First, the basic characteristics of magnetic materials
1. Magnetization curve of magnetic materials
Magnetic core material is composed of ferromagnetic substances or ferromagnetic substances, under the action of external magnetic field H, there must be a corresponding magnetization M or magnetic induction intensity B, they change with the magnetic field strength H curve called magnetization curve (M ~ H or B ~ H curve). The magnetization curve is generally nonlinear and has two characteristics: magnetic saturation phenomenon and hysteresis phenomenon. That is, when the magnetic field intensity H is large enough, the magnetization intensity M reaches a certain saturation value Ms, and continues to increase H, and Ms remains unchanged. When the M value of the material reaches saturation, and the external magnetic field H decreases to zero, M does not return to zero, but changes along the Ms-Mr curve. The working state of the material is equivalent to a certain point on the M-H curve or B-H curve, which is often called the working point.
Second, the common magnetic parameters of soft magnetic materials
Saturation magnetic induction intensity Bs: its size depends on the composition of the material, and its corresponding physical state is the magnetization vector neatly arranged inside the material.
Residual magnetic induction Br: is the characteristic parameter of the hysteresis loop, the B value when H returns to 0.
Rectangle ratio: Br/Bs
Coercive force Hc: is the amount that indicates the difficulty of magnetizing a material, depending on the composition and defects of the material (impurities, stresses, etc.).
Permeability μ : is the ratio of B to H corresponding to any point on the hysteresis loop, and is closely related to the operating state of the device.
Initial permeability μi, maximum permeability μm, differential permeability μd, amplitude permeability μa, effective permeability μe, pulse permeability μp.
Curie temperature Tc: The magnetization of ferromagnetic substances decreases with the increase of temperature, and when a certain temperature is reached, the spontaneous magnetization disappears and becomes paramagnetism, and the critical temperature is the Curie temperature. It determines the upper limit temperature at which the magnetic device can operate.