JPH1022128A - Iron core demagnetization method - Google Patents

Abstract

(57) [Abstract] [Problem] To contribute to miniaturization and downsizing of power supply equipment that outputs a voltage to an iron core without generating a high voltage or an arc voltage in the iron core, and to achieve high-accuracy residual magnetic flux in the iron core. The present invention provides a method for degaussing an iron core, which is capable of erasing an iron core. SOLUTION: A power supply equipment 1 capable of outputting a positive voltage and a negative voltage is provided, and the power supply equipment 1 outputs a positive voltage and a negative voltage to an iron core 9 alternately. At this time, initially, the voltage application time for each wave is extended, and an applied magnetic flux equal to or higher than the saturation magnetic flux of the iron core 9 is supplied to the iron core 9. Then, the applied magnetic flux is gradually reduced, and finally the applied magnetic flux is set to zero.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for demagnetizing an iron core for eliminating residual magnetic flux in an iron core provided in an induction electric machine.

[0002]

2. Description of the Related Art In general, when conducting a resistance measurement test or a polarity check test of an induction device, a DC current is applied to the induction device. The DC current causes the iron core in the induction device to be magnetized. Even if the current is removed, a residual magnetic flux will be generated in the iron core. Such a residual magnetic flux of the iron core has a disadvantage that the error characteristics and the saturation characteristics of the induction device are deteriorated. Therefore, it is necessary to eliminate the residual magnetic flux after conducting the test by supplying a direct current to the induction device.

[0003] Conventionally, there has been known a method of demagnetizing an iron core for eliminating residual magnetic flux from the iron core. For example, in the iron core demagnetization method shown in FIG. 9, an AC power supply 18 connected to the iron core 9 as a test device is used. That is, an AC voltage having a commercial frequency is output from the AC power supply 18 to the iron core 9 and the voltage is increased until the magnetic flux density in the iron core 9 becomes close to the saturation magnetic flux density. After that, gradually reduce the voltage until
To be reduced to Since the time integral of the voltage becomes magnetic flux,
When the voltage becomes 0, the applied magnetic flux also becomes 0, which means that the residual magnetic flux has been eliminated from the iron core 9.

In the method of degaussing the iron core shown in FIG. 10, a degaussing device having a DC power supply 16 and a polarity changeover switch 19 is used. This degaussing device includes a variable resistor 2 for controlling current and a current shunt 3 for measuring current.
Is provided. On the other hand, an iron core 9 is provided with an inductance 4 and a winding resistor 8 equivalently represented as a test device, and a coil 5 for use in voltage measurement.
It is included. A DC power supply 16, a changeover switch 19, a variable resistor 2, and a current shunt 3 are connected in series to the inductance 4 and the winding resistor 8. Further, a waveform measuring device 6 for measuring a voltage waveform and a current waveform of the iron core 9 is connected to the coil 5 and the current shunt 3.

In the method of degaussing an iron core using such a degaussing device, the switching interval t ₀ (shown in FIG. 11) of the changeover switch 19 is kept constant, and the variable resistor is switched each time the changeover switch 19 is operated to change the polarity. 2, the voltage applied to the inductance 4, that is, the magnetic flux, is gradually reduced. Finally, the voltage can be reduced to 0, and the applied magnetic flux can be set to 0 to eliminate the residual magnetic flux from the iron core 9. At this time, the voltage waveform 10 and the current waveform 13 measured by the waveform measuring device 6 are shown in FIG.
Further, the magnetic flux waveform 11 can be obtained by integrating the voltage (the dotted line portion in FIG. 11). Furthermore, if the magnetic flux-current characteristic 14 is written based on the magnetic flux waveform 11, it becomes as shown in FIG.
A, B, C, D, and A shown in FIGS.
Each point of E and F represents the same measurement point.

[0006]

However, the conventional methods of demagnetizing an iron core as described above have the following problems. That is, in the case of the degaussing method using the commercial frequency AC voltage shown in FIG.
Must be applied. Therefore, it is necessary to employ a large-capacity, large-sized power supply as the AC power supply 18,
In some cases, the degaussing operation of the iron core 9 becomes difficult depending on the use state of the induction electric device. Therefore, conventionally, there has been a demand for reducing the capacity and size of the power supply equipment used for degaussing the iron core.

