JPH0630596A - Oscillation detector for servo driver - Google Patents

Abstract

PURPOSE:To make it possible to easily and definitely ascertain an oscillating state of a servo driver without the use of an oscilloscope, or the like, even when servo sounds cannot be heard. CONSTITUTION:A detector for detecting the oscillation of a servo drive is provided with a smoothing circuit 15 for smoothing a current instruction value to be fed to a servo motor 1 that is driven by a servo driver whose gain is adjustable; and an indicator 13 that displays an oscillating state of the servo driver on the basis of a smoothed value obtained from this smoothing circuit 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting the oscillation state of a servo driver.

[0002]

2. Description of the Related Art Generally, a switching system is used for a servo driver. Hitherto, bipolar transistors have been used for driver switching, that is, for power output stages. Therefore, the switching frequency is generally 4 to 5 kHz. This switching frequency is just within a range that can be heard by the human ear in a stimulating manner, and is called a servo sound, which is an offensive sound.

In recent years, power devices (power FET, IGB
Since the switching characteristics have improved due to the development of T = insulated gate bipolar transistor), it has become possible to raise the switching frequency, and it has become possible to make it above the audible range of 20 kHz or higher.

Here, the structure and operation of a servo driver for a general AC servo motor will be described with reference to FIG. 5. In FIG. 5, reference numeral 1 is an AC servo motor, and 2 is a speed amplifier for receiving and amplifying a speed command signal. A speed feedback signal is input to the speed amplifier 2, and the difference between the speed feedback signal and the speed command signal is output from the speed amplifier 2 as a current command signal.

The current command signal from the speed amplifier is sent to U by the commutation circuit 3 according to the angle information of the AC servomotor 1.
Phase, V phase, W phase current values are converted into current amplifiers 4u, 4v, 4w and power elements 5u, 5v, 5 respectively.
It is applied to the AC servomotor 1 via w. The output currents of the power elements 5u, 5v, 5w are detected by the current sensors 6u, 6v, 6w, respectively, and the detection results are fed back to the current amplifiers 4u, 4v, 4w.

In the apparatus shown in FIG. 5, the resolver 7 performs speed detection and angle detection (commit sensor) of the AC servomotor 1. The excitation phase of the resolver 7 is excited by the excitation circuit 8, and the detection signal obtained from the detection phase of the resolver 7 is processed by the detection circuit 9 and R
It is output to the / D converter 10. And the R / D converter 1
0 converts the signal from the detection circuit 9 into a pulse train indicating the angle information and speed of the AC servomotor 1, outputs the angle information to the commutation circuit 3, and outputs the pulse train to the F / V converter 11. . Further, the F / V converter 11 converts the frequency of the pulse train into speed information of the AC servomotor 1, that is, a speed feedback signal, and outputs it to the speed amplifier 2.

[0007]

In the servo driver as described above, by using power elements 5u, 5v, 5w having good switching characteristics, it is possible to eliminate annoying servo sound, but the operator , By audibly distinguishing the servo sound, the oscillation state of the servo driver was immediately judged aurally. Therefore, if the servo sound cannot be heard, the oscillation state cannot be judged unless the motor current value is viewed with an oscilloscope. Came.

The present invention is intended to solve such a problem, and is an apparatus for easily and surely confirming the oscillation state of a servo driver without using an oscilloscope or the like even if the servo sound cannot be heard. The purpose is to provide.

[0009]

In order to achieve the above object, an oscillation detecting device for a servo driver according to the present invention (claim 1).
Is a smoothing circuit that smoothes a current value flowing through a servo motor driven by a gain adjustable servo driver or a current command value to the servo motor, and the servo driver based on the smoothed value obtained by the smoothing circuit. Is provided with a display means capable of displaying the oscillation state.

Further, the apparatus further comprises comparison means for comparing the smoothed value with a predetermined threshold value, and when the comparison means detects that the smoothed value exceeds the predetermined threshold value, the display means causes the servo driver to You may comprise so that it may display that it is an oscillation state (Claim 2).

[0011]

In the oscillation detecting device for a servo driver according to the present invention described above, small ripples are on the current value or the current command value in the normal state, whereas they are on the current command value in the case of oscillation. The ripple is increased, and when the oscillation further progresses and becomes the oscillation state, the waveform with almost only ripple is used.The smoothing circuit smooths the current value flowing through the servo motor or the current command value to the servo motor. The value is obtained, and the oscillation state of the servo driver is displayed by the display means based on the smoothed value. At this time, when the comparison unit detects that the smoothed value from the smoothing circuit exceeds the predetermined threshold value, the display unit displays that the servo driver is in the oscillation state.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 (a) and 1 (b) show an oscillation detecting device for a servo driver as a first embodiment of the present invention.
1A is a block diagram showing the detailed configuration thereof, and FIG. 1B is a block diagram showing the overall configuration of a servo driver to which the device of this embodiment is applied. As shown in FIG. 1 (b), the servo driver to which the device of this embodiment is applied is also configured in the same manner as that shown in FIG. 5, and the same reference numerals as those used above denote the same parts. Since it is shown, its description is omitted.

In this embodiment, as shown in FIG. 1B, a general servo driver is provided with an oscillation detection circuit 12 and an indicator (display means) 13 such as an indicator lamp. As shown in FIG. 1A, the oscillation detection circuit 12 of this embodiment smoothes the current command value after rectification by the rectifier circuit 14 that rectifies the current command value from the speed amplifier 2. Smoothing circuit 15 and a comparator (comparing means) 16 for comparing the smoothed value of the current command value from the smoothing circuit 15 with the reference value (predetermined threshold value) set by the reference value setting device 17. .

