Magnetic material magnetization curve of the magnetic material is composed of ferromagnetic substance or ferrimagnetic, in additional magnetic field H, there will be a corresponding magnetization M or magnetic induction intensity B, they are called magnetization curve along with the change of magnetic field intensity H curve (
M ~ ~ H or B H curve)
Magnetization curve is nonlinear in general, has two characteristics: magnetic saturation phenomenon and the hysteresis phenomenon.
Namely when the magnetic field intensity H is large enough, saturated magnetization M reaches a certain value of Ms, continue to increase H, Ms remains unchanged;
And when the material of M value after reaching saturation, reduced to zero, the external magnetic field H M not back to zero, but along the MsMr curve changes.
The working state of the material is equal to the M ~ ~ H curve or B H a point on the curve, which is often referred to as the working point.
Soft magnetic materials commonly used magnetic parameters of the saturated magnetic induction intensity of Bs: its size depends on the material composition, it corresponds to the physical state of magnetization vector lined up inside the material.
Residual magnetic induction intensity Br: it is the magnetic hysteresis characteristic parameters of on-line H back to zero when the value of B.
Rectangular than: Br/Bs coercive force Hc: is the ease of magnetization of the said material quantity, depends on the material composition and defects (
Impurities, stress, etc. )
Permeability mu: magnetic hysteresis at any point on the line corresponds to the ratio of B and H, is closely related to the device working state.
Initial permeability mu I, maximum permeability microns, differential permeability mu d amplitude magnetic permeability, mu a, effective permeability u e, pulse permeability u p.
Curie temperature Tc: magnetization of ferromagnetic substance varies with temperature drop, reaches a certain temperature, spontaneous magnetization disappear, into a paramagnetic, the critical temperature for the Curie temperature.
It determines the maximum temperature of magnetic devices work.
P loss: Ph hysteresis loss and eddy current loss Pe Ph + P = = af + Pe bf2 + c ∝ f2 t2 / Pe, rho, hysteresis losses Ph method is to reduce the coercive force Hc;
Method to reduce eddy current loss Pe is thinning the thickness of the magnetic material t and increase the resistivity of the material in rho.
In a free still air loss and the core of the core temperature relationship is: the total power dissipation (
/ surface area (
Magnetic parameters of soft magnetic materials and devices of the conversion between electrical parameters in the design of soft magnetic devices, first of all should be determined according to the requirement of the circuit components of voltage and current characteristics.
Voltage and current of the device characteristics is closely related to the core geometry and magnetization state.
The magnetization process designer must be familiar with material and material hold the conversion relationship of magnetic parameters and electric devices.
Design soft magnetic devices usually includes three steps: correct choose magnetic material;
The geometric shape and size of reasonable core;
In accordance with the requirements of magnetic parameters, the simulation of the magnetic core working condition of electrical parameters.