KR102113497B1 - Potable Rotor Diagnosis Device And Method for Induction Machines - Google Patents

Abstract

A portable rotor diagnostic apparatus for diagnosing a failure of an induction machine facility, comprising: a three-phase inverter 100; The embedded sensor that is connected to the output terminal of the inverter 100 to measure the current output and controls the inverter 100 and analyzes the current measured from the current sensor 200 to diagnose the presence or absence of a fault. It characterized in that it comprises a system 300, a three-phase inverter 100, the portable terminal of the induction machine facility 10 including a current sensor 200 installed in the output terminal of the inverter 100 to measure the output current A method of using a rotor diagnostic device, comprising: PWM switching in the inverter (100) to designate a command voltage (V _s ) specifying an AC signal size and frequency to be applied to the inducer facility (S100); Applying the V _s from the inverter 100 to the induction machine facility 10 (S200); Measuring currents of the rotor 11 and the stator 12 of the induction machine facility 10 in the current sensor 200 (S300); Converting the current measured in step S300 to ADC to obtain a current response i _s (S400); Obtaining an impedance Z _eq through the V _s and i _s obtained in the step (S400) (S500); Obtaining an equivalent resistance R _eq equivalent reactance X _eq from the Z _eq (S600); It characterized in that it comprises the step of calculating the rate of change of each of the _s , Z _eq , R _eq, X _eq (S700) and diagnosing a failure through the step (S700) (S800).

Description

How to use a portable rotor diagnostic device in an induction machine {Potable Rotor Diagnosis Device And Method for Induction Machines}

The present invention relates to a method of using a portable rotor diagnostic device of an induction machine.

Induction motors, which are the main distribution facilities of the system, fail due to various causes. Generally, failure occurs due to thermal, electrical and mechanical stress and deterioration or extreme external environments. Motor failures occur in the stator, rotor, and various positions, mainly stator defects mean breakdown of the windings, and rotor defects mean breakdown of the windings or bars. In addition, defects in the iron core of the stator and the rotor and eccentricity of the central axis of rotation are also one of the failure factors of the induction motor.

In particular, when the rotor bar of the induction motor is broken, it causes imbalance in the rotor circuit, and vibration and noise increase. If this is not repaired or the failure is not quickly recognized, the rotor bar may protrude outwards in severe cases, causing great damage to the insulation or the iron core of the stator winding, and short-circuiting in a large accident, which may adversely affect the entire system. Methods for diagnosing defects occurring in the rotor of an induction motor can be roughly divided into those diagnosed during operation and those diagnosed in a stopped state. There are advantages and disadvantages to the diagnostic method while driving and the diagnostic method while stopping, and each method is applied according to the diagnosis object and its needs. Diagnosis during operation is a method of acquiring and analyzing vibration, temperature, magnetic flux, and current in real time when the motor is in operation, so the test can be performed without stopping the motor, which has the advantage of frequent testing, but the effect of defects on the operation Because it is a method of indirectly observing and diagnosing, it may cause inaccurate results compared to the test method during suspension. On the other hand, the diagnostic method during stop has the advantage of being able to directly observe the defect while the motor is stopped, making it possible to more accurately determine the failure, but it is cumbersome because the motor cannot be tested frequently because it must be stopped or specially disassembled for testing. . Recently, a current spectrum analysis (MCSA) diagnostic method for acquiring and spectral-analyzing the current of a stator winding during operation using a current sensor in a motor control center (MCC) of a switchboard is widely used. However, in the MCSA diagnosis method applied to industrial sites, false positive diagnosis cases frequently wrongly diagnose a normal electric motor as having a rotor defect are frequently generated, and unnecessary inspection costs may be additionally generated due to incorrect diagnosis. In addition, in the case of a false negative diagnosis that incorrectly judges a defective motor as normal, the motor malfunctions during operation without notice, resulting in problems in the system such as the motor system and the entire process stop, not just a single motor problem. do. In order to overcome this, a complex diagnostic technique, in which the diagnosis method is additionally tested during stoppage after performing MCSA diagnosis during motor operation, is being applied to newly built power plants and industrial plant plants. The most reliable and long-lasting single-phase rotation test method (SPRT), which is the most reliable test method for diagnosing rotor failure, applies an alternating current 60Hz signal to two phases of the three phase windings of the stator of the induction motor as shown in FIG. Then, the rotor is rotated at regular intervals to determine the failure by observing the change in the current magnitude response with a current meter. At this time, a single-phase AC voltage is applied so that the current flowing through the stator winding becomes 1 / 8-1 / 4 of the rated current. This diagnostic method is usually performed for quality inspection after the manufacture of a motor. A reliable method or a transformer for obtaining a single-phase AC signal is required, and it is impossible to accurately determine the failure by checking the scale of the analog current meter only with the eyes of the tester.

