HK1087778B - Method of harmonic diagnosis for electric equipment - Google Patents

Description

Harmonic diagnostic method for electrical equipment

Technical Field

The present invention belongs to the field of electrical equipment diagnostics and relates to a method for harmonic diagnostics for electrical equipment such as motors and inverters.

Background

Recent electric apparatuses have been attempting to improve productivity through a continuous and integrated production process. Furthermore, energy saving devices such as transformers have been introduced in a large range together with highly automated execution systems in order to obtain very reliable equipment. Such mass production is required in various industrial fields.

Large-scale production facilities are typically operated continuously, while failures (shutdowns) in electrical facilities tend to bring the entire process to a standstill. Once a failure occurs, it can compromise not only the manufacturing process but also lose customer confidence or even have catastrophic consequences. Thus, the loss of downtime is immeasurable and can lead to a fatal problem.

Since there are no standard or uniform inspection rules currently, when a business purchases and inspects entirely new equipment (machines), they have to check to determine whether the equipment (machines) is functioning according to its specifications. However, recent automatic apparatuses (machines) have a comprehensive system structure in which a large number of apparatuses are connected via interface cables, and thus there may be a mismatch between the systems to cause a lot of troubles or even a fire accident in the future.

Furthermore, transportation equipment such as the rails and elevators of the conveying personnel must be regularly overhauled in accordance with regulations; however, the power conversion apparatus (AC-AC converter) and the inverter including the motor apparatus are only checked for the presence of a temperature rise or abnormal noise, leaving an unsolved safety problem.

The purpose of diagnosing abnormality and deterioration of the electrical equipment includes: increase the operating rate by reducing equipment downtime; reducing maintenance costs, including material and labor costs; other costs are reduced by extending replacement periods and reducing inspection maintenance; preventing a fault; and to improve safety, reliability, productivity and quality.

The background and the purpose of diagnosing the necessity of abnormality and deterioration of the electrical apparatus are described above. In sections 1 and 2 below, a conventional method of diagnosing abnormalities and deterioration in a motor and inverter according to the present invention will be briefly described.

1. Diagnosis of abnormality and deterioration of motor

The method for diagnosing abnormality and deterioration of a motor includes: (1) a vibration method; (2) a sonic method; (3) temperature method; (4) a torque method; (5) a current method; and (6) a waveform method, of which the vibration method most frequently applied will be described below. Other diagnostic methods will not be described here because they have already been described in the patents filed by the inventors of the present invention (Japanese patent application Nos. 2000-386603, 2001-265949, 2001-358718 and 2003-030807).

The diagnosis by vibration is simple and accurate. In a simple diagnosis, an abnormality is determined by the total value of vibration of a rotary machine in an electric motor or a loading apparatus including the electric motor by mounting a vibration pickup of an electric type, a piezoelectric type, or a displacement type (displacement) as close to a vibration source as possible. In accurate diagnosis, the cause and location of abnormalities and deteriorations are determined by vibration frequency analysis. Such diagnostics are limited to mechanical elements such as bearings and rotating shafts.

As described above, for simple diagnosis, some enterprises make a judgment between abnormal and normal with their own standards by a vibration total value based on accumulated data and experience. However, most other enterprises rely on the ISO standard, JIS standard or VDI standard (german engineers' relevant standards). However, these criteria provide only an average estimate and cannot be applied to all rotating machines. For example, ISO standards and JIS standards are ISO-2372 and JIS-B0906, respectively.

When an abnormality is judged by a simple diagnosis, it is necessary to judge the cause and the position with an accurate diagnosis. Typically, the vibration signal generated from a rotating machine is intricate and not simple at all. Frequency analysis is most widely used in order to obtain important information from the signal to accurately determine whether an anomaly is present. The frequency analysis taken on the vibration signal makes it possible to determine the cause and location of the abnormality.

For a rotary machine including these motors, it is not accurate because the relationship between the cause of abnormality and the number of vibration events is obtained from data accumulated over a long period of time.

