The Inductance for given numbers of turns can be calculated by using the following equation. |
· Inductor specification - Core part no.: OR400S125 ------- Sendust core - Number of winding: 20turns - Applied current: DC 10 Amperes · Calculation procedure 1) Inductance calculation at 0A Inductance could be calculated by below equation. |
When permeability is 125, AL value of OR400S125 would be 168nH/N2 in the table at page 54, Therefore inductance at 0 ampere is calculated as below, |
2) Magnetizing force(H:Oe) is calculated by Ampere’s law to achieve the roll off. |
3) When the magnetizing force(H) is 25.53(Oe), yielding 68% of initial permeability on page 14. Therefore, the inductance at 10A is as below, |
Core loss may be subdivided into three principal components, hysteresis loss and eddy-current loss, residual loss. The energy consumed in magnetizing and demagnetizing magnetic material is called the hysteresis loss. It is proportional to the frequency and to the area inside the hysteresis loop for the material used. As far as hysteresis loss and residual loss in powder cores, they are exceptionally low. |
For toroidal powder cores, the effective area(A) is the same as the cross sectional area. By definition and Ampere’s Law, the effective magnetic path length is the ratio of ampere-turns(NI) to the average magnetizing force across the core area from inside diameter to outside diameter. Using Ampere’s Law and averaging the magnetizing force gives the formula for effective path length. |
The Q factor is defined as the ratio of reactance to the effective resistance for an inductor and thus indicates its quality. The Q of wound core can be calculated using the following formula, when neglecting the effects of selfresonance caused by the distributed capacitance resulting from the differential voltage between adjacent turns. |