JP2007192602A - Device and method for magnetic measurement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and a method of magnetic measurement which is compact and easy to handle and in accordance with actual usage condition by controlling the temperature distribution of a sample, in the magnetic measurement device for measuring the physical properties such as magnetic properties of excited sample or magnetic deformation. <P>SOLUTION: The magnetic measurement device capable of exciting the sample and also measuring the physical properties of the sample is provided with a device for controlling the temperature distribution. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a magnetic measurement apparatus and method for measuring magnetic characteristics such as magnetic flux density and magnetostriction when a magnetic material is excited.

  In recent years, the characteristics required of magnetic materials have become more and more severe with the improvement in performance of electrical equipment. In addition to the material property evaluation that is generally performed immediately before shipment, an evaluation method that conforms to the actual usage conditions when used in actual devices such as transformers and rotating machines is required for the property evaluation. I came.

  For example, in electrical steel sheets used for transformers, heat is generated due to iron loss, etc. under actual use conditions, and the heat is released outside the iron core due to the temperature gradient in the iron core. Instead, there is a temperature distribution.

  That is, in many cases, a temperature distribution exists in the magnetic material under actual use conditions. Therefore, the stress is often applied to the material due to thermal expansion due to the temperature distribution. This stress generally works in a direction unrelated to the excitation direction.

  When stress is applied to the magnetic material, the magnetic domain structure may change greatly, and the magnetic properties (permeability, hysteresis loop, iron loss, etc.) and magnetostriction of the material may change greatly depending on the stress. For this reason, in order to improve the device performance, it is necessary to perform not only the magnetic property evaluation of a normal material, but also the magnetic property evaluation in the actually used temperature distribution or stress state.

In the conventional technology, when investigating the stress dependence of magnetic properties (permeability, hysteresis loop, iron loss, etc.), a method is used in which a strip-shaped test piece is pulled in the longitudinal direction and measured with a single plate magnetometer. I have been. The stress is generally applied by gripping both ends of the sample with a gripping jig or the like and applying a force to the gripping jig or the like. Such an example is disclosed in Patent Document 1, for example.
JP 2003-194903 A

  However, in the method disclosed in Patent Document 1 and the like, the direction of stress applied to the sample is parallel to the excitation direction, and stress in a direction perpendicular to the excitation direction cannot be applied. There are problems such as working in various directions as well as the direction, and the sample being easily deformed when compressive stress is applied.

  In addition, in the case of exciting a sample by passing an electric current through a winding arranged around the sample, if a stress is applied by a gripping jig or the like in a direction perpendicular to the excitation direction, the sample is disturbed by the winding. It was difficult to grab.

  Furthermore, when the stress direction and the excitation direction are parallel, the grip portion can be outside the excitation portion of the sample. However, when the stress direction and the excitation direction are perpendicular, the grip portion is outside the sample excitation portion. In the case of using a gripping jig or the like, it is difficult to eliminate the influence of the distortion on the sample and its magnetic properties.

  The present invention has been made in view of the above circumstances, and in a magnetic measuring apparatus and method for measuring physical properties such as magnetic properties and magnetostriction of an excited sample, the temperature distribution of the sample is controlled to control the magnetic material. It is an object of the present invention to provide a magnetic measuring apparatus and method that are compact and easy to handle in a form that conforms to actual use conditions.

  The invention according to claim 1 of the present invention is characterized in that a magnetic measuring device capable of exciting a sample and measuring physical properties of the sample is provided with a device for controlling the temperature distribution of the sample. It is a magnetic measurement device.

  The invention according to claim 2 of the present invention is a magnetic measuring device capable of exciting a sample and measuring the physical properties of the sample, comprising a device for controlling the temperature distribution of the sample in the excitation direction. Is a magnetic measuring device characterized by

  According to a third aspect of the present invention, in the magnetic measurement apparatus according to the first or second aspect, the temperatures of the central portion and both end portions in the excitation direction of the excited portion of the sample are controlled. This is a magnetic measurement device.

  According to a fourth aspect of the present invention, in the magnetic measurement apparatus according to any one of the first to third aspects, a winding is disposed around a part or all of the sample, and the winding is performed. A magnetic measuring device that excites a sample by passing a current through a wire.

