WO2017169170A1 - Method for determining characteristic feature quantity of three-phase induction motor - Google Patents

Abstract

This method, for determining a characteristic feature quantity of a three-phase induction motor required for calculation of a deterioration parameter used in diagnostics of a rotary mechanical system for which the three-phase induction motor is the drive source, involves: a first step for performing frequency analysis of an operation-time current signal of the three-phase induction motor 12; a second step in which the sidebands S_A, S_B present in a frequency region A on the low frequency side and a frequency region B on the high frequency side, said regions being centered on the power frequency spectrum S_L, are detected from the frequency analysis; and a third step in which the absolute value of the difference between the power frequency f_line and the peak position frequency of either of the sidebands S_A, S_B is set as the actual rotation frequency f_r of the three-phase induction motor 12, wherein the actual rotation frequency f_r is set as a first characteristic feature quantity.

Description

A method for determining the characteristic features of a three-phase induction motor.

When diagnosing the operating state of a rotating machine system using a three-phase induction motor as a drive source using the deterioration parameter obtained from the analysis of the current signal during operation of the three-phase induction motor, The present invention relates to a method for determining a characteristic feature of a three-phase induction motor necessary for calculation.

Conventionally, state diagnosis of a rotary machine system using a three-phase induction motor as a drive source is based on focusing on deterioration parameters defined in both the time domain and frequency (frequency) domain of vibration generated from the rotary machine system. It is done. However, in the state diagnosis of a rotating machine system existing in a remote place or a rotating machine system installed in an inaccessible place, vibrations of the rotating machine system cannot be directly measured. Therefore, the deterioration parameter is determined from the current spectrum (spectrum pattern) obtained by frequency analysis of the operating current signal of the three-phase induction motor, and the state of the rotating machine system is diagnosed by paying attention to the change of the deterioration parameter. (For example, refer nonpatent literature 1).

Toshio Toyoda, “Diagnosis technology for motor-driven rotating machines by current sign analysis MCSA”, Takada Technical Report, 2010, Vol. 20, p. 3-6

For example, the current spectrum obtained from the frequency analysis of the operating current signal of the three-phase induction motor having the number of poles p has both sides of the spectrum of the power supply frequency f _line (commercial power supply frequency) as shown in FIG. It is known that sidebands caused by the pole passing frequency f _pp exist on the low frequency side and the high frequency side centering on the f _line spectrum. Therefore, the relative ratio I _line / I _pole of the spectrum size I _line of the power source frequency f _line with respect to the magnitude of the sideband wave (current power value, peak height, the same _applies hereinafter) I _pole caused by the pole passing frequency f _pp As the deterioration parameter, it is determined whether or not the rotor bar of the three-phase induction motor is damaged from the change of the deterioration parameter.

Here, the pole pass frequency f _pp, three-phase induction motor of the actual rotational frequency f _r of the rotor _{(hereinafter,} the actual rotational frequency f _r refers to the actual rotational frequency f _r of the rotor), the three-phase induction motor synchronization The relationship of f _pp = (f _x −f _r ) p is established between the rotation frequency f _x and the number of poles p of the three-phase induction motor. Further, determined by the specification of the number of poles p is three-phase induction motor, synchronous rotation frequency f _x can be determined using the power frequency f _{line (commercial} power frequency) and the number of poles p. Therefore, if it is possible to measure the actual rotational frequency f _r of the three-phase induction motor, can isolate sidebands due to pole passing frequency f _pp in current spectrum, precisely it has been found correct size sidebands Can be obtained. However, if the actual rotational frequency f _r of the three-phase induction motor is unknown, estimates (e.g., a value according to the value and specifications previously measured) supposed to use, obtaining an accurate deterioration parameter This causes a problem that the state of the rotating machine system cannot be correctly diagnosed.

The present invention has been made in view of such circumstances, and diagnoses the state of a rotary machine system using a three-phase induction motor as a drive source by using deterioration parameters obtained from analysis of current signals during operation of the three-phase induction motor. In this case, an object of the present invention is to provide a method for determining a characteristic feature amount of a three-phase induction motor necessary for calculating a deterioration parameter.

