JPH11332278A - Ac servo motor control device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent hunting from being generated, by controlling an armature current at each phase according to a current command value signal of each phase being outputted from a three-phase AC coordinates converter, and modulating a pulse width for driving a motor. SOLUTION: A three-phase AC coordinates converter 6 uses a trigonometric function of a DC current command iq being outputted from a speed controller 5, and a current phase angle of θep being outputted from a trigonometric function value generator 7 for calculating a U-phase current command iud and a V-phase current command ivd. The U-phase and V-phase current commands iud and ivd are outputted to U-phase and V-phase current controllers 8a and 8b. Then, when the output commands iud and ivd deviate from the U-phase and V-phase motor currents iu and iv, they are outputted to a PWM inverter 9 as U-phase and V-phase motor voltage commands Vu and Vu. By modulating a pulse width by the inverter 9, the rotor of an AC servo motor 1 is rotated by a specific angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC servo motor control device and an AC servo motor control method for controlling the driving of an AC servo motor by an AC power supply formed based on a command value.

[0002]

2. Description of the Related Art In an AC servomotor control apparatus for performing feedback control of an AC servomotor, it is important that positioning control for the AC servomotor be performed quickly and with high accuracy. In order to obtain such an AC servo control device, it was necessary to enhance the frequency characteristics in the feedback control. In the conventional AC servomotor control device, the feedback gain is increased to improve the frequency characteristics of the feedback control.

Hereinafter, a specific conventional AC servomotor control device will be described with reference to FIG. FIG. 5 is a block diagram showing an example of the configuration of a conventional AC servomotor control device. As shown in FIG. 5, an encoder 2 is attached to an output shaft directly connected to a rotor of the AC servomotor 1, and this encoder 2 sends an A signal to a position / speed detector 3.
A pulse signal and an origin signal corresponding to the rotation angle of the rotor of the C servo motor 1 are output. The position / speed detector 3 uses the pulse signal output from the encoder 2 and the origin signal to
The current position θm from the origin, the rotational speed ω, and the current phase angle θe at which the power factor = 1 are calculated, and output to the input terminals of the position controller 4 and the speed controller 5.

The position controller 4 compares a position command θmd given from outside the apparatus with the current position θm calculated by the position / speed detector 3. The position controller 4
When there is a position deviation between the position command θmd and the current position θm, a signal obtained by multiplying the position deviation Δθ of the position deviation by a predetermined position gain is used as the motor speed command ωd as the speed controller 5.
Output to The speed controller 5 compares the motor speed command ωd input from the position controller 4 with the rotation speed ω calculated by the position / speed detector 3. When there is a deviation between the motor speed command ωd and the rotation speed ω, the speed controller 5 converts a signal obtained by multiplying the deviation amount by a predetermined speed gain into a DC current command (torque command) iq for three-phase AC coordinate conversion. Output to the container 6. The three-phase AC coordinate converter 6 uses the DC current command (torque command) iq and the trigonometric function value of the current phase angle θe output from the trigonometric function value generator 7 to generate a U-phase current command iud. And the V-phase current command ivd are calculated by the following equations (1) and (2).

[0005]

(Equation 1)

[0006]

(Equation 2)

[0007] The three-phase AC coordinate converter 6 receives a U-phase current command i.
ud to the U-phase current controller 8a, and outputs the V-phase current command iv
d is output to the V-phase current controller 8b. U-phase current controller 8
a, the detected U-phase motor current iu and the U-phase current command i
If there is a deviation between the current value and the Ud, a signal obtained by multiplying the deviation amount by a predetermined current gain is used as a U-phase motor voltage command Vu as PW
Output to M inverter 9. On the other hand, the V-phase current controller 8b
Now, the detected V-phase motor current iv and the V-phase current command iv
d, a signal obtained by multiplying the deviation amount by a predetermined current gain is used as a V-phase motor voltage command Vv in PWM.
Output to inverter 9.

The W-phase motor voltage command Vw is expressed as Vw =
It is calculated from the formula of -Vu-Vv. In the PWM inverter 9, voltages corresponding to the U-phase motor voltage command Vu, the V-phase motor voltage command Vu, and the W-phase motor voltage command Vw formed as described above are applied to each phase of the bridge circuit configuring the PWM inverter 9. Is done. When a voltage is applied to each phase of the bridge circuit in this manner, a current flows through the rotor winding of the AC servomotor 1 and the rotor of the AC servomotor 1 rotates by a predetermined angle. When the rotor of the AC servomotor 1 reaches the position indicated by the position command θmd given from outside the device and the rotation speed ω becomes zero, the outputs of the position controller 4 and the speed controller 5 become zero. At this time, the DC current command (torque command) iq becomes zero, the AC servomotor 1 stops, and the positioning operation is completed.

