and q-axis voltage command values ​​can also be calculated, for example, using Proportional-Integral (PI) control.

[0070] Vector control may include converting d-axis voltage command values ​​and q-axis voltage command values ​​into three-phase voltage command values ​​in a three-phase fixed coordinate system. The three-phase voltage command values ​​include: a first-phase voltage command value corresponding to the command value of the first-phase voltage, a second-phase voltage command value corresponding to the command value of the second-phase voltage, and a third-phase voltage command value corresponding to the command value of the third-phase voltage.

[0071] Vector control can include controlling the drive circuit by applying three-phase voltages corresponding to the command values ​​of phases 1 to 3 to the brushless motor. Specifically, vector control can individually control switches 1 to 6 by applying three-phase voltages corresponding to the command values ​​of phases 1 to 3 to the brushless motor. The control circuit can output drive signals 1 to 6 to switches 1 to 6 respectively, thereby controlling switches 1 to 6 individually (i.e., turning them on or off).

[0072] The second vector control can be arbitrarily different from the first vector control. The first vector control and the second vector control can be (i) at least one control region in the d-q coordinate system and / or (ii) at least one control condition associated with the control of the three-phase current and / or three-phase voltage that is different from each other. The migration regions of the current vectors in the d-q coordinate system described later in the first vector control and the second vector control can be partially different or completely different.

[0073] When the first control method is a control method other than vector control, the second vector control can also be simply referred to as "vector control". That is, in this case, the second vector control can include all kinds of vector control.

[0074] One embodiment may also have at least one of the features 1 to 13 described above, or alternatively, at least one of the following features.

[0075] • Feature 14: The first control method is a control method other than vector control.

[0076] • Feature 15: The first control method includes rectangular wave control. Rectangular wave control may include applying a rectangular wave voltage from the drive circuit to the brushless motor.

[0077] According to an electric work machine having at least features 1 to 15, the drive of a brushless motor can be easily and efficiently controlled in the first mode.

[0078] The term "rectangular wave control" can refer to (i) a control method opposite to the sinusoidal continuous modulation used in vector control and / or (ii) a control method that uses a drive circuit to drive a motor in a non-sinusoidal manner. Rectangular wave control can include control methods sometimes referred to in this art as 6-step control or trapezoidal wave control. Rectangular wave control can also include discretely switching the state of the drive circuit based on a specified electrical angle or a dynamically adjusted electrical angle. Examples of rectangular wave control include 6-step rectification, energizing angle control, and advance angle control.

[0079] Rectangular wave voltages have a rectangular wave or other non-rectangular wave waveform shape. Rectangular wave voltages can be generated based on the discrete switching states of the drive circuit. Multiple rectangular wave voltages can be applied separately to terminals 1 through 3 of the brushless motor.

[0080] A rectangular wave voltage is not limited to a voltage that strictly changes into a rectangular wave shape. Even if the shape of a strictly rectangular wave is distorted due to external disturbances such as noise or other factors (such as induced voltage), it can still be considered a voltage that changes into a rectangular wave shape or has a rectangular wave shape. For example, a voltage that changes along a trapezoidal shape or an approximately trapezoidal shape can be considered a rectangular wave voltage. Applying a rectangular wave voltage can include situations where the first phase voltage, the second phase voltage, and the third phase voltage are all in the form of a rectangular wave voltage (rectangular wave-shaped voltage).

[0081] Rectangular wave control may include generating three phase currents and / or three rectangular wave voltages with trapezoidal or rectangular wave waveform characteristics. Rectangular wave control can be applied to motors with trapezoidal back electromotive force characteristics, but is not limited to them.

[0082] Rectangular wave control can include outputting a rectangular wave drive signal to the drive circuit to activate the drive circuit. The rectangular wave drive signal can be a signal that specifies 6 steps of energization.

[0083] The magnitude of the three-phase power supplied to the brushless motor can be controlled by the energizing angle and / or advance angle, as described later. The magnitude of the three-phase power can be controlled by (i) driving the drive circuit using a pulse width modulation signal and (ii) adjusting the duty cycle of the pulse width modulation signal.

[0084] One embodiment may also have at least one of the features 1 to 15 described above, or alternatively, at least one of the following features.

[0085] • Feature 16: The drive circuit includes a three-phase bridge circuit.

[0086] • Feature 17: The three-phase bridge circuit has 6 switches.

[0087] • Feature 18: The first control method includes: during the period from the corresponding turn-on time to the point when the brushless motor has rotated by an angle equivalent to the energizing angle, the above 6 switches are turned on continuously or intermittently.

[0088] • Feature 19: The first control method includes advance angle control and / or energizing angle control.

[0089] • Feature 20: Advance angle control includes advancing the turn-on timing of each of the above 6 switches by an angle (or time) equivalent to the advance angle relative to the reference timing.

[0090] • Feature 21: Advance angle control includes adjusting the advance angle based on the operating state of the brushless motor.

[0091] • Feature 22: On-off angle control includes changing the on-off angle according to the operating state of the brushless motor.

[0092] According to the electric work machine having at least features 1 to 22, in the first mode, the brushless motor can be driven more efficiently.

[0093] The "first control mode" in features 18 and 19 can also be referred to as "rectangular wave control". The energizing angle and advance angle can be represented by electrical angles. The energizing angle can be set, for example, within the range of 120 to 180 degrees. Alternatively, the reference timing can occur whenever the brushless motor rotates by 60 degrees (or whenever a rotation of 60 degrees is detected).

[0094] One embodiment may also have at least one of the features 1 to 22 described above, or alternatively, at least one of the following features.

[0095] • Feature 23: The brushless motor has a first terminal, a second terminal, and a third terminal.

[0096] • Feature 24: Terminals 1, 2, and 3 are configured to receive three-phase current corresponding to three-phase power from the drive circuit.

[0097] • Feature 25: The first control mode includes the first vector control.

[0098] • Feature 26: The second vector control includes supplying three-phase current to the brushless motor by migrating the current vector (specifically its leading edge) of the three-phase current along the maximum torque / current curve of the brushless motor in the d-q coordinate system. The d-q coordinate system has mutually orthogonal d-axis and q-axis. The current vector is the vector sum of the d-axis current and the q-axis current. In other words, the current vector is the sum of the d-axis current vector and the q-axis current vector. The d-axis current corresponds to the d-axis component of the three-phase current. The q-axis current corresponds to the q-axis component of the three-phase current. The d-axis current vector is a vector that is (i) originating from the origin in the d-q coordinate system, (ii) along the d-axis, and (iii) has the magnitude of the d-axis current. The q-axis current vector is a vector that is (i) originating from the origin in the d-q coordinate system, (ii) along the q-axis, and (iii) has the magnitude of the q-axis current. In the second vector control, the current vector can always migrate along the maximum torque / current curve, but it can also sometimes deviate from the maximum torque / current curve depending on the operating conditions. The maximum torque / current curve can also be called the MTPA curve. "MTPA" is short for "Maximum Torque Per Ampere".

[0099] According to the electric work machine having at least features 1 to 13 and 23 to 26, in the second mode, the brushless motor can generate higher torque and can be driven efficiently.

[0100] One embodiment may also have at least one of the following features in addition to having at least one of the features 1 to 26 described above, or instead have at least one of the following features.

[0101] • Feature 27: The first vector control includes weak excitation control (or weak flux control).

[0102] • Feature 28: Weak excitation control includes supplying three-phase current to the brushless motor by migrating the current vector (specifically its front end) in the first region of the d-q coordinate system.

[0103] • Feature 29: Region 1 does not contain the maximum torque / current curve.

[0104] • Feature 30: Region 1 corresponds to the region that is closer to the negative side of the d-axis than the maximum torque / current curve.

[0105] According to the electric work machine having at least features 1 to 13 and 23 to 30, in the first mode, the brushless motor can be rotated at high speed, and the reduction of the output torque of the brushless motor can be suppressed. That is, even in the first mode, vector control can be used in principle, and by reducing the excitation flux compared to the vector control in the second mode (second vector control), it is possible to rotate at a higher speed than in the second mode.

[0106] Weak excitation control may include: shifting the current vector from the maximum torque / current curve along the constant current circle toward the negative d-axis.

[0107] The constant current circle is also called the current limiting circle. Weak excitation control may include shifting the current vector on the maximum torque / voltage curve (or maximum torque / magnetic flux curve) of the brushless motor in the d-q coordinate system.

[0108] Weak excitation control may include shifting the current vector along the voltage limiting ellipse of the brushless motor in the d-q coordinate system. The voltage limiting ellipse is also called a constant linkage flux ellipse or a constant induced voltage ellipse. Weak excitation control may include shifting the current vector along the positive d-axis in the region of the voltage limiting ellipse that is closer to the positive direction than the aforementioned MTPV curve (or MTPF curve).

[0109] One embodiment may also have at least one of the features 1 to 30 described above, or alternatively, at least one of the following features.

[0110] • Feature 31: The first vector control includes applying overmodulated voltages from the drive circuit to the first terminal, the second terminal, and the third terminal, respectively.

[0111] • Feature 32: The magnitude of the overmodulated voltage varies along a reference sine wave. The reference sine wave has an amplitude (i) larger than the magnitude of the DC voltage. The DC voltage can be applied to the drive circuit from a DC power supply. The reference sine wave can also be an imaginary sine wave.

[0112] • Feature 33: The magnitude of the overmodulated voltage is maintained at the magnitude of the DC voltage during the period when the magnitude of the reference sine wave is greater than the magnitude of the DC voltage.

[0113] Based on an electric work machine possessing at least features 1-13, 23-26, and 31-33, the voltage utilization rate of the DC power supply in Mode 1 can be improved. Accordingly, in principle, vector control can also be used in Mode 1, and rotation can be performed at a higher speed than in Mode 2.

[0114] The control circuit can arbitrarily generate overmodulated voltages. For example, the control circuit can generate a voltage command indicating the direction of generating a sinusoidal voltage. The sinusoidal voltage has an amplitude larger than the DC voltage of the DC power supply. The control circuit can use the voltage represented by this voltage command (i.e., the voltage along a reference sine wave) output from the drive circuit as a basis, and, during periods when the voltage represented by the voltage command is higher than the DC voltage, output a voltage from the drive circuit that is the same as or approximately the same as the DC voltage.

[0115] One embodiment may also have at least one of the features 1 to 33 described above, or alternatively, at least one of the following features.

[0116] • Feature 34: Manual switch.

[0117] • Feature 35: The manual switch is configured to allow for both a first manual operation and a second manual operation, which are operated by the user of the electric work machine.

[0118] • Feature 36: The control circuit is configured to set the operation mode to mode 1 based on the first manual operation performed on the manual switch.

[0119] • Feature 37: The control circuit is configured to set the operation mode to the second mode based on the second manual operation performed on the manual switch.

[0120] Based on electric work machines with at least features 1 to 13 and 34 to 37, users can freely switch operating modes at any time.

[0121] One embodiment may also have at least one of the following features in addition to having at least one of the features 1 to 37 described above, or instead have at least one of the following features.

[0122] • Feature 38: The control circuit is configured to set the operation mode to mode 1 based on the fulfillment of the mode 1 switching condition. The mode 1 switching condition can specify the conditions used to set or switch the operation mode to mode 1.

[0123] • Feature 39: The control circuit is configured to switch the operating mode to the first mode based on (i) the operating mode being set to the second mode and (ii) the first mode switching condition being met. The second mode switching condition may specify the conditions used to set or switch the operating mode to the second mode.

[0124] • Feature 40: The control circuit is configured to set the operation mode to the second mode based on the fact that the requirements for switching to the second mode have been met.

[0125] • Feature 41: The control circuit is configured to switch the operation mode to the second mode based on (i) the operation mode is set to the first mode and (ii) the conditions for switching to the second mode have been met.

[0126] According to an electric work machine having at least features 1 to 13 and 38 to 41, by appropriately setting the first mode switching element and the second mode switching element, the burden on the user can be reduced, and the operation mode can be appropriately set to the first mode or the second mode.

[0127] One embodiment may also have at least one of the features 1 to 41 described above, or alternatively, at least one of the following features.

[0128] • Feature 42: The second mode switching condition is met based on the load torque being above the first torque threshold. The load torque is applied to the brushless motor.

[0129] • Feature 43: Load torque is applied to the brushless motor via a front-end tool.

[0130] • Feature 44: The first mode switching requirement is met based on the load torque being below the second torque threshold.

[0131] • Feature 45: The second torque threshold is less than the first torque threshold.

[0132] • Feature 46: The second torque threshold is greater than zero.

[0133] Based on an electric work machine having at least features 1 to 13 and 38 to 46, the operating mode can be appropriately set according to the load torque.

[0134] The first torque threshold can be the value at which the operating mode should be switched to (or desired to switch to) the second mode when the load torque increases to or exceeds the first torque threshold in the first mode. The second torque threshold can be the value at which the operating mode should be switched to (or desired to switch to) the first mode when the load torque decreases to or falls below the second torque threshold in the second mode.

[0135] Electric work machines may include a torque sensor configured to detect load torque.

[0136] The torque sensor can be configured to output a torque signal representing the load torque. The control circuit can be configured to: (i) receive the torque signal, and (ii) acquire the load torque based on the torque signal. Alternatively, the control circuit can be configured to: (i) acquire a physical quantity that directly or indirectly represents the load torque (i.e., reflects the load torque), and (ii) calculate (or estimate) the load torque based on the physical quantity. The control circuit can determine whether the switching requirements for the first and second modes have been met based on the acquired or calculated load torque.

[0137] One embodiment may also have at least one of the features 1 to 46 described above, or alternatively, at least one of the following features.

[0138] • Feature 47: The second mode switching requirement is met based on the bus current being greater than or equal to the first current threshold. The bus current is the current supplied to the brushless motor from the DC power supply via the drive circuit.

[0139] In other words, the bus current is the current supplied from the DC power supply to the drive circuit when the DC power supply is supplied to the brushless motor through the drive circuit.

[0140] • Feature 48: The first mode switching requirement is satisfied based on the bus current being below the second current threshold.

[0141] • Feature 49: The second current threshold is less than the first current threshold.

[0142] • Feature 50: The second current threshold is greater than zero.

[0143] Based on an electric work machine with at least features 1 to 13, 38 to 41, and 47 to 50, the operating mode can be appropriately set according to the magnitude of the bus current.

