Forced air cooled quasi-planar 60A, 600μH inductor for a plasma cutting power supply

This paper presents the design and experimental results of a forced air cooled 60A, 600 μH quasi-planar buck converter inductor for a plasma cutting application. The inductor consists of PCBs (Printed Circuit Boards) with air ducts between the adjacent boards and conventional powder iron E cores. The winding assembly is simple and enables direct cooling of the PCB layers. A multi-physics based approach that considers factors like winding loss, air flow and heat transfer is used for the component design. Results from a 3-D FEA (Finite Element Analysis) based model that analyzes these physics are compared with experimental data from a proof-of-concept inductor prototype. A reasonable correlation is observed with average temperature errors in the 10-20% range. Factors affecting the performance of the model are also discussed. A comparison with an equivalent conventional inductor shows a four-fold increase in cooling efficiency and a three-fold reduction in copper usage. Thus, this approach is seen to be cost competitive and feasible for this application.