阅读说明：本技术 电动工具、控制方法和程序 (Electric tool, control method, and program ) 是由 米田文生 于 2019-06-14 设计创作，主要内容包括：目的是提供被配置为提高马达的操作效率的电动工具、控制方法和程序。电动工具包括马达(1)和马达控制装置(3)。马达控制装置(3)被配置为基于与在马达(1)的转动期间施加至马达(1)的负载的大小和马达(1)所用的直流电源(8)的电压(V_(dc))至少之一有关的参数,来更新马达(1)的速度的命令值(ω_2*)。(It is an object to provide an electric power tool, a control method, and a program configured to improve the operation efficiency of a motor. The electric tool includes a motor (1) and a motor control device (3). The motor control device (3) is configured to control the motor (1) based on the magnitude of a load applied to the motor (1) during rotation of the motor (1) and the voltage (V) of a direct current power supply (8) used by the motor (1) dc ) At least one parameter of interest, to update the command value (ω) of the speed of the motor (1) 2 *)。)

1. A power tool, comprising:

a motor; and

a control device for a motor, which is provided with a motor,

the motor control device is configured to update a command value of a speed of the motor based on a parameter relating to at least one of a magnitude of a load applied to the motor during rotation of the motor and a voltage of a direct-current power supply used by the motor.

2. The power tool according to claim 1,

the motor control device is configured to update the command value based on a result of comparison between the parameter and a threshold value.

3. The power tool according to claim 2,

the parameter includes a modulation degree.

4. The power tool according to claim 3,

the threshold value comprises a modulation degree threshold value, an

The motor control device is configured to decrease the command value if the modulation degree is higher than the modulation degree threshold.

5. The power tool according to claim 4,

the motor control device is configured to cause the command value to approach a target value of a speed of the motor if the modulation degree is lower than or equal to the modulation degree threshold.

6. The electric power tool according to any one of claims 2 to 5,

the parameter includes a torque current value representing a magnitude of a torque component of a current flowing through the motor.

7. The power tool according to claim 6,

the threshold comprises a current threshold, an

The motor control device is configured to decrease the command value if the torque current value is greater than the current threshold value.

8. The power tool according to claim 7,

the motor control device is configured to cause the command value to approach a target value of a speed of the motor in a case where the torque current value is less than or equal to the current threshold value.

9. The electric power tool according to any one of claims 2 to 8,

the parameter includes a power supply voltage value representing a magnitude of a voltage of the direct current power supply.

10. The power tool according to claim 9,

the threshold comprises a voltage threshold, an

The motor control device is configured to decrease the command value if the power supply voltage value is less than the voltage threshold value.

11. The power tool according to claim 10, wherein,

the motor control device is configured to cause the command value to approach a target value of a speed of the motor in a case where the power supply voltage value is greater than or equal to the voltage threshold value.

12. The electric power tool according to any one of claims 1 to 11,

the motor is a brushless motor.

13. The power tool according to claim 12, further comprising:

an inverter circuit unit configured to generate a driving voltage from the direct-current power supply and output the driving voltage to the motor,

wherein the motor control device is configured to determine a target value of the drive voltage so that the speed of the motor coincides with the command value, and supply the target value to the inverter circuit unit.

14. A control method of a motor, the control method comprising:

the command value of the speed of the motor is updated based on a parameter related to at least one of a magnitude of a load applied to the motor during rotation of the motor and a voltage of a direct current power source used by the motor.

15. A program for causing a computer system to execute the control method according to claim 14.

Technical Field

The present invention relates generally to a power tool, a control method, and a program. The present invention particularly relates to an electric power tool configured to control a motor by a direct-current power supply, a control method of controlling a motor by a direct-current power supply, and a program for executing the control method.

Background

Patent document 1 discloses an electric power tool. The electric power tool disclosed in patent document 1 includes: a motor; a drive circuit for supplying power from a power supply to the motor; and a control section for setting a target rotation number of the motor according to a mode selected from a plurality of modes, each mode having a corresponding target rotation number. The electric power tool further includes a voltage detection circuit for detecting a voltage of the power source when the motor is stopped, and the target rotation number is variably set based on the detected voltage.

In patent document 1, a target rotation number (speed of the motor) is set based on a voltage of a power supply when the motor is stopped. However, when the motor is rotating, the magnitude of the load applied to the motor and the voltage of the power supply may vary. Thus, in patent document 1, the rotation of the motor can be continued while the operation efficiency of the motor remains low.

Documents of the prior art

Patent document

Patent document 1: japanese patent 5408535

Disclosure of Invention

An object is to provide an electric power tool, a control method, and a program that can improve the operating efficiency of a motor.

An electric tool of an aspect of the present invention includes a motor and a motor control device. The motor control device is configured to update a command value of a speed of the motor based on a parameter. The parameter is related to at least one of a magnitude of a load applied to the motor during rotation of the motor and a voltage of a direct current power source used by the motor.

A control method of another aspect of the present invention is a control method of a motor, and includes: updating a command value for a speed of the motor based on a parameter. The parameter is related to at least one of a magnitude of a load applied to the motor during rotation of the motor and a voltage of a direct current power source used by the motor.

A program of still another aspect of the present invention is a program configured to cause a computer system to execute the control method.

Drawings

Fig. 1 is a block diagram showing an electric tool of the embodiment;

fig. 2 is a diagram showing control of the electric power tool by the motor control device;

fig. 3 is a flowchart showing the operation of the motor control device;

FIG. 4 is a graph showing the variation over time of the command value for the speed of the motor; and

fig. 5 is another graph showing a change in command value of the speed of the motor with time.

