KR101763359B1 - Method and apparatus for monitoring abnormal state of motor and bearing - Google Patents

Abstract

The present invention relates to a method of monitoring an abnormal state of a motor and a bearing, and more particularly to a method of monitoring an abnormal state of a motor and a bearing using a first sensor and a second sensor provided at a position adjacent to a bearing for rotatably supporting a rotation shaft of the motor The method of claim 1, further comprising: sensing a temperature, a natural frequency, a second harmonic, and a third harmonic of the bearing using the first sensor and the second sensor, The method comprising the steps of: normalizing values for a first harmonic, a second harmonic and a third harmonic; selecting at least two values of the plurality of normalized values; Wherein the step of selecting comprises the step of determining the temperature of the first time point and the temperature detected at the second time point after the first time point, A value obtained by squaring the difference between the normalized values and a value obtained by squaring a value normalized based on the natural frequencies sensed at the first and second points of time, A difference between a value obtained by squaring the difference between the normalized value based on the second harmonic detected at the time point and a value normalized based on the third harmonic detected at the first time point and the second time point, Calculating a distance value of a value obtained by adding all the values of the first and second time points to each other when the calculated distance value is equal to or greater than a preset threshold value; , Calculating a plurality of component values each having a difference between a normalized value based on the natural frequency, the second harmonic, and the third harmonic; And selecting a largest value and a second largest value among the plurality of component values, wherein the determining is performed by substituting a combination of the two selected component values into a predetermined look-up table, And the type of the abnormal state of the bearing is determined.
Accordingly, it is possible to simultaneously monitor the abnormality of the bearing and the motor by using the temperature of the bearing applied to the motor, the natural frequency, the second harmonic and the third harmonic, and also, A state in which the state of the motor is required to be checked, and a state in which the motor is in an abnormal state, and the like can be subdivided and quickly and easily grasped.

Description

[0001] METHOD AND APPARATUS FOR MONITORING ABNORMAL STATE OF MOTOR AND BEARING [0002]

The present invention relates to a motor and a method and apparatus for monitoring an abnormal state of a bearing that rotatably supports a rotary shaft of the motor.

Generally, in a industrial field, a motor is used as a power source of a machine, and in the event of a failure, it causes a considerable opportunity loss due to discontinuation of the machine. Therefore, various methods of diagnosing a fault by monitoring the state of the motor in real time have been developed and implemented come.

As an example of detecting a motor malfunction, various sensors can be used to detect stator voltage and current, air gap (air gap), external magnetic flux density, rotor position and speed, output torque, internal or external temperature, A thermal diagnostic method, a vibration diagnostic method, and a method of using electrical diagnostic methods have been used.

On the other hand, the failure of such a motor occurs by more than 80% due to a failure of the stator such as a bearing failure, insulation breakdown, rotor failure of the rotor bar, and mechanical failure. Particularly, even if there is no problem in the motor itself, if the bearing coupled to the motor is defective or damaged, the motor becomes difficult to drive normally, resulting in overheat or reduced output efficiency.

KR 10-1541884 B1 KR 10-2015-0136703 A

SUMMARY OF THE INVENTION The present invention provides a method and apparatus for monitoring an abnormal condition of a motor and a bearing capable of checking an abnormal state of a bearing or a motor based on a temperature and a vibration state of a bearing provided adjacent to a rotary shaft of the motor .

According to another aspect of the present invention, there is provided a method of monitoring an abnormal condition of a motor and a bearing, the method comprising: using a first sensor and a second sensor provided at a position adjacent to a bearing rotatably supporting a rotation shaft of the motor The method of monitoring an abnormal state of the motor and the bearing may include sensing a temperature, a natural frequency, a second harmonic, and a third harmonic of the bearing using the first sensor and the second sensor, , Normalizing the values of the sensed temperature, the eigenfrequency, the second harmonic, and the third harmonic, selecting at least two values of the normalized plurality of values, The method comprising the steps of: determining a type of an abnormal state of the motor and the bearing, A value obtained by squaring the difference between the normalized values based on the first and second time points and a value obtained by squaring the difference between values obtained by normalizing based on the natural frequencies sensed at the first and second points of time, A value obtained by squaring the difference between the values normalized based on the second harmonics detected at the second time point and a value obtained by normalizing the values obtained by normalizing the third harmonics detected at the first point and the second point of time Calculating a distance value of a value obtained by adding all values obtained by squaring the difference; Wherein the distance value is a denominator and the temperature, the eigenfrequency, the second harmonic, and the third harmonic, respectively, sensed at the first and second points of time, respectively, when the calculated distance value is greater than or equal to a preset threshold value Calculating a plurality of component values each having a difference between normalized values based on the plurality of component values; And selecting a largest value and a second largest value among the plurality of component values, wherein the determining is performed by substituting a combination of the two selected component values into a predetermined look-up table, And the type of the abnormal state of the bearing is determined.