[0144] The first current threshold can be the value at which the operation mode should be switched to (or desired to switch to) the second mode when the bus current increases to or exceeds the first current threshold in the first mode. The second current threshold can be the value at which the operation mode should be switched to (or desired to switch to) the first mode when the bus current decreases to or falls below the second current threshold in the second mode.

[0145] The electric work machine may include a bus current detection circuit configured to detect the magnitude of the bus current. The bus current detection circuit may be configured to output a bus current detection signal representing the magnitude of the bus current.

[0146] The control circuit can be configured to: (i) receive a bus current detection signal, and (ii) obtain the magnitude of the bus current based on the bus current detection signal. The control circuit can determine whether the switching requirements for the first and second modes have been met based on the obtained bus current magnitude.

[0147] One embodiment may also have at least one of the features 1 to 50 described above, or alternatively, at least one of the following features.

[0148] • Feature 51: The second mode switching requirement is met based on the current level being above the third current threshold. The current level directly or indirectly represents the amplitude of the three-phase current.

[0149] • Feature 52: The first mode switching requirement is satisfied based on the above current level being below the fourth current threshold.

[0150] • Feature 53: The fourth current threshold is less than the third current threshold.

[0151] • Feature 54: The fourth current threshold is greater than zero.

[0152] Based on an electric work machine having at least features 1 to 13, 23, 24, 38 to 41, and 51 to 54, the operating mode can be appropriately set according to the aforementioned current level.

[0153] The third current threshold can be the value at which the operation mode should be switched to (or desired to switch to) the second mode when the current level in the first mode increases to or exceeds the third current threshold. The fourth current threshold can be the value at which the operation mode should be switched to (or desired to switch to) the first mode when the current level in the second mode decreases to or falls below the fourth current threshold.

[0154] The current level can correspond to any one of the amplitudes of the first to third phase currents mentioned above. Alternatively, the current level can also correspond to a representative value (e.g., average, median, or RMS value) of the amplitudes of the first to third phase currents. Or, the current level can also correspond to the magnitude of the current vector of the three-phase currents in the d-q coordinate system.

[0155] The electric work machine may include: at least one phase current detection circuit (or phase current detection sensor). The at least one phase current detection circuit is configured to detect the magnitude of at least one of the three-phase currents (the aforementioned first to third phase currents). Each of the at least one phase current detection circuits may be configured to output a phase current detection signal representing the magnitude of the corresponding phase current. The control circuit may be configured to: (i) receive the phase current detection signal from the at least one phase current detection sensor, and (ii) acquire the current level based on the phase current detection signal. Alternatively, the control circuit may calculate the magnitude of the current vector based on the received phase current detection signal and acquire the calculated current vector magnitude as the current level. The control circuit may also determine whether the switching requirements for the first and second modes have been met based on the acquired current level.

[0156] One embodiment may also have at least one of the features 1 to 54 described above, or alternatively, at least one of the following features.

[0157] • Feature 55: The drive circuit is configured to receive a DC voltage corresponding to the aforementioned DC power from a DC power source.

[0158] • Feature 56: The second mode switching requirement is satisfied based on the fact that the magnitude of the DC voltage is above the first voltage threshold.

[0159] • Feature 57: The first mode switching requirement is satisfied based on the fact that the magnitude of the DC voltage mentioned above is below the second voltage threshold.

[0160] • Feature 58: The second voltage threshold is less than the first voltage threshold.

[0161] • Feature 59: The second voltage threshold is greater than zero.

[0162] According to an electric work machine having at least features 1 to 13, 38 to 41, and 55 to 59, the operating mode can be appropriately set according to the magnitude of the DC voltage. The electric work machine may include a power supply voltage detection sensor configured to detect the magnitude of the DC voltage.

[0163] The first voltage threshold can be the value at which the operation mode should be switched to (or desired to switch to) the second mode when the magnitude of the DC voltage in the first mode increases to or exceeds the first voltage threshold. The second voltage threshold can be the value at which the operation mode should be switched to (or desired to switch to) the first mode when the magnitude of the DC voltage in the second mode decreases to or is less than the second voltage threshold.

[0164] The power supply voltage detection sensor can be configured to output a voltage detection signal representing the magnitude of the DC voltage. The control circuit can be configured to: (i) receive the voltage detection signal, and (ii) acquire the magnitude of the DC voltage based on the voltage detection signal. The control circuit can determine whether the switching requirements for the first and second modes have been met based on the acquired magnitude of the DC voltage.

[0165] One embodiment may also have at least one of the features 1 to 59 described above, or alternatively, at least one of the following features.

[0166] • Feature 60: The second mode switching requirement is satisfied based on the temperature of the drive circuit being below the first temperature threshold.

[0167] • Feature 61: The first mode switching requirement is satisfied based on the temperature of the drive circuit being above the second temperature threshold.

[0168] • Feature 62: The first temperature threshold is less than the second temperature threshold.

[0169] • Feature 63: The first temperature threshold is greater than zero.

[0170] According to an electric work machine having at least features 1 to 13, 38 to 41, and 60 to 63, the operating mode can be appropriately set according to the temperature of the drive circuit (hereinafter referred to as "drive circuit temperature").

[0171] The first temperature threshold can be the value at which the operation mode should be switched to (or desired to switch to) the second mode when the drive circuit temperature decreases to or is lower than the first temperature threshold in the first mode. The second temperature threshold can be the value at which the operation mode should be switched to (or desired to switch to) the first mode when the drive circuit temperature increases to or exceeds the second temperature threshold in the second mode.

[0172] The electric work machine may include: a first temperature detection circuit configured to detect the temperature of the drive circuit. The first temperature detection circuit may be configured to output a first temperature detection signal representing the temperature of the drive circuit. The control circuit may be configured to: (i) receive the first temperature detection signal, and (ii) acquire the temperature of the drive circuit based on the first temperature detection signal. The control circuit may determine whether the switching requirements for the first and second modes have been met based on the acquired drive circuit temperature.

[0173] One embodiment may also have at least one of the features 1 to 63 described above, or alternatively, at least one of the following features.

[0174] • Feature 64: The second mode switching requirement is satisfied based on the brushless motor temperature being below the third temperature threshold.

[0175] • Feature 65: The first mode switching requirement is met based on the brushless motor temperature being above the fourth temperature threshold.

[0176] • Feature 66: The third temperature threshold is less than the fourth temperature threshold.

[0177] • Feature 67: The third temperature threshold is greater than zero.

[0178] Based on an electric work machine having at least features 1 to 13, 38 to 41, and 64 to 67, the operating mode can be appropriately set according to the temperature of the brushless motor (hereinafter referred to as "motor temperature").

[0179] The third temperature threshold can be the value at which the operation mode should be switched to (or desired to switch to) the second mode when the motor temperature decreases to or is below the third temperature threshold in the first mode. The fourth temperature threshold can be the value at which the operation mode should be switched to (or desired to switch to) the first mode when the motor temperature increases to or exceeds the fourth temperature threshold in the second mode.

[0180] The electric work machine may include: a second temperature detection circuit configured to detect the motor temperature. The second temperature detection circuit may be configured to output a second temperature detection signal representing the motor temperature. The control circuit may be configured to: (i) receive the second temperature detection signal, and (ii) acquire the motor temperature based on the second temperature detection signal. The control circuit may determine whether the switching requirements for the first and second modes have been met based on the acquired motor temperature.

[0181] One embodiment may also have at least one of the features 1 to 67 described above, or alternatively, at least one of the following features.

[0182] • Feature 68: The DC power supply includes a battery.

[0183] • Feature 69: The second mode switching requirement is met based on the battery temperature being below the fifth temperature threshold.

[0184] • Feature 70: The first mode switching requirement is met based on the battery temperature being above the sixth temperature threshold.

[0185] • Feature 71: The 5th temperature threshold is less than the 6th temperature threshold.

[0186] • Feature 72: The fifth temperature threshold is greater than zero.

[0187] According to an electric work machine having at least features 1 to 13, 38 to 41, and 68 to 72, the operating mode can be appropriately set according to the temperature of the battery (hereinafter referred to as "battery temperature").

[0188] The fifth temperature threshold can be the value at which the operating mode should be switched to (or desired to switch to) the second mode when the battery temperature decreases to or is below the fifth temperature threshold in the first mode. The sixth temperature threshold can be the value at which the operating mode should be switched to (or desired to switch to) the first mode when the battery temperature increases to or exceeds the sixth temperature threshold in the second mode.

[0189] The electric work machine may include a third temperature detection circuit configured to detect the battery temperature. The third temperature detection circuit may be configured to output a third temperature detection signal representing the battery temperature. The control circuit may be configured to: (i) receive the third temperature detection signal, and (ii) acquire the battery temperature based on the third temperature detection signal. The control circuit may determine whether the switching requirements for the first and second modes have been met based on the acquired battery temperature.

[0190] When the electric work machine is equipped with the battery assembly unit described later, the battery pack can be configured to send a third temperature detection signal to the control circuit via communication. In this case, the control circuit can be configured to: (i) receive the third temperature detection signal from the battery pack via communication, and (ii) obtain the battery temperature based on the received third temperature detection signal. Communication includes wired communication and wireless communication.

[0191] One embodiment may also have at least one of the features 1 to 72 described above, or alternatively have the following features.

[0192] • Feature 73: The control circuit is configured to switch the operating mode to the first mode in response to (i) the operation mode being set to the second mode and (ii) the brushless motor being continuously controlled in accordance with the second control method for more than the first time threshold.

[0193] According to an electric work machine having at least features 1 to 13, 34 to 37, and 73, it is possible to suppress the heat generation of the electric work machine. The "heat generation of the electric work machine" referred to herein may include: heat generation from the drive circuit, heat generation from the brushless motor, and / or heat generation from the DC power supply.

[0194] That is, the heat generated by the electric work machine in mode 2 can be greater than that in mode 1. Therefore, if the brushless motor is continuously driven for more than the first time threshold in mode 2, the heat generation (or overheating) of the electric work machine can be suppressed or prevented by automatically switching the operating mode to mode 1.

[0195] One embodiment may also have at least one of the features 1 to 73 described above, or alternatively have the following features.

[0196] • Feature 74: The control circuit is configured such that, in response to (i) the operating mode being set to mode 2 and (ii) the brushless motor being continuously controlled according to the second control method for a period of time exceeding a second time threshold, the supply of three-phase power from the drive circuit to the brushless motor is stopped. The second time threshold may be longer than the first time threshold, equal to the first time threshold, or shorter than the first time threshold.

[0197] According to the electric work machine having at least features 1 to 13, 34 to 37, and 74, it is possible to further suppress or prevent the electric work machine from generating heat.

[0198] One embodiment may also have at least one of the features 1 to 74 described above, or alternatively, at least one of the following features.

[0199] • Feature 75: The control circuit is configured to acquire assembly equipment information. This assembly equipment information pertains to the assembly equipment being assembled onto the electric work machine.

[0200] • Feature 76: The control circuit is configured to set the operation mode to the first mode based on the assembly equipment information having met the first setting requirement.

[0201] • Feature 77: The control circuit is configured to set the operation mode to the second mode based on the assembly equipment information having met the second setting requirement.

[0202] Based on an electric work machine having at least features 1 to 13 and 75 to 77, the operating mode can be appropriately set according to the assembly equipment.

[0203] The first setting requirement can specify the conditions for setting or switching the action mode to the first mode. The second setting requirement can specify the conditions for setting or switching the action mode to the second mode.

[0204] The assembly equipment can be detachably mounted to the electric work machine, or it can be fixed to the electric work machine in a way that prevents detachment.

[0205] One embodiment may also have at least one of the features 1 to 77 described above, or alternatively, at least one of the following features.

[0206] • Feature 78: A battery assembly is configured to detachably assemble a battery pack housing a battery. The battery pack may correspond to the assembly equipment.

[0207] • Feature 79: The control circuit is configured to obtain battery information from the battery pack assembled in the battery assembly.

[0208] • Feature 80: Battery information directly or indirectly indicates the performance of the battery.

[0209] • Feature 81: Assembly equipment information includes battery information.

[0210] Based on an electric work machine having at least features 1 to 13, 68, and 75 to 81, the operating mode can be appropriately set according to the performance of the battery.

[0211] One embodiment may also have at least one of the features 1 to 81 described above, or alternatively, at least one of the following features.

[0212] • Feature 82: The battery has internal resistance. The internal resistance may correspond to the aforementioned performance characteristics of the battery.

[0213] • Feature 83: Battery information includes the magnitude of internal resistance.

[0214] • Feature 84: The first setting condition is satisfied based on the internal resistance being greater than or equal to the first threshold.

[0215] • Feature 85: The second setting condition is satisfied based on the internal resistance being below the second threshold.

[0216] • Feature 86: The second threshold is less than the first threshold.

[0217] • Feature 87: The second threshold is greater than zero.

[0218] According to an electric work machine having at least features 1 to 13, 68, 75 to 87, the operating mode can be appropriately set according to the internal resistance of the battery.

[0219] The first threshold can be the value at which the operation mode should be switched to (or desired to switch to) the first mode when the internal resistance increases to or exceeds the first threshold in the second mode. The second threshold can be the value at which the operation mode should be switched to (or desired to switch to) the second mode when the internal resistance decreases to or falls below the second threshold in the first mode.

[0220] In other words, the higher the internal resistance of a battery, the more likely it is to be degraded. Thus, the internal resistance of a battery indirectly indicates the degree of battery degradation. When the operating mode is set to mode 2 when the battery is degraded, it may not be able to obtain sufficient output torque, or it may place a burden on the battery, accelerating its degradation. Therefore, when the battery's internal resistance is low, mode 2 should be used, and when the battery's internal resistance is high, mode 1 should be used, thereby reducing the burden on the battery.

[0221] One embodiment may also have at least one of the features 1 to 87 described above, or alternatively, at least one of the following features.

[0222] • Feature 88: The control circuit is configured to obtain type information from the battery pack assembled in the battery assembly. The type information indicates the type of the battery pack.

[0223] • Feature 89: Assembly equipment information includes type information.

[0224] Based on electric work machines with at least features 1 to 13, 68, 75 to 78, 88, and 89, the operating mode can be appropriately set according to the type of battery pack.