KR 10-1841577 B1 KR 10-1150503 B1

Therefore, the present invention is to solve the above-described problem, and to apply a single-phase rotation test method as one of the diagnostic methods during stoppage to detect a rotor failure of an induction motor, a portable inverter is used instead of a large and heavy transformer. . Through this, more various AC signals were tested on the motor to derive diagnostic parameters for rotor defects, and a simple diagnosis system was constructed to be used directly in the industrial field.

A portable rotor diagnostic apparatus for diagnosing a failure of an induction machine facility, comprising: a three-phase inverter 100; The embedded sensor that is connected to the output terminal of the inverter 100 to measure the current output and controls the inverter 100 and analyzes the current measured from the current sensor 200 to diagnose the presence or absence of a fault. It characterized in that it comprises a system 300, a three-phase inverter 100, the portable terminal of the induction machine facility 10 including a current sensor 200 installed in the output terminal of the inverter 100 to measure the output current A method of using a rotor diagnostic device, comprising: PWM switching in the inverter (100) to designate a command voltage (V _s ) specifying an AC signal size and frequency to be applied to the inducer facility (S100); Applying the V _s from the inverter 100 to the induction machine facility 10 (S200); Measuring currents of the rotor 11 and the stator 12 of the induction machine facility 10 in the current sensor 200 (S300); Converting the current measured in step S300 to ADC to obtain a current response i _s (S400); Obtaining an impedance Z _eq through the V _s and i _s obtained in the step (S400) (S500); Obtaining an equivalent resistance R _eq equivalent reactance X _eq from the Z _eq (S600); It characterized in that it comprises the step of calculating the rate of change of each of the _s , Z _eq , R _eq, X _eq (S700) and diagnosing a failure through the step (S700) (S800).

The present invention is easy to carry by using an inverter instead of a heavy transformer used in a rotor diagnostic apparatus of a conventional induction machine facility, and has an effect that can be clearly observed in low-voltage induction machines and high-voltage motors.

1 is a schematic diagram of a conventional single-phase rotation test (SPRT).
2 is a configuration diagram of a portable rotor diagnostic apparatus according to the present invention.
3 is an embodiment of a portable rotor diagnostic apparatus according to the present invention.
4 is a flow chart of a method of using a portable rotor diagnostic apparatus according to the present invention.
5 is a circuit conceptual diagram of the rotor diagnostic apparatus proposed in the present invention.
6 is an equivalent circuit diagram of an induction motor in a stopped state according to the present invention.
Figure 7 shows an embodiment according to the present invention when the rotor defect is 0 degrees, 90 degrees.
8 is a graph showing a change in current magnitude according to a rotor defect as an embodiment according to the present invention.
9 is a graph showing an impedance change according to a rotor defect as an embodiment according to the present invention.
10 shows a fault location of a low pressure and high pressure induction motor as an embodiment according to the present invention.
11 is a graph showing a current magnitude result of a low-pressure induction rotor failure as an embodiment according to the present invention.
12 is a graph showing an impedance result of a low-pressure induction rotor failure as an embodiment according to the present invention.
13 is a graph showing an impedance comparison before and after repair of a high pressure induction machine as an embodiment according to the present invention.

Hereinafter, with reference to the drawings according to an embodiment of the present invention, this is for easier understanding of the present invention, and the scope of the present invention is not limited thereto.

When a part of the specification "includes" a certain component, this means that other components may be further included instead of excluding other components, unless specifically stated to the contrary.

Throughout the specification, when a part is "connected" to another part, this includes not only "directly connected" but also "electrically connected" with another element in between. .

In the present specification, when one component 'transmits' data or a signal to another component, the component may directly transmit the data or signal to another component, and through at least one other component This means that data or signals can be transmitted to other components.

Prior to the description, a number of aspects and embodiments are described herein, and these are merely illustrative and not limiting.

