JPS6220771B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an operating state monitoring device suitable for multiple motors, particularly hysteresis motors driven by high frequency power sources.

Conventionally, the following methods have been used to achieve this purpose.

FIG. 1 shows a conventional example. In FIG. 1, 1 is a high frequency power source 2 is a power factor correction filter, 3 is a detector for detecting the average vector of current flowing through multiple motors such as hysteresis motors, and 4-1 to 4-n.
is a detector of the current vector flowing through each motor, 5-
1 to 5-n are electric motors to be monitored, and have characteristics shown in FIG. That is, when the power is turned on, the current vector flowing through each motor 5-1 to 5-n is I〓s, and during acceleration, the current vector I〓k follows the vector locus shown in [ ] until reaching the rated speed. When the motor moves in the direction of the arrow in the figure and reaches the rated speed, the current vector flowing through the motor becomes Ir.

At this time, when the signals obtained from the detectors 3 and 4-1 in FIG. 1 are input to the addition amplification circuit [A] shown in FIG. 3, the output of the addition amplification circuit [A] is The value is proportional to the difference between the average vector of the current flowing through the motors 5-n and 5-n and the current vector flowing through the motor 5-1. In other words, the operating state of the electric motor 5-1,
Differences in the average operating conditions of a large number of motors including the motor 5-1 can be known from the difference in voltage. That is, if the output voltage of the addition/amplification circuit A in FIG. FIG. 4 shows an example of the output of the addition/amplification circuit A shown in FIG. 3.

In Figure 4, [ ] is the characteristic when a certain motor goes out of step and the rotation speed decreases from a state in which all motors are rotating at the rated speed, and the horizontal axis shows the rotation speed of the motor that is out of step. . [ ] is the characteristic when one electric motor fails to start (rotation speed 0) and other electric motors are normally accelerated during startup/acceleration, and the horizontal axis is the average rotation speed of the normal motor in this case. shows. At this time, as shown in Figure 3,
When a discrimination circuit C is provided at the output of the addition/amplification circuit A and the operating status is determined based on the magnitude of the output from the voltage _V1 shown in Figure 4, Although step-out can be detected early (when the rotational speed is N2 or less), it has the disadvantage that it cannot be detected until a considerable amount of time has passed after startup (it cannot be detected until the other motors reach N1). Ta.

Further, when the discrimination voltage is set to _V2 , early discrimination is possible at startup, but there is a drawback that the detection operation becomes sensitive when all the units are operating at the rated rotation speed.

The present invention has been made in view of the above circumstances, and provides a monitoring device for multiple motors that can quickly identify motors that have stopped or failed to start at the time of startup, and that does not cause detection sensitivity to become too sensitive after all motors have reached their rated speed. The purpose is to obtain.

An embodiment of the present invention will be described below with reference to FIGS. 5 and 6.

The configuration shown in FIG. 5 is based on the configuration shown in FIG. 1, and in addition, when the motors 5-1 to 5-n are at rated rotation, a current that is the same as or proportional to the current vector (I〓r in FIG. 2) flowing through each motor is added to the configuration shown in FIG. A simulated load 6 adjusted to allow a current to flow therein and a detector 4d for detecting a current vector flowing through the simulated load 6 are added. The operation of each element will be explained below in order from the start of the multiple electric motors.

First, at startup, the discrimination level for a motor that has failed to start, that is, a stopped motor, is adjusted to V ₁ shown in Figure 8.Characteristic IV in Figure 8 is the current vector flowing to the stopped motor and the current flowing to each motor. Since the voltage value is generated by the difference from the average vector, when the average rotational speed of each motor reaches N1, startup failure can be confirmed by the output voltage of the addition amplification circuit A.

Next, in the process of accelerating all electric motors, the output Sd of the current vector detector 4-d flowing through the simulated load 6 and the average vector of the current flowing through the electric motors 5-1 to 5-n are detected. The output of the addition amplification circuit A shown in FIG. 6, which is generated due to the difference in the output Sa of the converter 3, has a characteristic V as shown in FIG. 7, and moves in the direction of the arrow as it is accelerated.