When the comparator 16 determines and detects that the smoothed value exceeds the reference value, the display 13 is switched from the extinguished state to the lit state or from the lit state to the extinguished state, and the servo is turned on. The display indicates that the driver is in an oscillating state.

In the first embodiment of the present invention, in the normal state, as shown in FIG. 2 (a), small ripples are present on the current command value from the speed amplifier 2, but they are oscillated. In this case, as shown in FIG. 2 (b), the fact that the ripple on the current command value increases and the oscillation further progresses and becomes an oscillating state results in a waveform with almost only ripple.

That is, the ripple on the current command value is detected to detect the oscillation state of the servo driver. If the smoothing value of the current command value obtained by the smoothing circuit 15 becomes large, the servo driver In this embodiment, when the comparator 16 detects that the smoothed value of the current command value from the speed amplifier 2 exceeds the reference value, the servo is displayed on the display unit 13. A message indicating that the driver is oscillating is displayed.

Therefore, since the comparator 16 automatically determines whether or not the servo driver is in the oscillation state based on the reference value set by the reference value setting device 17, the operator uses an oscilloscope or the like. Without
The oscillation state of the servo driver can be judged and confirmed very easily only by confirming the display state of the display unit 13.

FIG. 3 is a block diagram showing the detailed construction of a servo driver oscillation detecting apparatus as a second embodiment of the present invention. The apparatus of the second embodiment has substantially the same construction as the apparatus of the first embodiment. However, as shown in FIG. 3, in the oscillation detection circuit 12A of the present embodiment, the low cut filter 18 is provided in the preceding stage of the rectification circuit 14.

As a result, the same effect as the first embodiment can be obtained, and in the second embodiment, the oscillation state of the servo driver can be grasped more accurately. In addition,
Oscillation occurs at a few tens of Hz or higher
There is a frequency difference from the current fluctuation of about 0 Hz, and in order to use this, the frequency of the low-cut filter 18 is 20 to
30 Hz is generally suitable.

FIG. 4 is a block diagram showing the detailed construction of a servo driver oscillation detecting apparatus as a third embodiment of the present invention. The apparatus of the third embodiment has substantially the same construction as the apparatus of the second embodiment. However, as shown in FIG. 4, in the oscillation detection circuit 12B of the present embodiment, the comparator 16 and the gold dependent value setter 17 in the oscillation detection circuit 12A of the second embodiment are omitted, and the smoothing circuit 15 is used. The obtained smoothed value is directly analog-displayed on the meter 13A as a display means.

With the above-mentioned configuration, also in the apparatus of the second embodiment, by referring to the display value of the smoothed value on the meter 13A, the same effect as that of the first embodiment can be obtained, and the oscillation of the servo driver is obtained. Since the status can be displayed in analog, it is possible to detect the oscillation status in more detail, and it can be used as an inspection device in addition to the built-in servo driver.

In the above embodiment, the smoothing circuit 15 obtains the smoothed value for the current command value from the speed amplifier 2. However, the current value flowing through the servo motor 1 (outputs of the current sensors 6u, 6v, 6w) is obtained. ) May be obtained as a smoothed value.

[0023]

As described in detail above, according to the oscillation detecting device for a servo driver of the present invention, the current value flowing through the servo motor smoothed by the smoothing circuit or the smoothed value of the current command value to the servo motor is obtained. Since the oscillation state of the servo driver is configured to be displayed on the display means based on the above, the operator can easily and securely check the oscillation state of the servo driver by checking the display on the display means without using an oscilloscope or the like. There is an effect that can be confirmed.

Further, when the comparison means detects that the smoothed value exceeds the predetermined threshold value, the display means displays the fact that the servo driver is in an oscillating state, so that the servo driver oscillates. Since it is automatically determined whether or not the state has been displayed, the operator can very easily determine the oscillation state of the servo driver only by confirming the display state of the display means.

[Brief description of drawings]

FIG. 1 shows an oscillation detecting device for a servo driver according to a first embodiment of the present invention, (a) is a block diagram showing the detailed configuration thereof, and (b) is a servo to which the device of the present embodiment is applied. It is a block diagram which shows the whole structure of a driver.

FIG. 2A is a graph showing a current command value when the servo driver is in a normal state, and FIG. 2B is a graph showing a current command value when the servo driver is oscillating.

FIG. 3 is a block diagram showing a detailed configuration of a servo driver oscillation detecting apparatus as a second embodiment of the present invention.

FIG. 4 is a block diagram showing a detailed configuration of an oscillation detection device for a servo driver as a third embodiment of the present invention.

FIG. 5 is a block diagram showing an overall configuration of a servo driver of a general AC servo motor.

[Explanation of symbols]

 1 AC servo motor 2 Speed amplifier 3 Commutation circuit 4u, 4v, 4w Current amplifier 5u, 5v, 5w Power element 6u, 6v, 6w Current sensor 7 Resolver 8 Excitation circuit 9 Detection circuit 10 R / D converter 11 F / V Converter 12, 12A, 12B Oscillation detection circuit 13 Display (display means) 13A Meter (display means) 14 Rectifier circuit 15 Smoothing circuit 16 Comparator (comparison means) 17 Reference value setter 18 Low-cut filter

Claims (2)

[Claims] 1. A smoothing circuit for smoothing a current value flowing through a servo motor driven by a gain adjustable servo driver or a current command value for the servo motor, and a smoothing value obtained by the smoothing circuit. An oscillation detecting device for a servo driver, comprising: a display unit capable of displaying an oscillation state of the servo driver. 2. A comparison means for comparing the smoothed value with a predetermined threshold value is provided, and when the comparison means detects that the smoothed value exceeds the predetermined threshold value, the display means has the servo driver. An oscillation detecting device for a servo driver, which displays that the is in an oscillating state.