JP2007288829A - Method and device for detecting abnormality of machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect failure or impairment of a machine, based on the combination of abnormal current and abnormal frequency set as parameters, in matching with the machine to be used. <P>SOLUTION: The abnormality detector comprises an inverter for driving a motor 2 connected to a machine, a motor control section 5 for controlling an inverter main circuit 3 provided in the inverter, and a section 6 for detecting abnormality of the machine, and outputs an abnormality signal upon occurrence of abnormality, such as failure or impairment of the machine. The abnormality detecting section comprises a frequency detector 10, provided in the inverter and detecting the output frequency of a motor, a current detector 13 of the motor, an abnormal frequency setter 9 for presetting the abnormal frequency of the motor, an abnormal current setter 12 for presetting the abnormal current, and comparators 11 and 14 for comparing the values of two setters, respectively, with the values of the output frequency and of the current during operation. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a machine failure / machine deterioration detection method for an inverter used by being attached to a machine.

Conventionally, a method for detecting motor overload by comparing a value of a disturbance torque observer with a threshold value has been proposed as a method for detecting motor overload (see, for example, Patent Document 1).
This inverter mechanical failure detection method relies on an external input signal and does not detect the inverter itself. FIG. 3 is a block diagram showing a conventional mechanical failure detection method.
In FIG. 3, 112, 113, 114, Te, and ω are modeled and shown operations of the motor and the machine in consideration of the disturbance torque of the command current value Ia given to the motor. Reference numerals 115, 116, 117, 118, and <Te> denote disturbance torque observers, which output disturbance torque estimated values. With this value, the command current value Ia is manipulated to obtain a motor angular velocity ω that is less affected by disturbance torque. It is determined whether or not the disturbance torque observer value <Te> is equal to or greater than a threshold value. If the value is greater than or equal to the threshold value, it is determined that the motor is overloaded.
Thus, in the conventional overload detection method, a method of detecting a mechanical failure using the value of the disturbance torque observer has been adopted.
As another conventional example, there is one in which an abnormal signal on the machine side is input to an inverter. FIG. 4 is a configuration diagram showing a conventional external abnormality detection method for an inverter. In FIG. 4, the abnormality signal 123 output from the machine 120 is input to the external abnormality terminal 121 of the inverter and output to the abnormality output terminal 122. At the same time, the external abnormality terminal 121 is input to the motor control unit 5 as the motor stop signal 8 to stop the motor 2.
JP 2001-333589 A (first page, FIG. 3)

However, in the conventional mechanical failure detection method, it is determined whether or not the value of the disturbance torque observer is above a certain threshold, and if it is above the threshold, it is determined to be abnormal. Depends on. The disturbance torque observer has several parameters, and each setting accuracy directly affects the detection accuracy of the disturbance torque observer. Therefore, in order to increase the accuracy of abnormality determination, high-precision parameter setting is required. Since the observer simulates the state by calculation, there is a problem that if the parameter setting is not correct, the calculation result is inconsistent with the actual condition and the reliability of the abnormality determination is lowered.
Further, when the inverter itself does not detect it by relying on the input signal from the outside, it depends on the detection on the mechanical system side. For this reason, there is a problem that an abnormality detection error of the entire system is caused by inputting the detection error of the mechanical system as it is to the inverter.
The present invention has been made in view of such problems, and the inverter itself can detect a failure or deterioration of the mechanical system by simply setting two parameters according to the mechanical system. An object of the present invention is to provide a highly accurate abnormality detection method and apparatus free from mechanical system detection errors.