[0009]

In the above-described conventional method for controlling an AC servomotor, the frequency characteristics of feedback control have been enhanced in order to perform positioning at high speed and with high accuracy. For this reason, it is necessary to increase the feedback gain. However, even if the feedback loop is configured by an analog circuit or a digital circuit, there is a feedback delay time. As a result, according to the conventional control method of the AC servomotor, there is an oscillation frequency due to a dead time element, and if the feedback gain is increased too much, a phenomenon called hunting (periodic fluctuation) occurs. As described above, when the positioning control for stopping the AC servomotor at a predetermined angle is performed by the feedback control method, the response characteristic depends on the feedback characteristic. And other problems.

As a control device for solving such a problem, for example, there is an AC servo motor control device disclosed in Japanese Patent Application Laid-Open No. 7-123767. This AC servo motor control device is configured to be able to control an electrical phase angle between a magnetic pole position of a stator and a magnetic pole position of a rotor, which is generated by energizing a stator winding. When performing position control, the AC servo motor control device sets the electric phase angle to zero when the position deviation is at or near zero, and otherwise sets the electric phase angle to 90 degrees. Is the way.

However, according to this control method, even if the position deviation once becomes zero or a value close to zero, the position deviation becomes large due to overshoot. Is switched again to the feedback control in which is set to 90 degrees. Therefore, this control method has a problem that the response characteristic is deteriorated during the switched feedback control because the response characteristic depends on the feedback characteristic. Further, after the AC servomotor is stopped, it is necessary to supply a continuous current to the stator winding in order to hold the AC servomotor at the stop position, and there has been a problem that the AC servomotor generates heat due to the continuous current. The present invention solves the above problems,
It is an object of the present invention to provide an AC servomotor control method and an AC servomotor control device that can achieve high-speed response and high positional accuracy, prevent hunting, and suppress heat generation when the AC servomotor is stopped. Aim.

[0012]

In order to achieve the above object, an AC servomotor control device according to the present invention detects a rotation angle and a rotation speed of a motor and detects a position / speed signal for forming a position signal and a speed signal. The position deviation between the position signal from the position / speed detector and the position command signal of the motor is input, and a position controller that outputs a motor speed command signal; the speed signal from the position / speed detector; A speed controller that receives a speed deviation from a motor speed command signal from a position controller and outputs a DC current command signal; a first current phase angle signal from the position / speed detector and the first current phase angle A second current phase angle signal having a power factor of 0 obtained by adding 90 degrees to the signal, and outputting a second current phase angle signal when the position deviation becomes zero for the first time after the operation of the motor starts. Phase angle switching A triangular function value generator for converting a first current phase angle signal or a second current phase angle signal output from the current phase angle switching means into a trigonometric function value signal; and a DC output from the speed controller. A three-phase AC coordinate converter to which a current command is input and a trigonometric function value signal output from the trigonometric function value generator, and a current command value signal for each phase output from the three-phase AC coordinate converter , A current controller for controlling the armature current of each phase, and a PWM inverter for modulating a pulse width to drive the motor. According to the present invention, since the current phase angle is maintained at the current phase angle of the power factor = 0 when the positional deviation becomes zero for the first time, the response characteristic at the time of stopping does not depend on the feedback characteristic, The motor can be stopped at a desired position by the electric attraction of the rotor and the stator of the motor.