2. Diagnosis of converter abnormality and deterioration

The inverter has advantages of energy saving, productivity improvement and operability, so it is useful to realize various kinds of high-tech industrial machines. Inverters are now an essential device in motor installations, and their production capacity has increased year by year. According to the current production survey of MITI (now METI), the output of the Japanese industrial transformer exceeds 1,800,000 (equivalent to about 1000 billion yen) in the fiscal year 1999.

Incidentally, the inverter is formed of a large number of electronic components including, for example, an integrated circuit, a resistor, a capacitor, and a transistor, and other components such as a cooling fan and a relay. These elements cannot be used permanently, and their service life depends to a large extent on the working environment. The operating life of almost all electronic components follows the Arrhenius law (rule of doubling every 10 c: the operating life doubles every 10 c decrease in ambient temperature), so the converter needs to be serviced regularly.

For the diagnosis of abnormalities and deterioration of the converter, JEMA (Japan Electrical manufacturers Association) recommends regular maintenance in its manual "An environmental of Periodic Inspection of General-purpose-Purposelnverter" to prevent the occurrence of potential failures.

However, in the diagnosis of abnormality and deterioration of the inverter, determining the cause and location of the abnormality and deterioration requires stopping or even disassembling the inverter for inspection by a special measuring instrument for a special purpose. In fact, the converters are often used until they are disassembled. During this time, the converters tend to cause deterioration in their functions such as the energy saving function and the protection function, and cause abnormality in their output characteristics. In addition, the inverter tends to adversely affect other devices, such as causing a robot malfunction or motor failure.

Disclosure of Invention

Among diagnostic methods for abnormality and deterioration of a motor and an inverter, a vibration method is most widely used for the motor. Because its mounting affects the accuracy of the motor, the sensor (pickup) must be mounted close to the vibration source. In addition, the positions of abnormality and deterioration to be diagnosed are limited to mechanical elements such as bearings and rotating shafts. Furthermore, the measurement is time consuming and the diagnostic costs including the measurement device are expensive. For this reason, this diagnostic method is mainly used for relatively large and very important machines.

The explanation of other diagnostic methods for the motor will be omitted. Unlike the vibration method, all of these methods cannot determine the cause and location of abnormality and deterioration, and in particular, an online inspection system that can only diagnose abnormal loads is extremely expensive.

In addition, in the diagnosis of abnormality and deterioration of the inverter as described earlier, the judgment of the cause and location of the abnormality and deterioration requires stopping or even disassembling the inverter for inspection by a special measuring instrument for a professional. This is very cumbersome, time consuming, and expensive.

In order to diagnose the deterioration of the motor and the inverter, the inventor of the present invention applied for Japanese patent application Nos. 2000-386603, 2001-265949 and 2001-358718 as a new method for judging the degree of deterioration of the motor and the cause and position thereof by the magnitude of the relative harmonic content in the current.

However, these harmonic diagnosis methods invented by the inventors of the present invention are absolute methods in which calculation is performed by previously acquiring rated capacity, power supply impedance, load factors of the motor and the converter, parallel equivalent capacitance of loads other than these devices, operating voltage, harmonic measurement type, and the like. These time-consuming diagnostic methods are not necessarily simple methods. Further, the relationship between the harmonics and the location of the deterioration, i.e., the deteriorated portion, is unclear.

The harmonic diagnosis method for an electric apparatus such as a motor and an inverter according to the present invention can solve the existing problems by the harmonic diagnosis based on the above-described absolute method by the present inventors.

In a method of determining an abnormality of an electric motor or an inverter based on a diagnostic deterioration of current harmonics flowing into the electric motor and the inverter constituting an electric appliance, the deterioration is judged by comparing an indication value (indexvalue) obtained by dividing a relative harmonic content of each order of the current harmonics by a total harmonic distortion of a predetermined order of the current harmonics with a standard value obtained by multiplying a harmonic function of each order formed by the indication value by a calculated value for diagnosis of each order found by calculation from the relative harmonic content of each order. The degrees of deterioration of the motor and the inverter are distinguished from each other by weighting standard values, and the deteriorated portion is judged by a specific harmonic order of the current harmonic.

