Inductance cancellation in RF resonant power converters

摘要

Parasitic inductance cancellation is employed in order to operate a resonant power inverter at 27.12 MHz using a TO-220 through-hole package. A Cauer-type 1 LC network permits the coupling of inductors to achieve cancellation of multiple parasitic inductances and reduces semiconductor device stress in the same way as the Φ2 inverter topology. The elimination of parasitic inductances allows for system cost reduction, increased power handling, and/or relaxation of PCB layout constraints. The inductance cancellation technique is demonstrated through two prototypes (based upon the same silicon MOSFET die) providing 60 W of RF power to a 50 Ω load from a 48 V DC input: one prototype utilizes a small surface-mount package, and another a larger through-hole TO-220 package. (Without inductance cancellation, the lead inductance of the TO-220 is too large and cannot be used in a 27.12 MHz resonant application.) Inductance cancellation was verified through comparing impedances, operating waveforms, and efficiencies between the prototypes with different MOSFET packages.