Modeling and Design Optimization of Loosely Coupled PCB Spiral Coils in Inductive Power Transfer Systems

There are various possibilities to realize coil winding designs for an inductive power transfer system. In order to achieve high power transfer efficiency and power density and explore trade-offs between the two, design optimization around the coil link is needed and often requires multi-physics modeling. In addition, the speed of optimization depends on the models complexity and used tools. This paper proposes a systematic design optimization flow which achieves fast optimization by avoiding calling FEM simulations in each optimization iteration. The optimization flow utilizes electric circuit model, the electromagnetic model and the thermal model. The electromagnetic models used to predict inductances, coupling and losses of coils are pre-trained artificial neural networks. The temperature rise is modeled with thermal nodal networks. The electric circuit model calculates the efficiency and output voltage of each coil design. The multi-physics models are all implemented into Matlab optimization tool. In the end, one optimal design is prototyped and developed models have been verified experimentally.