Further, in the case of the degaussing method using the degaussing device shown in FIG.
And an arc voltage of 20 across the inductance 4
(Shown in FIG. 11) occurs. Therefore, the dotted lines from the points A, B, C, D, and E to the points A ', B', C ', D', and E 'in the magnetic flux-current characteristics 14 shown in FIG. Are indeterminate and discontinuous. Therefore, accurate magnetic flux-current characteristics 14 could not be obtained.
Further, the magnetic flux generated in the iron core 9 is also affected by the arc voltage 20, and it is difficult to demagnetize the iron core 9 with high accuracy.

The present invention has been proposed in order to solve the above-mentioned problems of the prior art, and its purpose is to generate a high voltage or an arc voltage in an iron core without causing any problem.
An object of the present invention is to provide a method of degaussing an iron core that contributes to a reduction in the capacity and size of power supply equipment that outputs a voltage to the iron core, and that can eliminate residual magnetic flux in the iron core with high accuracy.

[0009]

To achieve the above object, a first aspect of the present invention is a method of demagnetizing an iron core for eliminating residual magnetic flux in an iron core provided in an induction electric machine, comprising the steps of: Power supply equipment that can output a positive voltage and a negative voltage from the power supply equipment alternately to the iron core. Initially, the voltage application time for each wave is extended to increase the saturation magnetic flux of the iron core. The above applied magnetic flux is supplied to the iron core, the applied magnetic flux to the iron core is gradually reduced, and finally the applied magnetic flux is set to zero.

In the method for demagnetizing the iron core according to the first aspect, the power supply equipment alternately outputs positive and negative voltages to the iron core, and determines a voltage integrated value per wave, that is, an amount of magnetic flux generated in the iron core. Make it smaller than the previous waveform. Therefore, the voltage waveform itself is not specified, and the voltage waveform may be arbitrary.

In addition, since the saturation magnetic flux or more is supplied to the iron core by the initial voltage output, the iron core can be demagnetized with high accuracy regardless of the residual magnetic flux amount of the iron core before performing the degaussing operation. In addition, when supplying a large voltage integral value (magnetic flux) such as the saturation magnetic flux or more of the iron core, a large voltage output waveform is obtained by increasing the voltage application time for each wave instead of increasing the voltage value itself. . Therefore, the peak value of the voltage output waveform does not need to be large enough to cause a problem in electrical insulation, and there is no need to supply a high voltage higher than the rated voltage to the iron core. Therefore, a small-sized power supply equipment with a small capacity can be adopted. As a result, it is possible to reliably perform the degaussing operation of the iron core regardless of the usage state of the induction electric device.

Further, since a switch for switching the polarity is not used, the current does not become 0 and no arc voltage is generated in the iron core. Therefore, there is no indeterminate portion in the magnetic flux-current characteristics, and a highly accurate magnetic flux-current characteristic can be obtained. Further, the magnetic flux generated in the iron core is not affected by the arc voltage, and the iron core can be demagnetized with high accuracy.

According to a second aspect of the present invention, there is provided a method for demagnetizing an iron core for eliminating residual magnetic flux in an iron core provided in an induction electric machine,
First, a predetermined voltage is output to the iron core, a residual magnetic flux of the iron core is estimated from a current waveform flowing at that time, and an applied magnetic flux that cancels the estimated residual magnetic flux is supplied to the iron core. .

In the method of demagnetizing the iron core according to the second aspect, the residual magnetic flux of the iron core can be surely eliminated by supplying the applied magnetic flux that cancels out the residual magnetic flux estimated in advance. Therefore, as the power supply equipment, a small-scale power supply having a function of applying either the positive or negative polarity voltage to the iron core is sufficient. This allows
The power supply equipment can be further downsized.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings. The same members as those in the prior art shown in FIG.
Description is omitted.

