CN112327228A - Method and device for detecting loss-of-field state of permanent magnet by using current - Google Patents
Method and device for detecting loss-of-field state of permanent magnet by using current Download PDFInfo
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- CN112327228A CN112327228A CN202011137040.2A CN202011137040A CN112327228A CN 112327228 A CN112327228 A CN 112327228A CN 202011137040 A CN202011137040 A CN 202011137040A CN 112327228 A CN112327228 A CN 112327228A
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- 238000000034 method Methods 0.000 title claims abstract description 25
- 230000005347 demagnetization Effects 0.000 claims abstract description 6
- 238000004458 analytical method Methods 0.000 claims description 17
- 238000010586 diagram Methods 0.000 claims description 9
- 238000000354 decomposition reaction Methods 0.000 claims description 3
- 230000005389 magnetism Effects 0.000 abstract description 5
- 230000005284 excitation Effects 0.000 description 3
- 230000001360 synchronised effect Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/12—Measuring magnetic properties of articles or specimens of solids or fluids
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Abstract
The invention relates to a method for detecting the loss-of-field state of a permanent magnet by using current, which is applied to a permanent magnet motor and comprises the following steps: obtaining the fundamental wave amplitude of any phase current in the three-phase current of the permanent magnet traction motor; judging the total amount of demagnetization of the permanent magnet according to the amplitude of the fundamental wave; obtaining common mode current of three-phase current of the permanent magnet traction motor; and determining the demagnetizing position of the permanent magnet through the harmonic content value of the common-mode current. According to the method for detecting the loss of magnetism state of the permanent magnet, the problem that the permanent magnet cannot be judged after loss of magnetism is solved.
Description
Technical Field
The invention belongs to the field of permanent magnet generators, and particularly relates to a method and a device for detecting the loss of field of a permanent magnet by using current.
Background
The permanent magnet generator is also called a permanent magnet synchronous generator, along with the rapid development and continuous improvement of the performance of a permanent magnet material, the performance of the permanent magnet motor can be further improved, compared with the common motor, the permanent magnet motor has the advantages of high efficiency, energy conservation, low temperature rise, good starting performance, small size, light weight and the like, and is widely applied to the fields of aviation, electric vehicles, robots and the like. However, the permanent magnet material has a demagnetization characteristic, and when a high temperature of more than 150 ℃ occurs or the carrier frequency of the frequency converter is low, the permanent magnet is demagnetized, so that brake failure, control system overcurrent, further rapid expansion of the demagnetization and other problems occur.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a method and a device for detecting loss of magnetism of a permanent magnet, so that the problem of online loss of magnetism judgment of a permanent magnet motor is solved.
In order to realize the technical problem, the invention adopts the following technical scheme:
a method for detecting the loss-of-field state of a permanent magnet by using current is applied to a permanent magnet traction motor, and comprises the following steps:
obtaining the fundamental wave amplitude of any phase current in the three-phase current of the permanent magnet traction motor;
judging the total amount of demagnetization of the permanent magnet according to the amplitude of the fundamental wave;
obtaining common mode current of three-phase current of the permanent magnet traction motor;
and determining the demagnetizing position of the permanent magnet through the harmonic content value of the common-mode current.
Optionally, the method for obtaining the fundamental wave amplitude of any phase current comprises:
obtaining real-time data of the current through a current sensor arranged at the input end of the permanent magnet motor, and drawing a current oscillogram according to the real-time data;
obtaining the fundamental wave amplitude of the current by adopting a Fourier analysis method on the current waveform;
optionally, the method of obtaining the common mode current is: directly performing a turn-link to a three-phase power line through a current clamp, and measuring a common-mode current waveform in real time;
optionally, the method for obtaining the harmonic content value of the common mode current includes:
drawing a waveform diagram of the common mode current by detecting the obtained common mode current;
harmonic content values are obtained by fourier analysis of the common mode current waveform.
Optionally, the magnitude of the common mode current is inversely proportional to the symmetry of the magnetic field.
