Even with a very small gap, of the order of 0.01 mm, the effective magnetic permeability is much less than initial one. The leakage of joint of the core halves is of great importance. The core dimensions are subject to manufacturing tolerances. The µ i spread of the core is quite high and depends on the temperature. l e - effective magnetic flux path length of the core.A e - effective cross-sectional area of the core.µ e - effective magnetic permeability of the core.At the finish we find the inductance of the E core coil set:.When the coil is operating in the small signals mode, this value can be taken equal to the value of the initial magnetic permeability µ i. Where µ r is actual magnetic permeability of the core. The magnetic permeability of such a core is called the effective magnetic permeability: To take into account the effect of the gap in the magnetic circuit, that has a high reluctance, the gapped core is substituted by a non-gapped one, with the same electrical performance and with the same number of turns.Now we can find the effective parameters l e, A e, V e of the E core by the following formulas:.The core constants for the total magnetic circuit of the E core are:.Magnetic flux path lengths of the sections and the corresponding cross-section areas can be found by the following expressions:.For the EE-core set:: h = B - D q = C s = F / 2 p = (A - E) / 2 For each section the area and magnetic flux path length are determined.Īt the firs we find the initial dimensional parameters for the calculation from the reference datasheet dimensions. For the purpose of the calculation of the dimensional parameters, the closed magnetic circuit of the E core is divided into five sections. Effective cross-sectional area A e mm 2Ī small reluctance of ferrite in comparison with air leads to the fact that almost the all magnetic flux is concentrated inside the ferrite core, forming a closed magnetic circuit.These are indicated by the suffix “e” added to the symbol. The dimensional parameters of that substitute toroid. The method used Coil64 is recommended for the calculation of the dimensional parameters of E cores and is in accordance with IEC Publication 205, “ Calculation of Effective Parameters of Magnetic Piece Parts.” For this method of calculating the dimensional parameters of E cores, the E core set is substituted by an ideal toroidal core such that a coil wound on that toroid would give exactly the same electrical performance as a coil with same number of turns placed on the E core set. In this case, you can calculate such a coil if you know the physical dimensions of the core and its magnetic permeability. However, not all manufacturers publish A L values for their cores. The parameter A L can be found in the manufacturer specifications for each species of core. A L - inductance factor of the core (nH/turns square).Calculation of the coils with any ferromagnetic core uses method calculation with a special parameter A L - inductance factor of the core. Such cores are also used with the powder iron materials. E-shaped, U-shaped, pot cores of various modifications. Multilayer air core inductor on a rectangular formįerrite cores for inductors have a wide variety species.Self-capacitance of single-layer inductor.Features of calculation of power supply chokes.