After reading this specification, skilled artisans will appreciate that other aspects and embodiments are possible without departing from the scope of the invention.

Before addressing the details of the embodiments described below, some terms will be defined or clarified.

Inverter refers to a device that converts DC power into AC power.

The command voltage means designating a voltage to be applied to the load.

1 is a schematic diagram of a conventional single-phase rotation test method (SPRT), FIG. 2 is a configuration diagram of a portable rotor diagnostic apparatus according to the present invention, and FIG. 3 is an embodiment of a portable rotor diagnostic apparatus according to the present invention , FIG. 4 is a flow chart of a method of using the portable rotor diagnostic apparatus according to the present invention, FIG. 5 is a circuit conceptual diagram of the rotor diagnostic apparatus proposed in the present invention, and FIG. 6 is a stopped state according to the present invention 7 is an equivalent circuit diagram of an induction motor, and FIG. 7 shows a case where the rotor defect is 0 degrees and 90 degrees as an embodiment according to the present invention, and FIG. 8 is a graph showing a change in current magnitude due to a rotor defect as an embodiment according to the present invention 9 is a graph showing a change in impedance according to a rotor defect as an embodiment according to the present invention, FIG. 10 shows a fault location of a low pressure, high pressure induction motor as an embodiment according to the present invention, and FIG. 11 is the present invention According to an embodiment of the present invention, a graph showing a current magnitude result of a failure of a low-pressure induction rotor, FIG. 12 is a graph showing an impedance result of a failure of a low-pressure induction rotor, and FIG. 13 is a high-pressure example of an embodiment according to the present invention. This graph shows the comparison of impedance before and after repair of the induction machine.

A portable rotor diagnostic apparatus for diagnosing a failure of an induction machine facility, comprising: a three-phase inverter 100; The embedded sensor that is connected to the output terminal of the inverter 100 to measure the current output and controls the inverter 100 and analyzes the current measured from the current sensor 200 to diagnose the presence or absence of a fault. It characterized in that it comprises a system 300, a three-phase inverter 100, the portable terminal of the induction machine facility 10 including a current sensor 200 installed in the output terminal of the inverter 100 to measure the output current A method of using a rotor diagnostic device, comprising: PWM switching in the inverter (100) to designate a command voltage (V _s ) specifying an AC signal size and frequency to be applied to the inducer facility (S100); Applying the V _s from the inverter 100 to the induction machine facility 10 (S200); Measuring currents of the rotor 11 and the stator 12 of the induction machine facility 10 in the current sensor 200 (S300); Converting the current measured in step S300 to ADC to obtain a current response i _s (S400); Obtaining an impedance Z _eq through the V _s and i _s obtained in the step (S400) (S500); Obtaining an equivalent resistance R _eq equivalent reactance X _eq from the Z _eq (S600); It characterized in that it comprises the step of calculating the rate of change of each of the _s , Z _eq , R _eq, X _eq (S700) and diagnosing a failure through the step (S700) (S800).

In addition, in step S100, the V _s may be designated so that the inductor facility 10 can output a value between 1/8 to 1/4 of the rated current value.

In addition, in the step (S100), V _s may be designated so that the rotor 11 of the induction machine facility 10 can rotate 360 degrees.

In order to facilitate understanding, the present invention will be described by using a simulated rotor bar failure low-voltage induction motor (0.4kW) and a high-pressure induction motor (1500kW) in an actual industrial site in the laboratory environment.

The method proposed in the present invention for diagnosing a rotor failure of an induction motor is to diagnose an rotor failure of an induction motor by applying an alternating voltage to the stator winding using an inverter instead of a single winding transformer and detecting a current. As in the case of the single-phase AC rotation test, record the current measured at one position of the rotor, rotate the rotor constantly to the next position, and repeat the test. At this time, the position of the moving rotor is mechanically rotated one revolution. Referring to FIG. 5, a conceptual diagram of a proposed method using an inverter is shown, and is expressed by a 2-pole induction motor for easy interpretation.

In the technique of diagnosing an induction motor rotor failure using an inverter, which is a conventional technique, a diagnosis was performed by changing the position of an alternating magnetic field applied to the stator winding instead of rotating the rotor. However, this method has a disadvantage in that the fault diagnosis result is not clear due to the non-symmetrical nature of the stator winding of the induction motor. The method proposed in the present invention has an advantage of not affecting the asymmetry of the stator winding by rotating the rotor.