The harmonic diagnosis method of the electric apparatus according to the present invention is performed by measuring the current harmonics flowing into the motor and the inverter, however, this method does not depend on the capacitance of the motor or the inverter. This method is also independent of the power supply impedance, load factor, load parallel equivalent capacitance outside these devices, operating voltage, harmonic measurement type, etc., and is therefore a very simple diagnostic method.

Furthermore, the relationship between harmonics and the deteriorating parts of the motor and the converter has been elucidated with fundamental analytical methods. It is therefore possible to discriminate the degree of deterioration based on this basic analysis method, and the harmonic diagnosis method according to the present invention is very practical and potentially extends to the industrial society.

Drawings

Fig. 1 is a block diagram of a converter.

Fig. 2 is a view explaining generation of harmonics.

Fig. 3A to 3H are examples of oscillating current waveforms and their corresponding autocorrelation functions.

Fig. 4 is a flow chart for diagnosing the motor.

Fig. 5A to 5C are flowcharts of the diagnostic converter.

Detailed Description

Embodiments of the present invention will be described below with reference to the accompanying drawings.

Fig. 1 is a block diagram of a converter. Reference numeral 1 denotes a three-phase alternating current power supply, and input power 1' flows into a converter section 4 of an AC-AC inverter 3 that controls a motor 2. Reference numerals 5 and 6 denote a smoothing capacitor and an inverter section, respectively, and the output power 2' is controlled by a control section 7 and a drive section 8. The control section 7 and the drive section 8 are a control board and a drive board, respectively, on which electronic parts such as an integrated circuit, a resistor, a capacitor, and a transistor are mounted. When the AC-AC converter 3 is according to the sine wave PWM technique, the input current and the motor current (output current) have the waveforms shown in fig. 1.

After the converter section 4 rectifies all waveforms, the AC-AC converter 3 has an input current as shown in fig. 1 due to the presence of the smoothing capacitor 5. This phenomenon will be described below.

Fig. 2 shows an example of the generation of a single-phase harmonic. Since the smoothing capacitor 5 shown in fig. 1 is used to convert a three-phase alternating-current power supply into a direct-current power supply, the pulse-like current shown in fig. 2 flows into the capacitor 5 only during charging. In this figure, τ denotes the pulse width and H denotes the pulse height. The current difference between the ac power source and the dc power source generates harmonics.

Incidentally, when a sinusoidal current is supplied to the U-phase, the V-phase, and the W-phase of the motor, magnetomotive force F_u、F_vAnd F_wAre expressed by the following equations, respectively.

(numerical formula 1)

F_u＝AI_u sinωt[cosθ-(1/3)cid3θ+(1/5)cos5θ+……]

F_v＝AI_v

sin(ωt-120°)[cos(θ-120°)-(1/3)cos3(θ-120°)+(1/5)cos5(θ-120°)+……]

F_w＝AI_w

sin(ωt-240°)[cos(θ-240°)-(1/3)cos3(θ-240°)+(1/5)cos5(θ-240°)+……]

Numerical formula 1 indicates magnetomotive force at a distance θ (electrical angle) on the circumference with the magnetomotive force center of the rotor as a base point. A represents a constant; i is_u、I_vAnd I_wRespectively representing the effective values of the current at the U phase, the V phase and the W phase; ω is the angular velocity expressed by 2 π f (rad/s) with frequency f, and t represents time. Therefore, the synthesized magnetomotive force F is as follows, taking into account the nth harmonic.

