How to calculate the permeability of soft ferrite materials?
The magnetic field of the ferromagnetic material sample is magnetized, the same frequency, and the magnitude of the alternating magnetic field (amplitude) can be changed. Similar types described in the previous section DC hysteresis loop at low frequency, AC hysteresis loop, but when the frequency increases, due to the loss of the original core hysteresis width, in this period of time will be different from the DC magnetic hysteresis loop, therefore, the dynamic magnetization curve and static magnetization curve are also different. When the AC magnetic field amplitude is very small, change the soft ferrite soft magnetic materials of Mn Zn ferrite magnetic induction intensity ratio and magnetic field intensity, called initial permeability, also simplified as u I said: in fact, only closed in a uniform magnetic field (such as core toroidal core magnetic conductivity is true, so the initial permeability of the material commonly used standard try to ring, even if the coil N ratio measuring coil inductance L, and then press type calculation:
The type and inductance L unit is H (Henry), the diameter of the ring core is D, the inner diameter is D, the height (H), the unit m (m). When the magnetic core is in the presence of a gap, or different materials do, the magnetic component of the non-uniform cross-section, the effective permeability must be e:
Type L = = C1 = L (H) (N2) (nH) (Henry) effective magnetic permeability and geometry of the magnetic core, and smaller than the ring permeability (soft magnetic permeability). Open core, such as the great form, form the core thread of magnetic permeability, it was defined as the magnetic core inductance, insert the L, and the same core inductance ratio of the top ten, Mu said: application program = L / 10 (12) is more than this value the size and shape of the magnetic core and the shape of the coil, magnetic core transformer and the relative position of the coil. The use of large magnetic ferrite cores, some require the determination of permeability. The amplitude of this value is defined as the relative permeability peak of the ratio of the magnetic induction intensity to the peak of the magnetic field intensity under the condition of alternating magnetic field. Figure 1 - 9 shows the relationship between the permeability and the amplitude. It is shown that the maximum amplitude permeability can be obtained under the condition of appropriate magnetic induction amplitude. As the temperature changes, the value of 2 also changes.