Motor control device

Abstract

A motor control device includes an adder that outputs a first speed command based on a torque command, a speed limiter that obtains a second speed command after speed limitation by performing speed limitation on the first speed command, and a control mode switching section that outputs either the third speed command or the second speed command as a motor speed command based on a control mode command.

Description

TECHNICAL FIELD

[0001] One embodiment of the present application relates to a motor control device. BACKGROUND

[0002] In welding of a workpiece using a servo welding gun (welding gun) for spot welding, the workpiece is gripped by a welding tip of an electrode portion of the welding gun. Further, the workpiece is pressed by controlling a torque of a motor, and current is passed between the welding tips. Thus, the workpiece is welded. Such a welding gun moves to a position in contact with a press target by position control or speed control. Thereafter, the control mode is switched to a torque control mode, and the press target is pressed by the welding gun. Further, the torque control mode with a speed limit function is implemented so as to prevent the welding gun from colliding with the press target when the speed of the welding gun becomes excessively large at the time of switching the control mode to the torque control mode. When welding is completed, the control mode is switched to the position control mode or the speed control mode again, and the welding gun moves. In this way, in a case where the position control or the speed control and the torque control are used in combination, the control of the motor is performed while switching the control mode.

[0003] In the above example, the control mode is switched between the position control mode or the speed control mode and the torque control mode. At the time of such control mode switching, an impact is sometimes generated on the control target due to discontinuity of the torque command value. Therefore, in order to reduce the impact, the motor is stopped before the control mode is switched. Then, the control mode is switched after the torque command value becomes small. However, in the process of switching the control mode after the motor is stopped, useless time is generated, and it is difficult to speed up the mechanical operation.

[0004] An example of switching such a control mode without stopping the motor is described in Japanese Laid-Open Patent Publication No. 9-69013. A control mode switching method of a servo system using a servo motor is described in Japanese Laid-Open Patent Publication No. 9-69013. In the method, a servo motor is used in the servo system, and the control mode is switched between a torque control mode and a position control mode or a speed control mode. In the torque control mode, a value of an integrator of a speed loop is rewritten as a torque command in torque control. Further, when the control mode is switched from the torque control mode to the position control mode or the speed control mode, the value of the integrator is the torque command value supplied to the servo motor. However, in this method of rewriting the value of the integrator of the speed loop as the torque command in torque control, rewriting must be performed in each speed loop process, and the processing time increases. Further, the method is difficult to cope with switching from the position control mode or the speed control mode to the torque control mode. Further, in the torque control mode of the method, torque control without a speed limit function is implemented. Therefore, the method is difficult to cope with torque control with a speed limit function.

[0005] The method described in Japanese Patent Application Laid-Open No. 2009-141987 addresses torque control with a speed limit function and addresses switching from a position control mode or speed control mode to a torque control mode. The motor control device described in Japanese Patent Application Laid-Open No. 2009-141987 includes a speed control unit, a control switching unit, a torque command switch, and a current control unit. The speed control unit performs PI control to match the speed command with the motor's speed feedback and calculates an internal torque command. The control switching unit switches the control mode between speed control mode and torque control mode and outputs a switching signal. In speed control mode, speed control is performed based on an externally provided control switching signal to match the speed command with the speed feedback. In torque control mode, torque control is performed to match the external torque command with the generated torque of the motor. The torque command switch switches between the internal and external torque commands based on the switching signal and outputs the torque command. The current control unit drives the motor based on the torque command. Furthermore, the motor control device includes a correction torque calculation unit. In torque control mode, the correction torque calculation unit calculates a torque correction value used to correct the external torque command. When switching from speed control mode to torque control mode, the control switching unit calculates an initial value based on the external torque command and the value of the speed control unit integrator. The correction torque calculation unit calculates a torque correction value based on the speed limit command, speed feedback, and the initial value.

[0006] However, the method of Japanese Patent Application Laid-Open No. 2009-141987 is difficult to apply to control systems that do not include a correction torque calculation unit, which calculates a torque correction value used to correct an external torque command during torque control mode. Furthermore, this method makes it difficult to switch the control mode to a mode other than torque control with limited speed when switching from speed control mode to torque control mode. Furthermore, this method also has difficulty handling switching from torque control mode to position control mode or speed control mode. Summary of the Invention