  According to a fifth aspect of the present invention, in the magnetic measurement device according to any one of the first to fourth aspects, a magnetic circuit including a part or all of the sample is configured. This is a magnetic measurement device.

  According to a sixth aspect of the present invention, in the magnetic measurement apparatus according to the fifth aspect, a magnetic circuit is formed by contacting the sample with a yoke, and a central portion in an excitation direction in an excited portion of the sample. And a magnetic measuring device for controlling the temperature of the yoke.

  According to a seventh aspect of the present invention, in the magnetic measurement apparatus according to any one of the first to sixth aspects, the magnetic characteristic of the excited sample is measured. Device.

  The invention according to claim 8 of the present invention is the magnetic measurement apparatus according to any one of claims 1 to 6, wherein the magnetic strain of the excited sample is measured. Device.

  According to a ninth aspect of the present invention, in the magnetic measurement apparatus according to any one of the first to sixth aspects, the magnetic domain structure of the excited sample is measured. Device.

  According to a tenth aspect of the present invention, in the magnetic measurement method capable of exciting a sample and measuring the physical properties of the sample, stress is applied to the sample by controlling the temperature distribution of the sample. This is a magnetic measurement method.

  Further, according to an eleventh aspect of the present invention, in the magnetic measurement method capable of exciting a sample and measuring the physical properties of the sample, the stress is measured by controlling the temperature distribution of the sample in the excitation direction. It is a magnetic measurement method characterized by being given to.

  According to the present invention, when measuring physical properties such as magnetic properties and magnetostriction of an excited sample, the above-mentioned problems with the stress applying method using a gripping jig or the like can be solved, and the shape in accordance with the actual use conditions of the magnetic material can be solved. It is compact and can be measured easily.

  As a result of diligent research to elucidate the cause of the difference between the evaluation in single-plate magnetic measurement or Epstein measurement in grain-oriented electrical steel sheets and the evaluation in transformers under actual use conditions, We found that the influence of temperature distribution was relatively large. That is, in predicting the characteristics under actual use conditions from the material characteristics of the magnetic material, the prediction can be made more accurate by considering the influence of the temperature distribution of the magnetic material.

  Therefore, in order to predict the characteristics of magnetic materials under actual use conditions, it is important to measure the physical properties of the excited sample, such as magnetic characteristics, magnetostriction, and domain structure, in a state where the temperature distribution of the sample is controlled. .

  Although not necessarily clear, the influence of the temperature distribution on the physical properties of the sample is considered to be caused by the stress applied to the material due to the difference in thermal expansion due to the temperature distribution. The influence of stress parallel to the excitation direction can be measured relatively easily by the conventional measurement method, but it is difficult to measure the influence of stress perpendicular to the excitation direction by the conventional measurement method. In the present invention, it is possible to give a temperature gradient in the excitation direction and evaluate the influence of a stress component perpendicular to the excitation direction. If a temperature gradient is given to the sample by controlling the temperature at the center and both ends in the excitation direction in the excited part of the sample, analysis such as calculating thermal expansion from the measured temperature value of the sample and converting stress is easy. Become.

  The method for exciting the sample may be a method in which a current is passed through the winding, as in the widely used magnetic measurement apparatus. That is, a winding is arranged around a part or all of the sample, and the sample is excited by passing a current through the winding. The excitation waveform may be selected according to the purpose of investigation, and may be AC, DC, or an arbitrary waveform. In such an excitation method using windings, it is very easy to apply stress perpendicular to the excitation direction according to the present invention.

  In order to make the magnetic flux density of the sample uniform, it is desirable to construct a magnetic circuit including part or all of the sample. At that time, when the magnetic circuit is configured by contacting the sample with the yoke, the temperature gradient in the excitation direction is relatively easily given by controlling the temperature of the central portion of the excitation direction and the temperature of the yoke in the excited portion of the sample. It is done.

