JP2007014151A - Apparatus for diagnosing electric motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for diagnosing electric motor having a constitution simpler than conventional constitution and accurately diagnosing abnormalities. <P>SOLUTION: Phase currents are detected in an electric motor, and a current ratio is calculated between phases (ST1, ST2). The calculated current ratio between the phases is compared with reference K1. If the calculated current ratio is higher than the reference, it is determined that there is a layer shorted (ST4, ST5). A vibration sensor detects the vibration of a bearing in the electric motor, and a vibration spectrum is produced (ST5, ST6). If a level component at a predetermined frequency is higher than reference K2, it is determined that the bearing has been damaged (ST7, ST11). A temperature sensor detects the temperature of the electric motor: and if the detected temperature is higher than a reference temperature K3, it is determined that there is overheating (ST8, ST8, ST12). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electric motor diagnosis (system) device for diagnosing abnormality of an electric motor.

Conventionally, as a method for diagnosing an abnormality in an electric motor, in an induction motor that is in operation by receiving power supply from a three-phase AC power source, an input current of each phase of the induction motor and a specific harmonic component included in the input current A signal extraction means for detecting at least one of the signals; and a signal processing means for converting the output signal from the signal extraction means. The output processed by the signal processing means is an unbalance rate of the input current of the induction motor. , And a characteristic value of at least one of the harmonic components, and a method for diagnosing abnormality is proposed in which the cause and location of the abnormality of the induction motor can be identified by comparing this characteristic value with a predetermined criterion value. (For example, see Patent Document 1)
JP 2002-189064 A

  In the conventional motor abnormality diagnosis method described above, the environment is various in the actual motor installation location.For example, the harmonic component contained in the input current or output cannot be sufficiently extracted if the order is high, Further, even if extracted, it cannot be sufficiently determined whether it is from an electric motor or ambient noise, and as a result, there is a problem that an accurate abnormality diagnosis cannot be performed.

  The present invention has been made paying attention to the above-mentioned problems, and an object thereof is to provide an electric motor diagnosis apparatus capable of performing an abnormality diagnosis with a simpler configuration and higher accuracy than in the past.

  The motor diagnostic device of the present invention includes a plurality of phase current detectors that detect each phase current of a multiphase motor, and whether or not the current ratio between the phase currents detected by these phase current detectors is equal to or greater than a predetermined value. Based on the determination, the first diagnostic means for determining the presence or absence of the layer short, the vibration sensor provided in the bearing portion of the multiphase motor, and the order distribution of the vibration spectrum of the signal detected by the vibration sensor are obtained. And second diagnostic means for determining the presence or absence of bearing damage based on whether a level component at a predetermined frequency of the vibration spectrum is equal to or greater than a predetermined value.

  The vibration sensor used in the present invention includes, for example, a pickup rod whose one end abuts or approaches the bearing portion, a vibration plate provided at the other end of the pickup rod, an acoustic chamber for transmitting vibration sound of the vibration plate, A microphone composed of a microphone that converts sound in the acoustic room into an electrical signal is used.

  In the electric motor diagnosis apparatus of the present invention, a temperature sensor is further provided in or near the electric motor, and the temperature value detected by the temperature sensor or the degree of temperature rise is compared with a predetermined value, thereby heating the electric motor. Third diagnostic means for making a determination can be provided.

  According to the present invention, the first diagnostic means can not only determine the layer short-circuit, which is the most popular abnormality in the motor, but also detects the vibration signal generated in the bearing of the motor by the vibration sensor, and calculates the vibration spectrum of the signal. By detecting the degree of inclusion of the harmonic part, the wear of the bearing can be reliably determined. Furthermore, the temperature sensor can also determine overheating conditions caused by a comprehensive cause.

  In addition, a pickup rod whose one end is brought into contact with the bearing to the vibration sensor, a vibration plate provided at the other end of the pickup rod, an acoustic chamber for transmitting the vibration sound of the vibration plate, and the sound of the acoustic chamber are electrically If a microphone composed of a signal and a microphone is used, vibration noise outside the motor is not transmitted to the vibration sensor diaphragm, but only vibration from the motor bearing is detected. Therefore, it is possible to detect an abnormality only in the motor by detecting vibrations in the motor and from the bearing separately from external noise.

  Hereinafter, the present invention will be described in more detail with reference to embodiments. FIG. 1 is a block diagram showing a schematic configuration of an electric motor diagnosis (system) apparatus according to an embodiment of the present invention.