The method for determining the characteristic feature amount of the three-phase induction motor according to the present invention that meets the above-described object is a three-phase induction motor that is necessary for diagnosing the operating state of a rotary machine system that uses a three-phase induction motor as a drive source. A method for determining a characteristic feature of
A first step of measuring an operating current signal of the three-phase induction motor and performing a frequency analysis of the operating current signal;
Of the current spectrum obtained from the frequency analysis, a sideband of the power frequency spectrum of the three-phase induction motor, and a value of a difference between the power frequency f _line and the synchronous rotation frequency f _X of the three-phase induction motor the lower limit frequency, seeking the peak of maximum height the value obtained by adding the frequency value set in the range of 0.01 ~ 4 Hz to the lower limit frequency present in the frequency area a to the upper limit frequency and sidebands S _a A frequency region B having a value obtained by adding the synchronous rotation frequency f _X to the power supply frequency f _line as an upper limit frequency and a value obtained by subtracting a frequency value set in a range of 0.01 to 4 Hz from the upper limit frequency as a lower limit frequency a second step of the sidebands S _B seeking the peak of maximum height that exists within,
The sideband S _A, and a third step of the actual rotational frequency f _r of the absolute value the three-phase induction motor of the difference either between one peak position frequency the power supply frequency f _line of S _B,
The actual rotation frequency _fr is set as a first characteristic feature.

In the method of determining the specific characteristics of the three-phase induction motor according to the present invention, the actual rotational frequency f _r of the three-phase induction motor from operating when the current signal to be measured when diagnosing the condition during operation of the rotating machine system since the decision to the three-phase first specific feature of the induction motor, the actual rotational frequency f _r which is determined accurately reflect the state of rotation of the three-phase induction motor at the time of diagnosis. For this reason, if the deterioration parameter for determining the operating state of the rotating machine system is configured using the actual rotational frequency _fr , the state of the three-phase induction motor can be accurately evaluated using the deterioration parameter, and the rotating machine It is possible to improve the accuracy of system status diagnosis.
The actual rotational frequency f _r of the three-phase induction motor, in order to participate in the generation of sideband associated with the mechanical structure of the rotary mechanical system, to obtain a degradation parameter that reflects the mechanical structure of the rotary mechanical system accurately Is possible.

It is a schematic diagram of the sideband of the power frequency spectrum and the actual rotational frequency that appear in the current spectrum of the current signal during operation of the three-phase induction motor. It is a block diagram of the apparatus used with the method of determining the intrinsic | native feature-value of the three-phase induction motor which concerns on one Example of this invention. It is a schematic diagram of the sideband of the power supply frequency spectrum and the rotor bar slip frequency that appear in the current spectrum of the current signal during operation of the three-phase induction motor. It is a schematic diagram of the current spectrum obtained from the frequency analysis of the current signal during operation of the three-phase induction motor.

Subsequently, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
A method for determining a characteristic feature of a three-phase induction motor according to an embodiment of the present invention is based on a state of operation of a rotary machine system using a three-phase induction motor as a drive source, and an operating current signal of the three-phase induction motor. This is a method of determining the characteristic feature amount of the three-phase induction motor necessary for calculating the deterioration parameter when diagnosing using the deterioration parameter obtained from the analysis. Details will be described below.

The method of determining the characteristic feature of the three-phase induction motor is a first method of measuring the current signal during operation of the three-phase induction motor, performing frequency analysis of the current signal during operation, and logarithmically converting the obtained current spectrum value. process and, as shown in FIG. 1, from the current spectrum to logarithmic transformation, a sideband wave of the power frequency spectrum S _L of the three-phase induction motor, synchronous rotation frequency of the power supply frequency f _line and the three-phase induction motor f The peak of the maximum height existing in the frequency region A where the value of the difference from _X is the lower limit frequency and the lower limit frequency is set in the range of 0.01 to 4 Hz, for example, the value obtained by adding 2 Hz is the upper limit frequency. was a sideband _{S a} seeking, pull power frequency _{f line} in synchronized rotation frequency _{f X} values of the upper limit frequency plus the frequency value set in the range of 0.01 ~ 4 Hz from the upper limit frequency, for example, a 2Hz A second step of the sidebands S _B seeking the peak of maximum height values present in the frequency domain B to the lower limit frequency, sideband S _A, either one of the S _B, for example, side band S _A the third step of the actual rotational frequency f _r of the absolute value of the difference between the peak position frequency and supply frequency f _line of higher peak height (the larger the current power value) three-phase induction motor in the S _B And the actual rotational frequency _fr is the first characteristic feature of the three-phase induction motor.