In order to solve the above problem, the present invention is as follows.
According to a first aspect of the present invention, in the method for detecting an abnormality of a machine connected to a motor driven by an inverter, conditions for the output frequency and motor current of the motor are set in advance, and the output frequency and motor during operation are set. When the current value satisfies the two set conditions, it is determined that the machine is abnormal and an abnormality signal is output.
The invention according to claim 2 includes an inverter that drives a motor connected to a machine, a motor control unit that controls an inverter main circuit provided in the inverter, and an abnormality detection unit that detects an abnormality of the machine. In the abnormality detection device for a machine that outputs an abnormality signal when an abnormality such as failure or deterioration occurs in the machine, the abnormality detection unit is provided in the inverter and detects the output frequency of the motor. A current detector for detecting the current of the motor, an abnormal frequency setter for presetting the frequency of the motor, an abnormal current setter for presetting the value of the abnormal current, and the values of the two setters And a comparator for comparing the two values during operation.
According to a third aspect of the present invention, in the method for detecting an abnormality of a machine connected to a motor driven by an inverter, conditions for the rotational speed and motor current of the motor are set in advance, and the rotational speed and motor during operation are set. When the current value satisfies the two set conditions, it is determined that the machine is abnormal, and an abnormal signal is output.
The invention according to claim 4 includes an inverter that drives a motor connected to a machine, a motor control unit that controls an inverter main circuit provided in the inverter, and an abnormality detection unit that detects an abnormality of the machine. In the abnormality detection device for a machine that outputs an abnormality signal when an abnormality such as failure or deterioration occurs in the machine, the abnormality detection unit is provided in the inverter and detects the rotational speed of the motor. A current detector for detecting the current of the motor, an abnormal speed setter for presetting the speed of the motor, an abnormal current setter for presetting the value of the abnormal current, and the values of the two setters It comprises a comparator that compares the two values during operation.

According to the first and second aspects of the present invention, since the abnormality can be detected by setting the motor output frequency and the motor current condition in advance by the inverter, the operation of the mechanical system can be performed with simple operation and setting compared to the detection by the observer. The detection error is eliminated, and the accuracy of the entire system can be improved, such as stopping the motor and outputting abnormality information.
According to the third and fourth aspects of the present invention, it is possible to detect an abnormality corresponding to the actual operation of the machine more simply by detecting the motor speed by previously setting the conditions of the motor rotation speed and the motor current with the inverter. Therefore, abnormality detection suitable for the mechanical system can be performed, and abnormality detection accuracy of the entire system can be further improved.

  Hereinafter, specific examples of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of the present invention, and shows a configuration in which an abnormality in a machine is detected by a motor output frequency and a motor current by an inverter.
In the figure, 1 is a three-phase power source, 2 is a three-phase motor, 3 is an inverter main circuit, 4 is an inverter control circuit, 5 is a motor control unit, 6 is an abnormality detection unit, 7 is an abnormal signal detected, and 8 is A motor stop signal, 9 is an abnormal frequency setting device, 10 is a frequency detector, 11 and 14 are comparators, 12 is an abnormal current setting device, and 13 is a current detector.
The inverter main circuit 3 is connected to a three-phase power source 1 and a three-phase motor 2. The inverter main circuit 3 is connected to an inverter control circuit 4 that controls on / off of an internal switching element (not shown). A CT for detecting a drive current flowing through the motor 2 is connected between the inverter main circuit 3 and the motor 2. The motor 2 is used by being mounted on various machines, but abnormal conditions of the machine are different depending on the machine.
Next, the operation of this embodiment will be described.
(1) First, the output frequency of the motor 2 and the value of the motor current are set.
The abnormality of the machine that can be detected by the inverter can be determined by the condition of the output frequency and the motor current. Set as an inverter parameter.
For example, in accordance with the operation of the machine 120, the rotation speed value sets a lower limit, and the torque value sets an upper limit.
(2) The motor 2 is driven.
(3) Normal When the machine 120 is in a normal state, the motor current and output frequency are input to the current detector 13 and the frequency detector 10 of the abnormality detection unit 6 in the inverter control circuit 4 via CT. If the value of the detector is within the set value, the comparators 11 and 14 do not operate, so the abnormal signal 7 is not output.
(4) At the time of abnormality When the machine 120 is in an abnormal state such as a failure or machine deterioration, when the combination of the output frequency and the motor current value is outside the set value, the comparator 11 and the comparator 14 operate to output the abnormal signal 7. To do.
The abnormality detector 6 compares the output frequency of the motor detected by the frequency detector 10 with the abnormal frequency setter 9 by the comparator 11 and outputs a logic signal (logic value) 16. Similarly, the motor current value detected by the current detector 13 and the value set by the abnormal current setter 12 are compared by the comparator 14 and a logical value 17 is output. The logical operation unit (logical product) 15 outputs an abnormal signal 7 in response to the input of both the logical value 16 and the logical value 17 to notify the outside of the inverter.
(5) Motor stop When the machine 120 is in a normal state, the operation is continued, but in an abnormal state such as a failure or machine deterioration, the abnormal signal 7 is input to the motor control unit 5 as the motor stop signal 8 and the inverter main circuit The switching element 3 (not shown) is turned off to stop the rotation of the motor.

