CN102830375A - Device and method for measuring temperature properties of permanent magnet and permanent magnet material in open circuit - Google Patents

Abstract

The invention belongs to the technical field of permanent magnet material property measurement and discloses a device for measuring temperature properties of a permanent magnet and a permanent magnet material in an open circuit, comprising a sample box (2), a temperature detection and processing unit (3), an induction voltage generating unit (4), an induction voltage detecting and processing unit (5), a sample drawing and controlling unit (6), a temperature realizing unit (7) and a computer controlling and processing unit (8). The invention further provides a method for measuring the temperature properties of the permanent magnet and the permanent magnet material in the open circuit. The device and the method disclosed by the invention have the beneficial effects that the shape of a sample to be detected is not limited, an application range is wide, the automatic measurement can be realized, the measurement repeatability is good and the measurement accuracy is high, so that the device and the method disclosed by the invention are particularly suitable for measuring the permanent magnet material with smaller measured temperature coefficient.

Description

Device and method for measuring temperature characteristics of permanent magnets and permanent magnet materials in an open circuit

technical field

The invention relates to the technical field of measuring the characteristics of permanent magnet materials, in particular to a device and method for measuring the temperature characteristics of permanent magnets and permanent magnet materials in an open circuit. the

Background technique

Temperature characteristics are important characteristic parameters of permanent magnet materials, including reversible temperature coefficient and non-loss, which are especially concerned in the application of permanent magnet materials, so the measurement of temperature characteristics becomes more important. At present, there are three types of measurement methods for the temperature characteristics of permanent magnet materials: (1) The first type, such as the method required by the national standard GB/T24270-2009 "Measurement Method for Temperature Coefficient of Magnetic Properties of Permanent Magnetic Materials": measure different temperatures under a closed magnetic circuit The hysteresis loop or demagnetization curve of the permanent magnet material can be used to obtain the characteristic parameters of the permanent magnet material at different temperatures: coercive force B _r , magnetic flux density coercive force H _cB and magnetic polarization coercive force H _cJ and BH The maximum value of the energy product (BH) _max , and then calculate the temperature coefficient of the corresponding parameter. The disadvantage of the existing device for realizing this method is that it can only measure the situation above room temperature, and it is difficult to realize negative temperature or temperature above 250°C; the temperature control accuracy and measurement accuracy are low. (2) The second category, use a vibrating sample magnetometer to measure the magnetic moment of the test sample at different temperatures under the open magnetic circuit; or use a magnetometer to measure the magnetic flux density of the test sample at different temperatures; or use the principle of electromagnetic induction to use the detection coil The magnetic flux of the sample is measured, and then the temperature characteristic is calculated. The first method of vibrating or pulling the sample magnetometer to measure the magnetic moment is a commonly used measurement method in the prior art. The disadvantages of this method are that the size of the test sample is small, the sample positioning is difficult, the measurement repeatability is poor, and the equipment is complicated and expensive. . CN2114169U is an improved pull sample magnetometer, the method adds a field-free detection coil to measure open-circuit magnetic flux. The second method uses a magnetometer (Tesla meter) to measure the magnetic flux density under an open magnetic circuit. CN1036835A measures the air gap magnetic flux density in the magnetic circuit, rather than the parameters of the permanent magnet material itself, and the temperature control accuracy is low; the disadvantage of CN2352958Y is that the distance between the Hall probe and the sample is far, and the induction signal is weak. The special magnetic shielding device is also difficult to solve the problems of weak signal and insufficient sensitivity; the disadvantage of CN1797023A is that it is difficult to measure the temperature control of the Hall probe itself, the measurement repeatability is poor, the shape of the sample is limited to a ring, and the size is large. The third method adopts detection coils to measure temperature characteristics and has many shortcomings, and the CN2352958Y patent has explained the shortcomings of the third method; CN2384229Y has improved this method and realized multi-sample measurement. Interference between each other; CN101587175 is also an improvement to the third type, which overcomes many shortcomings of the existing methods, but the temperature resistance of the detection coil is limited. (3) The third category, the magnetic induction intensity is measured by nuclear magnetic resonance method under the open magnetic circuit. CN101109720B adopts this method exactly; CN101109720B requires that the magnetic field required for nuclear magnetic resonance is very uniform and cannot be affected by ambient temperature, so it is difficult to realize. Among the magnetic measurement methods, the accuracy of the NMR magnetometer is the highest, followed by the fluxmeter of the electromagnetic induction method, and the third of the magnetometer of the Hall effect method. Among the above three methods of measuring temperature characteristics, the first type uses Hall effect probes to measure magnetic field strength H in the early stage, and coils to measure magnetic flux density B or magnetic polarization J using electromagnetic induction methods. At present, the mainstream uses electromagnetic induction methods. The double coil measures the magnetic field strength H and the magnetic flux density B or the magnetic polarization J; the second type also uses the electromagnetic induction method and the Hall effect method respectively; the third type uses the nuclear magnetic resonance method. They have their own advantages and disadvantages, and there are various deficiencies in their measuring devices. In the practice of measuring the temperature characteristics of permanent magnet materials, especially permanent magnet materials with small temperature coefficients (temperature coefficients less than 0.01%/°C), the existing methods have problems of insufficient resolution and poor repeatability, and a better method is needed Measurement methods.

