Rapid Design of Compact Impedance Matching Transformers for Energy Harvesting Applications by Means of Inverse and Forward Surrogates

Abstract

The paper proposes a novel three-stage framework for rapid and reliable design optimization of complex impedance matching transformers for energy harvesting applications. Our approach involves inverse and forward surrogate modeling techniques. The inverse model is utilized to obtain a good initial transformer dimensions at the equivalent network modeling level. The forward surrogates (here, space mapping ones) permit rapid design closure at the full-wave EM simulation modeling level. The proposed methodology is demonstrated using a four-section compact transformer for energy harvesting applications. The circuit dimensions are scaled within wide ranges of the load impedance magnitude and phase (from 30 to 130 ohm and −26.5 to 26.5 degrees, respectively) at low computational cost corresponding to up to three EM analyses of the transformer structure. Reliability of the framework is validated through comprehensive numerical experiments as well as application case studies. The latter are provided to indicate that appropriate transformer design is critical for performance improvement of the rectifier circuits, both in terms of operational bandwidth and matching.