Optimized Planar Inductor for a High Current 3.5 kW Isolated DC/DC Converter

The paper presents several planar inductors optimized for low power loss in a 3.5 kW isolated full-bridge forward converter, which is operated at a large output current. The inductors are optimized by use of a winding configuration which is proven to have an AC-resistance that are unaffected by the height and parallel connection of the turns in its winding configuration. The current density is simulated in the turns of the inductors by using finite element method analysis with the Ansys Maxwell software. The Ansys simulations have an excellent accuracy which is proved by comparing the simulated equivalent circuit parameters values with measurements from an impedance analyzer. Two inductors are designed and constructed, and their total power loss is measured in the converter and compared. The peak-efficiency of the converter that utilizes the inductor with the lowest loss is measured to 97.7 %, whereas the inductor with the second lowest loss has a measured peak-efficiency of 97.6 %.