CN102445672A - Permanent magnet residual magnetism temperature coefficient measuring device and method - Google Patents

Abstract

The invention relates to a device and method for measuring the temperature coefficient of permanent magnet remanence. The setup is based on a non-coplanar ring laser with a Faraday rotation optical element placed in one of the capillaries. Place the permanent magnet to be tested on the surface near the Faraday rotation optical element outside the laser. A temperature sensor is pasted on the permanent magnet. Place the whole device in a high and low temperature box. Among them, the deviation amount

In the present invention, fused silica glass is selected as the optical rotation element, the temperature coefficient of its Verdet coefficient is less than 10ppm, the temperature coefficient of d is 0.5ppm, and the frequency stabilization control can ensure the stability of Δv _c within the range of -45°C to +70°C to be 10 ^{- 9} . The invention can measure the remanence temperature coefficient of the permanent magnet by measuring the variation of the bias frequency with temperature, the measurement accuracy is better than 3×10 ^-5 , and has the advantages of simplicity and ease of operation.

Description

Permanent magnet remanence temperature coefficient measuring device and measuring method

technical field

The invention belongs to the characteristic parameter measurement technology of permanent magnet materials, and relates to a permanent magnet remanence temperature coefficient measurement device and a measurement method.

Background technique

The commonly used method of measuring the temperature coefficient of permanent magnet remanence is to measure the demagnetization curve at different temperatures. The sample in the prior art is placed between two heating poles, and the two heating poles are arranged in the magnetization device and distributed as N poles and S poles. Moreover, the magnetic flux detection coil connected to the B(J) integrator is wound on the sample, and the magnetic field detection coil connected to the H integrator is arranged nearby, and both integrators are connected to an X-Y recorder or a computer. At the same time, the excitation power supply is connected with the magnetizing device and the B(J) integrator.

为：The measuring device calculates the temperature coefficient of remanence according to formula (1) for the corresponding Br under the measured _T1 and _T2 temperatures

for:

${\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; \%</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

The above method requires: before testing at each temperature point, the sample needs to be magnetized to saturation (or close to saturation) with the maximum magnetization field, and then the demagnetization test is completed at the test temperature point. Therefore, if you want to test the temperature characteristics of the remanence of the sample in a certain temperature range (multiple temperature points), you need to perform multiple magnetization and demagnetization treatments, and the demagnetization treatment process is more complicated and difficult to remove, which increases the actual measurement. difficulty.

Contents of the invention

The object of the present invention is to provide a measuring device for temperature coefficient of permanent magnet remanence with simple operation and high precision.

In addition, the present invention provides a method for measuring the temperature coefficient of permanent magnet remanence based on the above measuring device.

The technical solution of the present invention is: a permanent magnet remanence temperature coefficient measuring device, which is based on a non-coplanar ring laser, which has four sequentially connected capillary holes, and placed in one of the capillary holes There is a Faraday rotation element, and the permanent magnet to be tested is placed on the surface of the laser near the Faraday rotation element, and a temperature sensor is attached to the permanent magnet to be tested. In addition, a pair of A plane mirror and a pair of spherical mirrors with frequency-stabilized piezoelectric components, wherein the light-combining prism is installed on the plane mirror and connected to the photoelectric converter, while the photoelectric converter is connected to the control circuit, and the control circuit is directly connected to the non-coplanar ring laser The cathode and two anodes are connected, and two spherical mirrors with frequency stabilizing piezoelectric components and a temperature sensor are also connected to the control circuit.

The entire measurement device is placed in a high and low temperature test chamber, which provides different ambient temperatures.

The axes of the four capillary holes are not in one plane.

A method for measuring the temperature coefficient of permanent magnet remanence based on a permanent magnet remanence temperature coefficient measuring device, selects fused silica glass as the material of the optical rotation element, and based on formula (2), measures the offset frequency f _B of the non-coplanar ring laser with The amount of change in temperature, so as to obtain the permanent magnet remanence temperature coefficient,

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}\mathrm{<span\; class="notranslate">\; VBd\&Delta;</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Among them, f _B is the bias frequency of the non-coplanar ring laser, V is the Verdet coefficient of the optical rotator, B is the magnetic induction intensity of the permanent magnet to be tested on the optical rotator, d is the thickness of the optical rotator, and Δv _c is the non-coplanar The cavity frequency of a surface ring laser.