Detailed Description

1. Examples of the embodiments

1.1 summary

Fig. 1 shows a block diagram of an electric power tool 100 of the embodiment. The electric power tool 100 includes a motor 1 and a motor control device 3. The motor control device 3 is based on the magnitude of the load applied to the motor 1 during rotation of the motor 1 and the voltage V of the direct current power supply 8 for the motor 1_dcAt least one parameter of interest, to update the command value ω of the speed of the motor 1₂*。

In the electric power tool 100, the state during rotation of the motor 1 can be reflected in the command value ω₂In (1). That is, the motor control device 3 does not maintain the command value ω of the speed of the motor 1₂Constant, but the command value ω can be controlled dynamically (adaptively)₂*. Specifically, the state during rotation of the motor 1 includes the magnitude of the load applied to the motor 1 and the voltage V of the direct-current power supply 8 used for the motor 1_dcAt least one of, and the magnitude and voltage V_dcIt is possible to contribute to the improvement of the operation efficiency of the motor 1. As described above, the electric power tool 100 provides an effect that the operation efficiency of the motor 1 can be improved.

1.2 Structure

The electric power tool 100 of the present embodiment will be described in more detail below. The electric power tool 100 is a rotary impact tool (impact driver). As shown in fig. 1, the electric power tool 100 includes a motor 1, an inverter circuit unit 2, a motor control device 3, a main shaft 4, a hammer 5, an anvil 6, an input/output unit 7, and a direct current power supply 8. The power tool 100 also includes two phase current sensors 11.

The main shaft 4, the hammer 5, and the anvil 6 are devices for performing predetermined operations in the electric power tool 100. The main shaft 4 is coupled to an output shaft (rotor) of the motor 1. The spindle 4 is rotated by the rotation of the motor 1. A hammer 5 is coupled to the main shaft 4. The hammer 5 rotates together with the main shaft 4. Further, the hammer 5 is biased to the anvil 6 by a spring or the like, the hammer 5 and the anvil 6 are engaged with each other, and the rotation of the hammer 5 is transmitted to the anvil 6.

The motor 1 is coupled to a main shaft 4. The motor 1 is a DC (direct current) motor equipped with a brush, or a DC brushless motor. In the present embodiment, the motor 1 is a DC brushless motor (three-phase permanent magnet synchronous motor), and the motor 1 includes a rotor including permanent magnets and a stator including armature winding wires of three phases (i.e., U-phase, V-phase, and W-phase).

The dc power supply 8 is a power supply for driving the motor 1. In the present embodiment, the direct current power supply 8 is a secondary battery. The dc power supply 8 is a so-called battery pack. The direct-current power supply 8 also serves as a power supply for the inverter circuit unit 2 and the motor control device 3.

The inverter circuit unit 2 is a circuit for driving the motor 1. The inverter circuit unit 2 converts the voltage V from the DC power supply 8_dcInto the drive voltage V for the motor 1_a. In the present embodiment, the driving voltage V_aIs a three-phase ac voltage including a U-phase voltage, a V-phase voltage, and a W-phase voltage. In the following description, the U-phase voltage is defined by "v" as necessary_u"indicates that the V-phase voltage is represented by" V_v"denotes, and W phase voltage is represented by" v_w"means. In addition, the voltage v_u、v_vAnd v_wEach being a sinusoidal voltage. The inverter circuit unit 2 may be implemented by using a PWM inverter and a PWM converter. PWM converter according to driving voltage V_a(U phase voltage v)_uV phase voltage V_vAnd a W-phase voltage v_w) Target value (voltage command value) v of_u*、v_vA and v_wGenerating a pulse width modulated PWM signal. The PWM inverter converts the driving voltage V corresponding to the PWM signal_a(v_u,v_v,v_w) Is applied to the motor 1, thereby driving the motor 1. More specifically, the PWM inverter includes a three-phase half-bridge circuit and a driver. In a PWM inverter, a driver switches on/off a corresponding half-bridge circuit according to a PWM signalThereby will be related to the voltage command value v_u*、v_vA and v_wCorresponding driving voltage V_a(v_u、v_vAnd v_w) To the motor 1. Thus, the motor 1 is supplied with the driving voltage V_a(v_u、v_vAnd v_w) The corresponding drive current. The drive current comprises a U-phase current i_uPhase i of V-phase_vAnd W phase current i_w. Specifically, the U-phase current i_uPhase i of V-phase_vAnd W phase current i_wThe current of the U-phase armature winding wire, the current of the V-phase armature winding wire, and the current of the W-phase armature winding wire in the stator of the motor 1, respectively.

Two phase current sensors 11 measure U-phase current i of the drive current supplied from the inverter circuit unit 2 to the motor 1_uAnd V phase current i_v. Note that phase W current i_wCan be operated from U phase current i_uAnd V phase current i_vAnd (4) obtaining. Note that the electric power tool 10 may include a current detector including a shunt resistor or the like in place of the phase current sensor 11.

The input/output unit 7 is a user interface. The input/output unit 7 includes displays related to the operation of the electric power tool 100, settings for the operation of the electric power tool 100, and devices (e.g., a display device, an inputter, and an operation device) for providing the operation to the electric power tool 100. In the present embodiment, the input/output unit 7 has a target value ω for setting the speed of the motor 1₁Function of. For example, the input/output unit 7 determines the target value ω according to an operation given by the user₁And applying the target value ω₁Is supplied to the motor control device 3.