According to another aspect of the present invention, there is provided an apparatus for monitoring an abnormal condition of a motor and a bearing, comprising: a first sensor provided at a position adjacent to a bearing for rotatably supporting a rotation shaft of the motor and sensing a temperature value of the bearing; A second sensor provided at an adjacent position for detecting a frequency characteristic of the bearing to detect a value for a natural frequency, a second harmonic and a third harmonic, and a second sensor for detecting a value of the natural frequency, the second harmonic and the third harmonic, A selection unit for selecting at least two values among a plurality of normalized values, and a state determining unit for determining a kind of an abnormal state of the motor and the bearing using the selected two values, Wherein the selection unit is configured to select, based on the temperature sensed at each of the first time point and the second time point after the first time point, A value obtained by squaring a difference between the culminated values and a value obtained by squaring a difference between a value normalized based on the natural frequency sensed at the first time point and a natural frequency sensed at the second time point, A value obtained by squaring the difference between the values normalized based on the second harmonics sensed by the first harmonic and a value normalized based on the third harmonic detected at the first point and the second point, A first calculator for calculating a distance value of a value obtained by adding all the values of the distance values to the first and second points of time when the calculated distance value is equal to or greater than a preset threshold value, A second calculation section for calculating a plurality of component values each having a difference between a normalized value based on the temperature, the natural frequency, the second harmonic, and the third harmonic, Large value and second largest Wherein the state determining unit determines a type of an abnormal state of the motor and the bearing according to a corresponding state value by substituting a combination of the selected two component values into a predetermined lookup table .

According to the present invention, it is possible to simultaneously monitor the abnormality of the bearing and the motor by using the values of the temperature, natural frequency, second harmonic and third harmonic of the bearing applied to the motor, It is possible to quickly and easily grasp the state where the state of the motor needs to be checked and the state where the abnormality has occurred in the motor in addition to the replacement of the bearing.

1 is a block diagram showing the configuration of a monitoring apparatus relating to an abnormal state of a motor and a bearing according to an embodiment of the present invention,
2 is a flowchart illustrating a method for monitoring an abnormal state of a motor and a bearing according to an embodiment of the present invention,
FIG. 3 is a flowchart showing the selection step and the determination step in FIG. 2 in more detail.

The foregoing and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. Like reference numerals refer to like elements throughout the specification.

1 is a block diagram showing a configuration of a monitoring apparatus relating to an abnormal state of a motor and a bearing according to an embodiment of the present invention.

Referring to FIG. 1, an apparatus 200 for monitoring an abnormal condition of a motor and a bearing according to an embodiment of the present invention includes a first sensor 210, a second sensor 220, a normalization unit 230, 240 and a state determination unit 250. [

The first sensor 210 is provided at a position adjacent to the bearing 120 that rotatably supports the rotary shaft 110 of the motor 10 and senses a temperature value T _i of the bearing 120.

The second sensor 220 is provided at a position adjacent to the bearing 120 to sense the frequency characteristic of the bearing 120, like the first sensor 210.

As a result, the values for the natural frequency F _i , the second harmonic R _i , and the third harmonic S _i of the bearing 120 are detected.

Normalizing unit 230 includes a first sensor 210 and second temperature sensed by the sensor (220), (T _i), the natural frequency (F _i), the second harmonic (R _i) and a third harmonic (S _i ), And normalize them respectively.

Here, the normalization unit 230 may be configured to determine a predetermined component (for example, a temperature, a natural frequency, a second harmonic, and a third harmonic) measured by any one of the first sensor 210 and the second sensor 220 The normalized value can be calculated by taking the difference between the measured value for the parameter and the predetermined minimum value of the factor as a numerator and denoting the difference between the predetermined maximum value Max and the minimum value Min of the factor as a denominator.

Specifically, the normalization unit 230 uses the difference between the temperature value T _i sensed by the first sensor 210 and the preset minimum temperature value T _min as a numerical value and sets a predetermined maximum temperature value T _max ) And the minimum temperature value (T _min ) as a denominator, and calculate the first normalization value (N _Ti ).