In the first step, as shown in FIG. 2, for example, a non-contact clamp is applied to any one-phase wiring in the motor wiring 13 of the three-phase induction motor 12 in the electric board 11 of the rotating machine system 10. An operating current signal, which is an analog signal, is detected using the current sensor 14. When the electric board 11 and the rotating machine system 10 are close to each other, a non-contact clamp type current sensor is connected to an arbitrary one-phase cable among the power cables 15 connected to the three-phase induction motor 12. It is also possible to detect the operating current signal using. The operating current signal detected by the clamp type current sensor 14 is input to the A / D converter 16 and converted into a digital signal, and the frequency analyzer 18 that performs fast Fourier transform (an example of frequency analysis) through the transmission path 17. To enter. As a result, a current spectrum of the operating current signal is obtained.

As shown in FIG. 2, in the second step, the spectrum data (data indicating the relationship between the frequency and the current power value (peak height)) of the current spectrum of the operating current signal output from the frequency analyzer 18 is first. Is input to the data processing means 19 and is performed by the first data processing means 19.
In the second step, first, from the current spectrum, obtaining a power frequency spectrum S _L of the three-phase induction motor 12. Here, since the power supply frequency f _line is a commercial power supply frequency (50 Hz in eastern Japan, 60 Hz in western Japan) that supplies power to the three-phase induction motor 12, the frequency value is determined from the spectral data of the current spectrum. The spectrum data matching the frequency is obtained, and the current power value of the obtained spectrum data is set as the current power value of the power supply frequency spectrum S _L (the processing 1).

Then, the synchronized rotation frequency _{f X} of the three-phase induction motor 12, when the number of poles of the three-phase induction motor 12 is _p, since it is calculated as f _{X = 2f line} / p, in the current spectrum, the power supply frequency f The value f _line -f _X of the difference between the _line and the synchronous rotation frequency f _X of the three-phase induction motor 12, that is, f _line -2f _line / p is the lower limit frequency, and the lower limit frequency is added with 2 Hz, ie, f _line From the spectrum data existing in the frequency region A having −2f _line / p + 2 as the upper limit frequency, the spectrum data having the maximum current power value (the peak of the maximum height, the same applies hereinafter) is extracted. Then, the extracted frequency and current power value possessed by the spectral data, respectively the frequency and the current power value of the sideband S _A (above, processing 2).
Further, in the current spectrum, a value f _line + f _{X obtained} by adding the synchronous rotation frequency f _X to the power supply frequency f _line , that is, f _line + 2f _line / p is an upper limit frequency, and a value obtained by subtracting 2 Hz from the upper limit frequency, that is, Spectral data having the maximum current power value is extracted from the spectral data existing in the frequency region B having f _line + 2f _line / p−2 as the lower limit frequency. Then, the extracted frequency and current power value possessed by the spectral data, respectively the frequency and the current power value of the sideband S _B (or more, the process 3).
The first data processing means 19 can be configured, for example, by mounting a program for executing the processing 1 to 3 on a personal computer. Here, the commercial power supply frequency and the value of the number of poles p of the three-phase induction motor 12 are input to the first data processing means 19 in advance.

As shown in FIG. 2, in the third step, the data of the sideband wave S _A output from the first data processing means 19 (the current power value of the sideband wave S _A and the frequency f _A corresponding to the current power value) and performed by sidebands S _B of the data the second data processing means 20 is input to the second data processing means 20 (sidebands S _B of the current power value and current frequency f _B corresponding to the power _value).
In the third step, the current power value of the sideband wave S _{A and} the current power value of the sideband wave S _B are compared to identify a sideband wave having a large current power value, and the peak position frequency f _Smax of the identified sideband wave is obtained. . Then, the absolute value of the difference between the peak position frequency _{f Smax} and the power frequency _{f line |} and the three-phase induction actual rotational frequency _{f r} of the motor 12 | f _{Smax -f line.} For example, when the current power value of the sideband wave S _A is larger than the current power value of the sideband wave S _B , f _r = f _line −f _A , and the current power value of the side band wave S _B is greater than the current power value of the side band wave S _A. If it is large, f _r = f _B −f _line . The obtained actual rotation frequency _fr is output from the second data processing means 20. (Process 4).
Here, the 2nd data processing means 20 can be comprised by mounting the program which performs the process 4 on a personal computer, for example.