[0007] The motor control device includes: a speed detection unit for detecting the speed of the motor; a speed deviation calculator for calculating a first speed deviation based on the torque command based on the torque command; an adder for adding the first speed deviation based on the torque command and the speed output from the speed detection unit to obtain a first speed command based on the torque command, and outputting the first speed command based on the torque command; a speed limiter for limiting the first speed command based on the torque command according to a speed limit value indicated by the speed limit command to obtain a second speed command after the limit, and outputting the second speed command after the limit; and a control mode switching unit for selecting one of a speed control mode and a torque control mode based on the control mode command. as a control mode, and outputting either a third speed instruction or the second speed instruction after limitation as a motor speed instruction; a subtractor, which obtains a second speed deviation by subtracting the speed of the motor from the motor speed instruction, and outputs the second speed deviation; a speed controller, which performs a speed control operation using the second speed deviation as input and outputs a motor torque instruction; and a motor torque control unit, which causes the motor to output a torque based on the motor torque instruction, the speed controller having a proportional controller and an integral controller, the integral controller being capable of setting an initial value of an integral value, and being capable of performing an integral action and an action of stopping the integral action of the integrator and attenuating the value of the integrator. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a block diagram showing one embodiment of a motor control device and method.

[0009] Figure 2 A specific configuration example of a speed controller is shown.

[0010] Figure 3 This is a flowchart showing the flow of control of the speed controller by the speed controller setting processing unit.

[0011] Figure 4 This is a block diagram showing another embodiment of a motor control device and method (an example of switching the control mode between torque control and position control). DETAILED DESCRIPTION

[0012] In the following detailed description, for purposes of illustration, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. However, it will be apparent that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown for simplicity of drawing.

[0013] One object of the present invention is to provide the following motor control device. The motor control device can be applied to torque control with a speed limiting function in a control system that does not have a correction torque calculation unit that calculates a torque correction value. Furthermore, the motor control device can cope with any one or all of the following first to fourth switches without significantly increasing the processing time. The first switch is a switch from a position control mode or a speed control mode to a torque control mode in a state where speed limitation is not performed. The second switch is a switch from a position control mode or a speed control mode to a torque control mode in a state where speed limitation is performed. The third switch is a switch from a torque control mode in a state where speed limitation is not performed to a position control mode or a speed control mode. The fourth switch is a switch from a torque control mode in a state where speed limitation is performed to a position control mode or a speed control mode. According to the motor control device, the impact on the control object caused by the discontinuity of the torque instruction value can be suppressed.

[0014] A motor control device according to one embodiment of the present invention (the present motor control device) comprises: a speed detection unit for detecting the speed of the motor; a speed deviation calculator for calculating a first speed deviation based on the torque command based on the torque command; an adder for adding the first speed deviation based on the torque command and the speed output from the speed detection unit to obtain a first speed command based on the torque command, and outputting the first speed command based on the torque command; a speed limiting unit for limiting the first speed command based on the torque command according to a speed limit value indicated by the speed limit command to obtain a second speed command after the limit, and outputting the second speed command after the limit; a control mode switching unit for selecting a speed control mode and a torque control mode based on the control mode command. any one of the torque control modes as a control mode, and outputting a third speed instruction and any one of the second speed instruction after the limit as a motor speed instruction; a subtractor, which obtains a second speed deviation by subtracting the speed of the motor from the motor speed instruction, and outputs the second speed deviation; a speed controller, which performs a speed control operation using the second speed deviation as input and outputs a motor torque instruction; and a motor torque control unit, which causes the motor to output a torque based on the motor torque instruction, the speed controller having a proportional controller and an integral controller, the integral controller being capable of setting an initial value of an integral value, and being capable of performing an integral action and an action of stopping the integral action of the integrator and attenuating the value of the integrator.

[0015] Alternatively, the speed command may be derived from a position command.

[0016] The speed controller is switchable between a state in which it operates as a proportional-integral controller and a state in which it operates as the proportional controller based on a command selected by the control mode switching unit.

[0017] (Speed ​​controller control in steady state)

[0018] Preferably, when the speed control mode is selected by the control mode switching unit, the speed controller operates as a proportional-integral controller in which the proportional controller and the integral controller operate; when the torque control mode is selected by the control mode switching unit and the first speed command based on the torque command is smaller than the speed limit command, the speed controller operates as the proportional controller; and when the torque control mode is selected by the control mode switching unit and the first speed command based on the torque command is greater than the speed limit command, the speed controller operates as the proportional-integral controller in which the proportional controller and the integral controller operate.

[0019] [Control of speed controller in transfer state 1]

[0020] Preferably, when the control mode is switched from the speed control mode to the torque control mode and the first speed command based on the torque command is smaller than the speed limit command, the integral value of the integral controller is set to a predetermined initial value, a value obtained by multiplying the integrator by an integral attenuation gain is returned to the input of the integrator, and the output of the integrator decays to zero within a predetermined period, and the speed controller operating as a proportional-integral controller operates as the proportional controller. When the control mode is switched from the speed control mode to the torque control mode and the first speed command based on the torque command is greater than the speed limit command, the speed controller is maintained as a proportional-integral controller.