  The heater for controlling the temperature of the sample may be a heater heated by Joule heat by passing a current through a nichrome wire or the like. The heater may be controlled by a PID controller or the like using a temperature measurement value at a place where the temperature is controlled. In addition, when a heater is installed inside the winding used for excitation, a commercially available thin heater is suitable. Since the heater may affect the magnetic measurement, a non-magnetic material is preferable. However, the magnetic material may be corrected by measuring the influence of the heater on the magnetic measurement in advance. In particular, when measuring magnetostriction, the heater and the sample are preferably not in contact with each other in order to eliminate the influence of friction between the heater and the sample. When the temperature range to be measured is low, the heater may be used while the room temperature, the entire measuring instrument, or a part of the device such as the yoke is cooled.

  The temperature measurement may be performed with a thermocouple or the like. Separately from the measurement of magnetic properties, etc., if the temperature distribution of the sample under controlled temperature is measured with a thermocouple and the stress distribution of the sample is analyzed by the finite element method, the stress and magnetic properties, etc. The relationship becomes more accurate.

  Also, in ordinary magnetometers such as single-plate magnetic measurement and Epstein measurement, the length of the sample can be arbitrarily longer than the winding used for excitation, but the part outside this winding is also excited. Since it affects the stress of the sample in the part, it is necessary to consider. On the contrary, the stress of the sample in the excitation part can be controlled by changing the length of the sample or controlling the temperature of the sample part outside the winding part.

  It is extremely useful for transformer design or material development to evaluate the characteristics when the magnetic material has a temperature distribution as described above.

  A first embodiment according to the present invention will be described with reference to FIGS. FIG. 1 is a diagram illustrating an outline of a measurement apparatus according to the first embodiment. FIG. 2 is a cross-sectional view taken along line A-A ′ of FIG. 3 is a cross-sectional view taken along line B-B ′ of FIG. FIG. 4 is a graph showing the temperature distribution of Sample 1 in Example 1. Further, FIG. 5 is a diagram showing the magnetostriction change when the temperature at the center of the sample is constant and the yoke temperature is changed. In the figure, 1 is a sample, 2 is an excitation coil and a detection coil, 3 is a yoke, 4 is a yoke lower heater, 5 is a sample upper heater, 6 is a yoke lower heater, 7 is a yoke lower thermometer, and 8 is a sample. Upper thermometers and 9 represent yoke lower thermometers, respectively.

  A sample 1 obtained by cutting a magnetic steel sheet having a thickness of 0.3 mm into a width of 100 mm and a length of 300 mm was inserted into the excitation coil and the detection coil 2. Both sides of the sample 1 are arranged on the yoke 3, and the sample 1 and the yoke 3 are magnetically coupled to form a magnetic circuit. At this time, the excitation direction by the excitation coil and the detection coil 2 is parallel to the B-B 'line in FIG. Further, in the excitation coil and the detection coil 2, the sample upper heater 5 is arranged on the upper side of the sample 1 so as not to contact the sample as shown in FIGS. 1 to 3, and the yoke lower heaters 4 and 6 are shown in FIG. It arrange | positioned under the yoke 3 shown by 1-3. These heaters generate Joule heat by passing an electric current through the nichrome wire. The electric currents supplied to these heaters so that the temperature measurement values of the lower yoke thermometers 7 and 9 and the upper sample thermometer 8 are constant. The value was independently controlled with a PID controller.

  The temperature of the upper surface of the sample 1 is controlled by a thermocouple when the upper sample thermometer 8 is controlled to be constant at 50 ° C. and the lower yoke thermometers 7 and 9 are changed from room temperature of 23 ° C. to 60 ° C. did. The temperature of the upper surface of the sample on the A-A ′ line in FIG. 1 was constant, but the temperature of the upper surface of the sample on the B-B ′ line in FIG. 1 had a temperature distribution as shown in FIG. Thus, the temperature distribution of the sample in the excitation direction could be controlled. When the yoke lower thermometers 7 and 9 were controlled to a room temperature of 23 ° C., no current was passed through the yoke lower heaters 4 and 6.

  Here, the stress in the case where there is a temperature distribution as described above was estimated as follows. To simplify the calculation, the temperature at the center in the length direction of the sample (length: X) is constant, and the temperature at both ends in the length direction of the sample (length: 2Y) is the same and constant. It is assumed that the temperature difference is ΔT. Also, assuming that a rectangular plate with a uniform and constant temperature (ΔT = 0) is rectangular even when a temperature distribution (ΔT ≠ 0) occurs, it is compressed in the width direction that acts at the center of the sample in the length direction. Stress: σ can be expressed by the following equation, where thermal expansion coefficient: α and Young's modulus: E.