(1) First Embodiment A first embodiment corresponds to the invention of claim 1 and is a power supply facility capable of outputting a positive voltage and a negative voltage as shown in FIG. 1 and a computer 7 connected to a waveform measuring instrument 6 in a method of demagnetizing an iron core. The power supply 1 outputs the positive voltage and the negative voltage to the iron core 9 alternately. Further, the computer 7 takes in the data measured by the waveform measuring instrument 6 and performs an arithmetic processing for obtaining a magnetic flux by integrating a voltage with time based on the data.

FIG. 2 shows a voltage waveform 1 measured by the waveform measuring instrument 6.
0 and a current waveform 12 and a magnetic flux waveform 11 integrated and calculated by the computer 7 are shown. As is apparent from these waveforms, the first two waves at the initial stage when the power supply equipment 1 outputs a voltage supply a saturation magnetic flux or more, and the current has a very large value. When an applied magnetic flux equal to or higher than the saturation magnetic flux of the iron core 9 is supplied to the iron core 9, an applied magnetic flux equal to or higher than the saturation magnetic flux of the iron core 9 is obtained by increasing the voltage application time for each wave. Further, the saturation magnetic flux of the iron core 9 can be easily obtained from the specification or the like.

Thereafter, the voltage applied to the iron core 9, that is, the applied magnetic flux is gradually reduced, and finally, the applied magnetic flux is set to 0 to converge to the residual magnetic flux zero point 13 (shown in FIG. 2). In this way, the residual magnetic flux is eliminated from the iron core 9. If this is expressed as the magnetic flux-current characteristic 14 shown in FIG. 3, the state of the convergence is clearly understood.

In the first embodiment as described above,
Since the voltage integrated value per wave is only made smaller than the immediately preceding waveform, the voltage waveform itself is not specified, and the voltage waveform may be arbitrary. Further, since the saturation voltage or more is supplied to the iron core 9 by the initial voltage output, the degaussing of the iron core 9 can be performed accurately regardless of the residual magnetic flux amount of the iron core 9 before performing the degaussing operation. Moreover, in the first embodiment, by increasing the voltage application time for each wave, a large voltage output such as the saturation magnetic flux of the iron core 9 or more is obtained.
There is no need to supply a high voltage higher than the rated voltage to the iron core 9.
Therefore, the capacity and size of the power supply equipment 1 can be reduced, and the demagnetization work of the iron core 9 can be reliably performed irrespective of the usage state of the induction device.

Further, since the switch 19 for switching the polarity is not used unlike the degaussing method shown in FIG. 10, the current does not become 0 and the arc voltage does not occur in the iron core 9. Therefore, there is no uncertain portion in the magnetic flux-current characteristics 14, and the magnetic flux-current characteristics 14 with high precision can be obtained as shown in FIG.
Further, the magnetic flux generated in the core 9 is not affected by the arc voltage, and the core can be demagnetized with high accuracy.

(2) Second Embodiment A second embodiment corresponds to the second aspect of the present invention. As shown in FIG. 4, a DC power supply is used in place of the power supply equipment 1 in the first embodiment. This is a degaussing method using a switch 16 and a switch 17. In the second embodiment, first, a predetermined voltage is output to the iron core 9 and the residual magnetic flux of the iron core 9 is estimated from a current waveform flowing at that time. Then, the polarity of the DC power supply 16 and the O of the switch 17 are set so as to cancel the estimated residual magnetic flux.
N, OFF time is controlled. As a result, a voltage waveform 10 as shown in FIG. 5 is applied, and the computer 7 calculates a magnetic flux waveform 11 based on the waveform. Further, at this time, a current waveform 12 flows. FIG. 6 shows this magnetic flux-current characteristic. That is, starting from the first residual magnetic flux 21, it moves to the residual magnetic flux zero point 13 along the magnetic flux current curve 15.

In the second embodiment as described above,
It suffices to provide a DC power supply 16 for applying either positive or negative polarity voltage to the iron core 9 as power supply equipment. Therefore, the power supply equipment can be further downsized.