The difference between the proposed method and the existing single-phase rotation test is to inject a single-phase AC signal into an inverter, and its purpose is to design a system with a portable device so that it can be applied to actual industrial sites. This can increase the sensitivity of diagnosis by easily converting the size and frequency of the injection signal according to the target motor, and has the advantage of clarifying the relationship with the failure by analyzing the response of the applied voltage and current.

Next, the equivalent circuit analysis of the stopped induction motor will be described in detail with reference to the drawings. When a single-phase alternating current is applied to the three-phase stator winding of the Y-wired induction motor using an inverter as shown in FIG. 5, the DC voltage flows through the inverter switch S ₁ to the a-phase winding, passes through the neutral point, and b-phase, c-phase winding and It is applied to the inverters of the switches S ₆ and S ₂ . That is, current flows through the induction motor in the order of a-bc. In addition, through the switching of the inverters S ₃ , S ₅ , and S ₄ , an opposite voltage is applied, and an AC signal can be applied by flowing a current in the bc-a phase sequence. Then, PWM switching can be performed to supply an appropriate sinusoidal AC signal to the motor. This AC signal generates an alternating magnetic field with a fixed position in the stator as shown in FIG. 5.

Since the method proposed in the present invention is to apply a single-phase AC signal to the induction motor in a stopped state, the equivalent circuit of the induction motor when stopped is shown in FIG. 6. Since there is no rotational speed when the induction motor is stopped, slip s is equal to 1, and the rotor resistance in the equivalent circuit of FIG. 6 is expressed as R _r . In addition, since a single-phase voltage and current are applied to the electric motor, torque does not occur as in the characteristics of a single-phase inductor, and the rotor continues to stop. Therefore, the applied single-phase AC signal, such as the restraint test of the induction motor, can acquire the resistance and reactance components of the stator and the rotor through the current response. The sinusoidal AC signal generated by PWM switching of the proposed inverter through triangular wave comparison is expressed as the following equation.

-(1)

-(One)

-(2)

-(2)

-(3)

-(3)

를 기록할 수 있다. 또한 지령 전압과 취득한 전류로 등가 임피던스 Z_eq를 얻을 수 있다. 정지된 상태의 전동기는, 고정자(12) 자속이 회전자 내부로 깊숙하게 침투하기 매우 어렵기 때문에, 자화 리액턴스는 상대적으로 매우 크다. 즉,

와 같이 되어 등가 임피던스 Z_eq는 수식 (3)에서와 같이 R_eq와 X_eq로 구분할 수 있다. 이 때 등가 저항 R_eq는 고정자 저항 R_s와 회전자 저항 R_r로 구성되었으며, 등가 리액턴스 X_eq는 고정자 누설 리액턴스 X_ls와 회전자 누설 리액턴스 X_lr의 합으로 이루어 진다.V _s is an inverter command voltage value, which specifies the size and frequency, and i _s means the current response. It can be acquired through conversion of current sensor and ADC attached to a commercial inverter, and the size of the current

Can record. Also, the equivalent impedance Z _eq can be obtained from the command voltage and the obtained current. In the stationary motor, the magnetization reactance is relatively large because the stator 12 magnetic flux is very difficult to penetrate deeply into the rotor. In other words,

Equivalent impedance Z _eq can be divided into R _eq and X _eq as in Equation (3). At this time, the equivalent resistance R _eq is composed of the stator resistance R _s and the rotor resistance R _r , and the equivalent reactance X _eq is composed of the sum of the stator leakage reactance X _ls and the rotor leakage reactance X _lr .

, Z_eq , R_eq , X_eq 의 값은 변화하지 않는다. 이는 회전자가 평형상태이므로 인가한 교류 신호로 회전자에 유기된 전압이 회전자 회로를 통해 그 전류가 항상 일정할 것이기 때문이다.Next, the parameter analysis of the rotor bar failure will be described. In the case where the rotor bar is broken when the proposed method is implemented, the parameter change of the equivalent circuit mentioned above is as follows. Normal induction motors that do not have a broken rotor bar are parameterized wherever the rotor is located.

, Z _eq , R _eq , and X _eq values do not change. This is because, since the rotor is in a balanced state, the voltage induced in the rotor by the applied AC signal will always have a constant current through the rotor circuit.