Normalization unit 230, the second sensor 220 are detected by the natural frequency value (F _i) and a predetermined minimum natural frequency (F _min) for the value difference in the molecule and a predetermined maximum natural frequency value (F 2 can calculate the normalization value (N _Fi) to the difference between the _max) and the minimum natural frequency value (F _min) as the denominator.

The normalization unit 230 uses the difference between the second harmonic value R _i sensed by the second sensor 220 and a predetermined minimum second harmonic value R _min as a numerator and outputs a predetermined maximum second harmonic value The third normalization value N _Ri can be calculated with the difference between the minimum second harmonic (R _max ) and the minimum second harmonic (R _min ) as a denominator.

The normalization unit 230 determines the difference between the third harmonic value S _i sensed by the second sensor 220 and the predetermined minimum third harmonic value S _min as a numerator, The fourth normalized value N _Si can be calculated using the difference between the minimum third harmonic value S _max and the minimum third harmonic value S _min as denominator.

That is, the first normalization value N _Ti represents a characteristic relating to the temperature T _i , the second normalization value N _Fi represents a characteristic relating to the natural frequency value F _i , and the third normalization value N _Ri represents a characteristic relating to a second harmonic value R _i and a fourth normalized value N _Si represents a characteristic relating to a third harmonic value S _i .

In this case, the values (N _Ti , N _Fi , N N) normalized to the temperature T _i , the natural frequency F _i , the second harmonic R _i and the third harmonic S _i , _Ri , N _Si ) have the same range, that is, between 0 and 1, so that it is possible to compare each measurement data having different format and unit.

The selecting unit 240 selects at least two values among a plurality of normalized values normalized by the normalizing unit 230.

The selecting unit 240 may include a first calculating unit 242, a second calculating unit 244, and a data selecting unit 246, as shown in FIG.

Specifically, the first calculation unit 242 calculates a normalized value (T _A , T _B ) based on the temperatures (T _A , T _B ) sensed at the first point of time A and the second point of time B after the first point of time A, respectively (N _{TA- TB} ) ² obtained by squaring the difference between the values N _{TA and} N _TB and a natural frequency F _A detected at the first and second time points A and B, F _B), a value (N _{FA, FB} N) a difference value (N _{FA} -N _FB square of the normalized based on a ^2), a first point (a) and the second sensing each of the time (B) ({N _RA -N _RB } ² ) obtained by squaring the difference between the normalized values N _RA and N _RB based on the first and second harmonics R _A and R _B , ({N _SA -N _SB } ² ) obtained by squaring the difference between the normalized values (N _SA , N _SB ) based on the third harmonics (S _A , S _B ) And calculates a distance value D which is a value obtained by routing the summed value.

The distance value D is a difference between the normalized value of the first point of time A and the value of the second point of time B for each component of the temperature of the bearing 120, the eigenfrequency, the second harmonic and the third harmonic, These values are summarized and expressed by the following equation (1).

When the distance value D calculated by the first calculation unit 242 is equal to or greater than a preset threshold value D _TH , the second calculation unit 244 calculates the abnormal state of the motor 10 and the bearing 120 And performs judgment.

The determination of the abnormal condition is performed based on two values among the values of the temperature of the bearing 120, the natural frequency, the second harmonic, and the third harmonic, which are calculated based on the distance value D .

Specifically, the second calculation unit 244 calculates the temperature (T _A , T _B ), the natural frequency (T _B ), and the second frequency _B It is possible to calculate a plurality of component values each having a difference in the value normalized based on each of the first harmonics F _A and F _B and the second harmonics R _A and R _B and the third harmonics S _A and S _B (S320).

For example, the plurality of component values may be a value obtained by normalizing a value N (T _A , T _B ) based on temperatures (T _A , T _B ) sensed at a first point of time A and a second point of time B, _TA , and N _TB ) as a numerator.

Wherein the plurality of fundamental values are normalized values N _FA (F _A , F _B ) based on the natural frequencies (F _A , F _B ) sensed at the first and second points of time ( _A and _B ) , N _FB ) as a numerator.

The plurality of fractional values may be a value N normalized based on the second harmonics R _A and R _B sensed at the first and second points of time A and B using the distance value D as a denominator, _RA , N _RB ) of the first fraction.

The plurality of fractional values are obtained by multiplying the distance value D by the value N normalized based on the third harmonic waves S _A and S _B sensed at the first and second points of time _A and _B , _SA , and N _SB ) as a numerator.

The data selector 246 selects the largest value and the second largest value among the plurality of component values calculated by the second calculator 244.