Method for determining specific characteristics of the three-phase induction motor according to the present embodiment, a fourth step of the difference of the slip frequency f _s of the synchronous rotary frequency f _X and the actual rotational frequency f _r, from the current spectrum , Sidebands of the power frequency spectrum, present on the low frequency side and the high frequency side respectively due to the pole passing frequency f _pp defined as the product of the slip frequency f _s and the number of poles p of the three-phase induction motor 12 to sideband _{S PA} (peak frequency position _{f PA),} a fifth step of obtaining the sideband _{S PB} (peak frequency position _{f PB),} the peak of the maximum height that exists between the sidebands _{S PA} and sidebands _{S a} Is determined as a sideband wave S _LA, and a peak of the maximum height existing between the sideband wave S _PB and the sideband wave S _B is determined as a sideband wave S _LB , and the sideband waves S _LA , S _LB Either one, for example, the side Obiha S _LA, the seventh step of the rotor bar slip frequency f _rs of the absolute value of the difference between the peak position frequency and supply frequency f _line of higher peak height three-phase induction motor 12 in S _LB And an eighth step of dividing the rotor bar slip frequency f _rs by the slip frequency f _s to obtain the number of rotor bars h of the three-phase induction motor 12, and the number of rotor bars h is set to the three-phase induction motor 12. Of the second characteristic feature.

As shown in FIG. 2, the fourth to eighth steps are obtained in the first step and obtained from the first step, and the spectrum data of the current spectrum of the operating current signal (output from the frequency analyzer 18). The data of the sidebands S _LA and S _LB (obtained from the first data processing means 19) and the synchronous rotation frequency f _X of the three-phase induction motor 12 are obtained in the third step (from the second data processing means 20). The actual rotation frequency _fr is acquired and input to the third data processing means 21, which is performed by the third data processing means 21.

In the fourth step, the difference f _X −f _r is obtained from the synchronous rotation frequency f _X and the actual rotation frequency f _r acquired from the first and second data processing means 19 and 20, respectively, and is set as the slip frequency f _s ( Process 5).
In the fifth step, as shown in FIG. 3, due to the pole passing frequency f _pp defined as the product of the slip frequency f _s and the number of poles p of the three-phase induction motor 12, that is, Sideband wave S _PA (peak frequency position f _PA ) and sideband wave S present at frequency positions centered on the current spectrum peak of power supply frequency f _line and separated by the pole passing frequency f _pp on the low frequency side and the high frequency side, respectively. seeking _PB (peak frequency position _{f PB),} in the sixth step, seeking the peak of maximum height that exists between the sidebands _{S PA} and sideband _{S a} (i.e., sidebands _{S PA} and sidebands _{S a} The spectrum data having the maximum current power value is extracted from the spectrum data existing between the frequency and current power value of the extracted spectrum data. A peak frequency _{f LA} and the current power value of the _LA, seeking the peak of maximum height that exists between the sidebands _{S PB} and sideband _{S B} (i.e., exist between the sidebands _{S PB} and sidebands _{S B} from the spectral data, the current power value by extracting spectral data having the largest), and extracted frequency and current power value possessed by the spectral data and peak frequency f _LB and the current power value of each sideband S _LB (Processing 6).