일 때, 회전자가 파괴된 곳에는 전압이 유기되지 않는다. 이는 시간에 따라 교번하는 자속이 회전자 결함이 있는 곳에 거의 영향을 미치지 않기 때문이다. 따라서 현재 인가되는 교류 신호는 교번하는 자계를 만들고 이는 모두 정상인 회전자 바에 전압을 유기해 회전자 전류를 흐르게 한다. 즉, 등가회로의 파라미터

, Z_eq , R_eq , X_eq 의 값은 변화하지 않는다.On the other hand, if a defect occurs in the rotor bar, the result differs depending on the current rotor position, and the parameters change accordingly. 7 (a), the position of the rotor defect

When, the voltage is not induced where the rotor is destroyed. This is because alternating magnetic flux over time has little effect on rotor defects. Therefore, the alternating magnetic field currently applied creates an alternating magnetic field, which induces a voltage across the normal rotor bar to flow the rotor current. That is, the parameters of the equivalent circuit

, Z _eq , R _eq , and X _eq values do not change.

는 줄어들게 된다. 이는 곧 등가회로 상의 임피던스 Z_eq 가 증가하는 것으로 생각할 수 있다. 이 중 R_eq가 증가하는 이유는 회전자 회로가 끊어지기 때문이며, X_eq가 증가하는 이유는 부러진 회전자 바에 의해 누설되는 자속이 더욱 증가하기 때문이다.However, in the case of (b) of FIG. 7, the broken rotor bar is positioned at the point where the voltage is maximized by the alternating magnetic field. Then, the number of rotor bars through which the rotor current can flow is relatively reduced compared to FIG. 7 (a), and the magnitude of the current is reduced.

Will decrease. It can be thought that the impedance Z _eq on the equivalent circuit increases soon. Among them, the reason why R _eq increases is that the rotor circuit is cut off, and the reason why X _eq increases is that the magnetic flux leaked by the broken rotor bar further increases.

와 같이 변화한다. 이렇게 회전자 위치가 1회전 할 때, 각 파라미터의 변화를 예상해보면, 도 8 내지 도 9와 같이 나타난다. 도 7에서와 같이 극수는 2극이므로, 도 8 내지 도 9에서는 각 파라미터의 변화가 2번씩 반복하는 성분을 가진다. 이를 P극기에 대해 일반화 하면, 제안하는 방법을 시행했을 때 회전자가 기계각으로 2pi만큼 1회전하면 파라미터는 P번만큼 반복하는 결과를 가질 것이다.When the position of the rotor is mechanically rotated through the method proposed above, the rotor angle in FIG.

Changes as follows. In this way, when the rotor position is rotated by one rotation, if a change in each parameter is expected, it appears as in FIGS. Since the number of poles is 2 poles as in FIG. 7, in FIGS. 8 to 9, the change of each parameter has a component that is repeated twice. If this is generalized for the P polarity, when the proposed method is implemented, if the rotor rotates 1 by 2pi at the machine angle, the parameter will have the result of repeating P times.

In the present invention, each parameter was determined as a diagnostic factor for the rotor bar defect, and the rotor bar was rotated to 2 pi at a machine angle to perform a rotor bar failure diagnosis of the induction motor to analyze the results.

The following will be described in detail for the design and experiment method of the rotor bar failure diagnosis system of the induction motor based on the above method.

, Z_eq , R_eq , X_eq를 도출하였다. 도 2 내지 도 3에서는 제안한 방법을 수행하기 위한 고장 진단 시스템을 나타내었다. 좌측은 실험실에서 사용한 저압 유도 전동기로 모의 고장을 설계, 중앙은 시험 신호를 인가하는 3상 인버터, 그리고 우측은 인버터를 제어할 임베디드 시스템으로 구성되었다.To implement the diagnostic system that inputs the desired AC signal to the proposed method, the stationary electric motor, a commercial 3-phase inverter powered by 220 [V] was used, and NI and LabVIEW and myRIO were used to control the program and hardware. . At this time, the output value of the current sensor included in the three-phase output terminal of the inverter was read from the control unit and stored, and compared with the command voltage, which is the failure factor of the diagnostic system.

