Resonant converter topologies for constant current power supplies and their applications

Abstract

newlineResonant converters have been an active area of research in power electronics field due to variety of topologies, diverse, peculiar and useful characteristics, and, wide applicability for voltage regulator modules, fluorescent lamps ballasts, power factor correction, capacitor charging, induction heating, welding, inductive power transfer, high-voltage power supply etc., due to soft switching, high frequency operation, high efficiency, and small size. While the majority of the previous work on resonant converters has been directed towards developing methods of analysis and control techniques for the mentioned applications, very little has been done to explore their suitability for application as a constant-current power supply, which is either inherently required or can be advantageously applied in electric arc welding, laser diode drivers, magnet power supplies, capacitor charging, illumination systems, battery charging, electrochemical processes etc. Immittance converter topologies are suitable for transforming a voltage source to a current source and are deemed to be a promising alternative for developing topologies suitable for constant-current power supplies. This dissertation is dedicated to present an orderly search procedure for identification of a family of lumpedelement immittance converter topologies suitable for power converter circuits, termed here as the resonant immittance converter topologies (RICs). In all 24 RIC topologies are identified with three and four reactive elements, of which 15 are suitable for application as a constant-current power supply. Analysis and design procedure is exemplified with selected topologies. Fundamental frequency ac analysis is performed to gain insight into the steady-state characteristics, derive closed-form expressions for converter gain and the ratings of various components. A methodology to design the converter by minimizing the kVA/kW rating of resonant network is presented.