(numerical formula 2)

F＝(3B/2)

F_m{sin(θ-ωt)+(K_1，5/5)sin(5θ+ωt)+(K_1，7/7)sin(7θ-ωt)+(K_1，11/11)sin(11θ+ωt)+(K_1.13/13)sin(13θ-ωt)+……}

Wherein B represents a constant, F_mRepresents the maximum value of the amplitude of the fundamental magnetomotive force, and_1，nrepresenting the winding coefficient of the nth order harmonic.

Numerical formula 2 indicates as follows.

(1) When I is_u＝I_v＝I_wWhen n is 3, 9, 15 …, harmonics such as n become zero.

(2) Harmonics such as n-5, 11, 17 … are rotated with respect to the fundamental by omega/n,

(3) harmonics such as n 7, 13, 19 … are rotated in the same direction as the fundamental by ω/n,

on the other hand, making the current waveform shown in fig. 2 a rectangular pulse wave, f (x) can be represented by a fourier series in the following numerical formula.

(numerical formula 3)

Where x ═ ω t (ω: angular velocity, t: time) and n denote the harmonic order. As is apparent from numerical formula 3, when the smoothing capacitor 5 is in an ideal state, there is no pulse current caused by the charging current, and therefore f (x) is 0. The capacitance decreases as the smoothing capacitor 5 deteriorates, and harmonic components having a low order such as n-5, 7 increase in the numerical formula 3. Note that from numerical formula 1, it can be seen that n-3, or the 3 rd harmonic is very small (at I)_u＝I_v＝I_wZero in the case of (d).

The relationship between current harmonics and deterioration states of the motor and the inverter has first been elucidated by the inventors of the present invention. The contents are as follows.

The motor is designed to contain harmonics as small as possible because it contains harmonic components in the magnetomotive force as shown in numerical equation 2. Even so, the harmonic wave is larger than the theoretical value due to the unbalance of the power supply voltage and the like. In addition, it is well known that converters also generate harmonics.

The deteriorated portion of the motor will be described below. The deteriorated portion may be a mechanical element such as a bearing and a rotating shaft or an electrical element such as a stator winding. In particular, when there is degradation in the mechanical element, the motor current contains an irregular vibration component. This obviously also includes regular harmonic components. Therefore, by using the autocorrelation function R (τ) shown in the following numerical formula, only the fundamental harmonic component can be extracted from an arbitrary irregular current waveform.

(numerical formula 4)

Wherein, t: time, τ: 1/f₀(f₀Rotation frequency), T: time. Fig. 3A, 3B, 3C, and 3D are examples of arbitrary current waveforms from which the fundamental component has been removed, and autocorrelation functions corresponding to them are shown in fig. 3E, 3F, 3G, and 3H, respectively. FIGS. 3A-3H indicate when the DNA fragment is obtained by extraction fromWhen the correlation function finds that f changes randomly every second, R takes a value only if τ is 0 and becomes 0 in other cases. Thus, in the case of the waveforms shown in fig. 3A, 3B, 3C, and 3D, fig. 3D has the highest correlation between harmonics.

When there is deterioration in an electrical component such as a stator winding, a change in the magnetic flux inside the coil conductor causes an eddy current such as an eddy current to flow only inside the conductor. The eddy current causes a local temperature rise in the deteriorated portion of the coil insulator, thus causing imbalance between the respective phase currents. This results in I in numerical equation 1_u≠I_v≠I_wAnd prominent 3 rd order harmonics. Further, the 3 rd order harmonic repeats a phenomenon in which the temperature is locally continuously raised in the deteriorated portion.

On the other hand, the smoothing capacitor 5 shown in fig. 1 has been described above with respect to deterioration of the converter. When the other electric elements (the converter section 4 and the inverter section 6), the control section 1 and the drive section 8 are deteriorated, the harmonic component in the current of the output power 2' shown in fig. 1 increases, thereby showing an abnormal value. The inventors have found that motor and inverter degradation is associated with a number of specific harmonics. The following is an explanation regarding the determination of such deterioration.

