Load Resonant Converter Research Articles

Simple constant frequency constant current load-resonant power supply under variable load conditions

A power supply incorporating a load-resonant converter operating at a fixed frequency and capable of efficient operation with a constant current characteristic, independent of the load conditions, is presented. The simple resonant circuit is designed so that at one of its multiple resonant frequencies both the load current and the resonant frequency are independent of the value of the load. A power supply is designed and constructed which delivers over 1 kW to a variable load at a constant switching frequency of 82 kHz.

Series-parallel load-resonant converter for controlled-current arc welding power supply

An arc welding power supply requires the ability to limit the load current under short circuit conditions and limit the load voltage under open circuit conditions. The series–parallel load-resonant converter is a circuit configuration which can achieve this. The potential for high frequency operation in these converters minimises the size of the magnetic components in the converter and reduces output current ripple. The paper presents the theoretical and practical aspects of the design and construction of a series–parallel load-resonant converter, for use as a controlled current arc welding power supply. A converter with an output voltage of 25 V and output current of 200 A operating at 85 kHz is designed and constructed. A novel method of control of the resonant converter is described. Output power control is achieved by using an active rectifier modulating the DC supply voltage to the converter. Practical results of the converter in operation supplying 200 A to a low inductance load are presented.

Characteristics of load resonant converters operated in a high-power factor mode

The performance of the parallel resonant power converter and the combination series/parallel resonant power converter (LCC converter) when operated above resonance in a high power factor mode are determined and compared for single phase applications. When the DC voltage applied to the input of these converters is obtained from a single phase rectifier with a small DC link capacitor, a relatively high power factor inherently results, even with no active control of the input line current. This behavior is due to the pulsating nature of the DC link and the inherent capability of the converters to boost voltage during the valleys of the input AC wave. With no active control of the input line current, the power factor depends on the ratio of operating frequency to tank resonant frequency. With active control of the input line current, near-unity power factor and low-input harmonic currents can be obtained.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>