[0225] The type of battery pack can be information that identifies the specifications, performance, and / or physical composition of the battery pack. Examples of such information include: the rated voltage of the battery pack, the rated capacity of the battery pack, the types of battery cells that make up the battery pack, the maximum current that can be output from the battery pack, i.e., the maximum output current, and / or the communication protocol.

[0226] The rated DC voltage can vary depending on the type. Alternatively, the maximum output current can also vary depending on the type.

[0227] Therefore, for example, if the type information shows a low rated DC voltage (e.g., below the specified voltage value), the operating mode can be set to mode 1. Conversely, if the type information shows a high rated DC voltage (e.g., higher than the specified voltage value), the operating mode can be set to mode 2.

[0228] Additionally, for example, if the model information indicates a low maximum output current value (e.g., below the specified current value), the operating mode can be set to mode 1. Alternatively, for example, if the model information indicates a high maximum output current value (e.g., higher than the specified current value), the operating mode can be set to mode 2.

[0229] One embodiment may also have at least one of the features 1 to 89 described above, or alternatively, at least one of the following features.

[0230] • Feature 90: The control circuit is configured to acquire tool information. The tool information indicates the type of tool mounted on the front end of the electric work machine.

[0231] • Feature 91: Assembly equipment information includes tool information.

[0232] Based on an electric work machine with at least features 1 to 13, 75 to 77, 90, and 91, the action mode can be appropriately set according to the type of front-end tool.

[0233] That is, for example, the necessary (or desired) output torque tool can vary depending on the type of front-end tool. Additionally, for example, the necessary (or desired) rotational speed can vary depending on the type of front-end tool.

[0234] Therefore, for example, if the tool information indicates that a front-end tool is equipped with a design that envisions (or desires) being driven by high torque (e.g., above a specified torque), the operating mode can be set to mode 2. Conversely, if the tool information indicates that a front-end tool is equipped with a design that does not envision (or is less necessary) being driven by high torque, the operating mode can be set to mode 1.

[0235] Additionally, for example, if the tool information indicates that a front-end tool is equipped with a design that is intended (or desired) to be driven at a high speed (e.g., above a specified speed), the operation mode can be set to mode 1. Alternatively, for example, if the tool information indicates that a front-end tool is equipped with a design that is not intended (or less necessary) to be driven at a high speed, the operation mode can be set to mode 2.

[0236] One embodiment may also have at least one of the features 1 to 91 described above, or alternatively, at least one of the following features.

[0237] • Feature 92: The maximum rotational speed of the brushless motor in mode 1 is greater than the maximum rotational speed in mode 2.

[0238] • Feature 93: The maximum output torque of the brushless motor in mode 2 is greater than the maximum output torque in mode 1.

[0239] According to the electric work machine having at least features 1 to 13, 92, and 93, in the first mode, the brushless motor can be rotated at a higher speed, while in the second mode, the brushless motor can be rotated with a higher torque.

[0240] The maximum rotational speed can be, for example, the rotational speed under no-load conditions. The maximum output torque can be, for example, the maximum output torque that can be output using power from the battery pack.

[0241] One embodiment provides a control method for a brushless motor in an electric work machine having at least one of the following features.

[0242] • Feature 94: The operating mode of the electric work machine equipped with a brushless motor can be selectively set to either mode 1 or mode 2.

[0243] • Feature 95: During the period when the operating mode is set to mode 1, the drive of the brushless motor is controlled by a control method other than vector control (or without vector control, or according to a non-vector control method), or the drive of the brushless motor is controlled by first vector control (or using first vector control).

[0244] • Feature 96: During the period when the operating mode is set to mode 2, the drive of the brushless motor is controlled by second vector control (or using second vector control). The first vector control is different from the second vector control.

[0245] According to a method having at least features 94 to 96, an electric work machine equipped with a brushless motor can be provided that can appropriately respond to situations where high-speed rotation is desired and situations where high output torque is desired, respectively.

[0246] In one embodiment, the control circuitry may be integrated into a single electronic unit, a single electronic device, or a single circuit board.

[0247] In one embodiment, the control circuit may also be a combination of two or more electronic circuits, two or more electronic units, or two or more electronic devices respectively disposed on the electric work machine.

[0248] In one embodiment, the control circuitry includes: a microcomputer (or microcontroller, or microprocessor), wiring logic, a graphics processing unit (GPU), a neural network processing unit (NPU), an artificial intelligence (AI) processor, an AI chip, an application-specific integrated circuit (ASIC), an application-specific general-purpose component (ASSP), a programmable logic device (PLD), discrete electronic components, and / or combinations thereof. Examples of PLDs include field-programmable gate arrays (FPGAs), but are not limited to FPGAs.

[0249] Examples of electric work machines include various electrical devices (or field electrical devices) configured for use in (or applicable to) construction, manufacturing, agriculture, horticulture, civil engineering, construction, cleaning, amateur carpentry, and other work sites, and driven by DC power (such as batteries). Work sites are not limited to commercial sites, but also include home or personal work sites.

[0250] Specifically, examples of power work machines include: power tools for stonemasonry, metalworking, and woodworking; gardening work machines; and devices for preparing work sites. More specifically, examples of power work machines include: electric blowers, electric hammers, electric hammer drills, electric drills, electric vibratory drills, electric screwdrivers, electric wrenches, electric grinders, electric circular saws, electric reciprocating saws, electric wire saws, electric cutting tools, electric chainsaws, electric planers, electric nail machines (including riveting machines), electric hedge trimmers, electric lawn trimmers, and electric lawnmowers. Electric trimmers, electric hedge trimmers, electric lawnmowers, electric vacuum cleaners, electric flooring machines, electric vibrators, electric tampers, electric compactors, electric pumps, electric pile drivers, electric concrete road surface cutters, electric line marking machines, electric cutting saws, electric sprayers, electric spreaders, electric dust collectors, robot vacuum cleaners, robot lawnmowers, electric drills, electric weed cutters, battery-powered handcarts, battery-powered bicycles, electric air pumps, coffee machines (or coffee makers), fan vests, and heated vests.

[0251] In one embodiment, features 1 to 96 described above can be any combination. In another embodiment, any one of features 1 to 96 may be excluded.

[0252] 2. Specific exemplary implementation methods

[0253] The following provides several specific exemplary implementation methods.

[0254] 2-1. First Implementation Method

[0255] The first embodiment illustrates an electric work machine 1 as described below. The electric work machine 1 of the first embodiment is in the form of an electric chainsaw. However, such an electric work machine 1 is merely a simple example, and the present invention can be applied to all types of electric work machines.

[0256] 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 electric work machine 1 and are not intended to limit the orientation of the electric work machine 1. The electric work machine 1 can be configured in all orientations.

[0257] 2-1-1. Mechanical Structure of Electric Working Machines

[0258] like Figure 1 As shown, the electric work machine 1 has a housing 2. The motor 6, the power transmission unit (or output shaft) 7, and the controller 13 are housed inside the housing 2.

[0259] The electric work machine 1 includes a guide rod 8. The guide rod 8 is a plate-shaped component. The guide rod 8 protrudes from the outer casing 2 toward the front of the electric work machine 1.

[0260] The electric work machine 1 includes a front-end tool 9. The front-end tool 9 is an example of the assembly equipment summarized in the embodiments. In the first embodiment, the front-end tool 9 is in the form of a chainsaw. That is, the front-end tool 9 includes a plurality of interconnected cutting tools. The front-end tool 9 is detachably mounted to the periphery of the guide rod 8.

[0261] 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 front-end tool 9. The power transmission unit 7 transmits the rotational force (or rotational torque, specifically the rotational force or torque of the rotor 19) of the motor 6 to the front-end tool 9, thereby driving the front-end tool 9. When the motor 6 is driven, the front-end tool 9 moves along the periphery of the guide rod 8. Accordingly, the front-end tool 9 can perform operations on the workpiece. Specifically, the front-end tool 9 can cut materials such as wood, metal, and resin. The power transmission unit 7 (specifically the sprocket) is an example of an output shaft in the overall embodiment.

[0262] The outer casing 2 has a battery mounting section 3 at its rear. The battery pack 15 is detachably mounted to the battery mounting section 3. The battery pack 15 is an example of the mounting device summarized in the embodiments.

[0263] Figure 1This indicates that the battery pack 15 is assembled in the battery assembly section 3. The battery pack 15 houses a rechargeable battery 15a (see reference). Figure 2 Battery 15a is an example of a DC power supply in the general implementation method.

[0264] The 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 electric work machine 1. The battery 15a has internal resistance. That is, the battery 15a can be equivalently considered as a combination of a voltage source and an internal resistance connected in series. The magnitude of the internal resistance can change due to various reasons, such as the degree of degradation of the battery 15a. For example, the more degraded the battery 15a becomes, the greater its internal resistance becomes.

[0265] The electric 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 electric work machine 1. The electric 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 electric 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).

[0266] The electric work machine 1 includes 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 the first 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.

[0267] The electric work machine 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 the first embodiment, the unlocking stop 11 is provided on the rear handle 5. Therefore, the user can manually operate the trigger 10 while holding the rear handle 5 and manually operating the unlocking stop 11.

[0268] The electric work machine 1 includes an operation panel 12. In the first 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 mode setting switch 12a and a display 12b.

[0269] The mode setting switch 12a accepts various manual operations performed by the user. The mode setting switch 12a in the first embodiment is in the form of a momentum switch. When the mode setting switch 12a is pressed, it outputs an operation signal Sms. When the mode setting switch 12a is not pressed, it does not output the operation signal Sms.

[0270] The display 12b visually informs the user of the status of the electric work machine 1. The display 12b of the first embodiment includes an LED (not shown). In the following description, with respect to the display 12b, "on", "flickering" and "off" mean "on", "flickering" and "off" of the LED.

[0271] 2-1-2. Electrical Configuration of Electric Working Machines

[0272] Reference Figure 2 The electrical configuration of the electric work machine 1 will now be explained. The electric work machine 1 includes the aforementioned motor 6 and controller 13.

[0273] In the first embodiment, motor 6 is an internal rotor type brushless motor (specifically a three-phase brushless DC motor). In other embodiments, motor 6 may also be any other type of brushless motor (e.g., an external rotor type brushless motor).

[0274] Motor 6 includes a stator 17. Stator 17 includes a first coil 20a, a second coil 20b, and a third coil 20c. Stator 17 also includes a stator core (not shown) with multiple teeth (not shown). The multiple teeth are arranged at equal intervals along the rotation direction of rotor 19. The first to third coils 20a, 20b, and 20c are wound around the multiple teeth.

[0275] 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.

[0276] Motor 6 includes the aforementioned rotor 19. The rotor 19 is configured to pass through the stator 17 and is rotatably supported by bearings (not shown). The outer peripheral surface of the rotor 19 has multiple magnetic poles along the direction of rotation. Specifically, on the outer peripheral surface of the rotor 19, N poles and S poles are alternately arranged along the direction of rotation. Figure 2 The rotor 19, "N" schematically represents "N pole" and "S" schematically represents "S pole".

[0277] More specifically, the rotor 19 includes a rotor core (not shown) and a plurality of permanent magnets (not shown) arranged along the rotation direction at the rotor core. The plurality of permanent magnets generate the plurality of magnetic poles. In the first embodiment, the plurality of permanent magnets are embedded inside the rotor core. That is, the motor 6 of the first embodiment is of the aforementioned IPMSM type. However, the motor 6 can be of the type of permanent magnet synchronous motor different from the IPMSM (for example, the aforementioned SPMSM type).

[0278] Figure 2 For simplicity, the motor 6 is shown as a brushless motor with a 2-pole, 3-slot (i.e., 3-tooth) configuration. However, the brushless motor 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.

[0279] 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.

[0280] The electric work machine 1 is equipped with 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).

[0281] The position signal output circuit 21 includes a first rotation sensor 21a, a second rotation sensor 21b, and a third rotation sensor 21c. In the first embodiment, the first to third rotation sensors 21a to 21c are Hall sensors, but are not limited to Hall sensors.

[0282] The first to third rotation sensors 21a to 21c are configured to be spaced apart from the rotor 19 by a predetermined distance 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.

[0283] 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 Hu, Hv, 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 an electrical angle of 120 degrees.

[0284] The electric work machine 1 includes a power line Lp. The electric work machine 1 includes a positive terminal (not shown) and a negative terminal (not shown). When the battery pack 15 is assembled in the battery assembly section 3, the positive terminal is electrically connected to the positive terminal of the battery 15a, and the negative terminal is electrically connected to the negative terminal of the battery 15a. The power line Lp extends from the positive terminal toward the controller 13. The electric work machine 1 includes a grounding wire Ln. The grounding wire Ln extends from the negative terminal 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.

[0285] 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 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.

[0286] The controller 13 includes a control circuit 30. The control circuit 30 is activated by a power supply voltage Vc. The control circuit 30 is a microcomputer with a processor 30a and a memory 30b. 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 a program stored in the memory 30b. The processor 30a executes the program to perform the corresponding method.

[0287] 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). Additionally, in other embodiments, the control circuit 30 may 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: the aforementioned GPU, NPU, AI processor, AI chip, ASIC, ASSP, and / or PLD.

[0288] The controller 13 includes a drive circuit 31. The drive circuit 31 is electrically connected to a power supply line Lp and a ground line Ln. The drive circuit 31 receives battery voltage via the power supply line Lp and the ground line Ln. 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.

[0289] The drive circuit 31 generates a three-phase voltage (i.e., generates three-phase power) based on the battery voltage. The drive circuit 31 supplies the generated three-phase voltage to the motor 6 via leads 1 to 3, 26 to 28. In the following description, the current supplied to terminal 6a via lead 1, 26, is referred to as the U-phase current; the current supplied to terminal 6b via lead 2, 27, is referred to as the V-phase current; and the current supplied to terminal 6c via lead 3, 28, is referred to as the W-phase current. Furthermore, the voltage at terminal 1, 6a, is referred to as the U-phase voltage; the voltage at terminal 2, 6b, is referred to as the V-phase voltage; and the voltage at terminal 3, 6c, is referred to as the W-phase voltage.

[0290] The driving circuit 31 in the first embodiment is a three-phase bridge circuit (or a three-phase full-bridge circuit), but the driving circuit 31 is not limited to a three-phase bridge circuit.

