Learn More About Inductor Design

Magnetics® Inductor Design software is an aid to assist design engineers in selecting the optimum powder core for inductor applications, specifically in switch-mode power supply (SMPS) output filters, also known as DC Inductors.  As this name implies, most of the current flowing through the inductor is DC, with some amount of AC 'ripple' current (noted as Idelta) included as well (Figure 1). 


Figure 1: AC "ripple" current

Depending on the particular SMPS design, this ripple current value can either be insubstantial compared to the bulk DC output current in the inductor, or it may be quite large, and potentially limit the overall inductor design due to loss and temperature rise constraints.  This software package selects core sizes and materials largely to provide the smallest package size that will support the needed inductance and current, but also allows users to select deliberately larger cores with the intent of reducing losses and lowering the component's temperature rise.  Much more information on these topics is included in the Online Help sections distributed with the software, as well as in a number of other technical papers included in the Help file's Reference section.

Magnetics Inductor Design software uses a design algorithm intended to specify the smallest design package size for the given input parameters (currents, inductance values, frequency, etc.).  The program sizes the appropriate core based on the needed energy product, expressed as the full load inductance times the square of the peak (DC plus ripple) current flowing through the inductor.  Of course higher inductance values and higher current levels imply a larger core size.

Typical inductor designs will specify at least the required minimum inductance at full load current and the DC current in the windings.  Additional information, such as the amount of AC 'Ripple Current', current density (or wire size), highest acceptable temperature rise, and the maximum inductance at zero load current may also be supplied and can help to more accurately select the best core for the design.

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