The motor control device 3 determines and updates the command value ω of the speed of the motor 1₂*. In particular, the motor control device 3 is based on a target value ω of the speed of the motor 1 provided by the input/output unit 7₁To determine and update the command value ω of the speed of the motor 1₂*. Furthermore, the motor control device 3 determines the drive voltage V_aTarget value (voltage command value) v of_u*、v_vA and v_wMake the speed of the motor 1 and the command valueω₂And the motor control device 3 provides these target values to the inverter circuit unit 2.

The motor control device 3 will be described in more detail below. In the present embodiment, the motor control device 3 controls the motor 1 by vector control. Vector control is a motor control method of the type: decomposing a motor current into a current component that generates torque (rotational force) and a current component that generates magnetic flux; and independently control these current components.

Fig. 2 is an analysis model diagram of the motor 1 in the vector control. In fig. 2, U-phase, V-phase, and W-phase armature winding wire fixing shafts are shown. The vector control takes into account a rotating coordinate system that rotates at the same speed as the rotational speed of the magnetic flux generated by the permanent magnets provided by the rotor of the motor 1. In the rotating coordinate system, the direction of the magnetic flux generated by the permanent magnet is represented by a d-axis, and the control rotation axis corresponding to the d-axis is represented by a γ -axis. Further, the phase of the electrical angle advanced by 90 degrees from the d axis is represented by the q axis, and the phase of the electrical angle advanced by 90 degrees from the γ axis is represented by the δ axis. The rotational coordinate system corresponding to the real axis is a coordinate system obtained by selecting d and q axes as coordinate axes, and these coordinate axes are referred to as dq axes. The control rotation coordinate system is a coordinate system obtained by selecting a γ axis and a δ axis as coordinate axes, and these coordinate axes are referred to as γ δ axes.

The dq axis is rotating, and the rotational speed of the dq axis is denoted by ω. The gamma delta axis is also rotating and the rotation speed of the gamma delta axis is represented by omega_eAnd (4) showing. Further, on the dq axis, the angle (phase) of the d-axis viewed from the armature winding wire fixing axis of the U-phase is represented by θ. Similarly, on the γ δ axis, the angle (phase) of the γ axis viewed on the armature winding wire fixing axis of the U phase is represented by θ_eAnd (4) showing. From theta and theta_eThe angles represented are angles in electrical angle and are also commonly referred to as rotor positions or pole positions. From ω and ω_eThe indicated rotational speed is the angular velocity in electrical angle. In the following description, θ or θ is used as necessary_eAlso known as rotor position, and ω or ω_eAlso referred to simply as speed. In the case of deriving rotor position and motor speed by estimation, the sum of the gamma axesThe delta axis is also referred to as the control estimation axis.

The motor control device 3 basically performs vector control so that θ and θ_eIn agreement with each other. When theta and theta_eWhen they coincide with each other, the d-axis and the q-axis coincide with the γ -axis and the δ -axis, respectively. Note that in the following description, the drive voltage V is, as necessary, driven_aIs respectively controlled by the gamma-axis voltage v_γAnd delta axis voltage v_δAnd the gamma-axis component and the delta-axis component of the drive current are represented by the gamma-axis current i, respectively_γAnd delta axis current i_δAnd (4) showing.

Further, the γ -axis voltage v is represented_γAnd delta axis voltage v_δThe voltage command values of the target values are respectively defined by the gamma axis voltage command values v_γCommand values v for voltages on the x and delta axes_δDenotes. Represents the gamma axis current i_γAnd delta axis current i_δThe current command values of the target values are respectively set by the gamma-axis current command value i_γCommand values of x and delta axis current i_δDenotes.

The motor control device 3 performs vector control so that the gamma axis voltage v_γAnd delta axis voltage v_δRespectively follow the gamma axis voltage command value v_γCommand values v for voltages on the x and delta axes_δAnd gamma axis current i_γAnd delta axis current i_δRespectively follow the gamma axis current command value i_γCommand values of x and delta axis current i_δ*。

The motor control device 3 updates the command value (i) calculated (or detected) and outputted by the motor control device 3 itself at a predetermined update cycle_γ*、i_δ*、v_γ*、v_δ*、v_u*、v_vA and v_wAnd state variables (i)_u、i_v、i_γ、i_δ、θ_eAnd ω_e)。

The motor control means 3 may be implemented, for example, by a computer system comprising one or more processors (e.g., microprocessors) and one or more memories. That is, the one or more processors execute one or more programs stored in the one or more memories to serve as the motor control device 3. The one or more programs may be stored in advance in one or more memories, provided via a telecommunication network such as the internet, or provided through a non-transitory storage medium such as a memory card or the like that stores the programs.

As shown in fig. 1, the motor control device 3 includes a coordinate converter 12, a subtractor 13, a subtractor 14, a current controller 15, a magnetic flux controller 16, a speed controller 17, a coordinate converter 18, a subtractor 19, a position/speed estimator 20, a step-out detector 21, and a setting unit 22. Note that the coordinate converter 12, the subtractors 13, 14, and 19, the current controller 15, the magnetic flux controller 16, the speed controller 17, the coordinate converter 18, the position/speed estimator 20, the step-out detector 21, and the setting unit 22 do not necessarily represent the respective components as entities, but represent functions realized by the motor control device 3. Therefore, each element of the motor control device 3 can freely use each value generated in the motor control device 3.

