SiC-Based 4 MHz 10 kW ZVS Inverter With Fast Resonance Frequency Tracking Control for High-Density Plasma Generators

Abstract

A high-efficiency power conversion system to drive high-density plasma is proposed for plasma CO2 reforming (PCR). For high durability, the system is designed for inductively coupled plasma (ICP) without performance degradation. The proposed system consists of a novel control method and a 10 kW 4 MHz switching inverter to obtain a high-induced electromotive force that is necessary to generate and maintain ICP. The proposed control method quickly tracks the resonance frequency of plasma impedance with high-frequency resolution, which guarantees zero-voltage switching operation and power supply under highly variable plasma impedance. Moreover, the inverter is designed to be suitable for high-power high-frequency switching operation, consisting of SiC-mosfets and gate driver circuits with a negative turn-off voltage. Owing to the proposed system, plasma with much higher density than that of conventional plasma generators can be safely driven. A prototype system is presented to demonstrate the proposed operation, and the technical feasibility of PCR is verified. The proposed control can also be widely utilized for various high-frequency switching inverters that operate in variable load impedance.