The state determining unit 250 determines the type of the abnormal state of the motor 10 and the bearing 120 based on the combination of the two component values selected by the data selecting unit 246. [

The state determining unit 250 substitutes the combination of the two component values selected by the data selecting unit 246 into a predetermined lookup table and determines whether or not the abnormality of the motor 10 and the bearing 120 The type of state can be determined.

Table 1 below shows the measurement components based on the molecular values of the two values selected by the data selection unit 246, that is, the temperature (T _i ) measured by the first sensor 210 and the second sensor 220, the natural frequency (F _i), the second harmonic (R _i) and the time to the third harmonic (S _i) each of the horizontal direction component of components, such as the longitudinal direction component, the motor 10 corresponding to the combination of each component and And the types of abnormal states of the bearings 120 are summarized.

Here, the 'first state value' represents a value corresponding to a state in which the bearing 120 needs to be replaced, and the 'second state value' represents a state in which the bearing 120 needs to be replaced, Indicates a value corresponding to a state requiring confirmation, and a 'third state value' indicates a value corresponding to a state in which an abnormality occurs in the motor 10. [

The temperature (T _i ) The natural frequency (F _i ) A second harmonic (R _i) The third harmonic (S _i ) The temperature (T _i ) · The second state value The first state value The second state value The natural frequency (F _i ) The first state value · The second state value The second state value A second harmonic (R _i) The first state value The second state value · The third state value The third harmonic (S _i ) The second state value The second state value The third state value ·

Referring to Table 1, the state determining unit 250 determines whether any one of the two values selected by the data selecting unit 246 is detected at the first point of time A and the second point of time B, (N _TA -N _TB ) of the normalized values based on the temperatures (T _A and T _B ) Corresponds to the difference ('N _FA- N _FB ' or 'N _RA -N _RB ') of the normalized values based on the natural frequencies (F _A and F _B ) or the second harmonics (R _A and R _B ) , And the state in which the bearing 120 needs to be replaced ('first state value').

For example, when wear is generated on the surface of the bearing 120 by using the bearing 120 for a long time, the originally smooth surface is changed into a rugged shape, so that the temperature T during driving of the motor 10 rises sharply Or the second harmonic wave R corresponding to twice the frequency of the preset normal frequency is generated because the natural frequency F of the motor 10 deviates from the rated output of the predetermined motor 10, When the magnitude of the value obtained by normalizing the temperature T, the natural frequency F or the second harmonic R is greatest, it is determined that the bearing 120 needs to be replaced.

On the other hand, when the driving of the motor and the bearing is ideal, the second harmonic R is hardly generated when the signal waveform supplied to the motor 10 is a sinusoidal wave. If the signal waveform to be supplied to the motor 10 is a square wave, it is difficult to see that the second harmonic R is out of the normal state, If the type of the final abnormal state is determined by considering the back electromotive force characteristic and the driving signal waveform, a more accurate judgment result can be obtained.

The state determining unit 250 determines whether the molecular value of any one of the two values selected by the data selecting unit 246 is lower than the temperature T _A detected at the first time point A and the second time point B (N _TA- N _TB ), which is normalized based on the first harmonic (T _B , T _B ), and the other one of the molecular values corresponds to the third harmonic ( _NSA- N _SB ) of the normalized value on the basis of the state of the motor 10 (S _A , S _B ), it is necessary to replace the bearing 120, State value ').

In this case, the user can take measures to check whether the motor is abnormal after pre-replacement of the bearing.

For example, as described above, frictional heat is generated when the bearing 120 is worn or broken, the temperature T can be rapidly increased during driving of the motor 10, and the third (third) The temperature T and the third harmonic wave S may be different from each other in that the probability of occurrence of the harmonic wave S is high due to the degree of wear of the bearing 120. However, If the magnitude of the normalized value is the greatest, it is determined that it is necessary to check the presence or absence of abnormality of the motor 10 in addition to the replacement of the bearing 120. [

The state determiner 250 may determine that the two harmonic waves R _A and R _B detected at the first point of time A and the second point of time B of the two molecular values selected by the data selector 246, (N _RA- N _RB 'or N _SA N _SB '), which is normalized based on the third harmonic (S _A , S _B ) ('Third state value').

For example, as described above, in the case of the third harmonic S, there is a possibility that the third harmonic S may be caused by the degree of wear of the bearing 120. However, the probability of occurrence when the motor 10 has a problem is high, (S) and the second harmonic (R) have the greatest magnitude in terms of the fact that the magnitude of the value obtained by normalizing the third harmonic wave (S) and the second harmonic wave (R) It is determined that an abnormality has occurred in the motor 10.

