Magnetic units are the most complex and irregular in physics and the most difficult to understand. I hope it will be helpful to everyone.
|
Name of magnetic quantity
|
SI Symbols and Units
|
CGS Symbols and Units
|
Unit conversion
|
|
magnetic flux
|
Φ
|
Webb (Wb)
|
Φ
|
Maxwell (Mx)
|
1Mx=10-8 Wb
|
|
magnetic induction intensity
|
B
|
Tesla (T)
|
B
|
Gauss (Gs)
|
1Gs=10-4 T
|
|
magnetic field strength
|
H
|
Ann/meter (A/m)
|
H
|
Oe
|
1Oe=103/4Π A/m
|
|
magnetization intensity
|
M
|
Ann/meter (A/m)
|
M
|
Gauss (Gs)
|
1Gs=103 A/m
|
|
magnetic polarization intensity
|
J
|
Tesla (T)
|
4ΠM
|
Gauss (Gs)
|
1Gs=10-4 T
|
|
magnetic energy product
|
BH
|
coke/meter3(J/m3)
|
BH
|
GOE (GOE)
|
1MGOe=102/4Π kJ/m3
|
|
vacuum permeability
|
|
4Π•10-7H/m
|
－
|
1
|
－
|
Permanent magnet material: permanent magnet material is magnetized by an external magnetic field, the magnetism does not disappear, and can provide a stable magnetic field to the external space. NdFeB permanent magnets commonly used to measure the following four indicators:
When a magnet is magnetized by an external magnetic field in a closed-circuit environment to a technical saturation, the external magnetic field is canceled. At this time, the magnetic induction intensity of the magnet is called remanence. It represents the maximum magnetic flux value that the magnet can provide. It can be seen from the demagnetization curve that it corresponds to the case when the air gap is zero, so the magnetic induction intensity of the magnet in the actual magnetic circuit is less than the remanence. NdFeB is the highest practical permanent magnet material of Br found today.
The magnetic coercive force (Hcb) unit is ampere/meter (A/m) and Oersted (Oe) or 1 Oe ≈ 79.6A/m
The value of the reverse magnetic field strength required to reduce the magnetic induction intensity to zero when the magnet after the technical saturation magnetization is reversed is called the magnetic coercivity (Hcb). However, the magnetization of the magnet is not zero at this time, but the effect of the reverse magnetic field and the magnetization of the magnet cancel each other out. (The external magnetic induction intensity is zero) At this time, if the external magnetic field is withdrawn, the magnet still has certain magnetic properties. The coercivity of neodymium iron boron is generally more than 11000Oe.
Intrinsic coercivity (Hcj) units are A/m (A/m) and Oersted (Oe)1 Oe ≈ 79.6A/m
The strength of the reverse magnetic field required to reduce the magnetization of the magnet to zero is called the intrinsic coercivity. Intrinsic coercivity is a physical quantity to measure the anti-demagnetization ability of a magnet. If the applied magnetic field is equal to the intrinsic coercivity of the magnet, the magnetism of the magnet will be basically eliminated. The Hcj of NdFeB will decrease with the increase of temperature, so the brand with high Hcj should be selected when working in a high temperature environment.
The unit of magnetic energy product (BH) is coke/m3 (J/m3) or high (GOe) 1 MGOe ≈ 7.96 k J/m3
The product of B and H at any point on the demagnetization curve is BH, which is called the magnetic energy product, and the maximum value of B×H is called the maximum magnetic energy product (BH)max. The magnetic energy product is one of the important parameters of the energy stored in the constant magnet, and the greater the (BH)max, the greater the magnetic energy contained in the magnet. When designing the magnetic circuit, the working point of the magnet should be near B and H corresponding to the maximum magnetic energy product as much as possible.
isotropic magnet:A magnet with the same magnetic properties in any direction.
anisotropic magnets:The magnetic properties will be different in different directions; and there is a direction in which the magnet with the highest magnetic performance is obtained when oriented. Sintered NdFeB permanent magnets are anisotropic magnets.
Orientation direction:The direction in which an anisotropic magnet can obtain the best magnetic properties is called the orientation direction of the magnet. Also called "orientation axis", "easy axis".
Magnetic field strength:Refers to the size of a magnetic field somewhere in space, expressed in H, and its unit is an/meter (A/m).
Magnetization:Refers to the sum of the magnetic moment vectors per unit volume inside the material, expressed in m, and the unit is an/meter (A/m).
Magnetic induction intensity:The magnetic induction B is defined as: B = μ0(H + M), where H and M are the magnetization and magnetic field strength, respectively, and μ0 is the vacuum permeability. Magnetic induction intensity is also called magnetic flux density, that is, the magnetic flux per unit area. The unit is Tesla (T).
magnetic flux:The total magnetic induction in a given area. When the magnetic induction intensity B is uniformly distributed on the magnet surface A,
magnetic fluxThe general formula for Φ is Φ = B×A. The SI unit of magnetic flux is Maxwell.
Relative permeability:The ratio of the magnetic permeability of the medium to the magnetic permeability of the vacuum, I .e., μr = μ/μo. In the CGS unit system, o = 1. In addition, the relative magnetic permeability of air is often 1 in actual use, and the relative magnetic permeability of copper, aluminum and stainless steel materials is also approximately 1.
Permittance:The ratio of the magnetic flux Φ to the magnetomotive force F, similar to the conductance in a circuit. It is a physical quantity that reflects the magnetic permeability of materials.
Perconductance coefficient Pc:It is also the demagnetization coefficient. On the demagnetization curve, the ratio of the magnetic induction intensity Bd to the magnetic field intensity Hd, that is, Pc = Bd/Hd, and the magnetic permeability coefficient can be used to estimate the magnetic flux value under various conditions. For the isolated magnet Pc is only related to the size of the magnet. The intersection of the demagnetization curve and the Pc line is the working point of the magnet. The larger the Pc, the higher the working point of the magnet, and the less likely it is to be demagnetized. In general, for an isolated magnet orientation length is relatively large, Pc is larger. Therefore, Pc is an important physical quantity in the design of permanent magnetic circuit.
