-
-
-
Service Support
-
-
Measurement Method of DC B- H Curve of Soft Magnetic Materials
Release time:
2020-07-01
Source:
Www.fe2100.com Hunan Yongyi Technology Co., Ltd.
Measurement equipment for measuring parameters such as DC BH curve and magnetic properties of soft magnetic materials is roughly divided into two types: one is the use of nuclear magnetic resonance method; the other is the use of scanning method or impact method. Author: ding jiaquan Hunan yongyi technology co., ltd. reprinted to indicate the source
MeasurementDC BH curve of soft magnetic materialAs well as magnetic properties and other parameters of the measurement equipment is roughly divided into two types: one is the use of nuclear magnetic resonance method; the other is the use of scanning method or impact method.
The equipment using nuclear magnetic resonance method is to take the powder sample of soft magnetic material, which belongs to the measurement of open circuit sample, which is quite different from the actual device (closed circuit).
Equipment using scanning method or impact method (foreign equipment is scanning method, domestic equipment is impact method or both) is to take typical mode samples of soft magnetic materials for measurement, such as closed-circuit ring samples, CD type, EE type, etc.; Such as open-circuit long round rods, long strips, etc.; Or the open-circuit sample forms a closed circuit through the magnetic permeability of the yoke, which is converted into closed-circuit measurement, such as a magnetometer.
Below we pass
Hunan Yongyi Technology Co., Ltd.Produced
FE-2100SD soft magnetic DC B- H instrument（
DC Measuring Device for FE-2100SD Soft Magnetic Materials), to measure the magnetic properties of soft magnetic materials of various shapes.
1 Measurement of closed-circuit samples
The most classical model in the closed-circuit sample is the torus.
Note here: A/B ≤ 1.1 (old national standard A/B ≤ 1.25). This is to ensure a uniform distribution of the magnetic field strength H in the sample.
The 1.1 measurement principle is as follows:
First, two sets of coils are wound for the magnetic ring, N1 is the magnetization coil and N2 is the test coil. Control the constant current power supply to N1 to provide current I, if the magnetic circuit circumference of the magnetic ring is Le, the generated magnetic field strength
H=N1*I/Le
The induced voltage U of N2 is integrated to obtain the magnetic flux φ
If the cross-sectional area of the sample is AE, the magnetic flux density B can be calculated
B=φ/(N2*Ae)
1.2 test process
| 1 Prepare the sample ring waiting for testing and measure the size. |
3 Wrap the insulating tape. |
| 2 Weigh the weight. |
4 First wind the N2 coil, then wind the N1 coil, and remove the paint from the coil end. |
Note: N2 is wound first in order to measure the coil closer to the sample.
The number of turns of N2 is determined by the range size (20mWb) and resolution of the magnetic flux meter. Generally, about 20 turns are more appropriate. The amount of N1 is determined by the test condition H (the minimum magnetic field strength Hm at which the sample reaches saturation) and the current output of the current source (10A). So N1 ≥ Hm * Le/10.
Take a low carbon steel ring sample as an example, the sample size is Φ φ40*32*11.1, and the test condition is Hm = 15000A/m, so N2 is wound 20 turns and N1 is wound 240 turns.
Measured
hysteresis loopas follows.
Measured
magnetization curveas follows.
Other closed-circuit samples (CD type, EE type, etc.) were measured similarly.
2 Measurement of open-circuit samples
There are two methods for measuring open circuit samples: one is to measure the magnetic properties of open circuit samples with solenoids; the other is to measure the magnetic properties of open circuit samples with a magnetometer. In fact, the use of a magnetometer is to convert an open circuit measurement into a closed circuit measurement.
2.1 measurement of magnetic properties of open-circuit samples with solenoids
The test principle is as follows:
The constant current power supply energizes the solenoid, the current is I, the number of turns of the solenoid is N1, and the length of the solenoid is L, then the magnetic field strength generated by the center of the solenoid is H = N1 * I/L. A rod-shaped sample is placed at the center of the solenoid with a cross-sectional area of AE, and a measuring coil having a number of turns of N2 is sleeved, so that the magnetic flux density of the rod-shaped sample is B = φ/(N2 * AE).
Only open circuit measurement, the sample will produce a reverse magnetic field strength (demagnetizing field), thus affecting the measurement of H. The size of the demagnetizing field is related to the size of the applied magnetic field strength and the shape and size of the sample. Therefore, in order to reduce the influence of the demagnetizing field, the sample should be processed into a slender sample, that is, the aspect ratio is large and greater than 20.
Take the steel rod sample as an example, the size of the steel rod is φ14*260. Test conditions H = 24000A/m.
The measured hysteresis loop is as follows:
Due to the influence of the demagnetizing field on the open circuit sample, the hysteresis loop of the test will tilt to the right.
The software corrects the demagnetizing field to obtain a hysteresis loop similar to the closed-circuit sample, as follows:
Modified hysteresis loop.
Modified magnetization curve.
Other long strip type samples were similar.
2.2 MEASUREMENT OF MAGNETIC PROPERTY OF OPEN PATTERN SAMPLES WITH MAGNETOMETER
If the strip-shaped sample is wider and shorter, it is not suitable for solenoid measurement. We can measure its DC magnetic properties using the magnetometer method.
The principle is as follows:
The upper and lower yokes clamp the sheet sample to close the magnetic lines of force. The excitation coil is energized to generate a magnetic field strength H, and the magnetic flux is obtained by measuring the voltage integral of the coil, and then the magnetic flux density B is converted.
However, the remanence, coercivity and permeability of the yoke itself will affect the measurement results. The higher the magnetic permeability of the magnetic yoke, the smaller the coercive force, and the smaller the influence on the measurement results of the sample.
Taking the iron-cobalt alloy sheet sample as an example, the sample size is 100mm * 30mm * 1mm.
Test conditions H = 10000A/m.
The hysteresis loop is measured as follows:
The measured magnetization curve is as follows:
Of course, the magnetism meter can be divided into Class A magnetism meter and Class B magnetism meter. The above mentioned is Class A magnetism meter. The model of Class B magnetometer is basically the same, except that the excitation coil is wound on two magnetic yokes, and the H value it generates needs to be measured by a magnetic potential coil (magnetic potential meter or H coil).
There is also a method of converting open circuit measurement into closed circuit measurement, such as splicing four strip samples into a cut, and then winding two coils as closed circuit sample measurement.
If the size of the elongated sample is 30*300, it can be measured with an Epstein square circle, which is similar to the sub-shape of the lap joint of 4 samples.
If some samples are squares, cubes, or cylinders, we can measure them with a magnetometer scheme or even with an electromagnet.
Similarly, the electromagnet measurement method is the same as the magnetometer measurement method, and the magnetic properties of the yoke will affect the measurement results of the sample.
The measurement of all these open-circuit samples has two requirements for the sample: one is the same cross-sectional area; the other is that the two sides are parallel. This is conducive to the measurement process, but also make the measurement of magnetic parameters more accurate.
Related News
Hunan Forever Elegance Technology Co.,Ltd.
Address: 10th Floor, New Cooperation International Trade City, Economic and Technological Development Zone, Loudi City, Hunan Province (Intersection of Xiangyang Street East and Yingchun Road)
Douyin
Customer Message
Copyright © Hunan Forever Elegance Technology Co.,Ltd.
This site supports IPv4 IPv6.
Business License