Contents of the invention

In order to overcome the shortcomings of the existing methods for measuring the temperature characteristics of permanent magnet materials, the present invention proposes a device and method for measuring the temperature characteristics of permanent magnets and permanent magnet materials in an open circuit, which solves the problems of insufficient resolution and poor repeatability in the prior art The problem. the

The invention provides a device for measuring the temperature characteristics of permanent magnets and permanent magnet materials in an open circuit, including a sample box, a temperature detection and processing unit, an induced voltage generation unit, an induced voltage detection and processing unit, a sample pulling control unit, a temperature Implementation unit, computer control and processing unit. The sample box is used to place the sample to be tested and keep it warm; the sample box is a cylinder with a flat bottom. the

As a further improvement of the present invention: the sample box includes: the sample box body, made of non-magnetic material; the upper cover of the sample box, made of non-magnetic material, with a through hole in the middle; the sample box insulation layer; and The inner cavity of the sample box is used to place the sample to be tested. the

As a further improvement of the present invention: the temperature detection and processing unit is used to detect the temperature of the sample to be tested, and display and process the temperature, the temperature detection and processing unit includes: a temperature sensor and a temperature measuring instrument; The temperature sensor is used to measure the temperature signal, and is installed in the through hole of the upper cover of the sample box, and is in contact with the sample to be tested; the temperature measuring instrument is used to receive the signal of the temperature sensor, display the temperature value in real time, and record the temperature The signal is sent to the computer control and processing unit. the

As a further improvement of the present invention: the induced voltage generation unit is used to obtain the induced voltage signal generated by the sample to be tested, and the induced voltage generation unit includes: a Helmholtz coil, used to induce the induced voltage signal generated by the sample to be tested voltage signal; and the base of the Helmholtz coil, the upper and lower sides of the end face of the base are parallel to each other to ensure that the axis of the Helmholtz coil is perpendicular to the plane of the end face of the base, and there is a positioning groove on the base. the

As a further improvement of the present invention: the induced voltage detection and processing unit is used to detect and process the induced voltage signal, and convert the induced voltage signal into magnetic flux data, and the induced voltage detection and processing unit includes: a digital voltage integrator , whose input end is connected to the output end of the Helmholtz coil, for receiving the induced voltage and time signal of the Helmholtz coil; and a signal amplifier, whose input end is connected to the output end of the above-mentioned digital voltage integrator After the signal is amplified, its output terminal is connected with the computer control and processing unit. the

As a further improvement of the present invention: the induced voltage detection and processing unit is used to detect and process the induced voltage signal, and convert the induced voltage signal into magnetic flux data; the induced voltage detection and processing unit is a digital fluxmeter, The input end of the digital fluxmeter is connected with the output end of the Helmholtz coil, and the output end is connected with the computer control and processing unit. the

As a further improvement of the present invention: the sample lifting control unit is used to control and pull the sample box, and pull the sample box to a specified position, and the sample lifting control unit includes: a sample clamp for The sample box is placed and pulled by the sample lifting control unit; the sample holder slide rail is connected with the sample holder through the three through holes of the sample holder to ensure that the sample holder moves along the axis parallel to the Helmholtz coil axis ; The motor is used to drive the sample holder to move along the axis parallel to the Helmholtz coil axis; and the sample holder limit device is used to limit the position of the sample holder; the sample holder and the sample holder sliding rail are made of non-magnetic materials . the

As a further improvement of the present invention: the temperature realization unit controls the temperature of the sample to be tested to a predetermined temperature and keeps the temperature stable; it includes: a working room for placing the sample containing the sample to be tested and installing a temperature sensor box; a heating device, used to heat up the working chamber, the heating device is controlled by the computer control and processing unit; a cooling device, used to cool down the working chamber, the cooling device is controlled by the The above-mentioned computer control and processing unit; and a temperature detection and display device for detecting the temperature of the above-mentioned working room and displaying the temperature value in real time. the