[0021] [Control of speed controller in transfer state 2]

[0022] Preferably, when the control mode is switched from the torque control mode to the speed control mode and the first speed command based on the torque command before the switching is smaller than the speed limit command, the third speed command is set to a predetermined initial value, the integral value of the integral controller is set to a predetermined initial value, the speed controller operating as the proportional controller operates as a proportional-integral controller, and when the control mode is switched from the torque control mode to the speed control mode and the first speed command based on the torque command before the switching is greater than the speed limit command, the speed controller remains as the proportional-integral controller.

[0023] The present motor control device does not require a correction torque calculation unit that calculates a torque correction value and can be applied to torque control with a speed limiting function. The present motor control device can cope with any one or all of the following first to fourth switches without significantly increasing the processing time. The first switch is the switch from the position control mode or the speed control mode to the torque control mode in a state where speed limitation is not performed. The second switch is the switch from the position control mode or the speed control mode to the torque control mode in a state where speed limitation is performed. The third switch is the switch from the torque control mode in a state where speed limitation is not performed to the position control mode or the speed control mode. The fourth switch is the switch from the torque control mode in a state where speed limitation is performed to the position control mode or the speed control mode. According to the present motor control device, a motor control technology can be provided that can suppress the impact on the control object caused by the discontinuity of the torque command value.

[0024] Below, embodiments of the motor control device and motor control method of the present invention are described in detail based on the accompanying drawings. The technical scope of the present invention is not limited to the description of these embodiments. Technologies falling within the technical scope of each claim are encompassed within the technical scope of the present invention, regardless of their form.

[0025] (First embodiment)

[0026] Figure 1 One embodiment of a motor control device and method is shown.

[0027] Background art of a motor control device and a motor control method for limiting motor speed and controlling motor torque based on a torque command and a speed limit command is well known, and thus detailed description thereof will be omitted.

[0028] Figure 1 The figure shows a motor control device A according to a first embodiment of the present invention. As shown in the figure, the motor control device A controls the torque and speed of the motor 21. The motor control device A is configured to control the motor 21 based on a control mode command for either torque or speed. In the torque control mode, the motor control device A controls the speed of the motor 21 while controlling the speed according to a speed limit command. Furthermore, in the speed control mode, the motor control device A controls the speed of the motor 21 according to a speed command.

[0029] The motor control device A generally includes an encoder EN23, a speed detection unit 25, a speed deviation calculator 1, an adder 3, a speed limiter 5, a control mode switching unit 7, a subtractor 11, a speed controller 15, a speed controller setting processing unit 16, a motor torque controller (motor torque control unit) 17 and a motor 21, etc.

[0030] Figure 1The motor control device A shown is capable of switching between torque control and speed control. The functions of the various components of the motor control device A are as follows.

[0031] The speed detection unit 25 determines the speed of the motor by differentiating the position of the encoder EN23. The speed deviation calculator 1 calculates the speed of the motor based on the torque command T C , calculate the first speed deviation S based on the torque command DT That is, the torque command T C The speed deviation calculator 1 calculates the first speed deviation S based on the torque command. DT .

[0032] The adder 3 converts the first speed deviation S based on the torque command into DT The first speed command S is obtained by adding the speed V output from the speed detection unit 25. TC .

[0033] The speed limiting unit 5 is configured to limit the speed of the vehicle according to the speed limit instruction S. LC The speed limit value indicated is the first speed instruction S based on the torque instruction. TC Perform speed limitation and obtain the second speed instruction S after limitation CL , and output the second speed instruction S after the limit CL .

[0034] The control mode switching unit 7 is based on the control mode instruction M C , switch to the third speed instruction S C and the second speed command S after limitation CL , calculate the motor speed command S MC That is, the control mode switching unit 7 is based on the control mode instruction M C , select either the speed control mode or the torque control mode as the control mode, and set the third speed command S C or the second speed instruction S after the limitation CL Any one of the following is used as the motor speed command S MC Output. The control mode switching unit 7 outputs the control mode instruction M C In the case of speed control mode, the third speed instruction S C As the motor speed command S MC On the other hand, the control mode switching unit 7 is in the control mode instruction M C In the case of torque control mode, the second speed command S CL Set as motor speed command S MC .