Coordinate converter 12 is based on rotor position θ_eTo make U phase current i_uAnd V phase current i_vCoordinate transformation is carried out on a gamma delta axis to respectively calculate and output gamma axis current i_γAnd delta axis current i_δ. Here, the γ -axis current i_γCorresponding to the d-axis current, it is an excitation current, and is a current that hardly contributes to the torque. Delta axis current i_δCorresponds to the q-axis current and is the current that contributes significantly to the torque. Rotor position θ_eIs calculated by the position/velocity estimator 20.

Subtractor 19 refers to velocity ω_eAnd a command value omega₂By calculating speed ω_eAnd a command value omega₂Speed deviation (ω) between₂*-ω_e). Speed omega_eIs calculated by the position/velocity estimator 20.

The speed controller 17 calculates the δ -axis current command value i based on proportional-integral control or the like_δLet the speed deviate (ω)₂*-ω_e) Converges to zero, and the speed controller 17 outputs a δ -axis current command value i_δ*。

The flux controller 16 determines the gamma-axis current command value i_γAnd the gamma axis current command value i_γOutput to subtractor 14. Gamma axis current command value i_γMay take various values depending on the type of vector control performed by the motor control device 3 or the speed ω of the motor 1. For example, when the maximum torque control is performed so that the d-axis current is adjusted to zero, the γ -axis current command value i_γSet to 0. Further, when the flux weakening control is performed by causing the d-axis current to flow, the γ -axis current command value i_γIs set to be in accordance with the speed omega_eCorresponding negative values. The gamma-axis current command value i will be explained below_γExample where x is 0.

The subtractor 13 outputs the gamma-axis current command value i from the flux controller 16_γSubtracting the gamma axis current i output from the coordinate converter 12_γTo calculate the current error (i)_γ*-i_γ). The subtractor 14 outputs a value i from the speed controller 17_δSubtracting the delta axis current i output from the coordinate converter 12_δTo calculate the current error (i)_δ*-i_δ)。

The current controller 15 performs current feedback control by proportional-integral control or the like so that the two current errors (i)_γ*-i_γ) And (i)_δ*-i_δ) Converge to zero. At this time, the gamma-axis voltage command value v is calculated using a decoupling control for eliminating interference between the gamma axis and the delta axis_γCommand values v for voltages on the x and delta axes_δA, make (i)_γ*-i_γ) And (i)_δ*-i_δ) Both of which converge to zero.

The coordinate converter 18 is based on the rotor position θ output from the position/velocity estimator 20_eTo convert v supplied from the current controller 15_γA and v_δCoordinate transformation to three-phase fixed coordinate axis, thereby calculating and outputting voltage command value (v)_u*、v_vA and v_w*)。

The position/velocity estimator 20 estimates the rotor position θ_eAnd velocity ω_e. More specifically, the position-velocity estimator 20 is based on i from the coordinate converter 12_γAnd i_δAnd v from the current controller 15_γA and v_δAll or a part of the components are subjected to proportional integral control and the like. The position/velocity estimator 20 estimates the rotor position θ_eAnd velocity ω_eSo that the axis error (theta) between the d axis and the gamma axis_e- θ) converges to zero. Note that various methods have been proposed as the estimation of the rotor position θ_eAnd velocity ω_eAnd the position/velocity estimator 20 may adopt any known method.

The step-out detector 21 determines whether the motor 1 is out of step. More specifically, the step-out detector 21 determines whether the motor 1 is out of step based on the magnetic flux of the motor 1. The magnetic flux of the motor 1 is a command value v from d-axis current, q-axis current and gamma-axis voltage_γCommand values v for voltages on the x and delta axes_δObtained. The step-out detector 21 may determine that the motor 1 is out of step when the amplitude of the magnetic flux of the motor 1 is smaller than the threshold value. Note that the threshold value is defined accordingly based on the amplitude of the magnetic flux generated by the permanent magnet of the motor 1. Note that various methods have been proposed as the out-of-synchronization detection method, and the out-of-synchronization detector 154 may employ any known method.

The setting unit 22 determines and updates the command value ω in the motor control device 3₂*. Note that the target value ω is received from the input/output unit 7 at the setting unit 22₁Defining command values omega by means of a setting unit 22₂May be referred to as "command value ω₂Determination of. In addition, at "command value ω₂Determination of "any timing after defining the command value ω with the setting unit 22₂May be referred to as "command value ω₂Update of.

More specifically, the setting unit 22 is based on the target value ω received from the input/output unit 7₁To determine and update the command value omega₂*. The setting unit 22 determines and updates the command value ω with reference to the parameter₂*. The parameters are determined by the magnitude of the load applied to the motor 1 during rotation of the motor 1 and the voltage V of the dc power supply 8 used for the motor 1_dcAt least one associated value. In the present embodiment, the parameters include a modulation degree and a torque current value.