[0291] The drive circuit 31 has first to third current paths Lp1 to Lp3. The first to third current paths Lp1 to Lp3 correspond to the so-called upper 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.

[0292] The drive circuit 31 has 4th to 6th current paths Lp4 to Lp6. The 4th to 6th current paths Lp4 to Lp6 correspond to the so-called lower arm. The 4th to 6th current paths Lp4 to Lp6 electrically connect the ground wire Ln to the 1st to 3rd terminals 6a, 6b, and 6c of the motor 6, respectively.

[0293] 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.

[0294] Switches Q1 to Q3 (1) are respectively included in their corresponding upper arms, and (ii) function as so-called high-side switches. Switches Q4 to Q6 (1) are respectively included in their corresponding lower arms, and (ii) function as so-called low-side switches. Current paths Lp1 to Lp3 (1) are turned on or off by switches Q1 to Q3 (1) and (2) respectively. Current paths Lp4 to Lp6 (4) are turned on or off by switches Q4 to Q6 (4) and (5) respectively.

[0295] Switches Q1 to Q6 are semiconductor switches. In the first 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), gallium nitride field-effect transistors (GaN-FETs), etc.

[0296] 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 the first embodiment, the first to sixth drive signals UH, VH, WH, UL, VL, and WL can each be a pulse width modulation signal.

[0297] When motor 6 is driven, in principle, any one high-side switch and any one low-side switch are turned on. Accordingly, current (hereinafter referred to as "bus 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. More specifically, one high-side switch and two low-side switches can be turned on simultaneously. The two low-side switches are located on two different bridge arms than the bridge arm containing the one high-side switch. Alternatively, two high-side switches and one low-side switch can be turned on simultaneously. The one low-side switch is located on a different bridge arm than the bridge arm containing the two high-side switches.

[0298] The electric work machine 1 has a first current detection circuit 36 ​​on the first lead 26. The first current detection circuit 36 ​​detects the U-phase current value. The U-phase current value is the magnitude of the U-phase current. Specifically, the first current detection circuit 36 ​​outputs a U-phase current detection signal Siu corresponding to the U-phase current value. The U-phase current detection signal Siu is input to the control circuit 30.

[0299] The electric work machine 1 has a second current detection circuit 37 on the second lead 27. The second current detection circuit 37 detects the value of the V-phase current. The value of the V-phase current is the magnitude of the V-phase current. Specifically, the second current detection circuit 37 outputs a V-phase current detection signal Siv corresponding to the V-phase current value. The V-phase current detection signal Siv is input to the control circuit 30.

[0300] The electric work machine 1 has a third current detection circuit 38 on the third lead 28. The third current detection circuit 38 detects the value of the W-phase current. The value of the W-phase current is the magnitude of the W-phase current. Specifically, the third current detection circuit 38 outputs a W-phase current detection signal Siw corresponding to the W-phase current value. The W-phase current detection signal Siw is input to the control circuit 30. At least one of the first to third current detection circuits 36 to 38 can be located within the drive circuit 31.

[0301] The first to third current detection circuits 36 to 38 are provided for detecting the U-phase current value, V-phase current value, and W-phase current value. The U-phase current value, V-phase current value, and W-phase current value can be detected using any method. For example, the first to third current detection circuits 36 to 38 can also be located in a different place than the first to third leads 26 to 28. Specifically, the first to third current detection circuits 36 to 38 can be respectively located in the fourth to sixth current paths Lp4 to Lp6. One or two of the first to third current detection circuits 36 to 38 can also be omitted. For example, if the third current detection circuit 38 is omitted, the control circuit 30 can detect (or estimate) the W-phase current value based on the U-phase current detection signal Siu and / or the V-phase current detection signal Siv. For example, if the second and third current detection circuits 37 and 38 are omitted, the control circuit 30 can detect (or estimate) the V-phase current value and the W-phase current value based on the U-phase current detection signal Siu. Alternatively, the first to third current detection circuits 36 to 38 can also be omitted. In this case, the control circuit 30 can also calculate the U-W phase current values ​​based on the bus current value (described later).

[0302] The controller 13 includes a bus current detection circuit 33. The bus current detection circuit 33 is located on the current path through which the bus current flows. In the first embodiment, the bus current detection circuit 33 is located on the ground line Ln within the controller 13, and more specifically, on the current path between the drive circuit 31 and the ground. The bus current detection circuit 33 detects the bus current value. The bus current value is the magnitude of the bus current. Specifically, the bus current detection circuit 33 outputs a bus current detection signal Sib corresponding to the bus current value. The bus current detection signal Sib is input to the control circuit 30. The first to third current detection circuits 36 to 38 and the bus current detection circuit 33 may each have a structure capable of detecting the corresponding current value, etc. The first to third current detection circuits 36 to 38 and the bus current detection circuit 33 may each (i) for example, include a resistor configured to allow the corresponding current to flow (a so-called shunt resistor), and (ii) be configured to output a bus current detection signal Sib based on the voltage across the resistor.

[0303] The controller 13 includes a battery voltage detection circuit 34. The battery voltage detection circuit 34 is connected to the power line Lp and receives the battery voltage via the power line Lp. The battery voltage detection circuit 34 detects the battery voltage value. The battery voltage value is the magnitude of the battery voltage. Specifically, the battery voltage detection circuit 34 outputs a battery voltage detection signal Svb corresponding to the battery voltage value. The battery voltage detection signal Svb is input to the control circuit 30.

[0304] 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 and detects the temperature of the drive circuit. The drive circuit temperature is the temperature of 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 first temperature sensor (i.e., the drive circuit temperature). The first temperature detection signal Std is input to the control circuit 30.

[0305] The electric work machine 1 includes a second temperature detection circuit 23. The second temperature detection circuit 23 is located inside or beside the motor 6 and detects the motor temperature. The motor temperature is the temperature of 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 second temperature sensor (i.e., the motor temperature). The second temperature detection signal Stm is input to the control circuit 30.

[0306] The electric work machine 1 includes a tool detection unit 29. The tool detection unit 29 outputs tool information Sto. Tool information Sto indicates the type of the front-end tool 9 mounted on the electric work machine 1 (specifically, the guide rod 8). Tool information Sto is an example of the assembly equipment information in the general implementation. Tool information Sto is input to the control circuit 30. The control circuit 30 can detect the type of the front-end tool 9 based on tool information Sto. In the first implementation, the types of front-end tools 9 include: a first type of tool and a second type of tool. Although this is just one example, the first type of tool (i) is relatively heavy, and (ii) requires high torque (e.g., above a specified torque) to be driven. The second type of tool (i) is relatively light, and (ii) does not require high torque to drive.

[0307] The control circuit 30 can also detect the type of the front-end tool 9 without the tool detection unit 29. For example, the control circuit 30 can detect the type of the front-end tool 9 based on the operating conditions of the motor 6. The operating conditions of the motor 6 include, for example, changes in the current flowing through the motor 6 (e.g., U-phase current, V-phase current, W-phase current, and / or bus current), changes in the voltage applied to the motor 6, and / or (iii) changes in the load torque applied to the motor 6. For example, if the magnitude of the current flowing to the motor 6 or the load torque increases sharply (e.g., increases at a rate greater than a predetermined rate of increase) at the start of driving the motor 6, the control circuit 30 can determine that the assembled front-end tool 9 is a type 1 tool. Conversely, if the magnitude of the current flowing to the motor 6 increases slowly (e.g., increases at a rate less than a predetermined rate of increase) at the start of driving, the control circuit 30 can determine that the assembled front-end tool 9 is a type 2 tool.

[0308] The electric work machine 1 includes a trigger detection circuit 22 mechanically connected to the trigger 10. The trigger detection circuit 22 outputs a first trigger signal TR1 and a second trigger signal TR2, respectively corresponding to the state of the trigger 10. The first trigger signal TR1 is (i) a binary signal, and (ii) indicates 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 (i) an analog signal, and (ii) indicates the amount of movement (in other words, the amount of pulling) the trigger 10 has made from its initial position. The second trigger signal TR2 can be output during the period when the trigger 10 is manually operated.

[0309] 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 whether the trigger 10 is turned on (i.e., manually operated) and the amount of movement of the trigger 10.

[0310] The aforementioned mode setting switch 12a and display 12b are electrically connected to the control circuit 30. The control circuit 30 receives an operation signal Sms from the mode setting switch 12a. Based on the presence or absence of the operation signal Sms, the control circuit 30 can identify whether the mode setting switch 12a has been pressed.

[0311] In this first embodiment, even if the battery pack 15 is assembled into the battery assembly section 3, the power supply voltage Vc is not immediately generated. After the battery pack 15 is assembled, the power supply voltage Vc is generated when the mode setting switch 12a is pressed and held, thereby activating the control circuit 30. A "press and hold" means, for example, that the mode setting switch 12a has been pressed continuously for a first predetermined time (e.g., 3 seconds) or more.

[0312] The control circuit 30 sets the operating mode of the electric work machine 1 to either mode 1 or mode 2.

[0313] like Figure 5 As schematically shown, the first mode is an operating mode that prioritizes the rotational speed of the motor 6 over its output torque. That is, the first mode prioritizes rotating the motor 6 at a higher speed rather than outputting higher torque while simultaneously rotating it. In the first mode, the motor 6 can rotate at a higher speed compared to the second mode. Specifically, as... Figure 5 As illustrated, the maximum rotational speed in Mode 1 is greater than the maximum rotational speed in Mode 2. Mode 1 can be referred to as high-speed mode or silent mode, etc.

[0314] On the other hand, the second mode is an operation mode that prioritizes torque output over rotational speed. That is, the second mode prioritizes rotating the motor 6 with a greater output torque than rotating it at a higher speed. In the second mode, the motor 6 can be rotated with a higher torque compared to the first mode. Specifically, as... Figure 5 As illustrated, the maximum output torque in mode 2 is greater than the maximum output torque in mode 1. Mode 2 can be referred to as torque mode or high-power mode, etc.

[0315] The rotational speed-torque characteristics of the electric work machine in embodiments 2 to 6 described later also have (i) and Figure 5 Same as, or (ii) similar to Figure 5、or (iii) with Figure 5 At least partially, they exhibit the same trends (or operating characteristics). That is, even in embodiments 2 through 6, as in this first embodiment, the first mode is an operating mode that prioritizes rotational speed, and the second mode is an operating mode that prioritizes output torque. For example, in a torque region where the output torque is relatively low, the rotational speed of the first mode can be higher than that of the second mode. Furthermore, for example, in a speed region where the rotational speed is relatively low, the output torque of the second mode can be higher than that of the first mode.

[0316] The control circuit 30 sets the operation mode switching mode to either manual or automatic. In manual mode, the operation mode is switched manually by the user. In automatic mode, the operation mode switches automatically without user intervention.

[0317] Once started, the control circuit 30 will initially set the operating mode and the switching mode respectively. In the first embodiment, for example, the operating mode is initially set to the first mode, and the switching mode is initially set to the manual mode.

[0318] Subsequently, whenever a manual / automatic switching operation is performed on the mode setting switch 12a, the control circuit 30 switches the switching mode. For example, if the switching mode is set to manual mode and a manual / automatic switching operation is performed, the control circuit 30 switches the switching mode to automatic mode. If the switching mode is set to automatic mode and a manual / automatic switching operation is performed, the control circuit 30 switches the switching mode to manual mode.

[0319] While the switching mode is set to manual mode, the control circuit 30 sets the operating mode in response to either a first manual operation or a second manual operation performed on the mode setting switch 12a. Specifically, the control circuit 30 sets the operating mode to mode 1 in response to a first manual operation on the mode setting switch 12a. If the operating mode is set to mode 2, the first manual operation will switch the operating mode back to mode 1. Similarly, if the control circuit 30 performs a second manual operation on the mode setting switch 12a, the operating mode will switch to mode 2. If the operating mode is set to mode 1, the second manual operation will switch the operating mode back to mode 2.

[0320] The first manual operation and the second manual operation can each be any operation. In the first embodiment, both the first manual operation and the second manual operation are short presses of the mode setting switch 12a. In the following description, the term "operation mode switching operation" refers to the collective term for the aforementioned first manual operation and second manual operation, including both the first manual operation and the second manual operation.

[0321] The term "short press" means that the pressing operation of the mode setting switch 12a is released before a second predetermined time (e.g., 0.5 seconds) has elapsed after the mode setting switch 12a has been pressed. The second predetermined time is shorter than the first predetermined time.

[0322] The manual / automatic switching operation can be any operation. For example, the manual / automatic switching operation can be two consecutive short presses of the mode setting switch 12a. In this case, it can be required that the time from the end of the first short press to the start of the second short press is less than the upper limit of the interval. The upper limit of the interval is (i) greater than zero, (ii) can be appropriately determined in advance, and (iii) can be, for example, 1 second.

[0323] At the moment when the mode setting switch 12a is pressed once, the control circuit 30 cannot determine whether an operation mode switching operation or a manual / automatic switching operation has been performed. If, after the mode setting switch 12a is pressed once, there is no further operation of the mode setting switch 12a even after the interval limit has elapsed since the end of the press, the control circuit 30 determines that an operation mode switching operation has been performed.

[0324] The operation mode and the switching mode can also be set by separate manual switches. For example, in addition to the mode setting switch 12a, there can be another manual switch. Moreover, the switching mode can be switched in response to a manual operation (e.g., a short press) on the other switch, and the operation mode can be switched in response to a manual operation (e.g., a short press) on the mode setting switch 12a.

[0325] The control circuit 30 controls the display 12b (specifically, an LED in this first embodiment) according to the state of the electric work machine 1.

[0326] When the switching mode is set to manual mode and the operation mode is set to mode 1, the control circuit 30 illuminates the display 12b in a first configuration. The first configuration may, for example, illuminate the LED with a first color (e.g., green).

[0327] When the switching mode is set to manual mode and the operation mode is set to the second mode, the control circuit 30 illuminates the display 12b in a second configuration. For example, the second configuration may illuminate the LED with a second color (e.g., yellow).

[0328] When the switching mode is set to automatic mode and the operation mode is set to mode 1, the control circuit 30 illuminates the display 12b in a third configuration. For example, the third configuration may involve flashing the LED in a first color.