[0035] Then, based on the motor speed command S MC, the motor speed is controlled. Specifically, the speed is obtained by differentiating the position of the encoder EN23 installed on the motor. The subtractor 11 obtains the speed from the motor speed instruction S MC Subtract the speed from the value to obtain the second speed deviation S D And output the second speed deviation S D The speed controller 15 sets the second speed deviation S D As input, the speed control operation is performed to calculate the motor torque command T MT And output the motor torque command T MT .

[0036] The motor torque controller 17 controls the motor output based on the motor torque command T MT That is, through the motor torque controller 17, the motor output is in accordance with the motor torque instruction T MT The position of the motor rotated by the torque output from the motor is detected by the encoder EN23. Speed ​​control is performed so that the speed corresponding to the detected position is consistent with the motor speed instruction S MC consistent.

[0037] The speed controller 15 includes a proportional controller 15a. The speed controller 15 operates only the proportional controller 15a or both the proportional controller 15a and the integral controller 15b in response to a command from the speed controller setting processing unit 16 based on the control state.

[0038] The integral controller 15b is configured to be able to set an initial value of the integral value. Furthermore, the integral controller 15b can perform an integral operation (for example, the integral operation of the integrator 15b-2) and an operation to stop the integral operation of the integrator 15b-2 and attenuate the value of the integrator 15b-2.

[0039] The speed controller 15 is based on the control mode instruction M C , the first speed instruction S based on the torque instruction TC and speed limit instruction S LC , it is possible to switch between a state in which the controller operates as a proportional-integral controller and a state in which the controller operates as a proportional controller 15a.

[0040] Figure 2 express Figure 1 A more specific configuration example of the speed controller 15 in FIG. 1 is shown. The proportional controller 15a has a proportional gain 15a-1. The integral controller 15b has an integral gain 15b-1, an integrator 15b-2, an attenuation gain (integral attenuation gain) 15b-3, and a switch 15b-4.

[0041] To operate the speed controller 15 as a proportional-integral controller, connect terminal 1 of switch 15b-4 to integrator 15b-2. This causes integral controller 15b to perform an integrating operation. To operate the speed controller 15 as a proportional controller, connect terminal 2 of switch 15b-4 to attenuation gain 15b-3. The negative integral attenuation gain causes the value of integrator 15b-2 to decay to zero, and proportional controller 15a to perform a proportional operation. These motor control components can be implemented using software. Control calculations are performed for each control sample.

[0042] Next, the control mode command M is described in sequence. C Control action and control mode command M when in either speed control mode or torque control mode C Motor control operation when switching from one of the two control modes to the other.

[0043] First, in the control mode instruction M C In the case of the torque control mode, the control mode switching unit 7 selects the torque control mode and sets the limited second speed command S CL Select the motor speed command S MC Then, as described below, torque control with speed limiting function is implemented.

[0044] In this case, the speed controller 15 operates as a proportional controller 15a. If the gain of the proportional controller 15a is GP, the operation of the speed control loop is as follows.

[0045] Motor speed command S MC - Speed ​​V = second speed deviation S D ···(1)

[0046] The second speed deviation S D ×GP=Motor torque command T MT ···(2)

[0047] According to the above formula, according to the motor torque command T MT , the motor speed instruction S can be given as follows MC Perform the inverse operation.

[0048] The second speed deviation S D =Motor torque command T MT / GP···(3)

[0049] Motor speed command S MC = Second speed deviation S D +Speed ​​V···(4)

[0050] In the first embodiment, the torque command T C Using this calculation, the first speed command S based on the torque command is calculated. TC .

[0051] The first speed deviation S based on the torque command DT =Torque command T C / GP···(5)

[0052] The first speed command S based on the torque command TC = First speed deviation S based on torque command DT +Speed ​​V···(6)

[0053] Then, the first speed instruction S obtained based on the torque instruction is TC Based on the speed limit instruction S LC The speed limit value of the speed limit is indicated. Thus, the second speed instruction S after the limit is obtained CL If the second speed instruction S after the restriction is followed CL The motor speed proportional control is performed, and the motor torque command T MT as follows.

[0054] Motor torque command T MT = Second speed deviation S D ×GP=(motor speed command S MC - speed V) × GP = (second speed command S after limitation) CL -Speed ​​(V) × GP

[0055] Here, the first speed instruction S based on the torque instruction TC Speed ​​limit command S LC If the second speed command S is smaller, the limited second speed command S CL = First speed command S based on the torque command TC Therefore, the motor torque command T MT as follows.

[0056] Motor torque command T MT =(Second speed command after limitation S CL - speed V) × GP = (first speed command S based on torque command) TC -Speed ​​(V) × GP

[0057] ={(first speed deviation S based on torque command DT + speed V)-speed V) × GP

[0058] =(first speed deviation S based on torque command DT )×GP=Torque command T C / GP×GP=Torque command T C

[0059] Thus, the motor torque command T MT With torque command T C Based on the motor torque command T MT Perform torque control. The motor output is in accordance with the motor torque command T MT of motor torque.