As a further improvement of the present invention: the temperature realization unit controls the temperature of the sample to be tested to a predetermined temperature and keeps the temperature stable; it is a high and low temperature test chamber with a temperature detection and display device. the

As a further improvement of the present invention: the induced voltage generating unit, the sample pulling control unit and the temperature realization unit are separated, and the induced voltage generation unit and the sample pulling control unit are not placed in the temperature realization unit. the

As a further improvement of the present invention: the sample to be tested is a permanent magnet with a single magnetization direction. the

The present invention also provides a method for measuring the temperature characteristics of permanent magnets and permanent magnet materials in an open circuit. According to the principle of electromagnetic induction, the pulling method is used to use the sample pulling control unit to make the sample to be tested in the position of the induced voltage generating unit. The induced electromotive force generated in the Holtz coil is detected and obtained by the digital voltage integrator or fluxmeter of the induced voltage detection and processing unit. After the signal is amplified, the signal is transferred to the computer control and processing unit, and the computer control and The processing unit obtains the temperature coefficient of the parameters at different temperatures; the parameters include the magnetic moment m of the sample to be tested, the magnetization M _d of the working point, the magnetic flux density B _d of the working point, and the coercive B _r of the permanent magnetic material used , the magnetic flux density coercive force H _cB and the maximum value of the BH energy product (BH) _max , the temperature characteristics include the average temperature coefficient in the measurement temperature range, the irreversible loss and the temperature coefficient at any point.

The beneficial effects of the invention are: the shape of the sample to be tested is not limited, only a single magnetization direction is required, and the application range is wide; automatic measurement can be realized, and the measurement repeatability is good; the measurement accuracy of the method is high, and it is especially suitable for measuring temperature coefficients. Small (such as temperature coefficient less than 0.01%/℃) permanent magnet materials. the

【Description of drawings】

Fig. 1 is the device schematic diagram of embodiment 1 of the present invention;

2 is a schematic diagram of an induced voltage generating unit of the present invention;

Fig. 3 is a schematic diagram of a sample box of the present invention;

Fig. 4 is a schematic diagram of the sample pulling control unit of the present invention;

Fig. 5 is a bottom plan view of the sample holder of the sample pulling control unit of the present invention;

Fig. 6 is the schematic diagram of the device of embodiment 2 of the present invention;

Fig. 7 is a schematic diagram of the device of Embodiment 3 of the present invention.

【Detailed ways】

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

The invention provides a device for measuring the temperature characteristics of permanent magnets and permanent magnet materials in an open circuit, including a sample box 2, a temperature detection and processing unit 3, an induced voltage generation unit 4, an induced voltage detection and processing unit 5, and a sample pulling Control unit 6 , temperature realization unit 7 , computer control and processing unit 8 . The sample box 2 is used to place the sample 1 to be tested, and keep the sample 1 to be tested 1 insulated; the sample box 2 is a cylinder with a flat bottom, a cylinder of any shape, and one of the preferred designs is a cylinder. the

The sample box 2 includes: a sample box body 21 made of a non-magnetic material, one of the preferred options is polytetrafluoroethylene; a sample box upper cover 22 made of a non-magnetic material with a through hole in the middle; The insulating layer 23 of the sample box; and the cavity 24 of the sample box, which is used to place the sample 1 to be tested. In one embodiment, the sample box upper cover 22 adopts the same scheme as the sample box body 21, and the middle part has a through hole where the temperature sensor 31 can be installed; the sample box insulation layer 23; the filling insulation material, one of the preferred options is asbestos; and the sample The inner cavity 24 of the box is used to place the sample 1 to be tested. The shape of the inner cavity is designed according to the shape of the sample 1 to be tested, and one of the preferred options is cylindrical. the

The temperature detection and processing unit 3 is used to detect the temperature of the sample 1 to be tested, and display and process the temperature. The temperature detection and processing unit 3 includes: a temperature sensor 31 and a temperature measuring instrument 32; the temperature sensor 31 is used to measure the temperature signal, and is installed in the through hole of described sample box upper cover 22, contacts with the sample 1 to be tested; The temperature measuring instrument 32 is used for receiving the signal of temperature sensor 31, displays the temperature value in real time, And transmit the temperature signal to said computer control and processing unit 8. the

One of the preferred solutions of the temperature sensor 31 is a platinum resistor, which can be used for temperature measurement from -60°C to 260°C; the second preferred solution is a thermocouple, which can be used for temperature measurement from -210°C to 1300°C. the