[0329] When the switching mode is set to automatic mode and the operation mode is set to the second mode, the control circuit 30 illuminates the display 12b in a fourth configuration. For example, the fourth configuration may involve flashing the LED in a second color.

[0330] The control circuit 30 receives the first to third Hall signals Hu, Hv, and Hw from the position signal output circuit 21. As mentioned earlier, the phases of the first to third Hall signals Hu, Hv, and Hw are offset by an electrical angle of 120 degrees. Therefore, whenever the rotor 19 rotates by an electrical angle of 60 degrees, any 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) θ of the motor 6 and the actual rotational speed ω_m.

[0331] The control circuit 30 also receives a first temperature detection signal Std and a second temperature detection signal Stm. The control circuit 30 also receives a U-phase current detection signal Siu, a V-phase current detection signal Siv, a W-phase current detection signal Siw, a bus current detection signal Sib, and a battery voltage detection signal Svb.

[0332] The control circuit 30 is configured to communicate with the battery pack 15 (e.g., serial communication). The control circuit 30 can communicate with the battery pack 15 via either wired or wireless means. Wired communication can be performed while the battery pack 15 is assembled in the battery assembly section 3.

[0333] The control circuit 30 can obtain battery pack information Infb from the battery pack 15 via communication. The control circuit 30 can also request the battery pack information Infb from the battery pack 15 as needed. Alternatively, the battery pack 15 can be configured to periodically or irregularly send the battery pack information Infb to the control circuit 30 repeatedly, and the control circuit 30 can be configured to receive the battery pack information Infb.

[0334] The battery pack information Infb may include various types of information related to the battery pack 15. In the first embodiment, the battery pack information Infb includes battery information and type information. The battery information and type information are examples of the assembly equipment information summarized in the embodiments.

[0335] The type information indicates the type of the battery pack 15. The battery information directly or indirectly indicates the operating state and / or performance of the battery 15a. The battery information includes: the internal resistance of the battery 15a and the temperature of the battery 15a (hereinafter referred to as "battery temperature"). The battery information may include various parameters corresponding to the performance of the battery 15a. These parameters may include, for example, various protection thresholds. These protection thresholds are used in the battery pack 15 to protect the battery 15a. These protection thresholds may include, for example, overcurrent thresholds and overheat thresholds. The battery pack 15 may be configured to forcibly disconnect the discharge from the battery 15a in response to a discharge current exceeding the overcurrent threshold. The battery pack 15 may be configured to forcibly disconnect the discharge from the battery 15a in response to a temperature exceeding the overheat threshold. The various protection thresholds are determined based on the performance of the battery 15a. For example, the greater the power that the battery 15a can supply, the higher the overcurrent threshold and / or overheat threshold can be set to.

[0336] 2-1-3. Functions of the control circuit

[0337] The control circuit 30 of the first embodiment controls the motor 6 according to either the first control mode or the second control mode (directly controlling the drive circuit 31). When the operating mode is set to the first mode, the control circuit 30 controls the motor 6 according to the first control mode. When the operating mode is set to the second mode, the control circuit 30 controls the motor 6 according to the second control mode.

[0338] In the first embodiment, the first control method includes rectangular wave control, and the second control method includes vector control. In other words, the first control method is a control method that does not use vector control. The vector control in the second control method is an example of the second vector control in the overall embodiment.

[0339] When the operating mode is set to mode 1, the control circuit 30, as follows: Figure 4 As shown, it functions to perform rectangular wave control.

[0340] When the operating mode is set to mode 2, the control circuit 30, as follows: Figure 3 This function is indicated and vector control is executed accordingly.

[0341] The following is for reference Figure 3 as well as Figure 4 The functions of the control circuit 30 in each of the first and second modes will be explained in turn.

[0342] 2-1-3-1. Function of the control circuit in mode 2

[0343] When the operating mode is set to mode 2, the control circuit 30 performs vector control. Specifically, the control circuit 30 in mode 2 is as follows: Figure 3 As shown, it has the following functions: a position / 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 46, a voltage conversion unit 47, a mode setting unit 48, a battery communication unit 49, and a display control unit 50. While these functions are not limited, they are implemented, for example, by a processor 30a executing a computer program stored in a memory 30b.

[0344] As another example, at least one function 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 46, voltage conversion unit 47, mode setting unit 48, battery communication unit 49, and display control unit 50 can also be implemented not through software but through hardware (e.g., dedicated electronic circuits; more specifically, for example, the aforementioned logic circuits or hardwired logic connections). That is, the corresponding hardware can also be assembled into the control circuit 30.

[0345] Position / velocity calculation unit 41 outputs position signal from position signal output circuit 21 (see reference) Figure 2 The position / speed calculation unit 41 receives the first to third Hall signals Hu, Hv, and Hw. Based on these signals, it calculates the rotation angle θ and actual rotational speed ω_m of the rotor 19. The rotation angle θ represents the rotational position of the rotor 19 (specifically, an electrical angle). The actual rotational speed ω_m is the measured value of the actual rotational speed of the rotor 19. Specifically, the position / speed calculation unit 41 calculates the rotation angle θ and actual rotational speed ω_m whenever the logic value of any one of the first to third Hall signals Hu, Hv, and Hw changes (i.e., whenever the rotor 19 rotates an electrical angle of 60°).

[0346] The method for calculating the rotation angle θ and the actual rotation speed 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 / speed calculation unit 41 outputs the calculated rotation angle θ to the current conversion unit 42 and the voltage conversion unit 47, and outputs the calculated actual rotation speed ω_m to the speed control unit 44 and the limit value setting unit 45.

[0347] The current conversion unit 42 receives the U, V, and W phase current detection signals Siu, Siv, and Siw from the first to third current detection circuits 36, 37, and 38. The current conversion unit 42 converts the U-phase current value, V-phase current value, and W-phase current value represented by the U, V, and W phase current detection signals Siu, Siv, and Siw into the actual d-axis current value Id_m and the actual q-axis current value Iq_m. The actual d-axis current value Id_m corresponds to the d-axis current in the d-q coordinate system. That is, the actual d-axis current value Id_m represents the value of the actual d-axis current flowing through the motor 6. The actual q-axis current value Iq_m corresponds to the q-axis current in the d-q coordinate system. That is, the actual q-axis current value Iq_m represents the value of the actual q-axis current flowing through the motor 6.

[0348] In the d-q coordinate system, the actual current values ​​Id_m along the d-axis and Iq_m along the q-axis are represented by vectors. Specifically, the actual current value Id_m along the d-axis is represented by a d-axis vector that is (i) along the d-axis and (ii) has the magnitude of Id_m. The actual current value Iq_m along the q-axis is represented by a q-axis vector that is (i) along the q-axis and (ii) has the magnitude of Iq_m. The origin of the d-q coordinate system is the starting point of both the d-axis and q-axis vectors.

[0349] The sum of the d-axis vector and the q-axis vector is called the "current vector". The current conversion unit 42, for example, uses Clarke transformation and Park transformation to convert the U-phase current value, V-phase current value, and W-phase current value into the actual d-axis current value Id_m and the actual q-axis current value Iq_m. The current conversion unit 42 outputs the actual d-axis current value Id_m and the actual q-axis current value Iq_m to the current control unit 46.

[0350] The speed command unit 43 receives the first trigger signal TR1 and the second trigger signal TR2. 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.

[0351] The speed command value ω_r is the 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 as "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 according to the pulling amount of trigger 10 indicated by the second trigger signal TR2. Specifically, the speed command unit 43 calculates the speed command value ω_r in such a way that the larger the pulling amount, the larger the speed command value ω_r. The speed command unit 43 outputs the calculated speed command value ω_r to the speed control unit 44.

[0352] The speed control unit 44 receives the speed command value ω_r and the actual rotational speed ω_m. The speed control unit 44 also receives the d-axis current limit value Id_limit and the q-axis current limit value Iq_limit from the limit setting unit 45.

[0353] 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 actual rotational speed ω_m. Specifically, the speed control unit 44 uses PI control, for example, to calculate the d-axis current command value Id_r and the q-axis current command value Iq_r in such a way that the difference between the speed command value ω_r and the actual rotational speed ω_m is close to zero. At this time, the speed control unit 44 (i) calculates the d-axis current command value Id_r within the range not exceeding the d-axis current limit value Id_limit, and (ii) calculates the q-axis current command value Iq_r within the range not exceeding the q-axis current limit value Iq_limit. The speed control unit 44 outputs the calculated d-axis current command value Id_r and the q-axis current command value Iq_r to the current control unit 46.

[0354] The limit setting unit 45 receives the bus current detection signal Sib, the actual rotational speed ω_m, and the battery pack information Infb. Based on this information, the limit setting unit 45 sets the d-axis current limit value Id_limit and the q-axis current limit value Iq_limit.

[0355] The vector control in the first embodiment can be executed using any of a plurality of control modes. These modes include, for example, MTPA control mode, weak excitation control mode, and d-axis current zero control mode.

[0356] The MTPA control mode is: the mode that executes MTPA control. MTPA control is a type of vector control. MTPA control is a control method that controls motor 6 by migrating the current vector (specifically its leading edge) along the MTPA curve in the d-q coordinate system. The MTPA curve is defined according to various characteristics of motor 6.

[0357] Figure 6 Example 71 shows the MTPA curve of motor 6. Figure 6 The constant torque curve 72, constant current circle 73, and multiple voltage limiting ellipses 74 of motor 6 are also illustrated. Motor 6 may include multiple constant torque curves 72 and multiple constant current circles 73, but... Figure 6 Only one of these is shown. Figure 6 , Figure 12 and Figure 13 In the diagram, the horizontal axis is the d-axis, and the vertical axis is the q-axis.

[0358] In MTPA control mode, the current vector can also be controlled, for example, by migrating within the first range Pa of the MTPA curve 71. The first range Pa is defined as the point on the MTPA curve 71 from the origin to the point where it intersects with the constant current circle 73.

[0359] The weak excitation control mode is a mode that executes weak excitation control. Weak excitation control is a type of vector control. Compared to MTPA control, weak excitation control is a control method that increases the negative d-axis current of the current vector, thereby reducing the excitation flux.

[0360] More specifically, the weak excitation control includes controlling the motor 6 by migrating the current vector (specifically its leading edge) within the weak excitation region Rw in the d-q coordinate system. The weak excitation region Rw is an example of the first region in the general implementation. The weak excitation region Rw (i) does not include the MTPA curve 71, and (ii) is a region that is more negatively positioned towards the d-axis than the MTPA curve 71.

[0361] The weak excitation region Rw can be arbitrarily set. For example, the weak excitation region Rw can also be: (i) a region closer to the negative d-axis than the MTPA curve 71 and (ii) a region within a specific constant current circle 73. The weak excitation region Rw can also be: (i) a region closer to the negative d-axis than the MTPA curve 71, (ii) within a specific constant current circle 73 and (iii) a region omitting the interior of a specific voltage limiting ellipse 74. The weak excitation region Rw includes the outer periphery of the specific voltage limiting ellipse 74. As described later... Figure 12 As in the example, when an MTPV curve 75 exists in a specific constant current circle 73, the region that is closer to the negative d-axis than the MTPV curve 75 can also be excluded from the weak excitation region Rw.

[0362] The d-axis current zero control mode is the mode in which d-axis current zero control is performed. D-axis current zero control is a type of vector control. D-axis current zero control is a control method that controls the motor 6 by migrating the current vector (specifically its leading edge) along the q-axis in the d-q coordinate system (i.e., without generating a d-axis component). In d-axis current zero control mode, the current vector can also be controlled, for example, by migrating within a second range Pb on the q-axis. The second range Pb is defined as the point on the q-axis from the origin to the point intersecting with a specific constant current circle 73. D-axis current zero control can also be referred to as "Id = 0 control".

[0363] The aforementioned control modes can also include other control modes. Other control modes could include, for example, a mode that controls the motor 6 by migrating a current vector (specifically, its leading edge) within region R1. Region R1 is the area enclosed by the MTPA curve 71, the q-axis, and a specific constant current circle 73. Region R1 may or may not include the MTPA curve 71 and / or the q-axis.

[0364] The speed control unit 44 calculates the d-axis current command value Id_r and the q-axis current command value Iq_r corresponding to the determined control mode.

[0365] The current control unit 46 receives the d-axis current command value Id_r and the q-axis current command value Iq_r from the speed control unit 44. The current control unit 46 also receives the actual d-axis current value Id_m and the actual q-axis current value Iq_m from the current conversion unit 42.

[0366] The current control unit 46 calculates the d-axis voltage command value Vd_r and the q-axis voltage command value Vq_r based on the d-axis current command value Id_r, the q-axis actual current value Id_m, and the q-axis actual current value Iq_m. The current control unit 46 may also use PI control to calculate the d-axis voltage command value Vd_r and the q-axis voltage command value Vq_r. Specifically, the current control unit 46 may also calculate the d-axis voltage command value Vd_r and the q-axis voltage command value Vq_r by ensuring that the difference between the d-axis current command value Id_r and the d-axis actual current value Id_m, and the difference between the q-axis current command value Iq_r and the q-axis actual current value Iq_m are both close to zero.

[0367] The voltage conversion unit 47 receives the d-axis voltage command value Vd_r and the q-axis voltage command value Vq_r from the current control unit 46. The voltage conversion unit 47 also receives the rotation angle θ. The voltage conversion unit 47 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, and the rotation angle θ.

[0368] The voltage conversion unit 47 converts the d-axis voltage command value Vd_r and the q-axis voltage command value Vq_r into three-phase voltage command values ​​through, for example, inverse Clarke transformation and inverse Park transformation. Based on the calculated three-phase voltage command values, the voltage conversion unit 47 generates the first to sixth drive signals UH, VH, WH, UL, VL, and WL, and outputs them to the drive circuit 31.

[0369] The voltage conversion unit 47 also receives a battery voltage detection signal Svb. The voltage conversion unit 47 obtains the battery voltage value from the battery voltage detection signal Svb. The voltage conversion unit 47 can perform overmodulation control based on this battery voltage value. However, overmodulation control will be explained in detail in the third embodiment described later. Furthermore, in the third embodiment, overmodulation control can be performed in the first mode, but in the first embodiment, overmodulation control can be performed in the second mode.