The degree of modulation isA value related to the conversion of the direct voltage to the alternating voltage. The degree of modulation is also referred to as the modulation factor. In the present embodiment, the modulation degree is determined by the voltage V of the dc power supply 8 in the inverter circuit unit 2_dcAnd a drive voltage V supplied to the inverter circuit unit 2_aTarget value (voltage command value v)_u*、v_vA and v_wX) are defined. Specifically, the modulation degree is 2 × V_out/V_inThe method comprises the following steps: v_inIs the voltage V of the DC power supply 8_dcA value of and V_outIs a driving voltage V_aPeak value of the target value of (1). Drive voltage V_aThe peak values of the target values are respectively corresponding to the voltage command value v_u*、v_vA and v_wCorresponding U phase voltage v_uV phase voltage V_vAnd a W-phase voltage v_wThe respective peak value. Note that due to the U-phase voltage v_uV phase voltage V_vAnd a W-phase voltage v_wAre coincident with each other, and thus the driving voltage V_aThe peak value of the target value is equal to the voltage command value v_u*、v_vA and v_wCorresponding U phase voltage v_uV phase voltage V_vAnd a W-phase voltage v_wA peak value of any one of them.

The torque current value indicates the current flowing through the motor 1 (phase current i)_u、i_vAnd i_w) The magnitude of the torque component of (a). In the present embodiment, the δ -axis current i corresponding to the value of the q-axis current is used_δThe value of (d) is taken as the torque current value.

The setting unit 22 determines (updates) the command value ω based on the result of comparison between the parameter and the threshold value₂*. More specifically, the setting unit 22 determines whether the parameter satisfies the condition based on the comparison result of the parameter and the threshold. The condition is for switching the command value ω₂The condition of the manner of determination and update of the value is also referred to as a switching condition hereinafter. If the parameter does not satisfy the switching condition, the setting unit 22 makes the command value ω₂Target value ω of the speed of the approaching motor 1₁*. In contrast, if the parameter satisfies the switching condition, the setting unit 22 decreases the command value ω₂*. For example, the setting unit 22 may select the command value ω from the command values ω₂Subtracting the specified value. Alternatively, the setting unit 22 may set the command value ω by₂Set as the velocity ω obtained by the position-velocity estimator 20_eTo reduce the command value omega₂*. However, when the command value ω is₂When change, command value ω₂Within the range that the speed controller 17 can follow.

In the present embodiment, the parameter includes a modulation degree and a torque current value (value of q-axis current), and thus the threshold includes a modulation degree threshold corresponding to the modulation degree and a current threshold corresponding to the torque current value.

The modulation degree threshold value is, for example, a value for determining whether or not the operation of the inverter circuit unit 2 is within an allowable range. The modulation degree threshold may be selected from a range of modulation degrees (modulation degree allowable range) within which the output (drive voltage V) of the inverter circuit unit 2 is within_a) May vary linearly with respect to the modulation degree. The modulation degree threshold value may be an upper limit value of the modulation degree allowable range, or may be any value as long as the value is within the modulation degree allowable range. The upper limit value of the modulation degree allowable range also depends on the structure of the inverter circuit unit 2, but in many cases, the upper limit value is, for example, in the range of 75% to 125% or in the range of 85% to 115%, and in the present embodiment, the upper limit value is 100%. Of course, it is efficient that the modulation degree threshold value is close to the upper limit value of the modulation degree allowable range.

The current threshold value is, for example, a value for determining whether or not the load applied to the motor 1 while the motor 1 is rotating is within an allowable range. The current threshold value may be selected from a range of torque current values (load torque allowable range) when the load applied to the motor 1 during rotation of the motor 1 is within an allowable range. The current threshold value may be an upper limit value of the load torque allowable range, or may be any value as long as the value is within the load torque allowable range. Of course, it is efficient that the current threshold value approaches the upper limit value of the load torque allowable range, but in many cases, the current threshold value is limited by the current rating of the inverter circuit unit 2 and/or the current rating of the motor 1, and in the present embodiment, the current threshold value is the current rating of the inverter circuit unit 2.

The setting unit 22 determines that the parameter satisfies the switching condition if at least one of a first condition that the modulation degree exceeds the modulation degree threshold and a second condition that the torque current value (the value of the q-axis current) exceeds the current threshold is satisfied. In other words, in the case where neither the first condition nor the second condition is satisfied, the setting unit 22 determines that the parameter does not satisfy the switching condition.

1.3 operation

Next, the operation of the electric power tool 100 (in particular, the operation of the setting unit 22 of the motor control device 3) will be described with reference to the flowchart of fig. 3 and the graphs of fig. 4 and 5. Fig. 4 shows a command value ω in the case of tightening a wood screw with the electric power tool 100₂Change over time of. Fig. 5 shows a command value ω in the case of tightening a bolt with the electric power tool 100₂Change over time of.

The target value ω is received at the setting unit 22 from the input/output unit 7₁The setting unit 22 starts the command value ω at one time or at an arbitrary timing thereafter₂Determination of and processing of updates. First, the setting unit 22 acquires parameters (S11). Here, the setting unit 22 acquires the degree of modulation and the torque current value. Then, the setting unit 22 determines whether the parameters (the degree of modulation and the torque current value) satisfy the conditions (switching conditions) (S12). In the present embodiment, the setting unit 22 independently determines whether a first condition that the modulation degree exceeds the modulation degree threshold and a second condition that the torque current value exceeds the current threshold are satisfied.