In the seventh step, whereas one sideband S _LA, the S _LB, for example, by comparing the current power value of the current power value and sideband S _LB sidebands S _LA, specifying a large sideband current power value Then, the peak position frequency of the specified sideband is obtained. Then, the absolute value of the difference between the obtained peak position frequency and the power supply frequency f _line is set as the rotor bar slip frequency _frs of the three-phase induction motor 12. For example, when the current power value of the sideband wave S _LA is larger than the current power value of the sideband wave S _LB , f _rs = f _line −f _LA , and the current power value of the side band wave S _LB is larger than the current power value of the side band wave S _LA. If larger, f _rs = f _LB −f _line (process 7). In the eighth step, a value obtained by dividing the rotor bar slip frequency f _rs obtained in the seventh step by the slip frequency f _s (= f _X −f _r ) obtained in the fourth step is obtained. Is set to the number h of rotor bars of the three-phase induction motor 12 (process 8).
Here, the third data processing means 21 can be configured, for example, by mounting a program for executing the processing 5 to 8 on a personal computer.

As described above, the method for determining the characteristic features of the three-phase induction motor of the present invention is applied to the current spectrum obtained by performing frequency analysis of the current signal during operation of the three-phase induction motor 12. Accordingly, it is possible to determine the actual rotational frequency f _r of the three-phase induction motor 12, the first specific feature of the three-phase induction motor 12. As a result, using the actual rotation frequency f _r , the synchronous rotation frequency f _{X of} the three-phase induction motor 12, and the number of poles p of the three-phase induction motor 12, the pole passing frequency f _pp (= (f _X −f _r ) p). And the sideband of the pole passing frequency f _pp can be identified from the current spectrum. Thereby, the exact magnitude (current power value) of the sideband of the pole passing frequency f _pp is 20 log I _pole (where I _pole is a _pole obtained by fast Fourier transforming the current signal during operation of the three-phase induction motor 12) The sideband current power value caused by the pass frequency f _pp is known. For example, the sideband wave size 20 logI _{pole of} the pole pass frequency f _pp and the spectrum size 20 logI _line (where I _line is the power _line frequency f _{line). is,} 20logI line -20logI _pole constructed using the operation time current signal of the three-phase induction motor 12 current power value of the current spectrum of the power supply frequency obtained by fast Fourier transform), i.e., 20log _{(I line} / _{I pole} )) is used as a deterioration parameter. Therefore, it can be accurately diagnosed whether or not the rotor bar of the three-phase induction motor 12 is damaged.

Further, by applying the method for determining the characteristic feature of the three-phase induction motor of the present invention to the current spectrum of the current signal of the three-phase induction motor 12 during operation, the rotor bar of the three-phase induction motor 12 The number h can be determined and used as the second characteristic feature of the three-phase induction motor 12. As a result, the rotor bar slip frequency f _rs (= (f _X −f _r ) h) is obtained using the number h of rotor bars, the actual rotation frequency f _r , and the synchronous rotation frequency f _X of the three-phase induction motor 12. From the current spectrum, the sideband wave of the power supply frequency spectrum, which is caused by the rotor bar slip frequency _frs , can be identified. As a result, the exact magnitude of the sideband 20 logI _rs (I _rs is the rotor bar slip frequency obtained by fast Fourier transform of the operating current signal of the three-phase induction motor 12 due to the rotor bar slip frequency f _rs. f current power value of sidebands caused by _rs) found, for example, constructed using magnitude _{I line} of the spectrum of size 20LogI _rs and the power frequency _{f line} sidebands due to rotor bar slip frequency _{f rs} 20logI _line −20logI _rs , that is, 20 log (I _line / I _rs ) is used as a deterioration parameter, so that it is accurately determined whether or not the load torque of the three-phase induction motor 12 has changed due to the change in the deterioration parameter. Can be diagnosed.

The present invention has been described above with reference to the embodiments. However, the present invention is not limited to the configurations described in the above-described embodiments, and is within the scope of the matters described in the claims. Other possible embodiments and modifications are also included.
Further, the present invention includes a combination of components included in the present embodiment and other embodiments and modifications.
For example, the power supply frequency f _line of the power spectrum of the current spectrum is set to the fundamental frequency of the power supply that supplies AC power to the three-phase induction motor, but the power supply frequency f _line of the power supply frequency spectrum can also be set to the harmonic frequency. . As a result, even if the frequency of the sideband wave related to the mechanical structure of the rotating machine system exceeds the fundamental frequency of the power supply, the sideband wave can be detected and the deterioration related to the mechanical structure of the rotating machine system. It becomes possible to accurately evaluate the parameters.
Note that the present invention can be applied even if the power source for supplying AC power to the three-phase induction motor is an inverter power source.