Optionally, the calculation rule of the fourier analysis method is:
in a whole period, selecting equidistant N nodes, such as:
wherein aj and bj are coskx and coskx coefficients after Fourier decomposition.
Optionally, the permanent magnet is applied to a permanent magnet motor, and the device comprises:
an acquisition module: obtaining the fundamental wave amplitude of any phase current in the three-phase current of the permanent magnet traction motor; obtaining common mode current of three-phase current of the permanent magnet traction motor;
a drawing module: obtaining real-time data of the current through a current sensor arranged at the input end of the permanent magnet motor, and drawing a current oscillogram according to the real-time data; drawing a waveform diagram of the common mode current by detecting the obtained common mode current;
a determination module: obtaining the fundamental wave amplitude of the current by adopting a Fourier analysis method on the current waveform, and judging the total amount of loss of magnetism of the permanent magnet motor according to the fundamental wave amplitude; and carrying out Fourier analysis on the common-mode current waveform to obtain a harmonic content value, and judging the demagnetizing position of the permanent magnet according to the harmonic content value of the common-mode current.
Compared with the prior art, the technical scheme provided by the invention has the following beneficial effects:
the permanent magnet field state can be detected in time, technical guarantee is provided for taking measures for the permanent magnet synchronous generator at the first time, the safety risk of the loss of excitation fault on loss of excitation overload operation of the permanent magnet synchronous generator is reduced, the loss of excitation fault risk of the permanent magnet motor is greatly reduced, and the technical guarantee is provided for adopting the permanent magnet motor in a large range.
Other features of the present invention and advantages thereof will become apparent from the following detailed description of exemplary embodiments thereof, which proceeds with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive exercise.
FIG. 1 is a block diagram of the process for detecting the loss of field condition of a permanent magnet using current according to the present invention;
FIG. 2 is a schematic diagram of the present invention for detecting the loss of field of permanent magnet by current
Detailed Description
Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatus consistent with certain aspects of the invention, as detailed in the appended claims.
In order to make those skilled in the art better understand the technical solution of the present invention, the following detailed description of the present invention is provided with reference to the accompanying drawings and examples.
The method for detecting loss of field of the permanent magnet shown in fig. 1 is applied to a permanent magnet motor, and comprises the following steps:
a method for detecting a loss-of-field state of a permanent magnet applied to a permanent magnet motor using an electric current, the method comprising:
s1, obtaining real-time data of the current through a current sensor arranged at the input end of the permanent magnet motor, and drawing a current waveform diagram according to the real-time data;
obtaining the fundamental wave amplitude of any phase current in the three-phase current of the permanent magnet traction motor by adopting a Fourier analysis method on the current waveform;
and determining the total amount of demagnetization of the permanent magnet according to the amplitude of the fundamental wave.
S2, obtaining a common mode current of a three-phase current of the permanent magnet traction motor through a current sensor connected to a three-phase power line through a turn chain, wherein the magnitude of the common mode current is inversely proportional to the symmetry of a magnetic field;
drawing a waveform diagram of the common mode current by detecting the obtained common mode current;
obtaining a harmonic content value by carrying out Fourier analysis on the common-mode current waveform;
and determining the demagnetizing position of the permanent magnet through the harmonic content value of the common-mode current.
The calculation rule of the Fourier analysis method is as follows:
in a whole period, selecting equidistant N nodes, such as:
wherein aj and bj are coskx and coskx coefficients after Fourier decomposition.
An apparatus for detecting a loss-of-field state of a permanent magnet applied to a permanent magnet motor using a current, comprising:
an acquisition module: obtaining the fundamental wave amplitude of any phase current in the three-phase current of the permanent magnet traction motor; obtaining common mode current of three-phase current of the permanent magnet traction motor;
a drawing module: obtaining real-time data of the current through a current sensor arranged at the input end of the permanent magnet motor, and drawing a current oscillogram according to the real-time data; drawing a waveform diagram of the common mode current by detecting the obtained common mode current;
a determination module: obtaining the fundamental wave amplitude of the current by adopting a Fourier analysis method on the current waveform, and judging the total demagnetizing quantity of the permanent magnet according to the fundamental wave amplitude; and carrying out Fourier analysis on the common-mode current waveform to obtain a harmonic content value, and judging the demagnetizing position of the permanent magnet according to the harmonic content value of the common-mode current.