The induced voltage generating unit 4 is used to obtain the induced voltage signal generated by the sample to be tested 1, and the induced voltage generating unit 4 includes: a Helmholtz coil 41 for inducing the induced voltage generated by the sample to be tested 1 signal; and the base 42 of the Helmholtz coil 41, the upper and lower sides of the base 42 end faces are parallel to each other to ensure that the axis of the Helmholtz coil 41 is perpendicular to the plane of the base 42 end face, and there is a positioning groove on the base 42 . the

The induced voltage detection and processing unit 5 is used to detect and process the induced voltage signal, and convert the induced voltage signal into magnetic flux data. The induced voltage detection and processing unit 5 includes: a digital voltage integrator 51 whose input terminal Connected to the output end of the Helmholtz coil 41, used to receive the induced voltage and time signal of the Helmholtz coil 41; and a signal amplifier 52, whose input end is connected to the output end of the above-mentioned digital voltage integrator 51 After the signal is amplified, its output terminal is connected with the computer control and processing unit 8. the

The induced voltage detection and processing unit 5 is used to detect and process the induced voltage signal, and convert the induced voltage signal into magnetic flux data; the induced voltage detection and processing unit 5 is a digital fluxmeter, and the digital fluxmeter input The terminal is connected with the output terminal of the above-mentioned Helmholtz coil 41, and its output terminal is connected with the computer control and processing unit 8. the

The sample lifting control unit 6 is used to control and pull the sample box, and pull the sample box to a specified position. The sample lifting control unit 6 includes: a sample holder 61, which is used to place the sample box 2 , and is pulled by the sample pulling control unit 6; the sample holder slide rail 62 is connected with the sample holder 61 through the three through holes 611 of the sample holder 61 to ensure that the sample holder 61 is along the axis of the Helmholtz coil 41 The parallel axis moves; the motor 63 is used to drive the sample holder 61 to move along the axis parallel to the Helmholtz coil 41 axis; and the sample holder stopper 64 is used to limit the position of the sample holder 61; the sample holder 61 and the sample The clamp slide rail 62 is made of non-magnetic material. the

The temperature realization unit 7 controls the temperature of the sample 1 to be tested to a predetermined temperature and keeps the temperature stable; it includes: a working chamber 71 for placing the sample box 2 containing the sample 1 to be tested and installing a temperature sensor 31 The heating device 72 is used to heat up the working chamber 71, and the heating device 72 is controlled by the computer control and processing unit 8; the cooling device 73 is used to cool down the working chamber 71, the cooling The device 73 is controlled by the computer control and processing unit 8; and the temperature detection and display device 74 is used to detect the temperature of the working chamber 71 and display the temperature value in real time. the

The temperature realization unit 7 controls the temperature of the sample 1 to be tested to a predetermined temperature and keeps the temperature stable; it is a high and low temperature test chamber with a temperature detection and display device 74 . the

The induced voltage generation unit 4, the sample pulling control unit 6 and the temperature realization unit 7 are separated, and the induced voltage generation unit 4 and the sample pulling control unit 6 are not placed in the temperature realization unit 7, thereby eliminating the temperature impact. The induced voltage produces an adverse effect on the unit 4 . the

The sample to be tested 1 is a permanent magnet with a single magnetization direction. the

The present invention also provides a method for measuring the temperature characteristics of permanent magnets and permanent magnet materials in an open circuit. According to the principle of electromagnetic induction, the sample pulling control unit 6 is used to make the sample 1 to be tested in the induced voltage generating unit by using the pulling method. The induced electromotive force is generated in the Helmholtz coil 41 of 4, and the digital voltage integrator 51 or the fluxmeter of the induced voltage detection and processing unit 5 detects and obtains the induced electromotive force. After the signal is amplified, the signal is transferred to the computer control and The processing unit 8, the computer control and processing unit 8 obtains the temperature coefficient of the parameters at different temperatures; the parameters include the magnetic moment m of the sample 1 to be tested, the magnetization M _d of the working point, the magnetic flux density B _d of the working point, and The coercivity B _r , the magnetic flux density coercive force H _cB and the maximum value (BH) _max of the BH energy product of the permanent magnet material used, the temperature characteristics include the average temperature coefficient in the measurement temperature range, irreversible loss and any point Temperature Coefficient.