Fig. 4 is a flow chart for diagnosing the motor. Step S10 finds the Total Harmonic Distortion (THD) of the harmonics contained in the current of the output power 2' shown in fig. 1. The detection of current harmonics can be done using a well known device such as a clamp circuit measurement or a contactless electromagnetic field measurement with a search coil. The harmonic order from which the total harmonic distortion is found may be, for example, 2 nd to 40 TH orders, and step S11 performs an indication calculation to find an indication value (TH) by dividing the relative harmonic content (content) of each order by the total harmonic distortion found at step S10_k)。

Then, the process proceeds to step S12 to determine deterioration. CH (CH)_kIs a standard value of the K-TH harmonic wave to be described later, and is compared with TH found at step S11_kAnd (6) comparing. Thus, the process isThe motor proceeds to step S13 when it is in the standard state, and proceeds to step S14 when it deteriorates. A flow chart for diagnosing the converter is shown in fig. 5A to 5C. Fig. 5A is a flowchart of diagnosis of the smoothing capacitor 5 shown in fig. 1, which also judges deterioration by measuring a current harmonic of the input power 1' shown in fig. 1. Steps P100 and P112 have the same calculation contents as steps S10, S11, and S12 shown in fig. 4.

Fig. 5B is a flowchart of a diagnosis of the converter section 4, the inverter section 6, and the control section 7 shown in fig. 1, which also judges deterioration by measuring a current harmonic of the output power 2' shown in fig. 1. Steps P200, P211, and P212 have the same calculation contents as steps P100, P111, and P112 shown in fig. 5A.

Fig. 5C is a flow chart of a diagnosis of the drive section 8 shown in fig. 1, which also judges deterioration by measuring current harmonics of the output power 2' shown in fig. 1. At step P200 ', the 38 th harmonic content is found and the drive plate is diagnosed (step P201'). The diagnosis of the drive plate is based on the standard value CH of the 38 th harmonic_K1.0 (step P202'). In step P203', CH_kAnd the 38 th harmonic content (H)₃₈) And comparing to judge whether the driving plate is good or bad.

Standard value CH shown in fig. 4 and fig. 5A, 5B, 5C_kIt is found that K denotes the K-th harmonic, and C_kRepresents a calculated value for diagnosing the K-th harmonic.

Considering the electric motor:

(numerical formula 5)

CH_k＝C_k×f(M_k)

Wherein, f (M)_k) Is a kth order harmonic function.

Considering the converter:

(numerical formula 6)

CH_k＝C_k×f(N_S)

CH_k＝C_k×f(N_C)

CH_k＝C_k×f(N_P)

CH_k＝C_k×f(N_d)

Wherein f (N)_s)、f(N_c) And f (N)_p) Is a plurality of K-th order harmonic functions, and f (N)_d) 1.0 (CH only in this case)_k＝1.0)。

In numerical formulas 5 and 6, C_k、f(M_k)、f(N_s)、f(N_c) And f (N)_p) As will be explained in the following examples.

The degree of deterioration of the motor and the inverter (hereinafter referred to as a device) is determined as follows: "Normal"; "alarm required"; and "spoiling" to facilitate display quality. These "normal", "alarm required" and "damage" are referred to for convenience as A, B and C, respectively. Level B "alarm required" is also distinguished, depending on the degree of deterioration of the device: mild exacerbation B1 (exacerbation of the problem does not occur in about half year of operation); moderate exacerbations B2 (which will allow for about three months of operational exacerbations, but require trending control); and severe deterioration B3 (deterioration that requires preparation for replacement or repair because the probability of occurrence of a failure in the device is high).

The above described service period can be considered as only a principle, since the diagnosis and inspection period after deterioration depends on environmental conditions such as the number of hours of operation of the apparatus, the ambient temperature and the ventilation condition.