FIG. 2 is a flowchart illustrating a method for monitoring an abnormal state of a motor and a bearing according to an embodiment of the present invention, and FIG. 3 is a flowchart illustrating a selection step and a determination step of FIG. 2 in more detail.

1, a method for monitoring an abnormal state of a motor and a bearing according to the present invention includes a first sensor 120 provided adjacent to a bearing 120 that rotatably supports a rotary shaft 110 of a motor 10, (200) including a first sensor (210) and a second sensor (220).

Hereinafter, an abnormal state monitoring method of a motor and a bearing according to an embodiment of the present invention will be described with reference to the drawings.

First, the first sensor 210 and second temperature of the bearing 120 using the sensor (220), (T _i), the natural frequency (F _i), the second harmonic (R _i) and a third harmonic (S _i (S100), respectively.

For example, referring to FIG. 1, the first sensor 210 senses the temperature T _i of the bearing 120, and the second sensor 220 senses the frequency characteristic of the bearing 120 As a result, the natural frequency F _i , the second harmonic R _i , and the third harmonic S _i of the bearing 120 are sensed.

Next, the values for the temperature (T _i ), the natural frequency (F _i ), the second harmonic (R _i ), and the third harmonic (S _i ) sensed in step S100 are normalized (S200).

Here, the normalizing step S200 is a step of performing a normalization (S200) on the basis of a predetermined component (for example, a temperature, a natural frequency, a second harmonic, a third harmonic ) And a preset minimum value of the factor as a numerator, and a normalized value can be calculated with a difference between a predetermined maximum value (Max) and a minimum value (Min) of the factor as a denominator.

Specifically, the step (S200) for normalization, the said temperature value detected in step S100 (T _i) and a predetermined minimum temperature value up to a temperature value that is set to record the difference in the molecules of (T _min) (T _max) and The first normalization value N _Ti can be calculated using the difference between the minimum temperature value T _min as a denominator.

The step (S200) for normalization, the said natural frequency value (F _i) and a predetermined minimum natural frequency (F _min) the difference between the value of the molecular and the predetermined maximum natural frequency value detected in step S100 (F _max) and The second normalization value N _Fi can be calculated using the difference between the minimum eigenfrequency value F _min as a denominator.

The normalizing step S200 may be performed by using the difference between the second harmonic value R _i sensed in step S100 and the predetermined minimum second harmonic value R _min as a numerator and setting a predetermined maximum second harmonic value R _max ) and the minimum second harmonic (R _min ) value as a denominator, and calculate the third normalized value N _Ri .

The normalizing step S200 is a step of performing a normalization on the basis of the difference between the third harmonic value S _i detected in step S100 and the predetermined minimum third harmonic value S _min as a predetermined maximum third harmonic value S 4 can calculate a normalized value _(Si N) by the difference between the _max) and the minimum of the third harmonic value (S _min) as the denominator.

That is, the first normalization value N _Ti represents a characteristic relating to the temperature T _i , the second normalization value N _Fi represents a characteristic relating to the natural frequency value F _i , and the third normalization value N _Ri represents a characteristic relating to a second harmonic value R _i and a fourth normalized value N _Si represents a characteristic relating to a third harmonic value S _i .

In this case, the values (N _Ti , N _Fi , N N) normalized to the temperature T _i , the natural frequency F _i , the second harmonic R _i and the third harmonic S _i , _Ri , N _Si ) have the same range, that is, between 0 and 1, so that it is possible to compare each measurement data having different format and unit.

Next, at least two values of the plurality of normalized values normalized in step S200 are selected (S300), and the type of the abnormal state of the motor 10 and the bearing 120 is determined based on the selected two values (S400 ).

3, the selecting step S300 includes calculating (S310) a distance value D based on the value normalized in step S200, and calculating a distance (D) based on the distance value D, (S320) of calculating a component value of the calculated plurality of component values, and selecting (S330) two values of the calculated plurality of component values.

More specifically, the step of calculating the distance value D (S310) may include calculating the distance (D) between the first temperature (A) and the second temperature (B) after the first temperature ( _A) in _B) a value (N _TA, a value squared difference between _TB N) (N _{TA} -N _TB ²⁾ and the first point (a) and a second point (B) normalized on the basis of the respective detection ({ _NFA- N _FB } ² ) obtained by squaring the difference between the normalized values N _FA and N _FB based on the natural frequencies F _A and F _B , ({N _RA -N _RB } ² ) obtained by squaring the difference between the values (N _RA and N _RB ) normalized based on the second harmonics (R _A and R _B ) on the basis of the respectively detected at the point (a) and a second point (B) the third harmonic (S _a, S _B) by the square of the difference of the normalized value (N _{SA, SB} N) values ({N _SA -N _SB } ² ) is added to the distance value (D).