Further description will be given below through several examples. the

Embodiment 1: As shown in FIG. 1 , this embodiment is an automatic embodiment for measuring the temperature characteristics of permanent magnets and permanent magnetic materials in an open magnetic circuit. the

This embodiment consists of a sample box 2, a temperature detection and processing unit 3, an induced voltage generation unit 4, an induced voltage detection and processing unit 5, a sample pulling control unit 6, a temperature realization unit 7, and a computer realization and processing unit 8. the

The sample box 2 is used to place the sample to be tested 1 and keep the sample to be tested 1 insulated. As shown in FIG. in the lumen. the

The temperature detection and processing unit 3 is used to measure the temperature of the sample 1 to be tested and send the temperature signal to the computer control and processing unit 8 , which is composed of a temperature sensor 31 and a temperature measuring instrument 32 . The temperature sensor 31 is a platinum resistor or a thermocouple, and is connected with a temperature measuring instrument 32 . the

The induced voltage generating unit 4 is used for inducing the induced voltage signal generated by the sample to be tested 1, as shown in FIG. composition. The pulling control unit 6 pulls the sample box 2 out of the Helmholtz coil 41 to make the Helmholtz coil 41 generate an induced voltage signal. the

The induced voltage detection and processing unit 5 is used for collecting, amplifying and transmitting the voltage and time signals induced by the Helmholtz coil 41. It is composed of a digital voltage integrator 51 and a signal amplifier 52. The input terminal of the digital voltage integrator 51 is connected to the The output end of the Holtz coil 41 is connected to collect the voltage and time signals induced by the Helmholtz coil 41, the output end is connected to the input end of the signal amplifier 52, and the output end of the signal amplifier 52 is connected to the computer implementation and processing unit 8 connect. the

The sample pulling control unit 6 is used to pull the sample box 2 out of the Helmholtz coil 41, as shown in Fig. 4 and Fig. 5, the sample holder 61, slide rail 62, motor 63 and sample holder stopper 64; the output end of the sample pulling control unit 6 is connected with the computer implementation and processing unit 8, and the pulling position is controlled by the computer implementation and processing unit 8. the

The temperature realization unit 7 is composed of a working chamber 71 , a heating device 72 , a cooling device 73 and a temperature detection and display device 74 , and is connected and controlled with a computer realization and processing unit 8 . the

The heating device 72 is used to heat up the sample 1 to be tested in the sample box 2 inner cavity 24 placed in the working room 71. Specifically, it can be composed of a resistance wire, a blower, etc., and the resistance wire is mainly used to heat and increase the temperature in the working room 71. The temperature of the sample 1 to be tested in the inner cavity 24 of the sample box 2; when the temperature of the sample 1 to be tested is greater than the pre-required temperature, rely on the air blower to cool the working chamber 71 to dissipate heat until the pre-required temperature is reached. the

The cooling device 73 is used to cool down the sample 1 to be tested in the inner cavity 24 of the sample box 2 placed in the working chamber 71, which may be composed of a compressor and a refrigerant, or a liquid nitrogen device; when the temperature of the sample 1 to be tested is When the temperature is lower than the pre-required temperature, rely on the heating device 72 to heat the working chamber 71 to increase the temperature until reaching the pre-required temperature. the

The computer control and processing unit 8 sends temperature control instructions to the temperature realization unit 7, controls the heating device 72 and the cooling device 73 to work; records and stores the temperature signal sent by the temperature detection and processing unit 3; receives the induced voltage detection and sends the temperature signal sent by the processing unit 5 The signal and convert it into the corresponding magnetic flux value. the

Embodiment 2, with reference to shown in Figure 6, in the present embodiment, induced voltage detection and processing unit 5 is a digital fluxmeter, and the input end of the digital fluxmeter is connected with the output end of the Helmholtz coil 41, and its output end is connected with the computer The control and processing unit 8 is connected. The temperature realization unit 7 is a high and low temperature test box with a temperature detection and display device. Other structures are the same as in Embodiment 1. the

Embodiment 3, as shown in FIG. 7 with reference, all work of this embodiment is manually operated. In this embodiment, the induced voltage detection and processing unit 5 is a digital fluxmeter. The temperature realization unit 7 is a high and low temperature test box with a temperature detection and display device. The computer control and processing unit 8 sends temperature control instructions to the temperature realization unit 7 to control the heating device 72 and the cooling device 73 to work. Manually pull the sample box 2 out of the Helmholtz coil 41 , and the other structures are the same as those in Embodiment 1. the

A method for measuring the temperature characteristics of permanent magnet materials in an open circuit, using the principle of electromagnetic induction, using Helmholtz coils and fluxmeters, etc., to accurately measure the magnetic moment m of permanent magnets, the magnetization M _d at the working point, and the working The magnetic flux density B _d of the point, and the temperature coefficient of the permanent magnetic material used in the permanent magnet B _r and the magnetic flux density coercive force H _cB and irreversible loss. The present invention derives the relationship between the magnetic moment m of a permanent magnet and these parameters.