The above-mentioned levels: A. b1, B2, B3 and C are distinguished from each other by multiplying the weighting factors by the above-mentioned standard values. These factors will be explained in the following embodiments. The multivariate analysis technique is effectively used to perform an analysis by focusing on the relationship between the current harmonics and the deteriorated portion of the device, and thus such a technique will be explained below. In case there is no external criterion to judge the deterioration of the device according to the invention given earlier, the underlying analysis method in multivariate analysis is most suitable in order to analyze the relation between the characteristic values of the multidimensional events.

Since there are a large number of documents about the basic analysis method, a detailed description thereof will be omitted. The following description explains the relationship between the current harmonics and the deteriorated portion of each motor and converter by using the contribution rate (contribution rate) of the fundamental analysis method. In the following description, numerals in parentheses after the main component indicate contribution rates. The principal components are shown in descending order of feature values (principal component score assignment).

1. Electric motor

(1) An abnormality of the rotating shaft and the bearing (motor main body) or a damaged mounting of the motor. The main components of the four findings are: harmonics of order 2 (55), 3 (9), 4 (16) and 5 (6). The cumulative contribution rate of the major components employed is 86%, thus fully satisfying the commonly employed value of 60% or higher.

(2) Poor insulation of the stator windings (between phases and to ground). The main components of the four findings are: harmonics of order 2 (7), 3 (61), 4 (5) and 5 (22). The cumulative contribution is 95%.

(3) Damage of the rolling bearing and the housing (motor main body). The main components of the four findings are: harmonics of order 2 (23), 3 (10), 4 (41) and 5 (8). The cumulative contribution rate is 82%.

(4) The air gap between the stator and the rotor is not uniform (dirt adhesion and local overheating). The main components of the four findings are: harmonics of order 2 (6), 3 (20), 4 (8) and 5 (59). The cumulative contribution is 93%.

(5) Unbalance of the load end rotating shaft or poor coupling (coupling). The main components of the five findings are: harmonic of order 6 (5), 7 (53), 8 (7), 9 (11) and 10 (15). The cumulative contribution is 91%.

(6) Damage to the load end bearing or fouling of the load end system (e.g., the conduit valve of an air pump). The main components of the five findings are: harmonic 6 (7), harmonic 7 (29), harmonic 8 (35), harmonic 9 (13) and harmonic 10 (11). The cumulative contribution is 95%.

(7) Anomalies in the load end rotating shaft (e.g., shaft bending) or wear in the load end system (e.g., coupling between the conduit and valve of the air pump). The main components of the five findings are: the 6 th (5), 7 th (21), 8 th (25), 9 th (33) and 10 th (8) harmonics. The cumulative contribution is 92%.

(8) Damage to the load side pulley, clutch, V-belt, etc. The main components of the five findings are: the cumulative contribution of the 6 th harmonic (6), 7 th harmonic (23), 8 th harmonic (17), 9 th harmonic (15) and 10 th harmonic (30) is 93%.

2. Converter with a voltage regulator

(1) Degradation of smoothing capacitor

The current harmonics at the converter input are measured and two main components are found. The components found are the 5 th harmonic (62) and the 7 th harmonic (36), and the cumulative contribution is 98%.

(2) Abnormality of the control board (particularly deterioration of the electrolytic capacitor). The current harmonics on the converter output are measured and the six main components are found. The components found are: the cumulative contribution of 11 th harmonic (21), 13 th harmonic (17), 17 th harmonic (19), 19 th harmonic (13), 23 th harmonic (11), and 25 th harmonic (15) is 96%.

(3) Deterioration of power elements (particularly deterioration of inverse transform elements).

The current harmonics on the converter output are measured and sixteen principal components are found. The components found are: the harmonic wave generator comprises 2 nd order harmonic wave (3), 3 rd order harmonic wave (16), 4 th order harmonic wave (2), 5 th order harmonic wave (13), 6 th order harmonic wave (2), 7 th order harmonic wave (17), 8 th order harmonic wave (2), 9 th order harmonic wave (2), 10 th order harmonic wave (2), 11 th order harmonic wave (6), 13 th order harmonic wave (4), 17 th order harmonic wave (7), 19 th order harmonic wave (5), 23 th order harmonic wave (5), 25 th order harmonic wave (6) and 38 th order harmonic wave (7). The cumulative contribution is 99%.