Further, in the AC servo motor control method according to the present invention, a position / speed detector detects a rotation angle and a rotation speed of the motor to form a position signal and a speed signal. A position deviation between a position signal from a detector and a position command signal of the motor is input, and a step of outputting a motor speed command signal to a speed controller, from a speed signal from the position / speed detector and the position controller A step of receiving a speed deviation from a motor speed command signal and outputting a DC current command signal to a three-phase AC coordinate converter, wherein the current phase angle switching means outputs the first current phase angle signal from the position / speed detector and Power factor = 0 obtained by adding 90 degrees to the first current phase angle signal
Switching the second current phase angle signal and outputting the second current phase angle signal, and outputting the second current phase angle signal when the position deviation becomes zero for the first time since the start of the operation of the motor. A step of converting the first current phase angle signal or the second current phase angle signal output from the current phase angle switching means into a trigonometric function value signal; a DC output from the speed controller to a three-phase AC coordinate converter; A current command and a trigonometric function value signal output from the trigonometric function value generator are input, and a step of controlling armature current of each phase; a step of modulating a pulse width by a PWM inverter to drive the motor; Having. According to the present invention, the current phase angle is held at the current phase angle of the power factor = 0 when the positional deviation becomes zero for the first time, so that the electric attraction force of the rotor and the stator of the motor is independent of the feedback characteristics. As a result, the motor stops at a desired position, so that an AC servo motor control method having high-speed response and high positional accuracy is provided.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an AC servomotor control device and an AC servomotor control method according to the present invention will be described below with reference to the accompanying drawings. << Embodiment 1 >> FIG. 1 is a block diagram showing an AC servomotor control device according to Embodiment 1 of the present invention. In FIG. 1, an encoder 2 is attached to an output shaft directly connected to a rotor of an AC servomotor 1,
The encoder 2 outputs a pulse signal and an origin signal corresponding to the rotation angle of the rotor of the AC servomotor 1 to the position / speed detector 3. The position / speed detector 3 calculates a current position θm from the origin position, a rotational speed ω, and a current phase angle θe at which the power factor = 1, based on the pulse signal output from the encoder 2 and the origin signal. The position / speed detector 3 outputs the calculated current position θm to the subtractor connected to the input terminal of the position controller 4, and outputs the calculated rotation speed ω to the input terminal of the speed controller 5. Output to the subtractor.

In a subtractor connected to the input terminal of the position controller 4, a position command θmd given from outside the apparatus and a current position θm calculated by the position / speed detector 3 are subtracted. When there is a position deviation between the position command θmd and the current position θm, the position controller 4 sets a signal obtained by multiplying the position deviation amount Δθ of the position deviation by a predetermined position gain as the motor speed command ωd. Output to The subtractor connected to the input terminal of the speed controller 5 subtracts the motor speed command ωd input from the position controller 4 and the rotation speed ω calculated by the position / speed detector 3. The speed controller 5 determines the motor speed command ωd and the rotation speed ω
If there is a deviation between the two, a signal obtained by multiplying the deviation by a predetermined speed gain is output to the three-phase AC coordinate converter 6 as a DC current command (torque command) iq.

As shown in FIG. 1, the AC servomotor control device of the first embodiment is provided with a current phase angle switching means 10. The current phase angle switching means 10 includes a changeover switch 11, a switch switching signal generator 12, and a current phase angle storage 13. The switch switching signal generator 12 is configured to output a switch switching signal S to the switch 11 and the current phase angle storage 13 when the position deviation amount Δθ becomes zero for the first time after the AC servomotor 1 starts operating. I have. The current phase angle storage unit 13 uses the switch switching signal S output from the switch switching signal generation unit 12 to calculate the power factor output from the position / speed detector 3 =
One current phase angle θe is stored.

The changeover switch 11 is switched by a switch changeover signal S output from a switch changeover signal generating section 12, and by the changeover operation of the changeover switch 11, the power factor = 1 output from the position / speed detector 3 is output. Current phase angle θ
e or a power factor = 0 obtained by adding 90 degrees (π / 2 radians) to the current phase angle θe0 stored in the current phase angle storage unit 13.
Is output to the trigonometric function value generator 7 as the current phase angle θep. The switch switching signal generator 12 outputs a switch switching signal S when the positional deviation amount Δθ becomes zero for the first time after the AC servomotor 1 starts operating. Therefore, the trigonometric function value generator 7
Positional deviation Δ only after C servo motor 1 starts operation
Until θ becomes zero, the current phase angle θe of the power factor = 1 output from the position / speed detector 3 is input. After the position deviation amount Δθ becomes zero, the current phase angle θep input to the trigonometric function value generator is 90 degrees (π / 2 radians) corresponding to the current phase angle θe0 stored in the current phase angle storage unit 13. )
Is obtained, the current phase angle θe1 of the power factor = 0 is obtained.