, Z _eq , R _eq and X _eq were derived. 2 to 3 show a fault diagnosis system for performing the proposed method. On the left, the low-voltage induction motor used in the laboratory was designed to simulate the failure, the center consisted of a three-phase inverter that applied a test signal, and the right one consisted of an embedded system to control the inverter.

In order to conduct a simulated failure experiment, a low-pressure squirrel cage induction motor with 32 conductor bars, 4 poles, 0.4 [kW], 380 [V] /1.2 [A], and aluminum die-cast in a laboratory environment was used. The breakdown was designed by breaking two and three rotor bars, respectively, and compared them with a normal rotor. This was done by drilling a hole in the aluminum conductor bar as shown in FIG. 10.

In addition, the same experiment was conducted for a high-pressure induction motor that was operated in an industrial site. The test was repeated before and after the failure of the motor with cracks in the rotor bar requested by the motor repair company. At this time, the specifications of the high-voltage induction motor used are 4 poles, 1500 [kW], and 6 [kV] / 270 [A], and are the motors with cracks in 3 conductors as shown in FIG. 10 among 36 rotor bars.

Below, the results of the above experiment and the analysis were conducted.

The low-voltage induction motor for simulation rotor failure used in the laboratory environment has a rated current of 1.2 [A] when operating at 60 [Hz] AC frequency. When the single phase AC rotation test method described above is applied, an excitation signal of about 1 / 8-1 / 4 of the rated current is required when the proposed method is implemented. Accordingly, through repeated experiments, 0.3 [A], which is 1/4 of the rated current, was designed to flow through the stator winding. At this time, the magnitude of the applied AC voltage was 25 [V].

The magnitude of the current value is shown in FIG. 11 for the normal state, the two broken state, and the three broken state of the rotor bar of the low pressure induction motor used in the laboratory as shown in FIG. 10. This confirms that the magnitude of the current decreases when the magnetic field due to the applied alternating current is induced to the rotor bar where the failure occurs as expected as the equivalent circuit in FIG. 8.

Since the tested electric motor is a 4-pole, the section in which the magnitude of the current to the mechanical angle of the rotor is reduced to 4 times occurs four times. Through this, in the case of a P-pole, a sinusoidal signal repeated P times during a mechanical rotation of the rotor can be detected. As a result of the acquisition, Fourier transform was performed on the waveforms, and the dotted lines were represented by only DC and basic wave components. The maximum and minimum fluctuation rate compared to the average value calculated from the fundamental wave components is 0.14 [%] in normal cases, 3.62 [%] in 2 broken cases, and 9.32 [%] in 3 broken cases. It was found that failure detection was possible only by the rate of variation of. The equation of the rate of change for detecting the failure used at this time is as follows.

-(4)

-(4)

12 shows the magnitude of the impedance value for the rotor failure of the laboratory low-voltage induction motor. This confirms that the value of the impedance increases with respect to the position where the rotor bar is broken as expected in FIG. 9. In addition, when the fundamental wave components are analyzed by Fourier transforming each impedance, the fluctuation rate appears as 0.23 [%] in the normal case, 4.47 [%] in the two broken cases, and 10.15 [%] in the three broken cases. It seems possible. The results of analysis of fluctuation rates of the current magnitude and the impedance magnitude for the failure detection of FIGS. 11 to 12 are summarized as in Table 1.

Fault detection
Rate of change [%]
Normal rotor

2 broken
Rotor
3 broken
Rotor Current magnitude 0.14 3.62 9.32 Impedance size 0.23 4.47 10.15

Table 1. The rate of change of parameters of the low-pressure inducer for fault detection

Meanwhile, the proposed method was also verified for high-voltage induction motors at industrial sites. As shown in Figure 10, the electric motor commissioned to the electric motor repair company is actually operated in the industrial site, and three cracks have occurred in the rotor bar. The experiment was repeated after the proposed method was performed on three cracked electric motors, and the repair was completed and the test was repeated while the normal rotor was reassembled. For this motor, the current for conducting the test with a rated current of 270 [A] shall be excited with a current of 34 [A] or more, which is 1/8 of the rated current. However, due to the limitations of the portable rotor diagnostic system, it was impossible to excite a large current, and a test was conducted with a current of 5 [A]. At this time, the magnitude of the applied voltage is 12 [V] and the frequency is 60 [Hz].

