JPH02164295A - Controller for motor - Google Patents

Abstract

PURPOSE:To early discover the irregularity of the operating state of an AC motor by comparing the output signal of a rotating speed detector which is input through a P/I converter with an ACC signal output from a drive signal setter by an output detector, and operating, if there is an irregularity, the indicator. CONSTITUTION:The rotating speed of an AC motor 5 is detected by a rotating speed detector 13, input to an output detector 10 through a P/I converter 14, and an ACC signal is also input to the output detector 10. The output detector 10 compares the two signals to detect the difference therebetween. That is, a variable voltage variable frequency power source 7 inputs an output responsive to the ACC signal output from a drive signal setter 8 to the AC motor 5, and determines whether the AC motor 5 is operated at a normal rotating speed or not. If the difference between the ACC signal and the output signal of the P/I converter 14 falls within an irregularity range set by an irregularity range setter 11, an alarm is generated by the indicator 12.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a motor control device for controlling the drive of an AC motor using a variable voltage variable frequency power supply device.

[Prior Art] Fig. 2 is a block connection diagram showing a conventional electric motor control device. 3 is an input transformer, 4 is an output transformer, 5 is an AC motor to be controlled, 6 is an output detection transformer, and 7 is a variable voltage variable frequency power source. device (hereinafter abbreviated as VVVF), 8 is a setting drive signal such as a speed command signal for the AC motor 5 (hereinafter abbreviated as ACC signal)
This is a drive signal setting device that outputs a signal to the VVVF 7, and in this embodiment, outputs an automatic speed setting signal.

Next, the operation will be explained. First, when the input switch 1 is closed, the AC power of the system is supplied to the vV■F7 via the input transformer 3. Next, A for instructing the rotation speed of the AC motor 5 to a predetermined setting value from the drive signal setting device 8.
A CC signal is given to VVVF7. This VVVF7 outputs a voltage of a frequency corresponding to the ACC signal to the transformer 4.
and is input to the AC motor 5 via the output side switch 2. Therefore, the AC motor 5 is controlled to be driven at the specified rotation speed. Here, the drive signal setting device 8 also outputs A
The CC signal is output regardless of the output state of the VVVF 7, that is, the rotational speed of the AC motor 5 that is actually operating. Further, the output voltage of the output transformer 4 is determined by the output detection transformer 6.
For example, this VVVF7
It acts to stabilize the drift of the motor characteristics.

[Problems to be Solved by the Invention] Since the conventional motor control device is configured as described above, the VVVF 7 is connected to the AC output from the drive signal setting device 8.
Despite outputting a voltage commensurate with the C signal, it is not possible to determine whether or not the AC motor 5 is operating at a rotation speed that follows the ACC signal, resulting in problems such as the AC motor 5 being operated in an unchecked state. Ta.

As approximation techniques, there are techniques described in Utility Model Application Publication No. 59-44200 and Utility Model Application Publication No. 62-51993.

This invention was made in order to solve the above-mentioned problems, and it is possible to detect whether or not the rotation speed of the AC motor 5 is operating according to the set drive signal from the drive signal setting device 8. It is an object of the present invention to provide a motor control device that allows an operator or the like to immediately recognize an abnormality.

[Means for Solving the Problems] A motor control device according to the present invention outputs an output signal of a rotation speed detector inputted via a P/I converter and an ACC signal outputted from a drive signal setting device. If a detector detects an abnormality, an alarm or indicator is activated, and it is possible to monitor whether the AC motor is always being operated at a rotation speed corresponding to the ACC signal.

[Operation] The output detector in this invention compares the rotational speed of the AC motor with the ACC signal set by the drive signal setting device, and only when there is a difference as a result of the comparison, the output to the AC motor is abnormal. It is determined that this is the case, and an alarm or indicator is activated as necessary.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, the same parts as in FIG. 2 are denoted by the same reference numerals. In FIG.
This output detector 10 compares the ACC signal output from A with VVVF7 as the set drive signal.
An output corresponding to the CC signal is input to the AC motor 5, and it is determined whether or not it is being operated at a normal rotation speed.

Reference numeral 11 denotes an abnormal region setting device for determining whether the difference between the two signals obtained by the output detector 10 is outside a set value.

The output detector 10 is also connected to an alarm or indicator 12 that is activated when the difference between the two signals falls within the abnormal region set by the abnormal region setting device 11.

Next, the operation will be explained. First, when the input switch is closed, the AC power of the grid is changed to VVV through the input transformer 3.
Supplied to F7. Here, the ACC signal from the drive signal setter 8 that instructs the rotation speed of the AC motor 5 to the set value is VV.
When applied to VF7, VVVF7 inputs a voltage of a frequency corresponding to this ACC signal to AC motor 5 via output transformer 4 and output side switch 2. Therefore, the AC motor 5 is controlled to be driven at the specified rotation speed.

On the other hand, the rotational speed of the AC motor 5 is detected by a rotational speed detector 13, and then passed through a P/I converter 14 to an output detector l.
The ACC signal is also input to this output detector 1.
It is input to 0. The output detector 10 compares the two signals and detects the difference. That is, the VVVF 7 inputs an output corresponding to the ACC signal output from the drive signal setting device 8 to the AC motor 5, and determines whether or not the AC motor 5 is operating at a normal rotation speed. And the above AC
If there is a difference between the C signal and the output signal of the P/I converter 14, or if the difference falls within the abnormal area set by the abnormal area setting device 11, an alarm or indicator 12 will notify you. Provides warnings such as flashing lamps and buzzers.

Therefore, the operator can immediately recognize this display and take necessary countermeasures.

In the above embodiment, an example was explained in which the output detector 10 was provided outside the VVVF7, but as shown in the figure, the output detector 10 was provided outside the VVVF7.
F7 has a circuit configuration so as to take in both the ACC signal and the output signal of VVVF7, so by taking in the signals of the rotation speed detector 13 and P/I converter 14 into this VVVFT, the above embodiment can be achieved. It has a similar effect.

[Effects of the Invention] As described above, according to the present invention, the difference between the rotational speed of the AC motor and the ACC signal with respect to the output of the VVVF is constantly monitored by the output detector, so that abnormal output of the VVVF or other It becomes possible to detect an abnormal operating state of the AC motor at an early stage. Furthermore, since immediate measures can be taken in the event of an abnormality, the reliability of motor control can be greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a block connection diagram of a motor control device according to an embodiment of the present invention, and FIG. 2 is a block connection diagram of a conventional motor control device. In the figure, 5 is an AC motor, 7 is a variable voltage variable frequency power supply (V
VVF), 8 is a drive signal setting device, 10 is an output detector, 1
1 is an abnormal area setting device, 12 is an alarm or display device, 13 is a rotation speed detector, 14 is a P/ (two other people) +4: P/L change limiter

Claims (1)

[Scope of claims] In a motor control device that controls the operation of an AC motor by inputting a set drive signal output from a drive signal setting device to a variable voltage variable frequency power supply device, a rotation speed for detecting the rotation speed of the AC motor. a detector; and an output detector that compares the set drive signal output from the drive signal setter and the output signal via the P/I converter of the rotation speed detector, the comparison by the output detector. A motor control device characterized in that when the resulting error falls within an abnormal region of an abnormal region setting device, the AC motor is determined to be abnormal and an alarm or indicator is activated as necessary.