If neither the first condition nor the second condition is satisfied, the setting unit 22 determines that the parameter does not satisfy the switching condition (S12; n). In this case, the setting unit 22 judges the command value ω₂And target value omega₁Whether they are identical (S13). If the command value ω is₂And target value omega₁Disagreement (S13; n), the setting unit 22 makes the command value ω₂Approach to the target value ω₁(S14). That is, when the command value ω is₂Less than target value omega₁When, the setting unit 22 increases the command value ω₂And when the command value ω is₂Greater than targetValue omega₁When, the setting unit 22 decreases the command value ω₂*. When the command value ω₂And target value omega₁When there is coincidence (S13; y), the setting unit 22 maintains the command value ω₂*. For example, in fig. 4, the parameter does not satisfy the switching condition until time t₁₀Until now, and the setting unit 22 gradually changes the command value ω₂Make command value ω₂And target value omega₁All are consistent. Similarly, in FIG. 5, until time t₂₀Until then, the parameter does not satisfy the switching condition, and therefore the setting unit 22 gradually changes the command value ω₂Make command value ω₂And target value omega₁All are consistent.

In contrast, when at least one of the first condition and the second condition is satisfied, the setting unit 22 determines that the parameter satisfies the switching condition (S12; yes). In this case, the setting unit 22 decreases the command value ω₂(S15). For example, in FIG. 4, at time t₁₀The parameter satisfies the switching condition, and thereafter, regardless of the target value ω₁How, the setting unit 22 makes the command value ω₂Gradually decrease. Similarly, in FIG. 5, at time t₂₀The parameter satisfies the switching condition, and therefore, regardless of the target value ω₁How, the setting unit 22 makes the command value ω₂Gradually decrease. Thus, the motor control device 3 no longer attempts to forcibly maintain the speed of the motor 1, and therefore, the motor 1 is prevented from stepping out, so that the motor control device 3 can continue to drive the motor 1. In particular, in the case where the modulation degree threshold value is the upper limit value of the modulation allowable range, even at the voltage V of the dc power supply 8_dcIn the case of the change, the motor control device 3 may continue to drive the motor 1 at the maximum speed (maximum rotation speed) suitable for the modulation threshold.

As described above, when the parameter does not satisfy the switching condition (at the time of normal operation), the motor control device 3 sets the command value ω₂Bringing the speed ω of the motor 1 close to the target value ω supplied from the input/output unit 7₁(target rotation speed). That is, the motor control device 3 performs the command value ω₂Set as target value ω₁Control of (normal target value control).On the other hand, when the parameter satisfies the switching condition, regardless of the target value ω supplied from the input/output unit 7₁How the motor control means 3 make the command value ω₂Decrease. That is, the motor control device 3 updates the target value ω according to the parameter while the motor 1 is rotating₁Control of x (dynamic speed target control).

As described above, the electric power tool 100 can dynamically respond to a change in the load (e.g., load torque) applied while the motor 1 is rotating and/or the voltage V of the direct-current power supply 8_dcA change in (c). Thus, in response to changes in load torque and/or voltage V of the DC power supply 8_dcCan rotate the motor 1 continuously at a maximum rotation speed at which the motor 1 does not step out.

Thus, at a voltage V_dcIn the case of a drop and/or an increase in the load torque, the rotational speed of the motor 1 does not have to be set in advance to a relatively low value in order to operate the motor 1. In addition, the motor 1 can be optimally operated according to the type of the direct-current power supply 8 and/or the charging and discharging conditions. Therefore, it is not necessary to reset the target value ω of the speed of the motor 1 according to the type of the direct-current power supply 8 and/or the charging and discharging conditions₁*。

Further, when the work object (wood screw, bolt, etc.) and/or the target work (tightening, boring, tightening, etc.) are/is changed, the motor 1 can be operated at the maximum speed (maximum rotation speed) at which the motor 1 does not step out, in accordance with the work object and/or the target work. Therefore, complicated control and/or setting of the speed target value corresponding to the work mode is no longer required. As a result, the time required to complete the job can be shortened, and the job efficiency can be improved. In addition, the amount of power consumed by the dc power supply 8 can be reduced.

As described above, the electric power tool 100 of the present embodiment improves the work efficiency. In addition, the electric power tool 100 reduces the amount of power consumption. In addition, the electric power tool 100 improves the stability of work.

1.4 summary

As described above, the electric power tool 100 includes the motor 1 and the motor control device 3. The motor control device 3 is based on the motor 1The magnitude of the load applied to the motor 1 during rotation and the voltage V of the dc power supply 8 used for the motor 1_dcAt least one parameter of interest, to update the command value ω of the speed of the motor 1₂*. Thus, the electric power tool 100 improves the operation efficiency of the motor 1.

In other words, the motor control device 3 executes a control method (motor control method) described below. The control method is a control method of the motor 1, and includes: based on the magnitude of the load applied to the motor 1 during rotation of the motor 1 and the voltage V of the direct current power supply 8 used for the motor 1_dcAt least one parameter of interest, to update the command value ω of the speed of the motor 1₂*. This control method improves the operation efficiency of the motor 1.

The motor control device 3 is implemented by a computer system. That is, the motor control device 3 is realized by a program (motor control program) executed by a computer system. The program is a program for causing a computer system to execute a control method (motor control method). Such a procedure improves the operation efficiency of the motor 1 in a similar manner to the control method.

2. Modification example

Embodiments of the present invention are not limited to the above-described embodiments. Various modifications may be made in accordance with the design or the like as long as the object of the present invention is achieved. A modification of this embodiment will be described below.