The principle of the method is based on the electromagnetic induction method. In the homogeneous area of the Helmholtz coil magnetic field, the permanent magnet is regarded as a magnetic dipole. Therefore, the induced electromotive force generated in the Helmholtz coil by a permanent magnet with a magnetic moment m in an open magnetic circuit state can be expressed as ^[1] :

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}}{{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 9</span>}<span\; class="notranslate">\; )</span>$

$\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; \&CenterDot;</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; )</span>$

μ ₀ M _d ＝ B _d + μ ₀ H _d ............................( 11)

${\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}{{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; cB</span>}}}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 12</span>}<span\; class="notranslate">\; )</span>$

$\mathrm{<span\; class="notranslate">\; \&Phi;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 14</span>}<span\; class="notranslate">\; )</span>$

$\mathrm{<span\; class="notranslate">\; \&Phi;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 15</span>}<span\; class="notranslate">\; )</span>$

$\mathrm{<span\; class="notranslate">\; \&Phi;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 16</span>}<span\; class="notranslate">\; )</span>$

$\mathrm{<span\; class="notranslate">\; \&Phi;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; cB</span>}}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 17</span>}<span\; class="notranslate">\; )</span>$

$\mathrm{<span\; class="notranslate">\; \&Phi;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}<span\; class="notranslate">\; \&Center\; Dot;</span>\sqrt{\mathrm{<span\; class="notranslate">\; 4</span>}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; BH</span>}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; max</span>}}}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 18</span>}<span\; class="notranslate">\; )</span>$

In formula (1):

m _z ——the component of the magnetic moment m on the axis of the Helmholtz coil, A·m ² ;

E——The induced electromotive force generated by the magnetic moment m in the Helmholtz coil from the moment t ₁ (that is, the beginning) to the moment t ₂ (that is, the end), V;

C——Helmholtz coil constant, m;

——Magnetic constant, μ ₀ =4π×10 ^-7 H/m.

According to Faraday's principle of electromagnetic induction, the induced electromotive force generated by the change of the magnetic flux (△Φ) of the permanent magnet in the Helmholtz coil can be expressed as:

In formula (2):

ΔΦ——the magnetic flux change of the permanent magnet in the Helmholtz coil, Wb;

Φ ₁ ——The magnetic flux generated by the permanent magnet in the Helmholtz coil at t ₁ instant, Wb;

Φ ₂ ——The magnetic flux generated by the permanent magnet in the Helmholtz coil at t ₂ instant, Wb;

E——the induced electromotive force generated by the permanent magnet in the Helmholtz coil, V;

If the magnetic flux Φ ₁ = 0Wb generated at the instant t ₁ (i.e. at the beginning), and the magnetic flux Φ ₂ = Φ generated at the instant t ₂ (i.e. at the end), then:

Therefore, according to formula (1) and formula (3), the magnetic moment m and the average temperature coefficient a _m of the permanent magnet can be measured by measuring the change of the magnetic flux of the permanent magnet in the Helmholtz coil, namely:

In formula (5), the magnetic flux values Φ(T ₁ ) and Φ(T ₂ ) at temperatures T ₁ and T ₂ are measured by the Helmholtz coil and the fluxmeter (voltage integrator), respectively, and the permanent magnet can be calculated The average temperature coefficient of magnetic moment a _m . In practice, the resulting temperature coefficient is the average temperature coefficient over the range of temperatures _T1 and _T2 .

To obtain the temperature coefficient of any temperature point within the range of temperature T ₁ and T ₂ , measure the magnetic flux at least five temperature points in the measurement temperature area, and then use the principle of least squares to fit the measured data into the relationship between magnetic flux and temperature Polynomial curves, namely:

In formula (6):

n——the polynomial highest valence of the polynomial curve of magnetic flux Φ(T ₁ ) and temperature;

a _i —coefficients of its polynomial.

The temperature coefficient of any temperature point T can be expressed as:

Similarly, the irreversible loss of the permanent magnet is measured by the Helmholtz coil and the fluxmeter, namely:

In formula (8):

m ₁ ——magnetic moment when the temperature is T ₁ , A·m ² ;

m ₂ ——magnetic moment when returning from temperature T ₂ to temperature T ₁ , A·m ² ;

η _m ——Irreversible loss of permanent magnet, %.

According to the definition of permeability coefficient (or working point) P _c , the permeability coefficient P _c is:

In formula (9):

B _d ——The magnetic induction intensity produced by the permanent magnet, T;

H _d ——the internal demagnetization field strength of the permanent magnet, A·m ^-1 .