[0370] The mode setting unit 48 receives the U-phase current detection signal Siu, the V-phase current detection signal Siv, the W-phase current detection signal Siw, the bus current detection signal Sib, the battery voltage detection signal Svb, the first temperature detection signal Std, the second temperature detection signal Stm, the operation signal Sms, the battery pack information Infb, and the tool information Sto. Based on these various signals and / or various information, the mode setting unit 48 sets the operating mode and the switching mode respectively.

[0371] The battery communication unit 49 is responsible for processing communication with the battery pack 15. The battery communication unit 49 obtains battery pack information Infb from the battery pack 15. The battery communication unit 49 outputs the obtained battery pack information Infb to the mode setting unit 48 and the limit value setting unit 45.

[0372] The display control unit 50 controls the operation of the display 12b.

[0373] 2-1-3-2. Function of the control circuit in mode 1

[0374] When the operating mode is set to mode 1, the control circuit 30 performs rectangular wave control. Specifically, the control circuit 30 in mode 1 is as follows: Figure 4 As shown, it functions as a position / speed calculation unit 61, a speed command unit 62, a speed control unit 63, a voltage conversion unit 64, a mode setting unit 65, and a display control unit 66. While these functions are not limited, they are implemented, for example, by a processor 30a executing a computer program stored in the memory 30b.

[0375] As another example, at least one function of the position / speed calculation unit 61, speed command unit 62, speed control unit 63, voltage conversion unit 64, mode setting unit 65, and display control unit 66 can be implemented not through software but through hardware (e.g., dedicated electronic circuits; more specifically, for example, the aforementioned logic circuits or hardwired logic connections). That is, the corresponding hardware can also be assembled into the control circuit 30.

[0376] The position / velocity calculation unit 61 is configured in the same way as the position / velocity calculation unit 41 in the first embodiment, and calculates the rotation angle θ and the actual rotation speed ω_m in the same way as the position / velocity calculation unit 41. The position / velocity calculation unit 61 outputs the calculated rotation angle θ to the voltage conversion unit 64, and outputs the calculated actual rotation speed ω_m to the speed control unit 63.

[0377] Speed ​​command unit 62 and Figure 3 The speed command unit 43 functions similarly to calculate the speed command value ω_r.

[0378] The speed control unit 63 receives a speed command value ω_r and an actual rotational speed ω_m. Based on the speed command value ω_r and the actual rotational speed ω_m, the speed control unit 63 calculates a voltage command value V_r. Specifically, the speed control unit 63 uses, for example, PI control to calculate the voltage command value V_r in a manner where the difference between the speed command value ω_r and the actual rotational speed ω_m is close to zero. In the first embodiment, the voltage command value V_r represents the duty cycle. The speed control unit 63 outputs the calculated voltage command value V_r to the voltage conversion unit 64.

[0379] The voltage conversion unit 64 receives the voltage command value V_r and the rotation angle θ. Based on the voltage command value V_r and the rotation angle θ, the voltage conversion unit 64 generates the first to sixth drive signals UH, VH, WH, UL, VL, and WL, and outputs them to the drive circuit 31.

[0380] Figure 7 The following is an example of the first operation of the electric work machine 1 under rectangular wave control. Figure 7 As shown, whenever the rotor 19 rotates by an electrical angle of 60 degrees, edge changes are generated for the first to third Hall signals Hu, Hv, and Hw. An edge change refers to a change in the logic value of any one of the first to third Hall signals Hu, Hv, and Hw.

[0381] Whenever an edge change occurs, the control circuit 30 switches the drive pair according to the rotation angle θ at that time. The drive pair is a combination of one of the three high-side switches Q1 to Q3 that should be turned on and one of the three low-side switches Q4 to Q6 that should be turned on.

[0382] Switches Q1 to Q6 are configured as drive pairs and are driven within a specified energizing angle. "Driven" means either continuously switched on or intermittently switched on (i.e., repeatedly switched on and off). The energizing angle is, for example, an electrical angle of 120°. Figure 7An example is shown where switches Q1 to Q6, numbered 1 to 6, are driven intermittently during the first half of the energizing angle and continuously during the second half. During the intermittent driving period, the switching on and off is repeated periodically according to the aforementioned duty cycle. That is, the switch is always on when the duty cycle is 100%, and the on-time within one cycle decreases as the duty cycle falls below 100%. Switches Q1 to Q6, numbered 1 to 6, can also be driven intermittently during the second half of the energizing angle.

[0383] Driven by the drive circuit 31, a rectangular wave voltage is applied from the drive circuit 31 to the first to third terminals 6a, 6b, and 6c of the motor 6, respectively. Accordingly, the bus current is also... Figure 7 As illustrated schematically, it exhibits periodic changes. Figure 7 In this context, "energized" means that bus current flows, while "not energized" means that no bus current flows. Figure 8 The same applies to China.

[0384] Figure 8 The following is an example of the second operation of the electric work machine 1 under rectangular wave control. Even in this second operation, similar to the first operation, whenever an edge change occurs, the control circuit 30 switches the drive pair according to the rotation angle θ at that time. Switches Q1 to Q6, numbered 1 to 6, are respectively set as drive pairs and driven between energizing angles.

[0385] The difference between the second action example and the first action example is that: (i) the first to sixth switches Q1 to Q6 are continuously driven during the energizing angle, and (ii) energizing angle control and / or advance angle control are performed.

[0386] Regarding the fact that switches Q1 to Q6 are continuously driven during the energizing angle, it can be determined according to... Figure 8 (and with) Figure 7 (Through comparison) it is easy to understand.

[0387] The energizing angle control is variably set according to the operating state of the motor 6. More specifically, the energizing angle control may include, for example, controlling the energizing angle so that the actual rotational speed ω_m matches the speed command value ω_r. Therefore, in this second operating example, the voltage command value V_r from the speed control unit 63 can also represent the energizing angle. Moreover, the voltage conversion unit 64 can sequentially drive the drive pair according to the energizing angle indicated by the voltage command value V_r.

[0388] In energizing angle control, the energizing angle can be controlled within a range of electrical angles below the maximum energizing angle. The maximum energizing angle can be arbitrarily determined. For example, the maximum energizing angle can be 180°. In energizing angle control, the energizing angle can also be set such that the greater the difference between the actual rotational speed ω_m and the speed command value ω_r, the larger the energizing angle (i.e., closer to the maximum energizing angle).

[0389] Figure 8 An example of implementing energizing angle control is shown. Specifically, Figure 8 This illustrates an example where Toff is disconnected before the electrical angle is rotated 120° after the circuit is switched on.

[0390] The advance angle control includes advancing the turn-on timing of each of the 1st to 6th switches Q1 to Q6 by a time equivalent to the advance angle compared to a predetermined reference timing. The advance angle can be variably set according to the operating state of the motor 6. The turn-on timing is the timing when the switch changes from off to on by being set as a drive pair; in other words, it is the start timing of the energizing angle. The reference timing can also be, for example, the timing when the edge change occurs. By setting the advance angle according to the operating state and turning on earlier than the reference timing, the motor 6 can be driven efficiently.

[0391] In advance angle control, for example, the advance angle can be set such that the greater the difference between the actual rotational speed ω_m and the speed command value ω_r, the larger the advance angle.

[0392] Figure 8 An example without advance angle control is shown. In contrast, with advance angle control implemented, the turn-on timings of switches Q1 to Q6 (numbers 1-6) are... Figure 8 The turn-on timing (i.e., the timing when edge changes) is brought forward.

[0393] Even in this second operating example, a rectangular wave voltage is applied to terminals 6a, 6b, and 6c of motor 6, respectively. Accordingly, the bus current is also... Figure 8 As illustrated schematically, it exhibits periodic changes.

[0394] 2-1-4. Motor Control Processing

[0395] Reference Figure 9 To explain: The motor control processing is performed by the control circuit 30 (more specifically, the processor 30a) to achieve the various functions described above. When the motor is started upon receiving the power supply voltage Vc, the control circuit 30 performs the motor control processing.

[0396] Once motor control processing begins, control circuit 30 initially sets the operating mode and switching mode in S110. Specifically, for example, as mentioned above, the operating mode is set to mode 1, and the switching mode is set to manual mode.

[0397] In S120, the control circuit 30 performs motion information acquisition and processing. Details of the motion information acquisition and processing are as follows... Figure 10 As shown. When the control circuit 30 enters the action information acquisition and processing stage, in S210, the bus current value is acquired based on the bus current detection signal Sib.

[0398] In S220, the control circuit 30 obtains the battery voltage value based on the battery voltage detection signal Svb.

[0399] In S230, the control circuit 30 acquires the motor current value. Specifically, the control circuit 30 acquires the U-phase current value, V-phase current value, and W-phase current value based on the U, V, and W-phase current detection signals Siu, Siv, and Siw.

[0400] In S240, the control circuit 30 calculates the rotation angle θ and the actual rotation speed ω_m based on the first to third Hall signals Hu, Hv, and Hw.

[0401] In S250, the control circuit 30 obtains the battery temperature from the battery pack 15 via communication. In S250, the control circuit 30 may also obtain part or all of the battery pack information Infb in addition to obtaining the battery temperature.

[0402] In S260, the control circuit 30 obtains the temperature of the drive circuit based on the first temperature detection signal Std.

[0403] In S270, the control circuit 30 obtains the motor temperature based on the second temperature detection signal Stm. After processing in S270, this process is transferred to S130. Figure 9 ).

[0404] In S130, the control circuit 30 determines whether the driving requirements have been met. Driving requirements are necessary to drive the motor 6. Meeting the driving requirements means that the motor 6 should be driven. Not meeting the driving requirements means that power should be supplied to the motor 6 and the motor 6 should be stopped.

[0405] The driving requirements can be arbitrarily set. In the first embodiment, the driving requirements are satisfied based on the fact that the trigger 10 is manually operated and the control circuit 30 does not prohibit the driving of the motor 6. The trigger 10 being manually operated can also be described as follows: for example, the first trigger signal TR1 indicates that the trigger 10 has been manually operated. In principle, the control circuit 30 allows the driving of the motor 6. Therefore, in principle, if the trigger 10 is manually operated, the control circuit 30 drives the motor 6. However, if the control circuit 30 detects an abnormal state of the electric work machine 1, it prohibits the driving of the motor 6.

[0406] If the driving requirements are met in S130, the process proceeds to S160. In S160, the control circuit 30 drives the motor 6 according to the currently set operating mode. If the operating mode is set to mode 1, the control circuit 30 drives the motor 6 according to the first control method (specifically, rectangular wave control). In mode 1, the aforementioned energizing angle control and / or advance angle control can also be combined with rectangular wave control. If the operating mode is set to mode 2, the control circuit 30 drives the motor 6 according to the second control method (specifically, vector control).

[0407] In S170, the control circuit 30 performs notification processing. Specifically, based on the current operating mode and switching mode, as described above, the display 12b is activated. That is, for example, when the switching mode is set to manual mode and the operating mode is set to mode 1, the control circuit 30 activates the display 12b in mode 1. After processing in S170, this process proceeds to S120.

[0408] If the driving requirements are not met in S130, the process proceeds to S140. In S140, the control circuit 30 stops the motor 6. Specifically, it disconnects all switches Q1 to Q6, thereby stopping the supply of three-phase power to the motor 6.

[0409] In S150, control circuit 30 performs the operation mode switching process. Details of the operation mode switching process are as follows... Figure 11 As shown. Once the process transitions to the operation mode switching process, in S310, the control circuit 30 determines whether a manual / automatic switching operation has been performed on the mode setting switch 12a. If a manual / automatic switching operation has been performed, the process proceeds to S420.

[0410] In S420, the control circuit 30 determines the currently set switching mode. If the current switching mode is manual mode, the control circuit 30 switches the switching mode to automatic mode in S430. After processing in S430, this process proceeds to S320. If the current switching mode is automatic mode, the control circuit 30 switches the switching mode back to manual mode in S440. After processing in S440, this process proceeds to S320.

[0411] If no manual / automatic switching operation is performed in S310, the process proceeds to S320. In S320, the control circuit 30 determines the currently set switching mode. If the current switching mode is manual mode, the process proceeds to S330.

[0412] In step S330, the control circuit 30 determines whether an operation mode switching operation has been performed on the mode setting switch 12a. If no operation mode switching operation has been performed, this process proceeds to step S170. Figure 9 If an action mode switching operation is performed, this process is transferred to S340.

[0413] In step S340, the control circuit 30 determines the currently set operating mode. If the current operating mode is mode 1, the control circuit 30 switches the operating mode to mode 2 in step S350. After processing in step S350, the process proceeds to step S170. If the current operating mode is mode 2, the control circuit 30 switches the operating mode back to mode 1 in step S360. After processing in step S360, the process proceeds to step S170.

[0414] If the current switching mode is automatic in S320, the process proceeds to S370. In S370, the control circuit 30 determines the currently set operating mode. If the currently set operating mode is mode 1, the process proceeds to S380.

[0415] In S380, control circuit 30 determines whether the second mode switching requirement has been met. The second mode switching requirement is required to set the operation mode to the second mode. The fulfillment of the second mode switching requirement corresponds to the state where the operation mode should be set (or can be set) to the second mode. Details of the second mode switching requirement will be described later.

[0416] If the conditions for switching to the second mode are not met, the process proceeds to S170. If the conditions for switching to the second mode are met, the process proceeds to S390. In S390, the control circuit 30 switches the operating mode to the second mode. After the processing in S390, the process proceeds to S170.

[0417] In S370, if the currently set action mode is mode 2, this process proceeds to S400. In S400, it is determined whether the mode 1 switching requirement has been met. To set the action mode to mode 1, the mode 1 switching requirement is required. Meeting the mode 1 switching requirement corresponds to a state where the action mode should be set (or can be set) to mode 1. Details of the mode 1 switching requirement will be described later.

[0418] If the requirements for switching to mode 1 are not met, this process proceeds to S170.

[0419] If the requirements for switching to mode 1 are met, the process proceeds to S410. In S410, the control circuit 30 switches the operating mode to mode 1. After processing in S410, the process proceeds to S170.

[0420] Specifically explain the requirements for switching between the first and second modes.

[0421] The control circuit 30 can determine the switching requirements for the first and second modes based on the bus current detection signal Sib. Specifically, the second mode switching requirement can be satisfied when the bus current value is above the first current threshold, and the first mode switching requirement can be satisfied when the bus current value is below the second current threshold. The second current threshold is less than the first current threshold and greater than zero.