The specific working process is as follows:
measuring a current waveform through a single-phase current clamp, and measuring a common-mode current waveform through a three-phase current of a turn chain;
the device used in the invention monitors the running state of the motor in real time in the running process of the motor, tests one of the current real-time data in three phases through the current sensor, draws a oscillogram according to the measured current real-time data, performs Fourier transform, obtains the amplitude of fundamental wave through Fourier analysis, and judges the total loss-of-field state of the motor according to the amplitude;
three-phase common mode current real-time data is tested through a current sensor, the obtained common mode current is subjected to Fourier transform, common mode current fundamental wave amplitude and harmonic content are obtained through Fourier analysis, the symmetry of a magnetic field is judged through the fundamental wave amplitude, the demagnetizing position is supplemented by electromagnetism, so that the larger the current amplitude is, the more the demagnetizing is serious, the demagnetizing position and the shape are judged through the harmonic content, when no harmonic content exists, no demagnetizing phenomenon occurs, when 5 harmonics exist, the single-pole magnetic pole is demagnetized, and when 7 harmonics exist, the adjacent magnetic pole is demagnetized.
The foregoing are merely exemplary embodiments of the present invention, which enable those skilled in the art to understand or practice the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention.
It is to be understood that the present invention is not limited to what has been described above, and that various modifications and changes may be made without departing from the scope thereof. The scope of the invention is limited only by the appended claims.
Claims (7)
1. A method for detecting a loss of field condition of a permanent magnet using an electrical current, the method comprising:
obtaining the fundamental wave amplitude of any phase current in the three-phase current of the permanent magnet traction motor;
judging the total amount of demagnetization of the permanent magnet according to the amplitude of the fundamental wave;
obtaining common mode current of three-phase current of the permanent magnet traction motor;
and determining the demagnetizing position of the permanent magnet through the harmonic content value of the common-mode current.
2. The method for detecting the loss-of-field state of the permanent magnet by using the current according to claim 1, wherein the method for obtaining the fundamental wave amplitude of any one phase of the current comprises:
obtaining real-time data of the current through a current sensor arranged at the input end of the permanent magnet motor, and drawing a current oscillogram according to the real-time data;
the fundamental wave amplitude of the current is obtained by adopting a Fourier analysis method on the current waveform.
3. The method for detecting the loss-of-field state of the permanent magnet by using the current as claimed in claim 1, wherein the method for obtaining the common mode current is as follows: and a current sensor is arranged at the input end of the permanent magnet motor.
4. The method for detecting the loss-of-field state of the permanent magnet by using the current according to claim 1, wherein the harmonic content value of the common-mode current is obtained by:
drawing a waveform diagram of the common mode current by detecting the obtained common mode current;
harmonic content values are obtained by fourier analysis of the common mode current waveform.
5. The method for detecting the loss-of-field state of the permanent magnet according to claim 1, wherein the magnitude of the common mode current is inversely proportional to the symmetry of the magnetic field.
6. The method for detecting the loss of field of a permanent magnet by using current according to claim 2 or 4, wherein the calculation rule of the Fourier analysis method is as follows:
in a whole period, selecting equidistant N nodes, such as:
wherein aj and bj are coskx and coskx coefficients after Fourier decomposition.