According to the definition of magnetization, the magnetization is:

In formula ⑽:

m——Magnetic moment of permanent magnet, A·m ² ;

V——the volume of the permanent magnet, m ³ ;

ρ——the density of the permanent magnet, kg·m ^-3 ;

m _A ——mass of permanent magnet, kg

M——The magnetization intensity of the permanent magnet, A·m ^-1 .

According to the relationship between the magnetization intensity and the magnetic induction intensity, at the working point of the permanent magnet, there are:

In formula ⑾:

M _d ——the magnetization intensity of the permanent magnet, A·m ^-1 .

Since the BH demagnetization curve of the permanent magnet material is approximately a straight line, the relationship between the recovery permeability μ _r and the coercive force B _r , the magnetic flux density coercive force H _cB and the maximum value of the BH energy product (BH) _max is:

According to formula ⑷ and formula ⑽, the relationship between the magnetic flux of the permanent magnet and the magnetization and magnetic induction of the permanent magnet can be measured by the Helmholtz coil and the fluxmeter (voltage integrator):

Formulas ⒁ and ⒂ are the principles and methods for measuring the magnetization and magnetic induction of permanent magnets using Helmholtz coils and fluxmeters.

According to formulas ⑼, ⑿, ⒀ and formula ⒁, the magnetic flux of the permanent magnet and the coercivity B _r of the material, the magnetic flux density coercive force H The relationship between _cB and the maximum value of the BH energy product (BH) _max : Equations ⒃, ⒄ and ⒅ are the coercive force, magnetic flux density coercive force and energy The principle and method of the maximum value of the product.

According to the above principles and the definition of temperature coefficient, using the Helmholtz coil, fluxmeter and temperature realization device, the magnetic moment m, magnetization M _d , magnetic induction B _d of the permanent magnet and the remanence B _r of the material are accurately measured. The temperature coefficient corresponding to parameters such as magnetic flux density coercive force H _cB and energy product maximum (BH) _max can also be measured to obtain irreversible loss.

The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it cannot be assumed that the specific implementation of the present invention is limited to these descriptions. For those of ordinary skill in the technical field of the present invention, without departing from the concept of the present invention, some simple deduction or replacement can be made, which should be regarded as belonging to the protection scope of the present invention. the

Claims (13)

1. a device of in open circuit, measuring permanent magnet and permanent magnetic material temperature characterisitic is characterized in that: comprise that sample box (2), temperature detection and processing unit (3), induced voltage generation unit (4), induced voltage detect and processing unit (5), sample lift control module (6), temperature realizes unit (7), computer control and processing unit (8).

2. the device of in open circuit, measuring permanent magnet and permanent magnetic material temperature characterisitic according to claim 1, it is characterized in that: described sample box (2) is used to place testing sample (1), and testing sample (1) is incubated; Said sample box (2) is the cylinder on plane for the bottom.

3. the device of in open circuit, measuring permanent magnet and permanent magnetic material temperature characterisitic according to claim 1, it is characterized in that: described sample box (2) comprising: sample box body (21) is formed by non-magnet material; Sample box loam cake (22) is formed by non-magnet material, and there is through hole at the middle part; Sample box heat-insulation layer (23); And sample box inner chamber (24), be used to place testing sample (1).

4. the device of in open circuit, measuring permanent magnet and permanent magnetic material temperature characterisitic according to claim 1; It is characterized in that: described temperature detection and processing unit (3) are used to detect the temperature of testing sample (1); And temperature shown, handles, said temperature detection and processing unit (3) comprising: temperature sensor (31) and temperature measuring set (32); Said temperature sensor (31) is used to measure temperature signal, and is installed in the through hole of described sample box loam cake (22), contacts with testing sample (1); Said temperature measuring set (32) is used to accept the signal of temperature sensor (31), real-time displays temperature value, and temperature signal is sent to described computer control and processing unit (8).

5. the device of in open circuit, measuring permanent magnet and permanent magnetic material temperature characterisitic according to claim 1; It is characterized in that: described induced voltage generation unit (4) is used to obtain the induced voltage signal that testing sample (1) produces; Said induced voltage generation unit (4) comprising: Helmholtz coils (41) is used for the induced voltage signal that induction is produced by testing sample (1); And the pedestal (42) of Helmholtz coils (41), the top and bottom of pedestal (42) the end face axis with assurance Helmholtz coils (41) parallel to each other is vertical with the plane of pedestal (42) end face, and a locating slot is arranged on the pedestal (42).

