Development of 2-kW DC Power Supply for Tetrode-Based RF Amplifier

Abstract

This article comprises a design, simulation, development, and testing of 500-V, 4-A dc power supply based on the zero voltage switching (ZVS) scheme. Resonant converters have many variants. In this article, quasi-resonant converter (QRC)-ZVS-half bridge-constant frequency type has been used which is generally employed for fixed load application, but in the proposed novel design, tank circuit has been designed in such a way to keep ZVS instant intact even in the case of variable load conditions. Four modules of resonant buck converter of 125 V, 4 A each, have been connected in series to obtain the desired output. The proposed power supply has four sections, such as 12-pulse rectifier transformer, rectifier unit, resonant buck converter followed by a filter unit. A simulation study of the proposed topology was carried out using Power Simulation (PSIM) software. A hardware model of 2 kW consisting of four modules was implemented and tested on resistive load for different scenarios required by control grid (CG) biasing application for tetrode tube; results were analyzed for various modes of operation and ZVS profile was observed for each mode of operation depicting the intact ZVS instant with variable load. Power supply efficiency was measured using an energy analyzer which comes out to be ~90%.