In the above-described embodiment, the parameters include two parameters of the modulation degree and the torque current value, but the parameter may be only the modulation degree. In this case, if the modulation degree is lower than or equal to the modulation degree threshold, the motor control device 3 (setting unit 22) may cause the command value ω to be the command value ω₂Target value ω of the speed of the approaching motor 1₁*. In contrast, if the modulation degree exceeds the modulation degree threshold, the motor control device 3 (setting unit 22) may decrease the command value ω₂*. Alternatively, the parameter may be only the torque current value. In this case, if the torque current value (the value of the q-axis current) is less than or equal to the current threshold value, the motor control device 3 (the setting unit 22) may make the command value ω be the command value ω₂Target value ω of the speed of the approaching motor 1₁*. On the contrary, ifThe torque current value (the value of the q-axis current) exceeds the current threshold value, the motor control device 3 (the setting unit 22) may decrease the command value ω₂*。

The parameters are not limited to the modulation degree and the torque current value. As the parameter, the voltage V representing the dc power supply 8 may be used_dcThe magnitude of (2) is the value of the power supply voltage. In this case, a voltage threshold corresponding to the power supply voltage value is used as the threshold. The voltage threshold is, for example, a voltage V for determining the DC power supply 8_dcWhether the value of (b) is within the allowable range. The voltage threshold may be selected from a range (voltage allowable range) within which the driving voltage V from the direct current power supply 8 can be generated to satisfy_aTarget value (voltage command value v)_u*、v_vA and v_wV) of the driving voltage V_a. The voltage threshold may be a lower limit value of the voltage tolerance range, or may be any value as long as the value is within the voltage tolerance range. Of course, it is efficient that the voltage threshold approaches the upper limit of the voltage tolerance range. If the power supply voltage value is greater than or equal to the voltage threshold value, the motor control device 3 (setting unit 22) may cause the command value ω to be set₂Target value ω of the speed of the approaching motor 1₁*. In contrast, if the power supply voltage value is smaller than the voltage threshold value, the motor control device 3 (setting unit 22) may decrease the command value ω₂And also in this case, the same effect as that obtained when the parameter is the degree of modulation is obtained.

As described above, the parameter may include one or more values selected from a modulation degree, a torque current value, and a power supply voltage value. In the case where the parameter includes two or more values selected from the modulation degree, the torque current value, and the power supply voltage value, when the reduction command value ω is obtained with respect to any of the two or more values₂In the determination, it may be determined that the parameter satisfies the condition. Alternatively, a priority level may be provided for two or more values included in the parameter, and when the reduction command value ω is obtained with respect to a value of which the priority level is high₂In the determination, it can be determined that the parameter satisfies the condition regardless of other values.

In the above embodiment, the drive voltage V_aVoltage V of each of the U-phase, V-phase and W-phase_u、v_vAnd v_wAre all sinusoidal voltages. However, the driving voltage V_aVoltage V of each of the U-phase, V-phase and W-phase_u、v_vAnd v_wMay be a rectangular voltage. That is, the inverter circuit unit 2 may perform sine wave drive on the motor 1, or may perform rectangular wave drive on the motor 1.

In the above embodiment, the motor control device 3 controls the motor 1 by vector control without a sensor. The control method of the motor control device 3 is not limited to the vector control, but may be other methods such as 120-degree energization control and the like. Further, the electric power tool 100 may include a position sensor for detecting the position of the motor 1 (rotor rotation position). Further, a sensor (e.g., phase current sensor 11) configured to detect the current of the motor 1 may be omitted in other methods such as 120-degree energization control and the like. In the case of vector control, a shunt resistor or the like other than the phase current sensor 11 mounted in the inverter circuit unit 2 may be used. That is, a current measuring instrument including a shunt resistor or the like may be used instead of the phase current sensor 11. In these cases, a simplified method may be used as the control method of the motor control device 3, which simplifies the circuit and/or control.

In the above embodiment, the electric power tool 100 includes the main shaft 4, the hammer 5, and the anvil 6 as devices for performing prescribed work. However, such devices are not limited to the spindle 4, hammer 5 and anvil 6, but may be, for example, a drill and a saw. That is, the electric power tool 100 is not limited to the impact driver, but may be a drill or a jigsaw.

The main body of the execution motor control device 3 includes a computer system. The computer system includes a processor and a memory as hardware. The processor executes a program stored in the memory of the computer system, thereby realizing a function as a main body of the execution motor control device 3 in the present invention. The program may be stored in advance in a memory of the computer system or may be provided through a telecommunication network. Alternatively, the program may be distributed after having been recorded in some non-transitory storage medium such as a memory card, an optical disk, or a hard drive, any of which is readable by a computer system. The processor of the computer system includes one or more electronic circuits including a semiconductor Integrated Circuit (IC) or a large scale integrated circuit (LSI). An integrated circuit such as an IC or an LSI mentioned here may be referred to in other ways depending on the degree of integration. For example, the integrated circuit may be an integrated circuit called a system LSI, Very Large Scale Integration (VLSI), or Ultra Large Scale Integration (ULSI). A Field Programmable Gate Array (FPGA) which is programmable after the manufacture of the LSI or a reconfigurable logic device which allows the reconfiguration of connections in the LSI or the setting of circuit cells in the LSI can be used for the same purpose. These electronic circuits may be integrated together on a single chip or distributed over multiple chips, as appropriate. These multiple chips may be collected together in a single device or may be distributed among multiple devices.

3. Aspect(s)

As can be seen from the above-described embodiments and modifications, the present invention includes the following aspects. In the following description, reference numerals in parentheses are added only for clarifying the correspondence with the present embodiment.

