Performance and Design of an L-C-L Converter for Voltage Regulator Type Applications

In resonant converters, lagging power factor operation is preferred. Also, if the converter switches are operated at constant frequency, or during the operating load range, the change in frequency is kept minimum, then the switch as well as the converter components can be best utilized. The paper investigates a three-element L-C-L converter topology to operate with minimum change in operating frequency. The analysis and performance are reported for lagging power factor mode of operation. The analysis yields easy-to-use closed-form equations, which can be used to design the converter. Design criteria for voltage regulator type applications are discussed. The usefulness of the design methodology is proved by prototype experiments.