In FIG. 13, the equivalent impedance obtained by experimenting with a cracked high-voltage induction motor is divided into resistance components and reactance components, respectively. Since the number of poles of the tested motor is four, the component that repeats four times when the rotor is mechanically rotated must be observed. That is, if the rotor is rotated by 1/2, a sine wave of 2 [Hz] is generated in the impedance component that repeats when a failure occurs. In the embodiment of the present invention, the rotor is obtained up to the machine angle pi under the conditions of the field test, and the results are shown.

When the rotor circuit is broken due to cracks in the rotor bar, when the AC signal is applied, the equivalent resistance component of the circuit through which the current due to the voltage induced in the rotor circuit will flow becomes larger. In addition, the amount of magnetic flux that cannot be transmitted from the stator to the rotor circuit also increases, resulting in an increase in leakage inductance, which soon appears as an equivalent reactance component. Equivalent resistance and equivalent reactance, like the impedance results of a laboratory motor, can be seen to increase in value for a motor that has failed. As shown in Table 2, the results of FIG. 13 show the rate of change for failure detection for the fundamental wave.

Fault detection
Rate of change [%] Before repair
(3 broken rotors) After repair
(Normal rotor) Resistance size 18.08 0.05 Reactance size 5.06 0.05

Table 2. Impedance fluctuation rate of high pressure induction machine before and after repair

This shows that it is more sensitive to observe the resistance component of the impedance component when a rotor failure occurs. It should be noted that the results were clearly observed even when experiments were performed with a current of about 1.8 [%] compared to the rated current. Since the amount of magnetic flux to be excited is proportional to the magnitude of the applied current and inversely proportional to the frequency, it is judged that a current of 60 [Hz] generated sufficient magnetic flux to diagnose a rotor failure. If the applied frequency is increased, the excitation magnetic flux will be reduced, and the rate of change of the fundamental wave of each parameter will be reduced and it will be difficult to diagnose the rotor failure.

The embodiment of the portable rotor diagnostic apparatus of the induction machine facility according to the present invention and the method of using the same are exemplified by using a two-pole induction motor to help understanding of the present invention. Therefore, a 4-pole induction motor or the like may be applied, including a 2-pole induction motor.

Although described above with reference to the drawings according to embodiments of the present invention, those skilled in the art to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above.

10: Induction machine equipment
11: rotor
12: stator
100: 3-phase inverter
200: current sensor
300: embedded system

Claims (4)

delete Three-phase inverter 100; 2-pole or 4-pole including a current sensor 200 for measuring current and an embedded system 300 that controls the inverter 100 and analyzes the current measured from the current sensor 200 to diagnose the presence or absence of a fault. In the method of using a portable rotor diagnostic device for diagnosing the failure of the induction machine 10,
Designating a command voltage Vs specifying an AC signal size and frequency to be applied to the inducer facility 10 by PWM switching in the inverter 100 (S100);
Applying the Vs from the inverter 100 to the induction machine facility 10 (S200);
Measuring currents of the rotor 11 and the stator 12 of the induction machine facility 10 in the current sensor 200 (S300);
Converting the current measured in step S300 to ADC to obtain a current response is (S400);
Obtaining an impedance Zeq through the Vs and is obtained in the step (S400) (S500);
Obtaining an equivalent resistance Req and an equivalent reactance Xeq from the Zeq (S600);
Calculating the rate of change of each of the is, Zeq, Req, and Xeq (S700);
Including the step (S800) for diagnosing a failure through the step (S700),
In the step (S100), the Vs is designated so that the rotor 11 of the induction machine facility 10 can rotate 360 degrees,
The step of diagnosing the failure (S800) analyzes the equivalent circuit of the induction machine facility 10 when it is stopped, and for this purpose, PWM switching to supply a sinusoidal AC signal to the induction machine facility 10, the position of which is fixed at the stator Characterized in that the diagnosis by generating an alternating magnetic field,
In the step (S100), the Vs is characterized in that the inductor facility 10 is designated to output a value between 1/8 to 1/4 of the rated current value,
The step (S700),
Characterized in that it calculates the rate of change through the following rate of change equation,
The step (S800),
A method of using a portable rotor diagnostic device of an inductor facility, characterized in that a fault is diagnosed by Fourier transforming the impedance Zeq to analyze the fundamental component.

<Equation of variation rate for fault detection>
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