An electric power tool (100) of the first aspect includes a motor (1) and a motor control device (3). The motor control device (3) is configured to update a command value (ω) of the speed of the motor (1) based on the parameter₂*). The parameter is related to the magnitude of the load applied to the motor (1) during rotation of the motor (1) and the voltage (V) of a DC power supply (8) used by the motor (1)_dc) At least one of them. The first aspect makes it possible to improve the operating efficiency of the motor (1).

The electric power tool (100) of the second aspect may be realized in combination with the first aspect. In a second aspect, the motor control device (3) is configured to update the command value (ω) based on a result of comparison between the parameter and the threshold value₂*). The second aspect makes it possible to improve the operating efficiency of the motor (1).

The electric power tool (100) of the third aspect may be realized in combination with the second aspect. In a third aspect, the parameter comprises a degree of modulation. The third aspect makes it possible to improve the operating efficiency of the motor (1).

The electric power tool (100) of the fourth aspect may be implemented in combination with the third aspect. In a fourth aspect, the threshold comprises a modulation degree threshold. The motor control device (3) is configured to reduce the command value (ω) in the case where the modulation degree is higher than the modulation degree threshold value₂*). The fourth aspect reduces the possibility of step-out of the motor (1).

The electric power tool (100) of the fifth aspect may be realized in combination with the fourth aspect. In a fifth aspect, the motor control device (3) is configured such that the command value (ω) is made when the modulation degree is lower than or equal to the modulation degree threshold value₂Approaches a target value (ω) of the speed of the motor (1)₁*). The fifth aspect enables setting the speed of the motor (1) to a desired target value (ω)₁*)。

The electric power tool (100) of the sixth aspect may be implemented in combination with any one of the second to fifth aspects. In the sixth aspect, the parameter includes a torque current value representing a magnitude of a torque component of a current flowing through the motor (1). The sixth aspect makes it possible to improve the operating efficiency of the motor (1).

The electric power tool (100) of the seventh aspect may be implemented in combination with the sixth aspect. In a seventh aspect, the threshold comprises a current threshold. The motor control device (3) is configured to reduce the command value (ω) in the case where the torque current value is greater than the current threshold value₂*). The seventh aspect reduces the possibility of step-out of the motor (1).

The electric power tool (100) of the eighth aspect may be implemented in combination with the seventh aspect. In an eighth aspect, the motor control device (3) is configured such that the command value (ω) is made when the torque current value is less than or equal to the current threshold value₂Approaches a target value (ω) of the speed of the motor (1)₁*). The eighth aspect enables setting the speed of the motor (1) to a desired target value (ω)₁*)。

The electric power tool (100) of the ninth aspect may be realized in combination with any one of the second to eighth aspects. In a ninth aspect, the parameter comprises a supply voltage value representing a voltage of the direct current power supply (8)(V_dc) The size of (2). The ninth aspect makes it possible to improve the operating efficiency of the motor (1).

The electric power tool (100) of the tenth aspect may be realized in combination with the ninth aspect. In a tenth aspect, the threshold comprises a voltage threshold. The motor control device (3) is configured to reduce the command value (ω) in the case where the power supply voltage value is smaller than the voltage threshold value₂*). The tenth aspect reduces the possibility of step-out of the motor (1).

The electric power tool (100) of the eleventh aspect may be realized in combination with the tenth aspect. In an eleventh aspect, the motor control device (3) is configured to cause the command value (ω) to be larger than or equal to the voltage threshold value in a case where the power supply voltage value is larger than or equal to the voltage threshold value₂Approaches a target value (ω) of the speed of the motor (1)₁*). The eleventh aspect enables setting the speed of the motor (1) to a desired target value (ω)₁*)。

The electric power tool (100) of the twelfth aspect may be realized in combination with any one of the first to eleventh aspects. In a twelfth aspect, the motor (1) is a brushless motor. The twelfth aspect makes it possible to improve the operating efficiency of the motor (1).

The electric power tool (100) of the thirteenth aspect may be realized in combination with the twelfth aspect. In the thirteenth aspect, the electric power tool (100) further includes an inverter circuit unit (2), the inverter circuit unit (2) being configured to generate a drive voltage (V) from the direct-current power source (8)_a) And applying the driving voltage (V)_a) Output to the motor (1). The motor control device (3) is configured to determine a drive voltage (V)_a) Target value (v) of_u*、v_v*、v_wTo enable the speed of the motor (1) to be proportional to the command value (ω)₂And) and provides the target value to the inverter circuit unit (2). The thirteenth aspect makes it possible to improve the operating efficiency of the motor (1).

The control method of the fourteenth aspect is a control method of the motor (1). The control method comprises the following steps: based on the magnitude of a load applied to the motor (1) during rotation of the motor (1) and the voltage (V) of a DC power supply (8) used by the motor (1)_dc) At least one parameter of interest, to update the command value (ω) of the speed of the motor (1)₂*). Tenth itemThe fourth aspect provides an effect that the operating efficiency of the motor (1) can be improved.

The program of the fifteenth aspect is a program for causing a computer system to execute the control method of the fourteenth aspect. The fifteenth aspect provides an effect that the operating efficiency of the motor (1) can be improved.

Description of the reference numerals

100 electric tool

1 Motor

2 inverter circuit unit

3 Motor control device

8 DC power supply

ω₁Target value

ω₂Command value

V_aDriving voltage

v_u*,v_v*,v_wTarget value

V_dcVoltage of