  This embodiment of the motor diagnostic device includes a CPU 1 that executes diagnostic data fetching and diagnostic processing, and an R-phase current detector 2R, an S-phase current detector 2S, and a T-phase that detect respective three-phase currents of the motor to be diagnosed. Current detector 2T, A / D converters 5R, 5S, and 5T that convert the signals of these phase current detectors 2R, 2S, and 2T into digital signals and input them to CPU 1, respectively, and a bearing portion of motor 30 to be diagnosed The vibration sensor 3X for detecting the X-axis vibration component of 30A, the vibration sensor 3Y for detecting the Y-axis vibration component of the bearing portion, and the detection signals of these vibration sensors 3X and 3Y are converted into digital signals and input to the CPU 1 The A / D converters 5X and 5Y, the temperature sensor 4 provided in or near the diagnosis motor 30, and the output of the temperature sensor 4 are converted into digital signals to the CPU 1. An A / D converter 5 to force the current spectrum storage section 6, and a vibration spectrum storage section 7, a display unit 8, a.

  The phase current detectors 2R, 2S, 2T, the vibration sensors 3X, 3Y, and the temperature sensor 4 are provided in the diagnosis motor 30. The CPU 1, the A / D converters 5, 5R,..., 5Y, the current spectrum storage unit 6, the vibration spectrum storage unit 7, and the display unit 8 constitute a diagnostic device body 20.

  For example, the vibration sensor 3X (3Y) shown in FIG. 3 is used. The vibration sensor 3X is provided with a case 10 composed of a lower case 10A and an upper case 10B, and a pickup that protrudes outward from the lower case 10A and has a tip abutting against the bearing 30A of the electric motor 30 during diagnosis. The rod 11, the diaphragm 12 to which the base end of the pickup rod 11 is connected in the case 10, the acoustic chamber 13 for transmitting the vibration of the diaphragm 12 in the case 10, and the acoustic chamber 13 are transmitted. The microphone 14 that converts the vibration from the vibrating plate 12 into an electrical signal, and a cord 15 for connecting the microphone 14 to the diagnostic apparatus main body 20 are provided.

  When the vibration sensor 3X is brought into contact with the bearing portion 30A, the vibration of the bearing portion 30A is transmitted from the pickup rod 11 to the diaphragm 12, and is transmitted to the microphone 14 through the acoustic chamber 13, and the vibration of the bearing portion 30A. Can be taken into the diagnostic apparatus main body 20. On the other hand, even if vibration occurs around the vibration sensor 3 </ b> X, the diaphragm 12 does not vibrate and is not taken into the diagnostic apparatus main body 20.

  In the electric motor diagnosis apparatus according to this embodiment, each phase current detected by the R-phase current detector 2R, the S-phase current detector 2S, and the T-phase current detector 2T is captured and stored in the current spectrum storage unit 6. The CPU 1 calculates the current ratio between the phases R—S, ST, T—R of each phase current, and if the current ratio between phases is larger than a preset value, it is determined that there is a layer short. It has a function to do.

  In the motor diagnostic apparatus of this embodiment, the vibration sensors 3X and 3Y capture the detected vibration signal in the X-axis direction of the bearing portion and the vibration signal in the Y-axis direction orthogonal to the X-axis, The frequency component is stored in the vibration spectrum storage unit 7 and has a function of determining that the bearing is damaged if a higher-order wave component of a predetermined order or more of the vibration spectrum 6 is larger than a preset value.

  Further, in this embodiment of the motor diagnostic device, the detection signal of the temperature sensor 4 is taken into the CPU 1, and a reference value for presetting the detected temperature, or a temperature rise degree corresponding to the passage of the operating time of the detected temperature, A function of determining abnormal overheating of the electric motor 30 by comparing with a preset reference temperature increase degree is provided.

  Next, referring to the flowchart shown in FIG. 2, the diagnosis processing operation of the motor diagnosis apparatus of this embodiment will be described. When this diagnostic processing routine is entered, first, in step ST1, the phase current detectors 2R, 2S, 2T detect the R-phase, S-phase, and T-phase currents of the motor 30 to be diagnosed and load them into the CPU 1. Each phase current is stored in the current spectrum storage unit 6. Next, the process proceeds to step ST2.

  In step ST2, an interphase current ratio is calculated. Here, each current ratio between the R phase-S phase, the S phase-T phase, and the T phase-R phase is calculated based on the detected phase currents. Subsequently, the process proceeds to step ST3. In step ST3, the calculated inter-phase current ratio is displayed on the display unit 8. Next, the process proceeds to step ST4.

  In step ST4, the calculated correlation current ratios between the R phase-S phase, S phase-T phase, T phase-R phase, and a reference value K1 (for example, K1 = 3) stored in the internal memory of the CPU 1 in advance. %). As a result of the comparison, if none of the correlation current ratios is larger than the reference value K1, it is determined that there is no abnormality such as a layer short, and the process proceeds to step ST5. On the other hand, if any one of the correlation current ratios is larger than the reference value K1, the process proceeds to step ST10. In step ST10, a display to the effect that the layer short has been determined is displayed on the display unit 8, and a warning is given to the operator that an abnormality has occurred. Next, the process proceeds to step ST5.