Wherein, the temperature coefficient of the Verdet coefficient is less than 10ppm, and the temperature coefficient of the thickness d is 0.5ppm.

The advantages of the present invention are: the present invention can measure the remanence temperature coefficient of the permanent magnet by measuring the variation of the offset frequency of the non-coplanar ring laser with the temperature, the measurement accuracy is better than 3×10 ^-5 , and it has the advantages of simplicity and ease of use . At the same time, the invention only needs to magnetize the sample once before the test, and can realize continuous measurement to obtain the temperature characteristics of the remanence of the sample in a certain temperature range, which is much simpler than the traditional method for measuring the temperature coefficient of remanence.

Description of drawings

Fig. 1 is the structural representation of the measuring device of permanent magnet remanence temperature coefficient of the present invention;

Figure 2 is a schematic diagram of the gain curve and mode distribution in a non-coplanar ring laser,

1-Faraday rotation element, 2-temperature sensor, 3-spherical mirror with frequency-stabilized piezoelectric component, 4-anode, 5-cavity, 6-plane mirror, 7-cathode, 8-photoelectric converter, 9-combining prism , 13-permanent magnet to be tested, 14-four capillary holes, 18-control circuit.

Detailed ways

The present invention will be further described below through specific examples.

The permanent magnet remanence temperature coefficient measuring device of the present invention is based on a non-coplanar ring laser. The non-coplanar ring laser has four sequentially connected capillary holes for beam propagation, and the axes of the four capillary holes are not in one plane. A Faraday rotation optical element 1 is placed in one of the capillary holes 14 . The permanent magnet 13 to be tested is placed on the surface near the Faraday rotation optical element 1 outside the laser. A temperature sensor 2 is pasted on the permanent magnet 13 to be tested. Place the whole device in a high and low temperature box. The non-coplanar ring laser is controlled by the control circuit 18, and the variation curve of the deviation frequency with temperature is measured. In addition, a pair of flat mirrors 6 and a pair of spherical mirrors 3 with frequency-stabilized piezoelectric components are installed at the intersections of four capillary holes of the non-coplanar ring laser. Wherein, the light-combining prism 9 is installed on the plane mirror 6 and connected with the photoelectric converter 8 , and the photoelectric converter is connected with the control circuit 18 . The control circuit is directly connected to the cathode of the non-coplanar ring laser and the two anodes 4 , and the two spherical mirrors 3 with frequency stabilizing piezoelectric components and the temperature sensor 2 are also connected to the control circuit 18 . The entire measuring device mentioned above is placed in a high and low temperature test chamber, which provides different ambient temperatures.

The working principle of the method for measuring the temperature coefficient of permanent magnet remanence of the present invention is as follows: light waves of four frequencies are running in the non-coplanar ring laser, which are respectively left-handed counterclockwise light, left-handed clockwise light, right-handed clockwise light and right-handed light. Counterclockwise light, as shown in Figure 3, wherein the left-handed counterclockwise light and left-handed clockwise light form a left-handed gyroscope, and the right-handed clockwise light and right-handed counterclockwise light form a right-handed gyroscope. The frequency interval of the left-handed and right-handed gyroscopes is generally several hundred MHz, which is related to the non-coplanar angle of the optical path in the cavity 5 and the optical path length of the optical path. The bias frequency is provided to the left and right-handed gyroscopes through the Faraday effect, and the bias frequency is generally in the order of MHz, which is determined by formula (2):

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}\mathrm{<span\; class="notranslate">\; VBd\&Delta;</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Where V is the Verdet coefficient of the optical rotator, B is the magnetic induction intensity applied to the optical rotator by the permanent magnet to be tested, d is the thickness of the optical rotator, and Δv _c is the cavity frequency of the non-coplanar ring laser.

When the ring laser sensor rotates Ωin relative to the inertial space, the frequency difference of the left-handed gyroscope (the frequency difference between the left-handed clockwise light and the left-handed counterclockwise light) is:

Δf _L ＝f _B +Ω _in (3)

And the frequency difference of the right-handed gyroscope (the frequency difference between the right-handed counterclockwise light and the right-handed clockwise light) is:

Δf _R ＝f _B -Ω _in (4)

The frequency difference Δf _L and Δf _R of the left-handed and right-handed gyroscopes can be obtained through the demodulation of the control circuit 18, so the offset frequency can be obtained as:

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&Delta;f</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

The light-combining prism 9 combines the four beams of light output from the plane mirror 10 to generate an interference signal, which is converted into an electrical signal by the photoelectric converter 8 and demodulated by the control circuit 18 to obtain the offset frequency f _B . The temperature sensor 2 measures the temperature of the permanent magnet 13 to be tested.