FIG. 2 is a block diagram showing a second embodiment of the present invention, and shows a configuration in which an abnormality of the machine is detected by an inverter capable of detecting the motor rotation speed and current.
The operation of the present embodiment is substantially the same as that of the first embodiment except that the motor speed is detected by the speed detector.
In this case, a machine failure or machine deterioration can be detected by setting a combination of an abnormal current and an abnormal speed by an operator or the like in accordance with the machine on which the three-phase motor is mounted.
For example, in hoisting and unwinding applications such as elevators and cranes, the abnormal speed set value and the abnormal current set value are set to larger values than usual in order to detect load dropout. By doing so, the inverter itself can detect a machine abnormality and notify the outside of the inverter. If the inverter has a built-in brake opening / closing function, the inverter itself can close the brake.
Moreover, although it is normally operated at a constant speed in the conveyor application, there may be a case where the conveyor becomes slower than expected or stops due to a load abnormality or the like. In order to detect this state, the set value of the abnormal speed is set to a value smaller than the normal speed, and the set value of the abnormal current is set to a value larger than the normal load. By doing so, it is possible to detect and stop the abnormality of the conveyor by the inverter itself.

1 is a configuration diagram of a machine abnormality detection apparatus using an inverter according to Embodiment 1 of the present invention. The block diagram of the abnormality detection apparatus of the machine using the speed detector by the inverter which shows Example 2 of this invention Configuration diagram showing a conventional mechanical failure detection method Configuration diagram showing a conventional inverter external abnormality detection method

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power supply 2 Motor 3 Inverter main circuit 4 Inverter control circuit 5 Motor control part 6 Abnormality detection part 7 Abnormal signal 8 Motor stop signal 9 Abnormal frequency setting device 10 Frequency detector 11, 14 Comparator 12 Abnormal current setting device 13 Current detector 15 Logical operation unit (logical product)
16, 17 Logic signal (logical value)
18 Abnormal speed setter 19 Speed detector 112, 117 Proportional operation unit 113 Addition unit 114 Integration operation unit 115 Differentiation operation unit 116 Addition unit 118 Low pass filter 120 Machine 121 Inverter external abnormality terminal 122 Abnormal output terminal 123 Abnormal signal from machine
<Te> Disturbance torque observer
Te Disturbance torque ω Motor angular velocity
Ia Command current value

Claims (4)

In a method for detecting an abnormality in a machine connected to a motor driven by an inverter,
The conditions of the motor output frequency and motor current are set in advance, and when the output frequency and motor current values during operation satisfy the two set conditions, it is determined that the machine is abnormal and an abnormal signal is output. An abnormality detection method for a machine characterized by the above. An inverter that drives a motor connected to a machine, a motor control unit that controls an inverter main circuit provided in the inverter, and an abnormality detection unit that detects an abnormality of the machine. In an abnormality detection device for a machine that outputs an abnormality signal when an abnormality occurs,
The abnormality detection unit is provided in the inverter, and detects a frequency detector that detects the output frequency of the motor, a current detector that detects the current of the motor, and an abnormal frequency setting device that presets the frequency of the motor. And an abnormal current setter for presetting the value of the abnormal current, and a comparator for comparing the values of the two setters with the two values during operation, respectively. apparatus. In a method for detecting an abnormality in a machine connected to a motor driven by an inverter,
The motor speed and motor current conditions are set in advance, and when the rotational speed and motor current values during operation satisfy the two set conditions, it is determined that the machine is abnormal and an abnormal signal is output. A machine abnormality detection method characterized by the above. An inverter that drives a motor connected to a machine, a motor control unit that controls an inverter main circuit provided in the inverter, and an abnormality detection unit that detects an abnormality of the machine. In an abnormality detection device for a machine that outputs an abnormality signal when an abnormality occurs,
The abnormality detection unit is provided in the inverter and detects a rotation speed of the motor, a current detector that detects the current of the motor, and an abnormal speed setting device that presets the speed of the motor. And an abnormal current setter for presetting the value of the abnormal current, and a comparator for comparing the values of the two setters and the two values at the time of operation, respectively. .

Images