[0422] Alternatively, or in a different manner, the control circuit 30 may determine the switching conditions for the first and second modes based on the U, V, and W phase current detection signals Siu, Siv, and Siw. Specifically, the second mode switching condition may be satisfied when the three-phase current level is above a third current threshold, and the first mode switching condition may be satisfied when the three-phase current level is below a fourth current threshold. The fourth current threshold is less than the third current threshold and greater than zero. The three-phase current level directly or indirectly represents the amplitude of the three-phase current. The three-phase current level may also be, for example, the magnitude of the aforementioned current vector.

[0423] Alternatively, or in a different manner, the control circuit 30 determines the switching conditions for the first and second modes based on the battery voltage detection signal Svb. Specifically, the second mode switching condition can be met when the battery voltage value is above the first voltage threshold, and the first mode switching condition can be met when the battery voltage value is below the second voltage threshold. The second voltage threshold is less than the first voltage threshold and greater than zero.

[0424] Alternatively, or in a different manner, the control circuit 30 determines the switching conditions for the first and second modes based on the first temperature detection signal Std. Specifically, the second mode switching condition can be satisfied when the driving circuit temperature is below the first temperature threshold, and the first mode switching condition can be satisfied when the driving circuit temperature is above the second temperature threshold. The first temperature threshold is less than the second temperature threshold and is greater than zero.

[0425] Alternatively, or in a different manner, the control circuit 30 determines the switching conditions for the first and second modes based on the second temperature detection signal Stm. Specifically, the second mode switching condition can be met when the motor temperature is below the third temperature threshold, and the first mode switching condition can be met when the motor temperature is above the fourth temperature threshold. The third temperature threshold is less than the fourth temperature threshold and is greater than zero.

[0426] Alternatively, or in a different manner, the control circuit 30 determines the switching requirements for the first and second modes based on the battery pack information Infb. Specifically, the second mode switching requirement can be met when the battery temperature is below the fifth temperature threshold, and the first mode switching requirement can be met when the battery temperature is above the sixth temperature threshold. The fifth temperature threshold is less than the sixth temperature threshold and greater than zero.

[0427] 2-2. Second Implementation Method

[0428] The electric work machine of the second embodiment will be described. The electric work machine of the second embodiment differs from the electric work machine 1 of the first embodiment mainly in the following two aspects.

[0429] That is, in the first embodiment, rectangular wave control is performed in the first mode. In contrast, in the second embodiment, first vector control is performed in the first mode. The first vector control includes the aforementioned weak excitation control.

[0430] Furthermore, in the second embodiment, a second vector control is performed in the second mode. The second vector control differs from the first vector control and does not include the aforementioned weak excitation control. That is, in the first embodiment, MTPA control, weak excitation control, or d-axis current zero control are performed in the second mode; conversely, in the second embodiment, weak excitation control is not performed in the second mode.

[0431] Therefore, in the second embodiment, in both the first and second modes, the control circuit 30 is as follows: Figure 4 It functions as shown. That is, the control circuit 30 performs vector control in both the first and second modes. However, the specific content of the vector control differs as described above.

[0432] Apart from the two points mentioned above, the electric work machine of the second embodiment is constructed in the same principle as the electric work machine 1 of the first embodiment.

[0433] That is, even in the second embodiment, it is executed. Figures 9-11 The motor control processing is different from the motor control in the first embodiment. That is, in the second embodiment, in S160, when the operating mode is set to the first mode, the first vector control (i.e., weak excitation control) is executed, and when the operating mode is set to the second mode, the second vector control (e.g., MTPA control or d-axis current zero control) is executed.

[0434] Reference Figure 12 as well as Figure 13 Let's take an example to illustrate the current vector in the first vector control.

[0435] In the first vector control, for example, the current vector can also be set to... Figure 12 The illustrated weak excitation trajectory Pc migrates upwards in part or all. The weak excitation trajectory Pc includes: a first trajectory Pc1 and a second trajectory Pc2. The first trajectory Pc1 extends from the first intersection point 70a to the second intersection point 70b, but does not include the first intersection point 70a. The first intersection point 70a is the intersection of a specific constant current circle 73 and the MTPA curve 71. The second intersection point 70b is the intersection of the specific constant current circle 73 and the specific voltage limiting ellipse 74. The second trajectory Pc2 extends from the second intersection point 70b on the specific voltage limiting ellipse 74 to the third intersection point 70c. The third intersection point 70c is the intersection of the specific voltage limiting ellipse 74 and the d-axis.

[0436] Additionally, for example, motor 6 has Figure 13 In the case of the voltage limiting ellipse 76 as illustrated, in the first vector control, the current vector can be... Figure 13 Part or all of the weakly excitation trajectory Pd illustrated migrates upwards. Figure 13 In the example, the center of the voltage limiting ellipse 76 is contained within a specific constant current circle 73.

[0437] Figure 13The weak excitation trajectory Pd includes: trajectory Pd1, trajectory Pd2, and trajectory Pd3. Trajectory Pd1 extends from the first intersection point 70a to the fourth intersection point 70d, but does not include the first intersection point 70a. The fourth intersection point 70d is the intersection of a specific constant current circle 73 and the MTPV curve 75. Trajectory Pd2 extends from the fourth intersection point 70d to the fifth intersection point 70e on the MTPV curve 75. The fifth intersection point 70e is the intersection of the MTPV curve 75 and the voltage limiting ellipse 76. Trajectory Pd3 extends from the fifth intersection point 70e on the voltage limiting ellipse 76 to the trajectory endpoint 70f. The trajectory endpoint 70f corresponds to any position between the fifth intersection point 70e on the voltage limiting ellipse 76 and the d-axis. The trajectory endpoint 70f can be the intersection of the voltage limiting ellipse 76 and the d-axis (wherein, it is closer to the positive d-axis side than the MTPV curve 75).

[0438] Even in the second mode, weak excitation control can be performed. However, in this case, the reduction in excitation flux can be set less in the second mode compared to the first mode.

[0439] 2-3. Third Implementation Method

[0440] The electric work machine of the third embodiment is described below. The electric work machine of the third embodiment differs from the electric work machine 1 of the first embodiment in that: the first control method in the first mode.

[0441] That is, the first control method in the first embodiment is rectangular wave control. In contrast, the first control method in the third embodiment includes first vector control. However, this first vector control is different from the first vector control in the second embodiment.

[0442] In the third embodiment, the same vector control as in the first embodiment is performed in the second mode. For ease of explanation, the vector control performed in the second mode in the third embodiment will be referred to as the second vector control.

[0443] The main difference between the first vector control and the second vector control in the third embodiment is that the first vector control includes overmodulation control, while the second vector control does not. The first vector control may, for example, further apply overmodulation control to the second vector control. Specifically, for example, if the second vector control is MTPA control, the first vector control may further apply overmodulation control to the MTPA control. Additionally, for example, the first vector control may further apply overmodulation control to a vector control different from the second vector control. Specifically, for example, if the second vector control is MTPA control, the first vector control may further apply overmodulation control to weak excitation control (or a mixture of MTPA control and weak excitation control).

[0444] Overmodulation control includes controlling the drive circuit 31 by applying overmodulation voltages from the drive circuit 31 toward the first terminal 6a, the second terminal 6b, and the third terminal 6c, respectively. The overmodulation voltage includes a sinusoidal first-order component. Overmodulation control also includes maintaining the overmodulation voltage at an upper limit of the battery voltage value and at zero voltage. That is, the overmodulation voltage varies along a reference sine wave Sref. This reference sine wave Sref has an amplitude larger than the battery voltage value. Furthermore, during periods when the reference sine wave Sref is higher than the battery voltage value, the magnitude of the overmodulation voltage is maintained at the battery voltage value. The phrase "varies along the reference sine wave Sref" is not limited to strictly varying along the reference sine wave Sref, but includes varying in a sinusoidal shape (i.e., generally along a trajectory similar to a sine wave). For example, the overmodulation voltage may also include a substantially sinusoidal component (i.e., the first-order component) and one or more higher-order harmonic components (or similar components).

[0445] Figure 14 The upper paragraph illustrates the overmodulation voltage with a modulation rate of 1.3. The modulation rate is the ratio of the amplitude of the reference sine wave Sref to the battery voltage. A modulation rate of 1 corresponds to the amplitude of the reference sine wave Sref being equal to the battery voltage. When the amplitude of the reference sine wave Sref exceeds the battery voltage, the modulation rate exceeds 1.

[0446] Figure 14 In this context, "max" refers to the battery voltage value. Figure 14 The phase voltage and the line-to-line voltage are shown respectively. Figure 14 The vertical axis represents the ratio of different voltages when the battery voltage is "1". From Figure 14 It is evident from this that when the modulation rate exceeds 1, the phase voltage is modulated according to the modulation rate. Accordingly, the line-to-line voltage is also a slightly distorted version of its sinusoidal state.

[0447] To achieve the first vector control including such overmodulation control, the control circuit 30, in principle, even in the first mode, should... Figure 4 It functions as shown. However, the fact that modulation control has been performed is different from... Figure 4 The locality is different.

[0448] Specifically, in the first vector control of the third embodiment, the voltage conversion unit 47 obtains the battery voltage value from the battery voltage detection signal Svb. Furthermore, a modulation rate is set in the control circuit 30. Alternatively, the modulation rate can be set manually by the user or automatically based on the operating state of the electric work machine 1.

[0449] The voltage conversion unit 47 generates the first to sixth drive signals UH, VH, WH, UL, VL, and WL based on the set modulation rate and the battery voltage value. Specifically, the voltage conversion unit 47 generates the first to sixth drive signals UH, VH, WH, UL, VL, and WL by applying an overmodulation voltage corresponding to the set modulation rate to the first to third terminals 6a, 6b, and 6c, respectively.

[0450] 2-4. Fourth Implementation Method

[0451] The motor control processing of the first embodiment ( Figure 9 Another example is described as the fourth embodiment. Figure 15 The motor control process of this fourth embodiment, as shown, differs from the motor control process of the first embodiment by adding S101 and S102 instead of S110. Furthermore, the processing of S150 in the first embodiment is omitted. Figure 15 In China, regarding Figure 9 The same processing is applied to... Figure 9 The same reference numerals are used in the accompanying drawings. The following refers to... Figure 15 The motor control processing mainly focuses on... Figure 9 Explain the different points.

[0452] In the fourth embodiment, no switching mode is set. In other words, the user cannot manually switch the action mode; the action mode is set automatically in principle. However, even in the fourth embodiment, the action mode can be set manually. Specifically, the user can also manually change the action mode set in S102, which will be described later.

[0453] Once it begins Figure 15 The motor control process involves control circuit 30 acquiring assembly equipment information in S101. This assembly equipment information includes: the aforementioned battery pack information Infb, and / or tool information Sto.

[0454] In S102, the control circuit 30 sets the operation mode to either mode 1 or mode 2 based on the assembly equipment information obtained in S101. Specifically, the control circuit 30 sets the operation mode to mode 1 based on the assembly equipment information meeting the first setting requirement, and sets the operation mode to mode 2 based on the assembly equipment information meeting the second setting requirement.

[0455] The first and second setting requirements can be appropriately determined. For example, the equipment assembly information may include the magnitude of the internal resistance of the battery 15a. In this case, the first and second setting requirements can also be set based on the magnitude of the internal resistance. Specifically, the first setting requirement can be satisfied based on the internal resistance being greater than or equal to a first threshold. The second setting requirement can be satisfied based on the internal resistance being less than or equal to a second threshold. The second threshold is less than the first threshold and greater than zero. That is, in this case, if the internal resistance is greater than or equal to the first threshold, the control circuit 30 sets the operating mode to the first mode, and if the internal resistance is less than or equal to the second threshold, the operating mode is set to the second mode.

[0456] Additionally, for example, the assembly equipment information may include type information of the battery pack 15. In this case, the first and second setting requirements can be set based on the type represented by the type information. Specifically, the control circuit 30 may have type-mode correspondence information where multiple types are respectively associated with the first mode or the second mode. In this case, the first setting requirement can be satisfied based on the acquired type being associated with the first mode in the type-mode correspondence information. The second setting requirement can be satisfied based on the acquired type being associated with the second mode in the type-mode correspondence information.

[0457] Alternatively, for example, the assembly equipment information may also include tool information Sto. In this case, the first and second setting requirements can be set based on the type of front-end tool 9 represented by the tool information Sto. Specifically, the first setting requirement can be satisfied based on the front-end tool 9 being classified as the aforementioned first type of tool. The second setting requirement can be satisfied based on the front-end tool 9 being classified as the aforementioned second type of tool.

[0458] The processing of S120, S130, S140, and S160 is the same as in the first embodiment. In the fourth embodiment, after S140 and after S160, the process proceeds to S180.

[0459] In S180, the control circuit 30 performs notification processing. Specifically, when the operation mode is set to the first mode, the control circuit 30 illuminates the display 12b in a first configuration, and when the operation mode is set to the second mode, it illuminates the display 12b in a second configuration.

[0460] 2-5. Fifth Implementation Method

[0461] The motor control processing of the first embodiment ( Figure 9 Another example of this will be described as the fifth embodiment. Figure 16The motor control process of the fifth embodiment shown differs from that of the motor control process of the first embodiment in that S190 is added after S160.

[0462] In S190, control circuit 30 performs specific mode monitoring processing. Details of the specific mode monitoring processing are as follows... Figure 17 As shown.

[0463] Once the process transitions to a specific mode monitoring and processing, the control circuit 30 determines (or acquires) the currently set operating mode in S510. If the current operating mode is mode 1, the control circuit 30 maintains the operating mode as mode 1 in S520. After processing in S520, this process transitions to S170. Figure 16 If the current action mode is mode 2, this process is transferred to S530.

[0464] In S530, the control circuit 30 determines whether the continuous driving time of the second mode is greater than or equal to the first time threshold. The continuous driving time of the second mode means the time during which the motor 6 is continuously driven in the second mode. The continuous driving time of the second mode can also be described as the time during which the trigger 10 is continuously pressed in the second mode (therefore the motor 6 is continuously driven).

[0465] If the duration of continuous operation in mode 2 does not reach the first time threshold, the process proceeds to S540. In S540, the control circuit 30 maintains the operating mode as mode 2. After processing in S540, the process proceeds to S170.