(4) The deterioration of the drive plate (mainly the deterioration of the capacitor) the current harmonics at the converter output are measured. Only one principal component is sufficient and the component found is the 38 th harmonic. The contribution rate was 89%.

In the motor described above, the current harmonic on its input is measured without being controlled by the inverter, and the current harmonic (input of the motor) on its output is measured with it being controlled by the inverter.

The above description can be summarized into tables 1 and 2 shown below.

(Table 1)

Deteriorated part and current harmonics of motor apparatus

(Table 2)

Deteriorated part of converter equipment and current harmonic

Note that the smoothing capacitor has harmonics on the converter input, while the other capacitors have harmonics on the converter output.

Examples

With the embodiment of the present invention, the calculated value for diagnosis and the kth order harmonic function necessary for the deterioration judgment of the motor and the inverter will be described by citing specific examples. However, the present invention is not limited to this embodiment. In the following description, H_kIs the K-th order harmonic content.

(1) Diagnosis of the motor (diagnosis of the motor main body). When K is 2, 3, 4, 5, Σ is taken to be 2 to 5. The procedure for finding Ck is as follows.

1M_o＝(∑H² _k)^1/2

2A_k＝H_k/M_o

3T_o＝∑A_k

4C_k＝A_k/T_o

On the other hand, f (M)_k) The following values are possible. In the following numerical formula, I_kIndicating the value of the k-th harmonic.

f(M₂)＝S₁×(∑I_k-I³ ₂)

f(M₃)＝S₂×(∑I_k-I³ ₃)

f(M₄)＝S₁×(∑I_k-I₄)

f(M₅)＝S₂×(∑I_k-I³ ₅)

In the case of inverter-driven motors, S₁＝S₂1.0, and in the case of a separate motor (without inverter), S₁1.15 and S₂＝1.25。

(2) Diagnosis of the motor (diagnosis of motor load). When K is 6, 7, 8, 9 or 10, Σ is taken to be 6 to 10. The procedure for finding Ck is as follows.

1M_o＝(∑H² _k)^1/2

2A_k＝H_k/M_o

3T_o＝∑A_k

4C_k＝A_k/T_o

On the other hand, f (M)_k) The following values are possible. In the following numerical formula, I_kIndicating the value of the k-th harmonic.

f(M₇)＝S₂×(∑I_k-I³ ₇)

f(M₈)＝S₁×(∑I_k-I₈)

f(M₉)＝S₁×(∑I_k-I₉)

f(M₁₀)＝S₁×(∑I_k-I₁₀)

In the case of inverter-driven motors, S₁＝S₂1.0, and in the case of a single motor (without inverter), S₁1.15 and S₂＝1.25。

(3) Diagnosis of a converter

3.1. And (4) diagnosing a smoothing capacitor.

When K is 5 or 7, Σ takes K5 to 7. Discovery C_kThe procedure of (2) is as follows.

1M_o＝(∑H² _k)^1/2

2A_k＝H_k/M_o

3T_o＝∑A_k

4C_k＝A_k/T_o

On the other hand, f (N)_s) The following values are possible. In the following numerical formula, I_kIndicating the value of the k-th harmonic.

f(N_s)＝∑I_k

3.2. And controlling the diagnosis of the board.

When K is 11, 13, 17, 19, 23, or 25, Σ takes from 11 to 25. Discovery C_kThe procedure of (2) is as follows.

1M_o＝(∑H² _k)^1/2

2A_k＝H_k/M_o

3T_o＝∑A_k

4C_k＝A_k/T_o

On the other hand, f (N)_c) The following values are possible. In the following numerical formula, I_kIndicating the value of the k-th harmonic.

f(N_c)＝∑I_k-I² _k：f(N_c)₁₁、f(N_c)₁₃、f(N_c)₁₇、f(N_c)₁₉、f(N_c)₂₃And f (N)_c)₂₅Six function values of (1).

