Performance Analysis of Magnetic Resonant System Based on Electrical Circuit Theory

Abstract

In this chapter, performances of wireless resonant energy links(Karalis et al., 2008) based on nonradiative magnetic field(Kurs et al., 2007) generated by a pair of coils are analyzed using electrical circuit theory. (from now on, this type of energy link is simply called as magnetic resonant system.) Based on the analyses, several aspects of the magnetic resonant systems concerning their power transmission characteristics become clear. In addition, optimal design parameters of the system are obtained that maximize the power transmission efficiency or effective power supply. Simple and common processes based on the electrical circuit theory, other than specialized ones such that coupled-mode theory(Haus, 1984) or antenna theory(Stutzman, 2011), are applied to the analyses throughout this chapter. Therefore, intuitive and integrated comprehension of the magnetic resonant systems may be possible especially in the comparison of principle with the conventional electromagnetic induction systems as described in the next section. In section 2, the difference of principle of magnetic resonant systems from that of conventional electromagnetic induction systems is explained where the role of magnetic resonance become clear when the coils are located apart. In section 3, based on the difference from the conventional systems, the inherent characteristics of power transmission of magnetic resonant systems are explained focusing on the resonance current in coils that affects the efficiency of the power transmission. In section 4, based on the power transmission characteristics of magnetic resonant systems, optimal system designs are investigated that maximize the power transmission efficiency or effective power supply under constraints of coil sizes and voltages of power sources. Finally, section 5 summarizes these discussions.