High-Power-Factor LC Series Resonant Converter Operating Off-Resonance with Inductors Elaborated with a Composed Material of Resin/Iron Powder

Abstract

The most common problems with magnetic cores in high-stress applications are changes in their permeability and low saturation flux density, forcing designers to use special nanocrystalline cores, which raises the overall cost of the circuit. This paper evaluates the performance of a low-cost magnetic material composed of unsaturated polyester la mination resin COR61-AA-531EX and 200 mesh iron powder with a grain size of 74 µm, which has magnetic properties of the so-called “soft magnetic composites”, which have good magnetic characteristics in high-frequency and high-stress applications. This composite material was used for the elaboration of magnetic cores for the inductors of a resonant converter, which aims to achieve a high power factor, where in this type of application, there are large current and voltage excursions in the magnetic components that vary between high and low frequencies, being a suitable application for testing the inductors with a magnetic core of resin/iron powder. The converter was designed to operate off-resonance at different switching frequencies from 300 kHz to 800 kHz to feed a resistive load with a power output of 19 watts. The operation of the circuit was experimentally validated using a resistive load at the output, validating the theoretical analysis and achieving a power factor above 98%.