3.3. And (4) diagnosing the power element. When K is 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 17, 19, 23, 25, or 38, Σ takes from 2 to 38. Discovery C_kThe procedure of (2) is as follows.

1M_o＝(∑H² _k)^1/2

2A_k＝H_k/M_o

3T_o＝∑A_k

4C_k＝A_k/T_o

On the other hand, f (N)_P) The following values are possible. In the following numerical formula, I_kIndicating the value of the k-th harmonic.

f(N_P)＝∑I_k-I² _k：f(N_p)₂、f(N_p)₃、f(N_p)₄、f(N_p)₅、f(N_p)₆、f(N_P)₇、f(N_P)₈、f(N_p)₉、f(N_p)₁₀、f(N_p)₁₁、f(N_p)₁₃、f(N_p)₁₇、f(N_p)₁₉、f(N_p)₂₃、f(N_p)₂₅And f (N)_p)₃₈Sixteen function values.

3.4. Diagnosis of the driver board. As described above, the drive plate is diagnosed only by the magnitude of the 38 th harmonic content shown in FIG. 5C. Thus, C_k1.0, and f (N)_d)＝1.0。

Examples of differences between the deteriorated portions and the degrees of deterioration (A, B1, B2, B3, and C) of the electrical apparatus explained in the embodiments of the present invention are shown in tables 3 and 4 below.

(Table 3)

Distinction between deteriorated portion and degree of deterioration of motor

Wherein, CK: calculated value for diagnosing the K-th harmonic, f (M)_k)：Harmonic function of the K order

(Table 4)

Differentiation between deteriorated parts and degrees of deterioration of a converter arrangement

Wherein, Ck: calculated value for diagnosing the K-th harmonic, f (N)_s、N_c、N_p、N_d): the kth harmonic function.

Note that Ck and f (N) shown in Table 4_s、N_c、N_p、N_d) The numbers in (a) correspond to two smoothing capacitors, 6 control boards, 16 power elements, and one drive board. Therefore, in order to distinguish the degrees of deterioration, the drive plates are excluded from finding the degrees of deterioration and averaged, respectively. For example, the calculations of a-0, B1-1, B2-2, B3-3 and C-4 are completed and averaged (decimal rounding).

As described above, measuring the current harmonics can judge the deteriorated portion of the motor or the inverter of the electric apparatus, and can also distinguish the degree of deterioration.

Claims (5)

1. A harmonic diagnosis method for an electric apparatus for judging abnormality of a motor or a converter from current harmonics flowing to the motor and the converter forming the electric apparatus, determining deterioration by comparing an indicated value with a standard value, wherein the indicated value is obtained by dividing a relative harmonic content of each order of the current harmonics by a current harmonic total harmonic distortion of a predetermined order, the standard value is obtained by multiplying a harmonic function of each order formed by the indicated value by a calculated value for diagnosis of each order found by calculation from the relative harmonic content of each order, wherein degrees of deterioration of the motor and the converter are distinguished from each other by weighting the standard values, and the deteriorated portion is determined based on a specific harmonic order of the current harmonics.

2. The harmonic diagnostic method for an electrical device according to claim 1, wherein the specific harmonic orders are odd orders and even orders.

3. The harmonic diagnosis method for electric equipment according to claim 1, wherein the degree of deterioration is classified into "normal", "alarm required", and "damage".

4. The harmonic diagnostic method for an electrical device according to claim 2, wherein the odd-numbered and even-numbered orders are 2 nd, 3 rd, 4 th, 5 th, 6 th, 7 th, 8 th, 9 th, 10 th, 11 th, 13 th, 17 th, 19 th, 23 th, 25 th and 38 th orders.

5. The harmonic diagnosis method for electric equipment according to claim 3, wherein the "alarm required" is classified into: mild exacerbations, moderate exacerbations, and severe exacerbations.