7. An apparatus for detecting a loss-of-field state of a permanent magnet using a current, the permanent magnet being applied to a permanent magnet traction motor, the apparatus comprising:
an acquisition module: obtaining the fundamental wave amplitude of any phase current in the three-phase current of the permanent magnet traction motor; obtaining common mode current of three-phase current of the permanent magnet traction motor;
a drawing module: obtaining real-time data of the current through a current sensor arranged at the input end of the permanent magnet motor, and drawing a current oscillogram according to the real-time data; drawing a waveform diagram of the common mode current by detecting the obtained common mode current;
a determination module: obtaining the fundamental wave amplitude of the current by adopting a Fourier analysis method on the current waveform, and judging the total demagnetizing quantity of the permanent magnet according to the fundamental wave amplitude; and carrying out Fourier analysis on the common-mode current waveform to obtain a harmonic content value, and judging the demagnetizing position of the permanent magnet according to the harmonic content value of the common-mode current.
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| CN202011137040.2A CN112327228A (en) | 2020-10-22 | 2020-10-22 | Method and device for detecting loss-of-field state of permanent magnet by using current |
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| CN202011137040.2A CN112327228A (en) | 2020-10-22 | 2020-10-22 | Method and device for detecting loss-of-field state of permanent magnet by using current |
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Citations (10)
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| US20070236213A1 (en) * | 2006-03-30 | 2007-10-11 | Paden Bradley E | Telemetry method and apparatus using magnetically-driven mems resonant structure |
| JP2010239779A (en) * | 2009-03-31 | 2010-10-21 | Nissan Motor Co Ltd | Permanent magnet type motor |
| CN103454585A (en) * | 2013-08-27 | 2013-12-18 | 河海大学 | Permanent magnet synchronous motor field failure diagnosis method based on residual voltage after ac dump |
| CN103926533A (en) * | 2014-03-24 | 2014-07-16 | 河海大学 | Field failure on-line diagnostic method and system for permanent magnet synchronous motor |
| CN103969579A (en) * | 2014-03-24 | 2014-08-06 | 河海大学 | Asymmetric fault diagnosis method and system for stator of permanent magnet synchronous motor |
| DE102014205254A1 (en) * | 2014-03-20 | 2014-12-31 | Continental Automotive Gmbh | Method and device for determining a demagnetization of a permanent magnet of an electric motor, drive arrangement with the device |
| CN108680858A (en) * | 2018-06-01 | 2018-10-19 | 清华大学 | Method and system for monitoring permanent magnet failure |
| CN111090045A (en) * | 2019-12-27 | 2020-05-01 | 绍兴市上虞区理工高等研究院 | Method and device for diagnosing loss of field of permanent magnet synchronous motor |
-
2020
- 2020-10-22 CN CN202011137040.2A patent/CN112327228A/en active Pending
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003075516A (en) * | 2001-09-03 | 2003-03-12 | Ko Gijutsu Kenkyusho:Kk | Deterioration diagnosing method for electric device |
| JP2003156547A (en) * | 2001-11-26 | 2003-05-30 | Ko Gijutsu Kenkyusho:Kk | Diagnosis apparatus of failure and deterioration in electric equipment |
| US20070236213A1 (en) * | 2006-03-30 | 2007-10-11 | Paden Bradley E | Telemetry method and apparatus using magnetically-driven mems resonant structure |
| JP2010239779A (en) * | 2009-03-31 | 2010-10-21 | Nissan Motor Co Ltd | Permanent magnet type motor |
| CN103454585A (en) * | 2013-08-27 | 2013-12-18 | 河海大学 | Permanent magnet synchronous motor field failure diagnosis method based on residual voltage after ac dump |
| DE102014205254A1 (en) * | 2014-03-20 | 2014-12-31 | Continental Automotive Gmbh | Method and device for determining a demagnetization of a permanent magnet of an electric motor, drive arrangement with the device |
| CN103926533A (en) * | 2014-03-24 | 2014-07-16 | 河海大学 | Field failure on-line diagnostic method and system for permanent magnet synchronous motor |
| CN103969579A (en) * | 2014-03-24 | 2014-08-06 | 河海大学 | Asymmetric fault diagnosis method and system for stator of permanent magnet synchronous motor |
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