From the U ~ H curve of the soft magnetic material, the test coil turns N on the test results were studied during the measurement of the magnetic permeability u. The reason why the magnetic permeability U value is measured when N takes a certain value. With regard to the impact of testing magnetic field h on the test sample ring, the integral method is solved. It is pointed out the difference between the ring magnetic pervagase and the real magnetic permeability of the material. The method of measuring the material start magnetic permeability Ui using a simple instrument.
It is well known that $ Magneticivity is $ μ is a key technical indicator of soft magnetic material. The measurement of the magnetic permeability μ is basically measured on a standard prototype ring. The inductance amount L of its winding coil is measured, and then the magnetic permeability of the material is calculated. However, for the same sample ring, the measured material magnetic permeability μ varies widely with different instruments or with the same instrument. Sometimes there will be caused by supply, and the contradictions or disputes are required. In particular, the test μ value different from the number of turns of the test coil is different. Sometimes the number of μ values measured in the turns is lower, but sometimes the number of turns increases to increase. This will make some testers can't understand. This paper tries to clarify the test instrument, test coil turns and different methods of magnetic permeability testing.
About magnetic permeability concept
For a uniform magnetic medium, if it is placed in a uniform magnetic field h, the magnetic medium itself produces an additional magnetic field h ', h' and h. The total magnetic field strength of H 'and H stacks is called the magnetic flux density B [1] of this magnetic material. It can be seen that the magnetic flux density B and the magnetic field strength h are essentially physical quantities characterized by magnetic field. However, the names and units of the units they are different may be different. In the Gaussian unit system used in the usual use of H, the unit of OE, B is used in Gauss (GS), Oste and Gauss, and the name of the two units of the two units are completely equal. In the international unit system that is now emphasized, B unit use Tesla (T), H unit, and the unit of EtOAc (A / M), B and H is no longer equal, 1A / m = 410-7T . The ratio of the magnetic flux density and the magnetic field strength, referred to as the magnetic permeability of the material, the ratio of their value is referred to as an absolute magnetic permeability μ, and the ratio of these two physical quantities is referred to as the relative magnetic permeability μ. Obviously, in the Gaussian unit system, because of the units of B and H, the ratio of their value is equal to the ratio of their magnitude. Therefore, in the Gaussian unit system, the relative magnetic permeability of the material is equal to the absolute magnetic permeability, and does not distinguish the absolute magnetic permeability and the relative magnetic permeability. For vacuum, it does not produce additional magnetic fields, B is equal to H, so the magnetic permeability of the vacuum is equal to 1. In the international unit system, since the unit size of B and H is no longer equal, the ratio of their values must never represent their physical quantity ratio μ, and the relative magnetic permeability of the material is no longer equal to its absolute magnetores. For vacuum, since the additional magnetic fields, B and Hs cannot produce equal, the equivalent magnetic permeability μ of the vacuum is equal to 1. If the magnetic field strength h at a certain point in the vacuum is Ya / m, the magnetic flux density B of this point should be 4πy10-7T, so that the ratio of the B and H of the point is the ratio of the vacuum absolute magnet in the international unit system. Pasivity μ0 = 4π10-7H / m. The absolute magnetic permeability of the typical soft magnetic material can be obtained to obtain a relative magnetic permeability μ = b / μ0h by μ 0. If it is not added, the relative magnetic permeability is referred to when it is mentioned. Technology area
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