Modeling, design and performance of integrated power electronics using MEMS toroidal inductors

This paper presents the design and optimization of MEMS-microfabricated toroidal inductors targeted for use in integrated power electronics. The process is based on Monte-Carlo inductor synthesis, performance evaluation based on analytic inductor models and circuit simulation, and Pareto-optimal filtering. The models and simulation are verified through comparison with magnetic finite element analysis and measurements. The design process is illustrated through the development of a buck converter in a 25-W LED driver that uses air-core toroidal inductors and GaN transistors. Design results indicate that efficiencies higher than 90% and power densities higher than 100 W/in³ are possible. In the resulting designs the inductors are no longer the physically largest part of the converter.