The distance value D is a difference between the normalized value of the first point of time A and the value of the second point of time B for each component of the temperature of the bearing 120, the eigenfrequency, the second harmonic and the third harmonic, These values are summarized and expressed by the following formula (1).

The step S320 of calculating the plurality of component values may be performed when the distance value D calculated in the step S310 is equal to or larger than a preset threshold value D _TH , And performs state determination.

The determination of the abnormal condition is performed based on two values among the values of the temperature of the bearing 120, the natural frequency, the second harmonic, and the third harmonic, which are calculated based on the distance value D .

More specifically, the step of calculating the plurality of component values (S320) includes calculating the temperature (T _A , T _B ) detected at the first point of time (A) and the second point of time ( _B ) , The difference between the normalized values based on the natural frequencies (F _A and F _B ), the second harmonics (R _A and R _B ) and the third harmonics (S _A and S _B ), respectively, .

For example, the plurality of component values may be a value obtained by normalizing a value N (T _A , T _B ) based on temperatures (T _A , T _B ) sensed at a first point of time A and a second point of time B, _TA , and N _TB ) as a numerator.

The plurality of component values are normalized values N _FA (F _A , F _B ) based on the natural frequencies (F _A , F _B ) sensed at the first and second points of time ( _A and _B ) , N _FB ) as a numerator.

The plurality of component values may be a value N normalized based on the second harmonics R _A and R _B sensed at the first point A and the second point B with the distance value D as a denominator, _RA , N _RB ) of the first fraction.

The plurality of component values are obtained by multiplying the distance value D by the value N normalized based on the third harmonic waves S _A and S _B sensed at the first and second points of time _A and _B , _SA , and N _SB ) as a numerator.

Thereafter, in the selecting step S330, the largest value and the second largest value among the plurality of component values calculated in step S320 are selected.

The determining step S400 is a step of substituting the combination of the two component values selected in step S330 into a predetermined lookup table and determining the type of the abnormal state of the motor 10 and the bearing 120 according to the corresponding state value You can decide.

Table 1 above shows the measured components based on the molecular values of the two values selected in step S330, that is, the temperature T _i measured by the first sensor 210 and the second sensor 220, F _i), the second harmonic (R _i) and a third harmonic (S _i) when the respective components horizontal direction component and vertical direction component, such as a motor 10 and a bearing corresponding to the combination of the components (120 ) Are the kinds of abnormal states.

Referring to Table 1, the determining step (S400) is a step of determining whether any one of the two values selected in step S330 is a temperature detected at the first point (A) and the second point (B) T _a, T _B) corresponds to the difference of the normalized value (N _TA -N _TB) based on, of the other of the numerator each sensing a first point (a) and a second point (B) the natural frequency Corresponds to the difference ('N _FA- N _FB ' or 'N _RA -N _RB ') of the values normalized based on the first harmonic (F _A , F _B ) or the second harmonic (R _A , R _B ) 120) to be replaced ('first state value').

For example, when wear is generated on the surface of the bearing 120 by using the bearing 120 for a long time, the originally smooth surface is changed into a rugged shape, so that the temperature T during driving of the motor 10 rises sharply Or a second harmonic (R) whose natural frequency (F) measured by physical factors or design factors deviates from the natural frequency of the predetermined motor (10) It is determined that the bearing 120 needs to be replaced when the magnitude of the value obtained by normalizing the temperature T and the natural frequency F or the second harmonic R is the greatest.

On the other hand, when the driving of the motor and the bearing is ideal, the second harmonic R is hardly generated when the signal waveform supplied to the motor 10 is a sinusoidal wave. If the signal waveform to be supplied to the motor 10 is a square wave, it is difficult to see that the second harmonic R is out of the normal state, If the type of the final abnormal state is determined by considering the back electromotive force characteristic and the driving signal waveform, a more accurate judgment result can be obtained.

The determining step S400 may include determining whether any one of the two values selected in step S330 is the temperature T _A or T _B detected at the first point A or the second point _B , (S _A , S) corresponding to the difference (N _TA -N _TB ) of the normalized values based on the first time point (A) and the second time point (B) _B) the difference between a normalized value based on the (N _{SB SA} -N) the replacement of the bearing 120 is required, in the case corresponding to the first, and the required state ( "check for abnormality of the motor 10, the second state value, ').