The switching timing of the current phase angle θep input to the trigonometric function value generator 7 will be described with reference to FIG. FIG. 2 is a timing chart showing the switching timing of the current phase angle θep input to the trigonometric function value generator 7. Since a value having various levels is set as the position command θmd, a band-shaped area indicated by oblique lines in FIG. 2 indicates a range of a certain level in which the position command θmd is set, and is indicated by surrounding the band-shaped area. This shows a case where the position of the intersection in the solid line switches the position command θmd. Changeover switch 11 in current phase angle switching means 10
Is, for example, the position command θmd (t
-1) at the timing Ts1 at which the position command θmd (t) is switched from the contact 1 to the contact 2 at the time (t).
Switch the connection to. Next, at the timing To1 at which the position deviation amount Δθ becomes zero, the changeover switch 11
From the connection to the contact 1. Current phase angle switching means 1
The current phase angle θep output from 0 is converted into a trigonometric function value in a trigonometric function value generator 7 and output to a three-phase AC coordinate converter 6.

In the three-phase AC coordinate converter 6, a DC current command (torque command) iq output from the speed controller 5 is output.
And the current phase angle θe output from the trigonometric function value generator 7
Using the trigonometric function value of p, the U-phase current command iud and the V-phase current command ivd are calculated by the following equations (3) and (4).

[0020]

(Equation 3)

[0021]

(Equation 4)

The three-phase AC coordinate converter 6 outputs a U-phase current command i
ud to the U-phase current controller 8a, and outputs the V-phase current command iv
d is output to the V-phase current controller 8b. U-phase current controller 8
a, the detected U-phase motor current iu and the U-phase current command i
If there is a deviation between the current value and the Ud, a signal obtained by multiplying the deviation amount by a predetermined current gain is used as a U-phase motor voltage command Vu as PW
Output to M inverter 9. On the other hand, the V-phase current controller 8b
Now, the detected V-phase motor current iv and the V-phase current command iv
d, a signal obtained by multiplying the deviation amount by a predetermined current gain is used as a V-phase motor voltage command Vv in PWM.
Output to inverter 9. The W-phase motor voltage command V
w is calculated from the formula of Vw = −Vu−Vv.

In the PWM inverter 9, the respective voltages corresponding to the U-phase motor voltage command Vu, the V-phase motor voltage command Vv, and the W-phase motor voltage command Vw formed as described above constitute a bridge constituting the PWM inverter 9. Applied to each phase of the circuit. When a voltage is applied to each phase of the bridge circuit in this manner, a current flows through the rotor winding of the AC servomotor 1 and the rotor of the AC servomotor 1 rotates by a predetermined angle. The rotor of the AC servomotor 1 reaches the position indicated by the position command θmd given from outside the device, and the rotation speed ω becomes zero. At this time, the outputs of the position controller 4 and the speed controller 5 become zero, that is, the DC current command (torque command) iq becomes zero, the AC servomotor 1 stops, and the positioning operation is completed.

As described above, the AC servomotor control device of the first embodiment switches the current phase angle θep output from the current phase angle switching means 10 so that the rotor operates when the AC servomotor operates and when it stops. The current phase angle of the current flowing through the winding is switched, and the response characteristics at the time of stop do not depend on the feedback characteristics, and the rotor of the AC servomotor is driven by the electric attractive force of the rotor and the stator of the AC servomotor. Stop in position.

<< Embodiment 2 >> An embodiment 2 of an AC servomotor control device of the present invention will be described below with reference to the accompanying drawings. FIG. 3 is a block diagram illustrating an AC servomotor control device according to a second embodiment. In FIG. 2, components having the same functions and configurations as those of the AC servomotor control device of the first embodiment described above are denoted by the same reference numerals, and description thereof will be omitted.
As shown in FIG. 3, an encoder 2 is attached to an output shaft directly connected to a rotor of the AC servomotor 1,
The encoder 2 outputs a pulse signal and an origin signal corresponding to the rotation angle of the rotor of the AC servomotor 1 to the position / speed detector 3. The position / speed detector 3 calculates a current position θm from the origin position, a rotational speed ω, and a current phase angle θe at which the power factor = 1, based on the pulse signal output from the encoder 2 and the origin signal. The calculated current position θm and rotation speed ω are configured to be input to subtractors connected to the input terminals of the position controller 4 and the speed controller 5. Further, the current phase angle θe at which the power factor = 1 is configured to be input to the current phase angle switching means 10.