[0060] The first speed command S based on the torque command TC Speed ​​limit instruction S LC In the above case, the motor speed command S MC Speed ​​limit instruction S LC Therefore, the speed limit instruction S LC The speed of the motor is controlled by the speed limit instruction S LC Control speed. In addition, the first speed instruction S based on the torque instruction TC Speed ​​limit instruction S LC In the above case, the integral controller 15b of the speed controller 15 also operates. That is, the speed controller 15 operates as a proportional-integral controller to suppress the influence of disturbances such as friction.

[0061] In the control mode command M C When the speed control mode is selected, the control mode switching unit 7 selects the speed control mode as the control mode and sets the third speed instruction S C Select the motor speed command S MC And output. Thus, the motor speed instruction S MC Become the third speed instruction S C , based on the third speed instruction S C The speed controller 15 operates as a proportional-integral controller 15a and an integral controller 15b, and performs speed control while suppressing disturbances such as friction applied to the motor.

[0062] Here, when the control mode is switched from the speed control mode to the torque control mode, the control mode instruction M C The speed control mode is changed to the torque control mode. The control mode switching unit 7 changes the motor speed command S MC The connection object is from the third speed instruction S C Switch to the second speed command S after limitation CL In the first speed command S based on the torque command TC Speed ​​limit command S LC When the speed controller 15 has a proportional controller output, the output of the proportional controller is equal to the torque command TC Therefore, the initial value of the integrator 15b-2 of the integral controller 15b of the speed controller 15 is set to the following value.

[0063] Integral controller initial value = (motor torque command T before one control sampling of control mode switching) MT ')-(torque command T C )

[0064] Therefore, the motor torque command T when the control mode is switched to the torque control mode MT as follows.

[0065] Motor torque command T MT =(output of speed proportional controller) +(output of speed integral controller) =(torque command T C )+(initial value of integral controller)

[0066] =(Torque command T C )+(the motor torque command T before the control mode is switched MT ')-(torque command T C )

[0067] =(motor torque command T before one control sampling of control mode switching) MT ')

[0068] Thus, the motor torque command T MT Become a continuous action.

[0069] Then, the speed controller 15 is operated as a proportional controller 15a, causing the value of integrator 15b-2 to decay at a fixed time constant. Specifically, terminal 2 of switch 15b-4 of integral controller 15b is connected to integrator 15b-2. This causes the value of integrator 15b-2 to decay based on the integral decay gain and reach zero. Specifically, the value obtained by multiplying the integral decay gain by integrator 15b-2 is returned to the input of integrator 15b-2, and the output of integrator 15b-2 decays to zero within a predetermined period. Integrator 15b-2 is then stopped. Furthermore, the speed controller 15 performs a proportional operation. That is, the speed controller 15, which operates as both proportional-integral controllers 15a and 15b, operates as a proportional controller 15a.

[0070] As a result, the speed integral value decreases smoothly and becomes 0, achieving the torque command T C Torque control.

[0071] The first speed command S based on the torque command TC Speed ​​limit instruction S LCIn the above case, the speed controller 15 can be kept as a proportional-integral controller before and after the switch. Therefore, the integrator 15b-2 continues to operate. The initial value of the integrator 15b-2 is not set.

[0072] When the control mode is switched from the torque control mode to the speed control mode, the control mode instruction M C The torque control mode is changed to the speed control mode. The control mode switching unit 7 changes the motor speed command S MC The connection object is the second speed instruction S after the limit CL Switch to the third speed command S C The first speed instruction S based on the torque instruction before switching TC Speed ​​limit command S LC When the value is small, the speed controller 15 that operates as the proportional controller 15a operates as the proportional-integral controllers 15a and 15b. The initial value of the integrator 15b-2 is set to the following value.

[0073] Integral controller initial value = (motor torque command T before one control sampling of control mode switching) MT ')

[0074] In addition, the speed is output to the host controller. The host controller sets a predetermined initial value as the third speed instruction S C That is, the host controller sets the third speed instruction S C The initial value of is set to the following value.

[0075] The third speed instruction S C Initial value = (speed V' before control mode switching and one control sampling)

[0076] Therefore, when switching, the second speed deviation S D The output of the proportional controller 15a of the speed controller 15 also becomes 0. The motor torque command T when switching to the speed control mode MT as follows.