(3) Other Embodiments The present invention is not limited to the above embodiments. For example, in the first embodiment,
Using a current probe instead of the current shunt 3
A digital memory can be used as the waveform measuring device 6. It is also possible to add peripheral devices such as connecting a result output printer to the computer 7 as appropriate. Further, instead of the digital memory and the computer 7, the magnetic flux calculation is executed by an integrating circuit combining elements such as R, L, and C, and the magnetic flux calculation is performed by a non-memory measuring instrument such as a pen recorder or an XY recorder. The result may be output.

Further, as shown in FIG. 7, a method for demagnetizing the iron core characterized in that the magnetic flux generated in the iron core 9 is measured using the inductance 4 which is a voltage application terminal.
In this case, the following equation (1) is used to calculate the magnetic flux in the iron core 9.

[0025]

(Equation 1) According to such an embodiment, the error of the voltage drop due to the winding resistor 8 can be removed, and the degaussing operation of the iron core can be performed with higher accuracy.

Further, as shown in FIG. 8, a method of demagnetizing an iron core including only the power supply equipment 1 and the variable resistor 2 is included. In this degaussing method, the current shunt 3, the waveform measuring device 6, and the computer 7 are removed from the above-described embodiment. However, even with such a configuration, it is possible to perform the exactly same degaussing method as in the above-described embodiment.

[0027]

As described above, according to the present invention,
A power supply capable of outputting a positive voltage and a negative voltage is provided, and the positive voltage and the negative voltage are alternately output from the power supply to the iron core. By applying an applied magnetic flux higher than the saturation magnetic flux of the iron core to the iron core, gradually reducing the applied magnetic flux, and finally reducing the applied magnetic flux to zero, thereby generating a high voltage or an arc voltage in the iron core. In addition, the residual magnetic flux in the iron core can be eliminated with high accuracy while contributing to the reduction in the capacity and size of the power supply equipment that outputs voltage to the iron core.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a waveform example of voltage, magnetic flux, and current of an iron core in FIG. 1;

FIG. 3 is a magnetic flux-current characteristic diagram of FIG.

FIG. 4 is a circuit diagram showing a second embodiment of the present invention.

5 is a waveform example of voltage, magnetic flux, and current of the iron core in FIG. 4;

FIG. 6 is a magnetic flux-current characteristic diagram of FIG.

FIG. 7 is a circuit diagram showing another embodiment of the present invention.

FIG. 8 is a circuit diagram showing another embodiment of the present invention.

FIG. 9 is a circuit diagram showing a conventional method of degaussing an iron core using an AC voltage.

FIG. 10 is a circuit diagram showing a method of degaussing an iron core using a conventional polarity switch.

11 is a waveform example of voltage, magnetic flux, and current of the iron core in FIG.

FIG. 12 is a magnetic flux-current characteristic diagram of FIG. 11;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Power supply equipment 2 ... Variable resistor 3 ... Current shunt 4 ... Inductance 5 ... Coil 6 ... Waveform measuring instrument 7 ... Computer 8 ... Winding resistance 9 ... Iron core 10 ... Voltage waveform 11 ... Magnetic flux waveform 12 ... Current waveform 13 ... Residual Magnetic flux zero point 14 Magnetic flux-current characteristic 15 Magnetic flux current curve 16 DC power supply 17 Switch 18 AC power supply 19 Changeover switch 20 Arc voltage 21 Residual magnetic flux

Claims (2)

[Claims] An iron core degaussing method for eliminating residual magnetic flux in an iron core provided in an induction electric machine, comprising: a power supply facility capable of outputting a positive polarity voltage and a negative polarity voltage; The negative voltage and the negative voltage are alternately output to the iron core. Initially, the voltage application time for each wave is extended to supply the applied magnetic flux that is higher than the saturation magnetic flux of the iron core to the iron core, and gradually reduce the applied magnetic flux to the iron core. A method of demagnetizing an iron core, wherein the applied magnetic flux is finally reduced to zero. 2. A method for demagnetizing an iron core for erasing residual magnetic flux in an iron core provided in an induction electric device, comprising: first outputting a predetermined voltage to the iron core; estimating a residual magnetic flux of the iron core from a current waveform flowing at that time; A method of demagnetizing an iron core, wherein an applied magnetic flux that cancels out the estimated residual magnetic flux is supplied to the iron core.