In the position controller 4, if there is a position deviation between the position command θmd given from outside the apparatus and the current position θm of the position / speed detector 3, the position deviation Δθ
Is output as a motor speed command ωd. In the speed controller 5, when there is a deviation between the motor speed command ωd and the rotation speed ω, a signal obtained by multiplying the difference by a predetermined speed gain is used as a DC current command (torque command) iq. (Torque command) output to the switching means 14.

As shown in FIG. 3, in the AC servo motor control device of the second embodiment, a current phase angle switching means 10 having the same configuration as that of the first embodiment is provided. As shown in FIG. The current phase angle switching means 10 according to the second embodiment includes a changeover switch 11, a switch switching signal generation unit 12, and a current phase angle storage unit 13. The switch switching signal generator 12 generates a switch switching signal S when the position deviation amount Δθ becomes zero for the first time after the AC servomotor 1 starts operating. When a switch switching signal S from the switch switching signal generator 12 is input, the current phase angle storage 13
The current phase angle θe of the power factor = 1 is stored. The changeover switch 11 receives the current phase angle θe detected by the position / speed detector 2 and the current phase stored in the current phase angle storage section 13 when the switch switching signal S of the switch switching signal generation section 12 is input. Switching is made between the current phase angle θe1 of the power factor = 0 obtained by adding 90 degrees (π / 2 radians) to the angle θe0. The current phase angle θe or the current phase angle θe1 from the changeover switch 11 is output to the trigonometric function value generator 7.

As shown in FIG. 3, a DC current command (torque command) switching means 14 is provided in the AC servomotor control device of the second embodiment. DC current command switching means 14
When the position deviation Δθ becomes zero for the first time since the operation of the AC servomotor 1 is started, that is, when the switch switching signal S is input from the switch switching signal generator 12 of the current phase angle switching means 10, the DC current command switching is performed. The changeover switch 15 in the means 14 switches between the contact 1 and the contact 2. The motor-converted torque value (DC current value) iq0 of the mechanism driven by the AC servomotor 1 in a steady load state is input to the contact 1 of the changeover switch 15. The contact 2 of the changeover switch 15 has a motor speed command iq of the speed controller 5
Is entered.

Hereinafter, a specific example of the motor converted torque value (DC current value) iq0 input to the contact 1 of the changeover switch 15 will be described. For example, a ball screw (radius RB, radius RB,
Consider a mechanism in which the reduction ratio r) is directly connected, a load of mass M is attached to this ball screw, and the ball screw is operated in the vertical direction. In this case, when the gravitational acceleration is g, A
The motor-converted torque value (direct current value) iq0 of the mechanism connected to the C servo motor 1 is calculated by the following equation (5).

[0030]

(Equation 5)

Therefore, the current phase angle θep input to the trigonometric function value generator 7 until the position deviation amount Δθ becomes zero for the first time after the operation of the AC servomotor 1 is started is equal to the current phase angle from the position / speed detector 3. The angle θe. Further, the DC current command (torque command) iqp input to the three-phase AC coordinate converter 6 becomes the DC current command iq of the speed controller 5. On the other hand, after the positional deviation amount Δθ becomes zero, the current phase angle θep input to the trigonometric function value generator 7 becomes 90 degrees (π / 2) as the current phase angle θe0 stored in the current phase angle storage unit 13. (Radian) plus the current phase angle θ at power factor = 0
e1. Further, the DC current command (torque command) iqp input to the three-phase AC coordinate converter is a motor-converted torque value (DC current value) iq0. Three-phase AC coordinate converter 6
, Using the DC current command (torque command) iqp and the trigonometric function value of the current phase angle θep output from the trigonometric function value generator 7, the U-phase current command iud is calculated by the following equations (6) and (7). V-phase current command ivd is calculated.

[0032]

(Equation 6)

[0033]

(Equation 7)

The timing of switching the current phase angle θep input to the trigonometric function value generator 7 and the switching timing of the DC current command (torque command) iqp input to the three-phase AC coordinate converter 6 will be described with reference to FIG. Will be explained. FIG. 4 shows the current phase angle θep by the changeover switch 11 and the changeover switch 15
6 is a timing chart showing the timing of switching of a DC current command (torque command) iqp according to FIG. The changeover switch 11 in the current phase angle changeover means 10 and the changeover switch 15 in the DC current command (torque command) changeover means 14, for example, each have a position command θmd at time (t−t).
At the timing Ts1 at which the position command θmd (t-1) of 1) is switched to the position command θmd (t) of time (t), the connection is switched from the contact 1 to the contact 2 respectively. Next, the timing T0 when the positional deviation amount Δθ becomes zero
In 1, the connection of the changeover switches 11 and 15 is switched from the contact 2 to the contact 1, respectively.

