A 1-MHz GaN-Based LCLC Resonant Step-Up Converter With Air-Core Transformer for Satellite Electric Propulsion Application

A gallium nitride (GaN)-based resonant step-up converter is proposed for the application in the satellite electric propulsion (EP) system. This converter consists of a full-bridge inverter, a resonant tank, and a multistage Cockcroft-Walton voltage multiplier to provide a high voltage gain. Additionally, the air-core transformer is introduced due to the megahertz switching frequency allowed by the GaN device. Thus, the limited magnetizing inductance of transformer and the remarkable junction capacitance of diode have to be carefully considered in the resonant tank design, especially after considering that this converter normally operates at the light load in the EP system. In this work, the fourth-order LCLC resonant converter is investigated. The recommended parameter selection for the fourth-order resonant tank is also provided. A 1.2-MHz, 23-V/2.5-kV, and 6-W prototype is demonstrated. It achieves a low harmonics distortion and a low power loss with the zero voltage switching.