The present invention, in diagnosing the state during operation of the rotating machine system as a drive source a three-phase induction motor, to determine the actual rotational frequency f _r from the running time of the current signal, the inherent characteristic of the three-phase induction motor It is what. Actual rotational frequency f _r which is determined is accurately reflects the state of rotation of the three-phase induction motor at the time of diagnosis, the use of actual rotational frequency f _r, it is possible to obtain the accurate deterioration parameter, the deterioration parameter It can be used to accurately evaluate the state of the three-phase induction motor. Therefore, it is possible to perform state diagnosis on a rotating machine system that exists in a remote place or a rotating machine system that is installed in an inaccessible place, and it is possible to improve the accuracy of the state diagnosis.

10: Rotating mechanical system, 11: Electric board, 12: Three-phase induction motor, 13: Motor wiring, 14: Clamp-type current sensor, 15: Power cable, 16: A / D converter, 17: Transmission path, 18: Frequency analyzer, 19: first data processing means, 20: second data processing means, 21: third data processing means

Claims (3)

A method for determining the characteristic features of a three-phase induction motor necessary for diagnosing the operating state of a rotating machine system using a three-phase induction motor as a drive source,
A first step of measuring an operating current signal of the three-phase induction motor and performing a frequency analysis of the operating current signal;
Of the current spectrum obtained from the frequency analysis, a sideband of the power frequency spectrum of the three-phase induction motor, and a value of a difference between the power frequency f _line and the synchronous rotation frequency f _X of the three-phase induction motor the lower limit frequency, seeking the peak of maximum height the value obtained by adding the frequency value set in the range of 0.01 ~ 4 Hz to the lower limit frequency present in the frequency area a to the upper limit frequency and sidebands S _a A frequency region B having a value obtained by adding the synchronous rotation frequency f _X to the power supply frequency f _line as an upper limit frequency and a value obtained by subtracting a frequency value set in a range of 0.01 to 4 Hz from the upper limit frequency as a lower limit frequency a second step of the sidebands S _B seeking the peak of maximum height that exists within,
The sideband S _A, and a third step of the actual rotational frequency f _r of the absolute value the three-phase induction motor of the difference either between one peak position frequency the power supply frequency f _line of S _B,
A method for determining a characteristic feature of a three-phase induction motor, wherein the actual rotational frequency _fr is a first characteristic feature. A method of determining the specific characteristics of the three-phase induction motor according to claim 1, a fourth step of the difference of the slip frequency f _s of the synchronous rotary frequency f _X wherein the actual rotational frequency f _r,
Of the current spectrum, a sideband of the power supply frequency spectrum, which is a low frequency due to a pole passing frequency f _pp defined as a product of the slip frequency f _s and the number of poles p of the three-phase induction motor A fifth step for obtaining sidebands S _PA and S _PB existing on the side and the high frequency side,
The sideband S seeking the peak of maximum height that exists between the _PA and the sidebands S _A and sidebands S _LA, the maximum height that exists between the sidebands S _PB said sidebands S _B a sixth step of the sidebands S _LB seeking peak,
A seventh step in which the absolute value of the difference between the peak position frequency of either one of the sidebands S _LA and S _LB and the power supply frequency f _line is set as the rotor bar slip frequency f _{rs of the} three-phase induction motor;
Further comprising an eighth step of the rotor bar slip frequency f _rs by dividing the slip frequency f _s and the rotor bar number of the three-phase induction motor,
A method for determining a characteristic feature of a three-phase induction motor, wherein the number of rotor bars is set as a second characteristic feature. In the method for determining the characteristic feature amount of the three-phase induction motor according to claim 1 or 2, the frequency region A has a value obtained by adding 2 Hz to a lower limit frequency of the frequency region A as an upper limit frequency of the frequency region A, In the frequency domain B, a characteristic value of the three-phase induction motor is determined, wherein a value obtained by subtracting 2 Hz from the upper limit frequency of the frequency domain B is set as a lower limit frequency of the frequency domain B.

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