The current phase angle θep output from the current phase angle switching means 10 is converted into a trigonometric function value by the trigonometric function value generator 7 and output to the three-phase AC coordinate converter 6.
The three-phase AC coordinate converter 6 uses the DC current command (torque command) iq output from the speed controller 5 and the trigonometric function value of the current phase angle θep output from the trigonometric function value generator 7. , U-phase current command uid and V-phase current command ivd are calculated by the above equations (6) and (7). The three-phase AC coordinate converter 6 outputs the U-phase current command iud to the U-phase current controller 8a, and outputs the V-phase current command ivd to the V-phase current controller 8a.
Output to b. When there is a difference between the detected U-phase motor current iu and the above-mentioned U-phase current command iud, the U-phase current controller 8a outputs a signal obtained by multiplying the difference by a predetermined current gain to the U-phase motor voltage command. PWM inverter 9 as Vu
Output to

On the other hand, if there is a deviation between the detected V-phase motor current iv and the V-phase current command ivd, the V-phase current controller 8b outputs a signal obtained by multiplying the deviation by a predetermined current gain. It outputs to the PWM inverter 9 as the motor voltage command Vv. Note that the W-phase motor voltage command Vw is Vw = −
It is calculated from the formula of Vu-Vv. In the PWM inverter 9, voltages corresponding to the U-phase motor voltage command Vu, the V-phase motor voltage command Vv, and the W-phase motor voltage command Vw formed as described above are applied to each phase of the bridge circuit configuring the PWM inverter 9. Applied. When a voltage is applied to each phase of the bridge circuit in this manner, the AC servomotor 1
Current flows through the rotor winding of the AC servo motor 1, and the rotor of the AC servomotor 1 rotates by a predetermined angle. The rotor of the AC servomotor 1 reaches the position indicated by the position command θmd given from outside the device, and the rotation speed ω becomes zero. At this time, the outputs of the position controller 4 and the speed controller 5 become zero, that is, the DC current command (torque command) iq becomes zero, the AC servomotor 1 stops, and the positioning operation is completed.

As described above, the AC servomotor control device according to the second embodiment includes the current phase angle θep input to the trigonometric function value generator 7 and the DC current command (torque) input to the three-phase AC coordinate converter. Command) by switching iqp, A
The current phase angle of the current flowing through the rotor winding is switched between when the C servo motor is operating and when the motor is stopped, and the response characteristic when the motor is stopped does not depend on the feedback characteristics. The rotor of the AC servomotor is stopped at a desired position by the suction force, and the motor can be stopped even when a steady load such as a vertical load is applied to the AC servomotor.

[0038]

As described above, according to the present invention, the phase characteristic of the current flowing through the rotor winding is switched between when the AC servomotor is operating and when it is stopped. Does not depend on the feedback characteristics, but is driven by the electric attraction of the rotor and stator of the AC servomotor.
The rotor of the servomotor can be stopped at a desired position, high-speed response and high positional accuracy can be achieved in the drive control of the AC servomotor, and hunting is prevented and the response characteristics before stopping are improved. Can be planned.

According to the present invention, the phase angle of the current flowing through the rotor winding and the command value (torque command value) of the DC current flowing through the AC servomotor are switched between when the AC servomotor is operating and when it is stopped. The response characteristic at the time of stop does not depend on the feedback characteristic,
A due to the electric attraction of the rotor and stator of the servomotor
The rotor of the C servomotor can be stopped at a desired position. Further, according to the present invention, even when a steady load such as a vertical load is applied to the AC servomotor, the motor can be stopped and held, so that high-speed response and high positional accuracy of the motor stop control can be realized, and hunting can be prevented. And improvement of the response characteristics up to the stop can be realized. Furthermore, according to the present invention, even when a steady load such as a vertical load is applied to the AC servomotor, the motor torque conversion value of the steady load can be set to the command value. Thus, the heat generation of the motor can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an AC servomotor control device according to a first embodiment, which is one embodiment of the present invention.