Therefore, the immediately before synchronization determination circuit B in FIG.
If the adjustment is made to detect that the output of the addition amplification circuit A is equal to or less than _VN , it can be determined that each electric motor has been accelerated to near its rated rotation speed.

When the immediate-synchronization determination circuit B determines that the rotation speed of each motor is close to the rated speed, the determination level of the abnormality determination circuit C in FIG. 6 is changed from V ₁ to V ₂ .
Change to Based on this change, after each electric motor reaches its rated rotational speed, a reduction in rotational speed due to step-out is determined by comparing the outputs of the addition amplification circuits A ₁ to An with V ₂ . From Figure 8, the output of each addition amplification circuit is greater than V ₂ because the rotational speed of the motor is
This is the case when the voltage is below N2, and if the discrimination voltage is not switched, an abnormal signal will be generated due to a slight deviation in the rotation speed, but it is possible to achieve more stable operation.

As described above, according to the present invention, the following effects can be obtained.

(1) Motors that fail to start can be detected early.

(2) After each motor reaches its rated rotational speed, the sensitivity for determining the out-of-control motor can be set to an appropriate level without being too sensitive.

(3) In the multi-motor operation system described in the present invention, the power supply capacity required for rated operation is smaller than the power supply capacity required for startup and acceleration, so a power supply device for normal rated operation and a power supply for startup are required. - A method is used in which the acceleration power supply is separated, the startup/acceleration power supply is used for acceleration, and the rated rotational speed is reached before connecting to the rated operation power supply.
In this case, it is necessary to detect that the accelerating motor has reached its rated rotation speed, but in the present invention,
Since the acceleration state of all electric motors is monitored, it is also possible to issue a power supply switching signal in the same way as discrimination level switching.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a configuration example of a conventional motor monitoring device, Fig. 2 is a vector diagram showing the current characteristics of the motor, Fig. 3 is a detection circuit diagram, and Fig. 4 is a block diagram showing a configuration example of a conventional motor monitoring device.
5 is a block diagram showing the configuration of the present invention. FIG. 6 is a block diagram showing the functions of the present invention. FIG. 7 is a waveform diagram showing the output of the adding amplification circuit in FIG. FIG. 8 is a waveform diagram showing the output of the width circuit A. FIG. 8 is a waveform diagram showing the output of the addition amplification circuits A ₁ to An of FIG. 1...Power supply device, 2...Power factor improvement filter,
3...Detector for detecting the average vector, 4-1~
4-n...Detector for detecting the current vector flowing in each motor, 4-d...Detector for detecting the current vector flowing in the simulated load, 5-1 to 5-n...Motor, 6...Simulation Pseudo loads are A: addition amplification circuit, B: immediately before synchronization judgment circuit, and C: abnormality judgment circuit.

Claims (1)

[Claims] 1 A first detector detects the average vector of current flowing through multiple motors to be monitored, a second detector detects the current vector flowing through each individual motor, and each motor is synchronized with the power supply. A simulated load that is adjusted so that a current equal to or proportional to the current vector flowing during rotation flows and is connected to the same power source is provided, and the current vector flowing through the simulated load is detected. When starting or accelerating a large number of motors that have three detectors, the average vector of each motor detected by the first detector, and the vector flowing to each individual motor detected by the second detector. When the difference exceeds a certain value, it is determined that the motor has failed to start, and during acceleration, the average vector of each motor detected by the first detector and the average vector of each motor detected by the third detector are compared. The vectors of the currents flowing through the detected simulated loads are constantly compared, and when the difference is less than a certain value, it is determined that the multiple motors are approaching the rated rotation speed, and the multiple motors are rotated until the rotation speed approaches the rated speed. After acceleration, the average vector of each motor detected by the first detector is compared with the vector flowing to each individual motor detected by the second detector, and the difference exceeds a certain value. The present invention is characterized in that the motor is determined to be out of synchronization, but the determination level is switched after it is determined that the number of rotations of the multiple motors approaches the rated rotation speed. Monitoring device for multiple electric motors.