[0077] Motor torque command T MT = (output of speed proportional controller) + (output of speed integral controller) = 0 + (initial value of integral controller)

[0078] =(motor torque command T before one control sampling of control mode switching) MT ')

[0079] Motor torque command T MT The motor torque command T before the control mode is switched is MT ', becoming a continuous action.

[0080] The first speed command S based on the torque command before switching TC Speed ​​limit instruction S LC In the above case, the speed controller 15 can be kept as a proportional-integral controller. Therefore, the integrator 15b-2 continues to operate. The initial value of the integrator 15b-2 is not set.

[0081] Usually, when the control mode is switched from torque control mode to speed control mode, the motor is usually stopped. In this case, the upper controller only needs to set the third speed instruction S C The initial value of can be set as 0.

[0082] Figure 3 : is a flowchart showing the flow of control of the speed controller setting processing unit 16. Figure 3 In the process, the speed controller setting processing unit 16 first starts processing (Start), and in step S1, determines the command control mode.

[0083] If the control mode is the torque control mode, the speed controller setting processing unit 16 proceeds to step S2. In step S2, the speed controller setting processing unit 16 determines whether the immediately preceding control is speed control. If the determination result is "No" (if the immediately preceding control is torque control), the speed controller setting processing unit 16 proceeds to step S3. Here, the speed controller setting processing unit 16 performs a first speed command S based on the torque command. TC Is it a speed limit instruction S LC The above judgment. In the case of "No" (the first speed instruction S based on the torque instruction TC Speed ​​limit command S LC If the result of the determination in step S3 is “Yes” (when the first speed instruction S based on the torque instruction is smaller), the speed controller setting processing unit 16 proceeds to step S4 and causes the speed controller 15 to operate only as the proportional controller 15a. TC Speed ​​limit instruction S LC In the above case), the speed controller setting processing unit 16 proceeds to step S5 and operates the speed controller 15 as the proportional controller 15a and the integral controller 15b.

[0084] If the control mode is speed control mode in step S1, the speed controller setting processing unit 16 proceeds to step S10. In step S10, the speed controller setting processing unit 16 determines whether the immediately preceding control mode was torque control. If the determination result is "no" (if the immediately preceding control mode was speed control), the speed controller setting processing unit 16 proceeds to step S11 and operates the speed controller 15 as the proportional controller 15a and the integral controller 15b.

[0085] If the control mode is the torque control mode in step S1 and the result of determination in step S2 is "yes" (if the immediately preceding control is the speed control), the speed controller setting processing unit 16 proceeds to step S6. Here, the speed controller setting processing unit 16 performs a first speed command S based on the torque command. TC Is it a speed limit instruction S LC The above judgment. In the case of "No" (the first speed instruction S based on the torque instruction TC Speed ​​limit command S LC If the speed controller 15 is smaller than the speed controller 15, the speed controller setting processing unit 16 proceeds to steps S7 and S8. Specifically, in step S7, the speed controller setting processing unit 16 sets the initial value of the integrator. Furthermore, in step S8, the speed controller setting processing unit 16 operates the speed controller 15 as a proportional controller and causes the integrator value to decay to zero with a fixed time constant.

[0086] In step S6, if the result of the determination is “Yes” (the first speed instruction S based on the torque instruction is TC Speed ​​limit instruction S LC In the above case, the speed controller setting processing unit 16 proceeds to step S9 and operates the speed controller 15 as the proportional controller 15a and the integral controller 15b (sets it as a proportional-integral controller).

[0087] If the control mode is the speed control mode in step S1 and the result of the determination in step S10 is "yes" (if the immediately preceding control is the torque control), the speed controller setting processing unit 16 proceeds to step S12. Here, the speed controller setting processing unit 16 performs a first speed command S based on the torque command. TC Is it a speed limit instruction S LC The above judgment. In the case of "No" (the first speed instruction S based on the torque instruction TC Speed ​​limit command S LCIf the first speed command S1 is smaller than the first speed command S2, the speed controller setting processing unit 16 proceeds to steps S13 and S14. That is, the speed controller setting processing unit 16 sets the initial value of the speed command and the initial value of the integrator in S13, and operates the speed controller 15 as a proportional integral controller in S14. If the judgment result in step S12 is "yes" (the first speed command S1 is smaller than the first speed command S2 based on the torque command), the speed controller setting processing unit 16 proceeds to steps S13 and S14. TC Speed ​​limit instruction S LC In the above case), the speed controller setting processing unit 16 proceeds to step S11 and operates the speed controller 15 as a proportional-integral controller.

[0088] (Second embodiment)

[0089] Figure 4 A motor control device B according to a second embodiment of the present invention is shown. The motor control device B according to the second embodiment is an example of a motor control device capable of switching between torque control and position control.