σ = ΔT ・ E ・ α ・ 2Y ÷ (X + 2Y)
Here, in the 3 mass% Si steel, α is about 14 × 10 ⁻⁶ , Young's modulus is about 19000 kgf / mm ² , X is 100 mm, 2Y is 200 mm, and ΔT is 10 ° C., σ is 1.8 kgf / mm ² or so. The magnitude of this stress is sufficient to affect the magnetic domain structure in the electromagnetic steel sheet, and is considered to affect the magnetic properties and magnetostriction. It should be noted that since the actual sample has a swelled shape instead of a rectangle, the stress is considered to be smaller than this value. When a more detailed stress value is required, it may be calculated in detail by a finite element method or the like.

  Here, FIG. 5 shows the magnetostriction λp-p in FIG. 1 when the yoke temperature and the sample center temperature are both normal, and when the temperature of the sample center is fixed at 50 ° C. and the yoke temperature is changed. From this figure, it can be seen that the temperature distribution generated in the sample has a considerable influence on the physical properties (magnetostriction) of the material.

  According to the measurement apparatus in the first embodiment described above, the temperature distribution of the sample in the excitation direction can be controlled, and a normal magnetic measurement is possible. In addition, it is possible to measure magnetostriction by attaching a reflecting mirror to a sample and measuring the variation of the reflecting mirror with laser light, or by attaching a strain gauge to the sample.

  Embodiment 2 according to the present invention will be described with reference to FIGS. FIG. 6 is a diagram illustrating an outline of a measuring apparatus according to the second embodiment. FIG. 7 is a cross-sectional view taken along line A-A ′ of FIG. Further, FIG. 8 is a cross-sectional view taken along line B-B ′ of FIG. 6. FIG. 9 is a graph showing the temperature distribution of Sample 1 in Example 2. Since the numbers in the figure are the same as those in the first embodiment, the description thereof is omitted.

  A sample 1 obtained by cutting a magnetic steel sheet having a thickness of 0.3 mm into a width of 100 mm and a length of 300 mm was inserted into the excitation coil and the detection coil 2. Both sides of the sample 1 are arranged on the yoke 3, and the sample 1 and the yoke 3 are magnetically coupled to form a magnetic circuit. At this time, the excitation direction by the excitation coil and the detection coil 2 is parallel to the B-B 'line in FIG. Further, in the excitation coil and the detection coil 2, the sample upper heater 5 is arranged on the upper side of the sample 1 so as not to contact the sample as shown in FIGS. 6 to 8, and the yoke lower heaters 4 and 6 are arranged. 6 and 8 are disposed below the yoke 3 shown in FIGS. These heaters generate Joule heat by passing an electric current through the nichrome wire, and the current values passed through these heaters so that the temperature measurement values of the lower yoke thermometers 7 and 9 and the upper sample thermometer 8 are constant. Were controlled independently by a PID controller.

  The temperature of the upper surface of the sample 1 when the sample upper side thermometer 8 was changed from room temperature of 23 ° C. to 60 ° C. was measured with a thermocouple. The temperature of the upper surface of the sample on the B-B ′ line in FIG. 6 was constant, but the temperature of the upper surface of the sample on the A-A ′ line in FIG. 6 had a temperature distribution as shown in FIG. Thus, the temperature distribution of the sample in the direction perpendicular to the excitation direction could be controlled. The yoke lower thermometers 7 and 9 were controlled so that the temperature of the upper surface of the sample on the B-B ′ line in FIG. 6 was constant.

  According to the measurement apparatus in Example 2 described above, the temperature distribution of the sample in the direction perpendicular to the excitation direction can be controlled, and normal magnetic measurement is possible. In addition, it is possible to measure magnetostriction by attaching a reflecting mirror to a sample and measuring the variation of the reflecting mirror with laser light, or by attaching a strain gauge to the sample.

  By combining the first embodiment and the second embodiment described above, or by changing the shape of the heater, the temperature distribution in the width direction and the length direction of the sample can be controlled simultaneously.