FIG. 2 is a timing chart showing a switching timing of a current phase angle according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing an AC servo motor control device according to a second embodiment which is an embodiment of the present invention.

FIG. 4 is a timing chart showing a switching timing of a current phase angle and a DC current command (torque command) in Embodiment 2 of the present invention.

FIG. 5 is a block diagram showing a conventional AC servomotor control device.

[Explanation of symbols]

 Reference Signs List 1 AC servo motor 2 Encoder 3 Position / speed detector 4 Position controller 5 Speed controller 6 3-phase AC coordinate converter 7 Trigonometric function value generator 8a U-phase current controller 8b V-phase current controller 9 PWM inverter 10 Current Phase angle switching means 11 changeover switch 12 switch changeover signal generator 13 current phase angle storage

Claims (6)

[Claims] 1. Detecting a rotation angle and a rotation speed of a motor,
A position / speed detector that forms a position signal and a speed signal, a position controller that receives a position deviation between the position signal from the position / speed detector and the position command signal of the motor, and outputs a motor speed command signal; A speed controller that receives a speed deviation between a speed signal from the position / speed detector and a motor speed command signal from the position controller and outputs a DC current command signal; a first speed controller from the position / speed detector Switching between a current phase angle signal and a second current phase angle signal having a power factor of 0 obtained by adding 90 degrees to the first current phase angle signal, and when the position deviation becomes zero for the first time since the operation of the motor is started; Current phase angle switching means for outputting a second current phase angle signal, and converting the first current phase angle signal or the second current phase angle signal output from the current phase angle switching means into a trigonometric function value signal. Trigonometric function value A three-phase AC coordinate converter to which a DC current command output from the speed controller is input and a trigonometric function value signal output from the trigonometric function value generator is input; And a current controller for controlling the armature current of each phase by the current command value signal of each phase output from the controller and driving the motor by modulating the pulse width.
An AC servomotor control device comprising a WM inverter. 2. A switch switching signal generating section for outputting a switch switching signal when the position deviation becomes zero for the first time after the start of operation of the motor, the current phase angle switching means comprising: a power factor = A current phase angle storage unit for storing the first current phase angle signal; a force obtained by adding 90 degrees to the first current phase angle signal stored in the current phase angle storage unit by the switch switching signal 2. The AC servomotor control device according to claim 1, further comprising: a first switch for switching to output a second current phase angle signal having a rate of 0 to the trigonometric function value generator. 3. A three-phase DC current command output from the speed controller and a motor converted torque value signal of a steady load of a mechanism connected to a motor are switched by a switch switching signal of a switch switching signal generator. 3. The AC servomotor control device according to claim 2, further comprising a DC current command value switching means having a second switch for outputting to the AC coordinate converter. 4. A step of detecting a rotation angle and a rotation speed of a motor by a position / speed detector to form a position signal and a speed signal. A position controller and a position signal from the position / speed detector and the motor A position deviation from a position command signal is input, and a motor speed command signal is output to a speed controller.A speed deviation between a speed signal from the position / speed detector and a motor speed command signal from the position controller is input. Outputting a DC current command signal to the three-phase AC coordinate converter, wherein the current phase angle switching means outputs the first current from the position / speed detector.
And a second current phase angle signal having a power factor of 0 obtained by adding 90 degrees to the first current phase angle signal, and outputs the same. And outputting a second current phase angle signal when the first current phase angle signal is output from the current phase angle switching means. Converting into a function value signal; a DC current command output from the speed controller and a trigonometric function value signal output from the trigonometric function value generator are input to a three-phase AC coordinate converter; An AC servomotor control method, comprising: controlling an armature current; and driving the motor by modulating a pulse width by a PWM inverter. 5. When the position deviation becomes zero for the first time after the start of operation of the motor, a switch switching signal is output, and the first current phase angle signal stored in the current phase angle storage section is output by the switch switching signal. Power factor with 90 degrees added = 0
5. The method of controlling an AC servo motor according to claim 4, further comprising the step of switching the second current phase angle signal to be output to the trigonometric function value generator. 6. A three-phase alternating current system in which a DC current command output from a speed controller and a motor-converted torque value signal of a steady load of a mechanism connected to a motor are switched by a switch switching signal of a switch switching signal generator. 6. The method of controlling an AC servomotor according to claim 5, further comprising a step of outputting to a coordinate converter.