6. the device of in open circuit, measuring permanent magnet and permanent magnetic material temperature characterisitic according to claim 5; It is characterized in that: described induced voltage detects and processing unit (5); Be used for detecting and handling induced voltage signal; Convert induced voltage signal to the magnetic flux data; Said induced voltage detects and processing unit (5) comprising: digital voltage integrator (51), and its input end is connected with the output terminal of said Helmholtz coils (41), is used to receive the induced voltage and the time signal of this Helmholtz coils (41); And signal amplifier (52), its input end is connected with the output terminal of above-mentioned digital voltage integrator (51), signal is amplified the back be connected with processing unit (8) with described computer control by its output terminal.

7. the device of in open circuit, measuring permanent magnet and permanent magnetic material temperature characterisitic according to claim 5; It is characterized in that: described induced voltage detects and processing unit (5); Be used for detecting and handling induced voltage signal, convert induced voltage signal to the magnetic flux data; Said induced voltage detects and processing unit (5) is digital fluxmeter, and digital fluxmeter input end is connected with the output terminal of above-mentioned Helmholtz coils (41), and its output terminal is connected with processing unit (8) with described computer control.

8. the device of in open circuit, measuring permanent magnet and permanent magnetic material temperature characterisitic according to claim 1; It is characterized in that: described sample lifts control module (6); Be used for control and lift sample box, sample box is lifted the position of stipulating, described sample lifts control module (6) and comprising: sample clamp (61); Be used to place sample box (2), and lifted control module (6) by sample and lift; Sample clamp slide rail (62), three through holes (611) through sample clamp (61) are connected with sample clamp (61), are used to guarantee that the axis of sample clamp (61) edge and Helmholtz coils (41) parallel axes moves; Motor (63), the axis that is used to drive sample clamp (61) edge and Helmholtz coils (41) parallel axes moves; And sample clamp stop means (64), be used to limit the position of sample clamp (61); Sample clamp (61) and sample clamp slide rail (62) form for non-magnet material.

9. the device of in open circuit, measuring permanent magnet and permanent magnetic material temperature characterisitic according to claim 1 is characterized in that: described temperature realizes unit (7), makes the temperature of testing sample (1) control to predetermined temperature, and keeps temperature stabilization; It comprises: operating room (71) are used for placing the sample box (2) that contains testing sample (1) and mounting temperature sensor (31); Heating arrangement (72) is used for the heat temperature raising with said operating room (71), and this heating arrangement (72) is controlled by described computer control and processing unit (8); Cooling device (73) is used for said operating room (71) are cooled, and this cooling device (73) is controlled by described computer control and processing unit (8); And temperature detection and display device (74), be used to detect the temperature of above-mentioned operating room (71), and displays temperature value in real time.

10. the device of in open circuit, measuring permanent magnet and permanent magnetic material temperature characterisitic according to claim 1 is characterized in that: described temperature realizes unit (7), makes the temperature of testing sample (1) control to predetermined temperature, and keeps temperature stabilization; It is the high and low temperature chamber of band temperature detection and display device (74).

11. according to claim 1,5,8,9 or 10 arbitrary described devices of in open circuit, measuring permanent magnet and permanent magnetic material temperature characterisitic; It is characterized in that: described induced voltage generation unit (4), sample lift control module (6) and realize that with temperature unit (7) separates, and induced voltage generation unit (4) and sample lift control module (6) and be not positioned in the temperature realization unit (7).

12., it is characterized in that: the permanent magnet of described testing sample (1) for having single DOM according to the arbitrary described device of in open circuit, measuring permanent magnet and permanent magnetic material temperature characterisitic of claim 1 to 11.

13. method of in open circuit, measuring the device of permanent magnet and permanent magnetic material temperature characterisitic; It is characterized in that: according to electromagnetic induction principle; Adopting czochralski method to utilize sample to lift control module (6) makes testing sample (1) in the Helmholtz coils (41) of induced voltage generation unit (4), produce induction electromotive force; Detect with the digital voltage integrator (51) or the fluxmeter detection of processing unit (5) and obtain induction electromotive force by induced voltage; After signal amplified, to computer control and processing unit (8), computer control and processing unit (8) obtained the temperature coefficient of parameter under the different temperatures with transfer of signals; Said parameter comprises the magnetic moment of testing sample (1) m , the working point the magnetization M _d , the working point magnetic flux density B _d , and the magnetic remanence of used permanent magnetic material B _r >, the magnetic flux density coercive force H _CB And BHThe maximal value of energy product (BH) _Max , said temperature characterisitic is included in the temperature coefficient of average temperature coefficient, irreversible loss and the arbitrfary point of measuring temperature range.

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