Core Selection Exampleĭetermine core size and number of turns to meet the following requirement: Design options for this core are to consider a larger core, a lower permeability material, a lower loss material or some combination of these three. If AC core losses will result in too much heating, or efficiency below requirements, then the inductor may be loss-limited rather than saturation-limited. If a significant ripple current will be present, estimate the core losses using the Core Loss Calculation procedure. (Core area and window area can be found on the core datasheet or the catalog page.)ħ. Verify that the winding factor is acceptable by referencing the various winding approaches described here. Divide the total wire area by the core window area to obtain the winding factor of the design. To calculate winding factor, multiply the number of turns by the wire area found on the Wire Table to find the total wire area. Duty cycles below 100% allow smaller wire sizes and lower winding factors, but do not allow smaller core sizes.Ħ. Choose the correct wire size using the Wire Table. (f) Iterate steps 4 (b), (c) and (d) if needed to adjust biased inductance up or down until it is satisfactorily close to the target.ĥ. This will yield an inductance close to the required value after steps 4 (b), (c) and (d) are repeated. (e) Increase the number of turns by dividing the initial number of turns (from step 4(a)) by the per unit initial value of permeability. (d) Multiply the required inductance by the per unit rolloff to find the inductance with bias current applied. Curve fit equations shown in the catalog can simplify this step.
DC Bias curves, determine the rolloff in per unit of initial permeability for the previously calculated bias level. With this information, calculate the number of turns needed to obtain the required inductance from: Determine the minimum A L by using the worst case negative tolerance (generally -8%). (a) The inductance factor (A L in nH/T 2) for the core is obtained from the core data sheet. Calculate the number of turns by using the following procedure: Inductance, core size, and permeability are now known. Selecting the permeability indicated will tend to be the best trade-off between A L and DC bias.Ĥ. The permeability line is sectioned into standard available core permeabilities. This is the smallest core size that can be used.ģ.
Follow this coordinate to the intersection with the first core size that lies above the diagonal permeability line. Locate the LI 2 value on the Core Selector Chart.
L = inductance required with DC bias (mH)Ģ. Use the following procedure to determine the core size and number of turns. Only two parameters of the design application must be known to select a core for a current-limited inductor inductance required with DC bias and the DC current.
AIR CORE INDUCTOR CALCULATOR MM CODE
The calculators below can be used to determine the proper parameters for either a circular or square cross section Toroid inductor. Credit for the initial Javascript code used in the calculator is given to Ray Allen who has a number of similar useful calculators on his website, Pulsed Power Portal.Inductor Design with Magnetics Powder Coresįor assistance in determining a Magnetics core(s) to use in specific inductor designs, download our Inductor Design tool or contact Magnetics with your Custom Inductor Design request. Where N is the number of turns, h is the height of the winding (in cm), r 1 is the inner radius (in cm), and r 2 is the outer radius (in cm). Alternate Equation for a Square Cross Section Toroid Inductor