Differential-Evolution-Assisted Optimization of Classical Compensation Topologies for 1 W Current-Fed IMD Wireless Charging Systems

Implantable medical devices (IMDs) necessitate a consistent energy supply, commonly sourced from an embedded battery. However, given the finite lifespan of batteries, periodic replacement becomes imperative. This paper addresses the challenge by introducing a wireless power transfer system designed specifically for implantable medical devices (IMDs). It begins with a detailed analysis of the four conventional topologies. Following this, the paper provides a thorough explanation for choosing the PS topology, highlighting its advantages and suitability for the intended application. The primary parallel capacitance necessitates power from current sources; thus, a Class-E amplifier was implemented. Additionally, the selected circuit was engineered to deliver 1 W at the biocompatible resonance frequency of 13.56 MHz. The delineation of the resonance parameters hinges on multifaceted solutions, encompassing bifurcation-free operation and the attainment of peak efficiency. To ensure the feasibility of the proposed solution, a Differential-Evolution-based algorithm was employed. The results obtained from simulation-based evaluations indicated that the system achieved an efficiency exceeding 86%. This efficiency level was maintained even in the face of frequency fluctuations and variations in the coupling between the coils, thereby ensuring stable operational performance. This aligns seamlessly with the specified application prerequisites, guaranteeing a feasible and reliable operation.