[0466] In S530, if the continuous driving time of the second mode reaches the first time threshold, this process proceeds to S550. In S550, the control circuit 30 switches the operating mode back to the first mode. After the processing in S550, this process proceeds to S170.

[0467] As mentioned earlier, the second mode prioritizes output torque. Therefore, when the continuous driving time in the second mode exceeds the first time threshold, the temperature of the drive circuit, motor, and / or battery rises, potentially affecting the operation or reliability of the drive circuit 31, motor 6, and / or battery 15a. Therefore, if the continuous driving time in the second mode becomes longer, the control circuit 30 forcibly switches to the first mode. Accordingly, the drive circuit 31, motor 6, and / or battery 15a are protected against overheating.

[0468] 2-6. Sixth Implementation Method

[0469] The motor control processing of the first embodiment ( Figure 9 Another example of this will be described as the sixth embodiment. Figure 18 The motor control processing of the sixth embodiment shown is different from the motor control processing of the fifth embodiment. Figure 16 The difference is that S191 is executed instead of S190, and S610 to S640 are added after S191.

[0470] In S191, the control circuit 30 performs a specific mode monitoring process. This specific mode monitoring process differs from the specific mode monitoring process in S190 of the fifth embodiment. Details of the specific mode monitoring process in S191 are as follows: Figure 19 As shown.

[0471] Figure 19 Specific mode monitoring and processing Figure 17 The difference between the specific mode monitoring and processing is that S531 is executed instead of S530, and S551 is executed instead of S550.

[0472] In S531, the control circuit 30 determines whether the continuous driving time of the second mode is above a second time threshold. The second time threshold may be the same as or different from the first time threshold in the fifth embodiment.

[0473] If the duration of the second mode drive does not reach the second time threshold, the process proceeds to S540. If the duration of the second mode drive reaches the second time threshold, the process proceeds to S551.

[0474] In S551, control circuit 30 sets the drive disable request flag. After processing in S551, this process is transferred to S610 ( Figure 18 ).

[0475] In step S610, the control circuit 30 determines whether a drive disabling request flag is set. If the drive disabling request flag is not set, the process proceeds to step S170. If the drive disabling request flag is set, the process proceeds to step S620.

[0476] In S620, the control circuit 30 stops the motor 6. That is, it disconnects all switches Q1 to Q6, thereby stopping the supply of three-phase power to the motor 6.

[0477] In S630, the control circuit 30 determines whether the user has re-triggered the trigger. Re-triggering means temporarily disabling the manual operation of trigger 10 and then manually operating it again. If there is no re-trigger (i.e., the manual operation of trigger 10 is maintained), the process proceeds to S620. That is, in this case, the motor 6 remains stopped. On the other hand, if there is a re-trigger, the process proceeds to S640.

[0478] In S640, the control circuit 30 initially sets the operating mode. Specifically, the control circuit 30 can also initially set the operating mode in the same way as in S110. After processing in S640, this process proceeds to S170.

[0479] 3. Other implementation methods

[0480] The above describes the embodiments of the present invention, but the present invention is not limited to the embodiments described above and can be implemented in various modifications.

[0481] (3-1) In automatic mode, the control circuit 30 can also switch the operation mode based on any judgment criteria.

[0482] For example, the second mode switching requirement can also be satisfied based on the load torque applied to the motor 6 via the front-end tool 9 being greater than or equal to the first torque threshold. The first mode switching requirement can also be satisfied based on the load torque being less than or equal to the second torque threshold. In this case, the second torque threshold is less than the first torque threshold and greater than zero.

[0483] The control circuit 30 can also arbitrarily acquire the load torque. The electric work machine 1 may include, for example, a torque sensor for detecting the load torque. The torque sensor may be installed, for example, in the power transmission unit 7. The torque sensor may be configured to output a torque signal. The torque signal may correspond to the magnitude of the mechanical torsion generated in the power transmission unit 7 due to the load torque. The control circuit 30 may also acquire the load torque based on the torque signal from the torque sensor. Alternatively, the control circuit 30 may also detect (or estimate) the load torque based on the operating state of the motor 6. For example, the control circuit 30 may also detect the load torque based on the bus current value.

[0484] (3-2) Electric work machines may only have automatic or manual modes. That is, electric work machines may not have the function of setting and switching modes.

[0485] (3-3) Motor 6 can also be controlled in a so-called sensorless manner. That is, the electric work machine 1 may not have a position signal output circuit 21. In this case, the control circuit 30 can calculate the rotation angle θ and the actual rotation speed ω_m based on the induced voltage generated by the first to third terminals 6a, 6b, 6c of motor 6.

[0486] (3-4) In the above embodiments, the multiple functions of one constituent element can be accomplished by multiple constituent elements, and the single function of one constituent element can be accomplished by multiple constituent elements. Furthermore, the multiple functions of multiple constituent elements can be accomplished by one constituent element, and the single function accomplished by multiple constituent elements can also be accomplished by one constituent element. Additionally, in the above embodiments, a portion of the constituent element may be omitted. Furthermore, at least a portion of the constituent element of one embodiment may be added to, or substituted for, the constituent element of any other embodiment.

Claims

1. An electric work machine, comprising: A brushless motor, configured to drive a front-end tool; The drive circuit is configured to (i) receive DC power from a DC power source, (ii) generate three-phase power from the received DC power, and (iii) supply the generated three-phase power to the brushless motor to drive the brushless motor; and Control circuit, The control circuit is configured as follows: The operating mode of the control circuit can be selectively set to either mode 1 or mode 2. Based on the fact that the operating mode has been set to the first mode, the brushless motor is controlled by the drive circuit according to the first control method, wherein the first control method (i) is a control method other than vector control, or (ii) includes the first vector control. Based on the fact that the operation mode has been set to the second mode, the brushless motor is controlled by means of the drive circuit according to the second control method, wherein the second control method (i) is different from the first control method, and (ii) includes a second vector control that is different from the first vector control.

2. The electric work machine according to claim 1, characterized in that, The first control method (i) is a control method other than the vector control, and (ii) includes rectangular wave control.

3. The electric work machine according to claim 2, characterized in that, The drive circuit includes a three-phase bridge circuit with six switches. The first control method includes: continuously or intermittently energizing each of the six switches from its corresponding energizing moment until the brushless motor has rotated by an angle equivalent to the energizing angle; and advance angle control and / or energizing angle control. The advance angle control includes: (i) advancing the turn-on timing of each of the six switches by a time equivalent to the advance angle relative to a reference timing, and (ii) changing the advance angle according to the operating state of the brushless motor. The energizing angle control includes changing the energizing angle according to the operating state of the brushless motor.

4. The electric work machine according to claim 1, characterized in that, The brushless motor includes a first terminal, a second terminal, and a third terminal configured to receive a three-phase current corresponding to the three-phase power from the drive circuit. The first control method includes the first vector control. The second vector control includes supplying the three-phase current to the brushless motor in a manner that the current vector of the three-phase current migrates along the maximum torque / current curve of the brushless motor in the d-q coordinate system. The d-q coordinate system has mutually orthogonal d-axis and q-axis. The current vector is the vector sum of the d-axis current and the q-axis current, where the d-axis current corresponds to the d-axis component of the three-phase current and the q-axis current corresponds to the q-axis component of the three-phase current.

5. The electric work machine according to claim 4, characterized in that, The first vector control includes weak excitation control. The weak excitation control includes supplying the three-phase current to the brushless motor in a manner in which the current vector migrates within the first region of the d-q coordinate system. The first region (i) does not contain the maximum torque / current curve, and (ii) corresponds to a region that is closer to the negative side of the d-axis than the maximum torque / current curve.

6. The electric work machine according to claim 4 or 5, characterized in that, The first vector control includes applying an overmodulated voltage from the drive circuit toward the first terminal, the second terminal, and the third terminal, respectively. The magnitude (i) of the overmodulation voltage varies along the reference sine wave. The reference sine wave has an amplitude larger than that of the DC voltage. The DC voltage is applied from the DC power supply toward the drive circuit. The magnitude (ii) of the overmodulated voltage is maintained at the magnitude of the DC voltage during the period when the magnitude of the reference sine wave is greater than the magnitude of the DC voltage.

7. The electric work machine according to any one of claims 1 to 6, characterized in that, The electric work machine is equipped with a manual switch, which is configured to allow the user of the electric work machine to perform a first manual operation and a second manual operation. The control circuit is configured as follows: Based on the first manual operation performed on the manual switch, the action mode is set to the first mode. Based on the second manual operation performed on the manual switch, the action mode is set to the second mode.

8. The electric work machine according to any one of claims 1 to 6, characterized in that, The control circuit is configured as follows: Based on (i) the action mode has been set to the second mode and (ii) the switching requirements for the first mode have been met, the action mode is switched to the first mode, and / or, Based on (i) the action mode has been set to the first mode and (ii) the conditions for switching to the second mode have been met, the action mode is switched to the second mode.

9. The electric work machine according to claim 8, characterized in that, The second mode switching requirement is met based on the load torque being greater than or equal to the first torque threshold. The load torque is the torque applied to the brushless motor via the front-end tool. The first mode switching requirement is met based on the load torque being below the second torque threshold. The second torque threshold is less than the first torque threshold and greater than zero.

10. The electric work machine according to claim 8 or 9, characterized in that, The second mode switching requirement is met based on the bus current being greater than or equal to the first current threshold. The bus current is the current supplied from the DC power supply to the brushless motor via the drive circuit. The first mode switching requirement is met based on the fact that the magnitude of the bus current is below a second current threshold. The second current threshold is less than the first current threshold and greater than zero.

11. The electric work machine according to any one of claims 8 to 10, characterized in that, The brushless motor includes a first terminal, a second terminal, and a third terminal configured to receive a three-phase current corresponding to the three-phase power from the drive circuit. The second mode switching requirement is met based on the current level being above the third current threshold. The current level directly or indirectly represents the amplitude of the three-phase current. The first mode switching requirement is met based on the current level being below the fourth current threshold. The fourth current threshold is less than the third current threshold and greater than zero.

12. The electric work machine according to any one of claims 8 to 11, characterized in that, The drive circuit is configured to receive a DC voltage corresponding to the DC power from the DC power source. The second mode switching requirement is met based on the fact that the magnitude of the DC voltage is above the first voltage threshold. The first mode switching requirement is satisfied based on the fact that the magnitude of the DC voltage is below a second voltage threshold. The second voltage threshold is less than the first voltage threshold and greater than zero.

13. The electric work machine according to any one of claims 8 to 12, characterized in that, The second mode switching requirement is met based on the fact that the temperature of the drive circuit is below the first temperature threshold. The first mode switching requirement is met based on the fact that the temperature of the driving circuit is above a second temperature threshold. The first temperature threshold is less than the second temperature threshold and greater than zero.

14. The electric work machine according to any one of claims 8 to 13, characterized in that, The second mode switching requirement is met based on the brushless motor temperature being below a third temperature threshold. The first mode switching requirement is met based on the brushless motor's temperature being above a fourth temperature threshold. The third temperature threshold is less than the fourth temperature threshold and greater than zero.

15. The electric work machine according to any one of claims 8 to 14, characterized in that, The DC power supply includes a battery. The second mode switching requirement is met based on the battery temperature being below the fifth temperature threshold. The first mode switching requirement is met based on the battery temperature being above the sixth temperature threshold. The fifth temperature threshold is less than the sixth temperature threshold and greater than zero.

16. The electric work machine according to any one of claims 7 to 15, characterized in that, The control circuit is configured to switch the operation mode to the first mode in response to (i) the operation mode being set to the second mode and (ii) the brushless motor being continuously controlled according to the second control method for a period of time or more.

17. The electric work machine according to any one of claims 7 to 15, characterized in that, The control circuit is configured to: in response to (i) the operation mode being set to the second mode and (ii) the brushless motor being continuously controlled according to the second control method for a second time threshold or more, stop supplying the three-phase power from the drive circuit to the brushless motor.

18. The electric work machine according to any one of claims 1 to 6, characterized in that, The control circuit is configured as follows: Obtain assembly equipment information related to the assembly equipment assembled on the electric work machine. Based on the fact that the assembly equipment information has met the first setting requirement, the operation mode is set to the first mode. The operation mode is set to the second mode based on the fact that the assembly equipment information has met the second setting requirement.

19. The electric work machine according to claim 18, characterized in that, The DC power supply includes a battery. The electric work machine includes a battery assembly section configured to detachably assemble a battery pack. The battery pack houses the batteries. The control circuit is configured to acquire battery information from the battery pack assembled in the battery assembly. The battery information directly or indirectly represents the performance of the battery. The assembly equipment information includes the battery information.

20. The electric work machine according to claim 19, characterized in that, The battery has internal resistance. The battery information includes the magnitude of its internal resistance. The first setting requirement is satisfied based on the internal resistance being greater than or equal to a first threshold. The second setting requirement is satisfied based on the fact that the magnitude of the internal resistance is below a second threshold. The second threshold is less than the first threshold and greater than zero.

21. The electric work machine according to claim 18, characterized in that, The DC power supply includes a battery. The electric work machine includes a battery assembly section configured to detachably assemble a battery pack. The battery pack houses the batteries. The control circuit is configured to obtain type information from the battery pack assembled in the battery assembly. The type information indicates the type of the battery pack. The assembly equipment information includes the type information.

22. The electric work machine according to claim 18, characterized in that, The control circuit is configured to acquire tool information. The tool information indicates the type of front-end tool assembled on the electric work machine. The assembly equipment information includes the tool information.

23. The electric work machine according to any one of claims 1 to 22, characterized in that, The maximum rotational speed of the brushless motor in the first mode is greater than the maximum rotational speed in the second mode, and / or, The maximum output torque of the brushless motor in the second mode is greater than the maximum output torque in the first mode.

24. A control method for a brushless motor of an electric work machine, comprising: The operating mode of the electric work machine equipped with a brushless motor can be selectively set to either mode 1 or mode 2. During the period when the operating mode is set to the first mode, the drive of the brushless motor is controlled by a control method other than vector control, or the drive of the brushless motor is controlled by the first vector control. During the period when the operating mode is set to the second mode, the drive of the brushless motor is controlled by the second vector control. The first vector control is different from the second vector control.

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