Fused silica glass is selected as the material of the optical rotator. The temperature coefficient of the Verdet coefficient is less than 10ppm, and the temperature coefficient of the thickness d of the optical rotator is 0.5ppm. The control circuit can ensure the stability of Δv _c within the range of -45°C to +70°C. on ^10-9 . When the temperature changes, since the temperature coefficient of the above three items is small, the temperature coefficient of the permanent magnet remanence is reflected by the bias frequency of the non-coplanar ring laser, and the variation of the bias frequency with temperature can be measured by the control circuit 18. The permanent magnet remanence temperature coefficient is obtained, and the measurement accuracy is better than 3×10 ^-5 , and the temperature coefficient of the permanent magnet is calculated according to formula (6)

${\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; \%</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

Therefore, the permanent magnet remanence temperature coefficient measuring method of the present invention is based on the above-mentioned permanent magnet remanence temperature coefficient measuring device. After the measuring device is built and debugged, based on formula (2), the permanent magnet remanence can be measured by measuring the variation of the bias frequency with temperature. The magnetic temperature coefficient, the measurement accuracy is better than 3×10 ^-5 , and has the advantages of simplicity and ease of operation. At the same time, the invention only needs to magnetize the sample once before the test, and can realize continuous measurement to obtain the temperature characteristics of the remanence of the sample in a certain temperature range, which is much simpler than the traditional method for measuring the temperature coefficient of remanence.

Claims (5)

1. permanent magnet remanent magnetism temperature coefficient measurement mechanism; It is characterized in that: based on a non-coplane ring laser, have four pores that communicate successively in this non-coplane ring laser, be placed with faraday optical rotation components [1] in the pore therein; Permanent magnet to be measured [13] is placed on the face of laser instrument outside near faraday optical rotation components [1]; Post temperature sensor [2] on the permanent magnet to be measured [13], in addition, four pores of said non-coplane ring laser intersection in twos are equipped with the spherical mirror [3] of pair of planar mirror [6] and a pair of band frequency stabilization piezoelectric element; Wherein, Light-combining prism [9] is installed on the level crossing [6], and joins with photoelectric commutator [8], and photoelectric commutator links to each other with control circuit [18]; This control circuit directly links to each other with negative electrode and two anodes [4] of non-coplane ring laser, and the spherical mirror [3] of two band frequency stabilization piezoelectric elements also links to each other with control circuit [18] with temperature sensor [2] simultaneously.

2. permanent magnet remanent magnetism temperature coefficient measurement mechanism according to claim 1, it is characterized in that: entire measuring device is placed in the high-low temperature test chamber, by high-low temperature test chamber the different environment temperature is provided.

3. permanent magnet remanent magnetism temperature coefficient measurement mechanism according to claim 1 is characterized in that: the axis of said four pores is not in a plane.

4. permanent magnet remanent magnetism temperature coefficient measuring method based on each said permanent magnet remanent magnetism temperature coefficient measurement mechanism of claim 1 to 3; It is characterized in that; Select the material of fused quartz glass,, measure the offset frequency amount f of non-coplane ring laser based on formula (2) as the optically-active element _BWith the variation of temperature amount, thereby obtain permanent magnet remanent magnetism temperature coefficient,

$f_B=\frac{1}{\mathrm{\&pi;}}\mathrm{VBd\&Delta;}{v}_c---\left(2\right)$

Wherein, f _BBe the offset frequency amount of non-coplane ring laser, V is the Verdet coefficient of optically-active element, and B is that permanent magnet to be measured is applied to the magnetic induction density on the optically-active element, and d is the thickness of optically-active element, Δ v _cCavity frequency for non-coplane ring laser.

5. permanent magnet remanent magnetism temperature coefficient measuring method according to claim 4 is characterized in that: wherein, the temperature coefficient of verdet coefficient is less than 10ppm, and the temperature coefficient of its thickness d is 0.5ppm.

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