Impedance Compressing Matching Network Based on Two-Port Network Analysis for Wireless Power Transfer System
Authors: Euihoon Chung, Jung-Ik Ha, Anas Al Bastami, David J. Perreault
Extended Abstract:
This paper proposes a novel design approach for impedance matching networks applicable to diverse industrial fields, including plasma drive systems and wireless power transfer systems. In these industrial applications, the load impedance exhibits a wide range of variation rather than maintaining a fixed value. For instance, in a capacitive-coupled plasma drive system, the load impedance may vary depending on the composition and pressure of the gas. This load impedance variation significantly degrades the output characteristics and efficiency of power amplifiers such as class E or class Φ2. Therefore, to ensure the efficient operation of the power amplifiers, it is essential to have a matching network that compresses load impedance variations.
In traditional systems, tunable matching networks have been commonly employed to match the variable load impedance to a fixed input impedance. However, this approach often relies on mechanical devices such as vacuum variable capacitors (VVC), which increase system volume and costs while degrading dynamic performance. To address these issues, a three-port impedance compression network has been proposed that eliminates the need for a mechanical tuning process. However, it still has limitations as it requires implementing two or more independent loads.
This paper aims to develop an impedance compressing matching network (ICMN) based on a two-port network architecture. To achieve this, the general model of the two-port network has been mathematically analyzed to maximize the inherent design flexibility of the two-port network. The paper identifies limitations in the compressing capability arising from insufficient design freedom and introduces a new design methodology termed ‘two-frequency design’. This design approach has shown that the impedance compressing capabilities can be significantly enhanced by using narrow-range frequency tuning. In this paper, the effectiveness of the proposed concept has been validated through an example considering the practical impedance variations of a plasma drive system operating at frequencies of 13.56MHz and 27.12MHz.