  FIG. 10 is a diagram illustrating an outline of a measurement jig in the third embodiment. Reference numeral 1 denotes a sample, 10 denotes a high temperature part, and 11 denotes an unevenness prevention jig.

  A thermometer and a circular heater (not shown) having a diameter of 10 mm were attached to the center of the back surface of Sample 1 obtained by cutting a 0.3 mm thick electromagnetic steel sheet to a width of 100 mm and a length of 100 mm. The heater current was controlled so that the value of the thermometer on the back of the sample was 50 ° C. In the sample in the atmosphere at room temperature, the high temperature portion 10 in the center of the sample tends to swell due to thermal expansion, so that substantially isotropic compressive stress acts in the sample surface.

  In order to prevent the sample from warping (raising), the sample was restrained with a cross-shaped uneven projection preventing jig shown in FIG. It is relatively easy to observe the magnetic domain structure (measurement of magnetic domain width, number density of lancet magnetic domains, etc.) by a bitter method or the like in a state in which a magnetic field is applied to the sample from the outside.

  It should be noted that the shapes and structures of the respective parts shown in the above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention is limitedly interpreted by these. Must not be done. That is, the present invention can be implemented in various forms without departing from the spirit and main features thereof.

1 is a diagram showing an outline of a measuring apparatus in Example 1. FIG. It is sectional drawing in the A-A 'line of FIG. It is sectional drawing in the B-B 'line | wire of FIG. FIG. 4 is a diagram showing a temperature distribution of Sample 1 in Example 1. It is a figure which shows the magnetostriction change when the temperature of the sample center is made constant and the yoke temperature is changed. FIG. 6 is a diagram showing an outline of a measuring apparatus in Example 2. It is sectional drawing in the A-A 'line of FIG. It is sectional drawing in the B-B 'line of FIG. 6 is a diagram showing a temperature distribution of Sample 1 in Example 2. FIG. FIG. 6 is a diagram showing an outline of a measurement jig in Example 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sample 2 Excitation coil and detection coil 3 Yoke 4 Yoke lower heater 5 Sample upper heater 6 Yoke lower heater 7 Yoke lower thermometer 8 Sample upper thermometer 9 Yoke lower thermometer 10 High temperature part 11 Unevenness prevention jig

Claims (11)

In a magnetic measuring apparatus capable of exciting a sample and measuring physical properties of the sample,
A magnetic measuring device comprising a device for controlling the temperature distribution of the sample. In a magnetic measuring apparatus capable of exciting a sample and measuring physical properties of the sample,
A magnetic measuring device comprising a device for controlling the temperature distribution of the sample in the excitation direction. In the magnetic measuring device according to claim 1 or 2,
A magnetic measuring device for controlling the temperature of the central portion and both end portions in the exciting direction of the excited portion of the sample. The magnetic measurement apparatus according to any one of claims 1 to 3,
A magnetic measuring apparatus, wherein a winding is arranged around a part or all of the sample, and the sample is excited by passing a current through the winding. The magnetic measurement apparatus according to any one of claims 1 to 4,
A magnetic measuring apparatus comprising a magnetic circuit including a part or all of the sample. The magnetic measurement device according to claim 5,
A magnetic measuring apparatus comprising: a magnetic circuit configured by contacting the sample with a yoke; and controlling the temperature of the central portion of the excitation direction and the yoke in the excited portion of the sample. The magnetic measurement apparatus according to any one of claims 1 to 6,
A magnetic measuring device for measuring magnetic properties of an excited sample. The magnetic measurement apparatus according to any one of claims 1 to 6,
A magnetic measuring device for measuring magnetostriction of an excited sample. The magnetic measurement apparatus according to any one of claims 1 to 6,
A magnetic measuring apparatus for measuring a magnetic domain structure of an excited sample. In a magnetic measurement method capable of exciting a sample and measuring physical properties of the sample,
A magnetic measurement method, wherein stress is applied to a sample by controlling a temperature distribution of the sample. In a magnetic measurement method capable of exciting a sample and measuring physical properties of the sample,
A magnetic measurement method, wherein stress is applied to a sample by controlling a temperature distribution of the sample in an excitation direction.

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