High efficiency omnidirectional mobile inductive power transfer systems

Abstract

Essential technologies in the high efficiency omnidirectional inductive power transfer systems (IPTSs) are widely researched throughout this dissertation. Crossed dipole coils are newly proposed to transfer power from a transmitter (Tx) coil to receiver (Rx) coils regardless of rotations and positions of the Rx coils. The misconception that coupled magnetic resonance systems (CMRSs) are distinguished from IPTSs is corrected by verifying a simplified CMRS design with lumped transformers substituting unnecessary air-coils in conven-tional CMRSs. Unlike other IPTSs, two dipole coils, few meters apart each other, are tested in metal surround-ings to identify applicability of IPTSs to wireless sensors with arbitrary distributed conductors. Novel soft-switching converters are proposed to be deployed as a power factor correction circuit and a regulator in IPTSs for high system efficiency. In Chapter 1, crossed dipole coils for the wide-range 3-D omnidirectional inductive power transfer (IPT) are proposed. The 3-D omnidirectional IPT is first realized for both the plate type $T_x$ and $R_x$ coils. Sim-ulation-based design of the proposed crossed dipole coils for a uniform magnetic field distribution is provided, and the 3-D omnidirectional IPT is experimentally verified by prototype $R_x$ coils for a wireless power zone of 1 $m^3$. In Chapter 2, an innovative CMRS, introducing two lumped impedance transformers, is proposed. There are three major magnetic couplings between coils in CMRS: $source-T_x$, $T_x- R_x$, and $R_x-load$ couplings, respectively. Except for $T_x-R_x$ coupling, other couplings do not directly contribute to wireless power transfer. Hence, in this paper, this miscellaneous coupling is replaced with a lumped transformer with ferrite core. In Chapter 3, a dipole-coil-based extremely loosely coupled IPTS for wireless sensors over a wide range is proposed. The powering capabilities of the proposed IPTS were experimentally compared inside and outside of a metal container at different frequencies. A comparative analysis of the maximum amounts of load power among different core materials, i.e., two ferrite cores and an amorphous core, is conducted in rela-tion to the design of an $R_x$ coil. In Chapters 4 and 5, a new single active switch based zero voltage and zero current switching (ZVZCS) tapped boost converter is proposed. For the ZVZCS operation of the converter, three diodes and two capacitors are added to an ordinary tapped boost converter. The voltage stress of the active switch is always less than load voltage, and soft switching turn-on and off is achieved without cumbersome current or voltage sensing. A detailed analysis for both a continuous conduction mode (CCM) and a discontinuous conduction mode (DCM) are fully established and experimentally verified.