[0090] Here, in the motor control device B, the position command L C Derive the third speed instruction S C .

[0091] In the motor control device B, the torque command T C The speed deviation calculator 1 calculates the first speed deviation S based on the torque command. DT By setting the first speed deviation S based on the torque command DT Add to the speed V to obtain the first speed command S based on the torque command TC By following the speed limit instruction S LC The speed limit value indicated is the first speed instruction S based on the torque instruction. TC Perform speed limitation and obtain the second speed instruction S after limitation CL By setting the position instruction L C The position error is calculated by comparing it with the position detected by the encoder EN23. The position error is passed through the position controller 35 to calculate the third speed instruction S. C The position controller 35 includes a proportional controller. The gain of the proportional controller is defined as KP. The control mode switching unit 7 is based on the control mode instruction M. C , switch to the third speed instruction S C and the second speed command S after limitation CL , calculate the motor speed command S MC .

[0092] The motor control device B is the motor control device A of the first embodiment and further includes a method for obtaining the third speed command S. CThe configuration and functions of the motor control device B other than these are the same as those of the motor control device A, and therefore their description is omitted.

[0093] Next, the operation of the motor control in the second embodiment will be described.

[0094] In the second embodiment, the same control action as the first embodiment is performed based on the substantially same structure and function as the first embodiment. The difference between the control action of the second embodiment and the control action of the first embodiment is that the second embodiment adds the method of obtaining the third speed instruction S based on the above method. C Control actions of the structure and functions up to now.

[0095] That is, in the motor control device B of the second embodiment, first, the torque command T C The speed deviation calculator 1 calculates the first speed deviation S based on the torque command. DT Then, by converting the first speed deviation S based on the torque command DT Add to the speed V to obtain the first speed command S based on the torque command TC Then, according to the speed limit instruction S LC The speed limit value indicated is the first speed instruction S based on the torque instruction. TC Perform speed limitation and obtain the second speed instruction S after limitation CL .

[0096] On the other hand, by setting the position instruction L C The position error is calculated by comparing it with the position detected by the encoder EN23. The position error is passed through the position controller 35 to calculate the third speed instruction S. C Here, the position controller 35 includes a proportional controller. The gain of the proportional controller is defined as KP. The control mode switching unit 7 is based on the control mode instruction M. C , switch to the third speed instruction S C and the second speed command S after limitation CL , calculate the motor speed command S MC .

[0097] Thus, the control operation in the second embodiment has the following features in addition to the control operation in the first embodiment: C The control operation in the second embodiment other than this operation is the same as that in the first embodiment, and therefore its description is omitted.

[0098] As described above, in the motor control device according to the embodiment of the present invention, a method for performing the inverse operation of the calculation of the motor torque command from the motor speed command in the speed control loop is used to calculate a first speed command based on the torque command. Furthermore, the first speed command is speed-limited to obtain a limited second speed command. Then, based on the control mode command, a third speed command and the limited second speed command are switched, and either the third speed command or the second speed command is obtained as the motor speed command. Speed ​​control is then implemented using this motor speed command. Consequently, since a correction torque calculation unit for calculating a torque correction value is not required, the configuration of the motor control device can be simplified.

[0099] In addition, the motor control device of the embodiment of the present invention copes with any one or all of the following first to fourth switches. The first switch is the switch from the position control mode or the speed control mode to the torque control mode in a state where speed limitation is not performed. The second switch is the switch from the position control mode or the speed control mode to the torque control mode in a state where speed limitation is performed. The third switch is the switch from the torque control mode in a state where speed limitation is not performed to the position control mode or the speed control mode. The fourth switch is the switch from the torque control mode in a state where speed limitation is performed to the position control mode or the speed control mode. According to this motor control device, only a small amount of processing time is required when switching the control mode, and the impact on the control object caused by the discontinuity of the torque instruction value can be suppressed.

[0100] Each of the above embodiments represents one embodiment of the present invention. The technology of the present invention itself is not limited to the specific configurations represented by these embodiments. The technical scope of the present invention includes all contents that can be conceived by those skilled in the art based on the matters described in the claims.

[0101] Furthermore, the technology of one aspect of the present invention can be considered to relate to a motor control device having a control mode switching function.