  In step ST5, the vibration sensor 3X and the vibration sensor 3Y detect the X component and the Y component of the vibration generated in the bearing portion 30A of the motor 30 to be diagnosed, and import them into the CPU 1. Next, the process proceeds to step ST6. In step ST6, a vibration spectrum is created from signals from the vibration sensors SX, 3Y and stored in the vibration spectrum storage unit 7. An example of the vibration spectrum is shown in FIG. (A) of FIG. 4 shows the level of the fundamental component of the detected vibration at 100%, and the horizontal axis indicates the order (frequency) from the fundamental to the secondary, tertiary,. ), And the level at each frequency is shown as a percentage with the fundamental wave as 100. Subsequently, the process proceeds to step ST7.

  In step ST7, it is determined whether or not a component (level) value of a frequency equal to or higher than a predetermined frequency (for example, a 10th-order frequency) is greater than a reference value K2. If the bearing 30A of the motor 30 to be diagnosed is not worn and is in a normal state, the vibration spectrum has almost no level component at the 10th and higher frequencies as illustrated in FIG. Much smaller than K2. Therefore, in this case, the process proceeds to step ST8 with a determination NO. However, when the wear of the bearing portion 30A is large, the vibration noise is abnormal as compared with the normal state, and the vibration spectrum in this case is the level of the 10th or higher frequency as illustrated in FIG. Contains a fairly large amount of ingredients. When the level component of the frequency of these higher-order waves is larger than the reference value K2, it is determined that an abnormality has occurred in the bearing portion 30A, and the process proceeds to step ST11.

  In step ST11, the display unit 8 displays that bearing damage has been determined. Next, the process proceeds to step ST8. In step ST8, the temperature inside the diagnosis motor 30 is detected by the temperature sensor 4, and the detected temperature is stored in the internal memory of the CPU 1. In step ST9, the detected temperature is compared with a reference temperature K3 stored in advance. If the detected temperature is equal to or lower than the reference temperature K3, it is determined that there is no abnormality and the process is terminated. On the other hand, when the detected temperature is higher than the reference temperature K3, the process proceeds to step ST12.

In step ST12, the display unit 8 displays that the overheat abnormality has been determined.
As a result, the operator is warned of overheating abnormality. This overheating determination may be made in conjunction with a layer short determination, a bearing damage determination, or other abnormality, and an early response to the occurrence of the abnormality is taken together with the above other determination conditions. I can do it.

  In the above embodiment, the overheat determination is performed by comparing the detected temperature with the reference temperature. Instead, how the temperature at the start of operation of the motor changes as the operation progresses is a temperature rise degree. May be stored in advance as a reference temperature rise degree, and the temperature rise degree of the detected temperature may be compared with the reference temperature rise degree to determine overheating.

  Further, in the above embodiment, the layer short determination, the bearing damage determination, and the overheat determination are sequentially performed in serial determination processing. However, these processing may be performed by simultaneous parallel processing or at predetermined intervals. Or may be independently processed as necessary.

1 is a block diagram showing a schematic configuration of an electric motor diagnosis apparatus according to an embodiment of the present invention. It is a flowchart for demonstrating the processing operation of the electric motor diagnostic apparatus of the embodiment. It is a figure which shows the specific example of the vibration sensor used with the same embodiment motor diagnostic device. It is a vibration spectrum characteristic view explaining the vibration spectrum of the same embodiment motor diagnostic device.

Explanation of symbols

1 CPU
2R R phase current detector 2S S phase current detector 2T T phase current detector 3X, 3Y Vibration sensor 4 Temperature sensor 5 A / D converter 5R, 5S, 5T A / D converter 5X, 5Y A / D converter 6 Current Spectrum Storage Unit 7 Vibration Spectrum Storage Unit 8 Display Unit 20 Diagnostic Device Main Body 30 Diagnosed Motor 30A Bearing Unit

Claims (3)

A plurality of phase current detectors for detecting each phase current of the multiphase motor;
A first diagnostic means for determining the presence or absence of a layer short circuit based on the determination as to whether or not the current ratio between the phase currents detected by these phase current detectors is greater than or equal to a predetermined value;
A vibration sensor provided in the bearing portion of the multiphase motor;
Means for obtaining the order distribution of the vibration spectrum of the signal detected by the vibration sensor;
An electric motor diagnosis apparatus comprising: a second diagnosis unit that determines whether or not a bearing is damaged based on whether or not a level component at a predetermined frequency of the vibration spectrum is a predetermined value or more.   The vibration sensor includes a pickup rod whose one end is brought into contact with the bearing portion, a vibration plate provided at the other end of the pickup rod, an acoustic chamber for transmitting vibration sound of the vibration plate, and an audio signal of acoustic quality. The motor diagnostic apparatus according to claim 1, further comprising: a microphone that converts to a motor.   A temperature sensor is provided in or near the electric motor, and a third diagnostic means for determining the electric motor heating is provided by comparing a temperature value detected by the temperature sensor or a temperature rise degree with a predetermined value. The motor diagnostic apparatus according to claim 1 or 2, characterized by the above.

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