In this case, the user can take measures to check whether the motor is abnormal after pre-replacement of the bearing.

For example, when the bearing 120 is worn or broken, frictional heat is generated, and the temperature T of the motor 10 can be rapidly increased during operation. The third harmonic S corresponding to three times the predetermined normal frequency The magnitude of the value obtained by normalizing the temperature T and the third harmonic S from the point of view of high probability of occurrence when there is a problem in the motor 10 although there is a possibility of occurrence due to the degree of wear of the bearing 120, It is determined that it is necessary to confirm whether or not the motor 10 is abnormal in addition to the replacement of the bearing 120. [

In addition, the determining step S400 may include determining the second harmonic waves R _A and R _B detected at the first and second points A and B, respectively, (Corresponding to 'N _RA- N _RB ' or 'N _SA -N _SB ') of the normalized values based on the respective harmonics S _A and S _B , Third state value ').

For example, in the case of the third harmonic S, there is a possibility that the third harmonic S may occur due to the degree of wear of the bearing 120. However, the probability of occurrence of a problem in the motor 10 is high, In the case where the magnitude of the value obtained by normalizing the third harmonic wave S and the second harmonic wave R is greatest, there is a case where the motor 10 As shown in FIG.

Therefore, according to the present invention, it is possible to simultaneously monitor the abnormality of the bearing and the motor by using the temperature, the natural frequency, the second harmonic and the third harmonic of the bearing applied to the motor, A necessary state, a state in which the state of the motor needs to be checked in addition to the replacement of the bearing, and a state in which an abnormality has occurred in the motor can be classified and quickly and easily grasped.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.

10: motor 110:
120: Bearing 200: Monitoring device
210: first sensor 220: second sensor
230: Normalization unit 240:
242: first calculation section 244: second calculation section
246: Data selection unit 250:

Claims (12)

