Optimal and Miniaturized Strongly Coupled Magnetic Resonant Systems

Optimal and Miniaturized Strongly Coupled Magnetic Resonant Systems

This research focuses on developing models and methodologies for designing optimal SCMR systems based on novel element geometries. Our theoretical method will provide a straightforward way to design SCMR systems that are optimal (in terms of their efficiency) at the desired frequency of operation. Also, our research will develop miniaturized designs that are suitable for various applications, where maintaining a small size for a device is critical. The miniaturization of SCMR systems will significantly enhance the field of biomedical implants by providing small, highly efficient wireless powering systems that can support safe and wireless operation of bio-implants, thereby eliminating transcutaneous wires that can lead to discomfort and infection.

1. Optimal Design of Spiral Self-Resonator

Analytically, formulas of L, C, Rrad and Rohm are used to determine the resonant frequency f0 and quality factor Q. Known some parameters, other geometrical parameters could be achieved. Based on the performance requirements, (e.g. f0 , η ), an optimal SCMR system based on spiral resonators with maximum power transfer efficiency could be implemented.

Fig. 1. Process of optimal design for SCMR system using spiral structure.

Fig. 1. Process of optimal design for SCMR system using spiral structure.

2. SCMR System Based on SRR

In SRR, self inductance and capacitance form a tank resonator. Parallel coupled lines with an open-circuited end have been adopted to replace the lumped element capacitor. The resonant frequency of the SRR element can change by varying its capacitance, which depends on the spacing, length and area of capacitive gap.

Fig. 2. SCMR wireless power transfer system based on SRR

Fig. 3. Comparison of the efficiency of inductive coupling with SCMR system based on SRRs

Fig. 4. Simulation results regarding (a) length of parallel coupled lines, (b) distance between parallel coupled lines and (c) thickness of parallel coupled lines.



3. Miniaturized SCMR System

Previous work has been performed on SCMR wireless powering using loops or coils. However, there is limited research on how to design SCMR systems using other resonators and how to miniaturize their dimension. Therefore, other SCMR elements with compact size are needed in order to meet the requirements of various wireless powering applications in modern portable communication devices.

Dielectric Split-ring Resonator (DSRR), in which the split-ring resonator (SRR) is immerged in a dielectric substrate is developed to realize resonator in SCMR system that is more compact (reduced by more than 50%) and efficient. With only a half size of the conventional SCMR system, miniaturized SCMR system performs excellently, with 93% as the power transfer efficiency at 41MHz.

Fig. 5. Miniaturized SCMR wireless power transfer system based on square DSRR.

Fig. 6. Simulation results of the miniaturized SCMR system based on square DSRR: (a) system power efficiency. (b) S-parameters




About Kun Bao