[0102] A motor control device according to one embodiment of the present invention may be the following first motor control device. In a motor control device that controls a motor based on a control mode instruction of either torque or speed, the first motor control device limits the speed according to a speed limit instruction in a torque control mode and controls the torque of the motor, and controls the speed of the motor according to a speed instruction in a speed control mode. The motor control device is characterized in that the motor control device comprises: a speed detection unit that detects the speed of the motor; a speed deviation calculator that calculates a speed deviation based on the torque instruction based on the torque instruction; an adder that adds the speed deviation based on the torque instruction to the speed output from the speed detection unit and outputs a speed instruction based on the torque instruction; and a speed limiting unit that adjusts the speed deviation based on the torque instruction based on the speed limit value indicated by the speed limit instruction. A speed instruction of the torque instruction is speed-limited and the limited speed instruction is output; a control mode switching unit, based on the control mode instruction, outputs a motor speed instruction capable of switching the speed instruction and the limited speed instruction; a subtractor, subtracting the speed of the motor from the motor speed instruction and outputting a speed deviation; a speed controller, performing a speed control operation using the speed deviation as input and outputting a motor torque instruction; and a motor torque control unit, outputting a torque based on the motor torque instruction, the speed controller having a proportional controller and an integral controller, the integral controller being capable of being set to an initial value of an integral value and being capable of performing an integral action and an action of stopping the integral action and attenuating the value of the integrator.

[0103] The detailed description has been presented for purposes of illustration and description. Numerous variations and modifications are possible in light of the above teachings. The detailed description is not intended to be exhaustive or to limit the subject matter described herein. Although the subject matter has been described in terms of specific structural features and / or methodological procedures, it should be understood that the subject matter defined in the claims is not necessarily limited to the specific features or procedures described. Rather, the specific features and procedures described are described as examples of implementing the claims.

Claims

1. A motor control device, characterized in that: have: A speed detection unit, detecting the speed of the motor; A speed deviation calculator, based on the torque command, calculates a first speed deviation based on the torque command; an adder for adding the first speed deviation based on the torque command and the speed output from the speed detection unit to obtain a first speed command based on the torque command, and outputting the first speed command based on the torque command; a speed limiting unit that limits the first speed command based on the torque command according to a speed limit value indicated by a speed limit command, thereby obtaining a limited second speed command and outputting the limited second speed command; a control mode switching unit that selects one of a speed control mode and a torque control mode as a control mode based on the control mode command, and outputs one of a third speed command and the limited second speed command as a motor speed command; a subtractor for obtaining a second speed deviation by subtracting the speed of the motor from the motor speed command and outputting the second speed deviation; a speed controller, taking the second speed deviation as input to perform a speed control operation and output a motor torque command; as well as a motor torque control unit configured to cause the motor to output a torque based on the motor torque command; The speed controller has a proportional controller and an integral controller, The integral controller is capable of setting an initial value of the integral value, and is capable of performing an integral operation and an operation of stopping the integral operation of the integrator and decaying the value of the integrator.

2. The motor control device according to claim 1, wherein: The third speed command is derived from the position command.

3. The motor control device according to claim 1 or 2, characterized in that: The speed controller is switchable between a state of operating as a proportional-integral controller and a state of operating as the proportional controller based on the control mode command, the first speed command based on the torque command, and the speed limit command.

4. The motor control device according to claim 1 or 2, characterized in that: When the speed control mode is selected by the control mode switching unit, the speed controller operates as a proportional-integral controller that operates as both the proportional controller and the integral controller. When the torque control mode is selected by the control mode switching unit and the first speed command based on the torque command is smaller than the speed limit command, the speed controller operates as the proportional controller. When the torque control mode is selected by the control mode switching unit and the first speed command based on the torque command is equal to or greater than a speed limit command, the speed controller operates as the proportional-integral controller including the proportional controller and the integral controller.

5. The motor control device according to claim 1 or 2, characterized in that: When the control mode is switched from the speed control mode to the torque control mode, and the first speed command based on the torque command is smaller than the speed limit command, The integral value of the integral controller is set to a specified initial value, The value obtained by multiplying the integrator by the integral attenuation gain is returned to the input of the integrator, and the output of the integrator decays to zero within a predetermined period. The speed controller that acts as a proportional-integral controller acts as the proportional controller, When the control mode is switched from the speed control mode to the torque control mode, and the first speed command based on the torque command is equal to or greater than the speed limit command, The speed controller remains a proportional-integral controller.

6. The motor control device according to claim 1 or 2, characterized in that: When the control mode is switched from the torque control mode to the speed control mode, and a first speed command based on the torque command before the switching is smaller than a speed limit command, The third speed instruction is set to a predetermined initial value. The integral value of the integral controller is set to a specified initial value, The speed controller that acts as the proportional controller acts as a proportional-integral controller, When the control mode is switched from the torque control mode to the speed control mode, and a first speed command based on the torque command before the switching is equal to or greater than a speed limit command, The speed controller remains the proportional-integral controller.

Images