Core loss analysis for compact high step-up converters and fast resonance frequency tracking control for high density plasma

Abstract

In Chapter 1, a core loss analysis method is presented for compact converters generating a high output voltage. The proposed method focuses on analyzing the core loss of asymmetrical and discontinuous current to design compact converters with a high efficiency. Owing to the proposed method, an accurate core loss for asymmetrical and discontinuous current can be analyzed intuitively and practically, without additional measurement data in a wide frequency range. A compact high step-up converter is presented as an example to demonstrate the validity of the proposed analysis method through measurement results. This method can also be utilized for analyzing core losses in various compact switching mode power supplies that operate in discontinuous conduction mode.

In Chapter 2, a high-efficiency power conversion system to drive coreless inductively coupled plasma (ICP) is proposed for high-density plasma generation. The proposed system consists a novel control method and a 10 kW 4 MHz switching inverter to obtain a high-induced electromotive force which is necessary to generate and maintain the ICP. The proposed control method quickly track the resonance frequency of plasma impedance with high-frequency resolution, which guarantees zero voltage switching (ZVS) operation of the inverter and power supply to the electrodeless plasma under highly variable plasma impedance. Moreover, the inverter is designed to be suitable for high-power high-frequency switching operation by consisting of SiC-MOSFETs and gate driver circuits with a negative turn-off voltage. Through the proposed system, plasma etching performance was improved by 50% compared to the commercial ferrite ICP generator. The proposed control can also be widely utilized for various high-frequency switching inverters that operate in variable load impedance.