A method for monitoring an abnormal state of a motor and a bearing using a first sensor and a second sensor provided at a position adjacent to a bearing rotatably supporting a rotation shaft of the motor,
Detecting a temperature, a natural frequency, a second harmonic, and a third harmonic of the bearing using the first sensor and the second sensor, respectively;
Normalizing the values for the sensed temperature, eigenfrequency, second harmonic, and third harmonic, respectively;
Selecting at least two values of the plurality of normalized values; And
Determining a type of an abnormal state of the motor and the bearing by using two selected values,
Wherein the selecting comprises:
A value obtained by squaring a difference between a normalized value based on the sensed temperature at a first point in time and a second point in time after the first point in time, A value obtained by squaring the difference between the normalized value based on the second harmonic and a value obtained by squaring the difference between the value obtained by normalizing the first harmonic and the second harmonic detected at the first point and the second point, Calculating a distance value of a sum of values obtained by squaring the difference between the normalized values based on the third harmonic detected at the second time point;
Wherein the distance value is a denominator and the temperature, the eigenfrequency, the second harmonic, and the third harmonic, respectively, sensed at the first and second points of time, respectively, when the calculated distance value is greater than or equal to a preset threshold value Calculating a plurality of component values each having a difference between normalized values based on the plurality of component values; And
Selecting a largest value and a second largest value among the plurality of component values,
Wherein the determining comprises:
Wherein a type of an abnormal state of the bearing is determined according to a corresponding state value by substituting a combination of two selected component values into a predetermined lookup table. delete The method according to claim 1,
Wherein the normalizing step comprises:
Calculating a first normalized value by using a difference between the sensed temperature value and a predetermined minimum temperature value as a numerator, denoting a difference between the preset maximum temperature value and the minimum temperature value as a denominator,
Calculating a second normalization value by using a difference between the detected natural frequency value and a preset minimum natural frequency value as a numerator and denominator as a difference between a predetermined maximum natural frequency value and the minimum natural frequency value,
Calculating a third normalized value by using a difference between the second harmonic value and a predetermined minimum second harmonic value as a numerator and denominating a difference between a predetermined maximum second harmonic value and the minimum second harmonic value as a denominator,
And calculating a fourth normalized value by taking the difference between the detected third harmonic value and a predetermined minimum third harmonic value as a numerator and denoting a difference between a predetermined maximum third harmonic value and the minimum third harmonic value as a denominator And monitoring the abnormality of the motor and the bearing. The method according to claim 1,
Wherein the determining comprises:
Wherein a molecular value of any one of the selected two component values corresponds to a difference of a normalized value based on the temperature sensed at the first point of time and the second point of time, And when it corresponds to a difference between a normalized value based on the natural frequency or the second harmonic detected at the second time point, How to monitor. The method according to claim 1,
Wherein the determining comprises:
Wherein a molecular value of any one of the selected two component values corresponds to a difference of a normalized value based on the temperature sensed at the first point of time and the second point of time, And determining whether the bearing needs to be replaced and needs to be checked for an abnormality if it corresponds to a difference between normalized values based on the third harmonic detected at the second time point, How to monitor abnormal condition of motor and bearing. The method according to claim 1,
Wherein the determining comprises:
When the two selected molecular values correspond to the difference between the normalized values based on the second harmonic and the third harmonic respectively sensed at the first point and the second point of time, Wherein the abnormality monitoring means determines the abnormality state of the motor and the bearing. A first sensor provided at a position adjacent to a bearing rotatably supporting a rotation axis of the motor and sensing a temperature value of the bearing;
A second sensor provided at a position adjacent to the bearing and detecting a frequency characteristic of the bearing to detect a value of a natural frequency, a second harmonic, and a third harmonic, respectively;
A normalizer for receiving and normalizing the sensed values of the temperature, eigenfrequency, second harmonic, and third harmonic, respectively;
A selector for selecting at least two values of the plurality of normalized values; And
And a state determination unit for determining a type of an abnormal state of the motor and the bearing by using two selected values,
Wherein the selection unit comprises:
A value obtained by squaring a difference between a normalized value based on the sensed temperature at a first point in time and a second point in time after the first point in time, A value obtained by squaring the difference between the normalized value based on the second harmonic and a value obtained by squaring the difference between the value obtained by normalizing the first harmonic and the second harmonic detected at the first point and the second point, A first calculation unit for calculating a distance value of a value obtained by adding squares of the differences of the normalized values based on the third harmonic detected at the second time point,
Wherein the distance value is a denominator and the temperature, the eigenfrequency, the second harmonic, and the third harmonic, respectively, sensed at the first and second points of time, respectively, when the calculated distance value is greater than or equal to a preset threshold value A second calculation section for calculating a plurality of component values each having a difference between the values normalized based on the plurality of component values;
And a data selector for selecting a largest value and a second largest value among the plurality of component values,
Wherein the state determination unit determines,
Wherein the controller determines a kind of an abnormal state of the motor and the bearing according to a corresponding state value by substituting a combination of the selected two component values into a predetermined lookup table. delete 8. The method of claim 7,
The normalization unit may include:
Calculating a first normalized value by using a difference between the sensed temperature value and a predetermined minimum temperature value as a numerator, denoting a difference between the preset maximum temperature value and the minimum temperature value as a denominator,
Calculating a second normalization value by using a difference between the detected natural frequency value and a preset minimum natural frequency value as a numerator and denominator as a difference between a predetermined maximum natural frequency value and the minimum natural frequency value,
Calculating a third normalized value by using a difference between the second harmonic value and a predetermined minimum second harmonic value as a numerator and denominating a difference between a predetermined maximum second harmonic value and the minimum second harmonic value as a denominator,
And calculating a fourth normalized value by taking the difference between the detected third harmonic value and a predetermined minimum third harmonic value as a numerator and denoting a difference between a predetermined maximum third harmonic value and the minimum third harmonic value as a denominator To monitor the abnormal condition of the motor and the bearing. 8. The method of claim 7,
Wherein the state determination unit determines,
Wherein a molecular value of any one of the selected two component values corresponds to a difference of a normalized value based on the temperature sensed at the first point of time and the second point of time, And when it corresponds to a difference between a normalized value based on the natural frequency or the second harmonic detected at the second time point, Monitoring device. 8. The method of claim 7,
Wherein the state determination unit determines,
Wherein a molecular value of any one of the selected two component values corresponds to a difference of a normalized value based on the temperature sensed at the first point of time and the second point of time, And determining whether the bearing needs to be replaced and needs to be checked for an abnormality if it corresponds to a difference between normalized values based on the third harmonic detected at the second time point, A monitoring device for abnormality of motors and bearings. 8. The method of claim 7,
Wherein the state determination unit determines,
When a molecular value of the selected two component values corresponds to a difference between a normalized value based on each of the second harmonic and the third harmonic detected at the first point of time and the second point of time, Wherein the abnormality monitoring unit determines that the abnormality of the motor and the bearing has occurred.

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