Novel design methodology and comparative analysis for ZVT PWM converters with resonant auxiliary circuit

The zero-voltage transition (ZVT) pulsewidth-modulation (PWM) converters with resonant auxiliary circuit (RAC) are gathered and analyzed by means of a common topology derived in this paper. Its operation modes are identified and analyzed. Moreover, a similarity transformation is applied to the three-state-variable system in such a way that the whole system dynamics can be represented in a two-dimensional state space. With this representation, the soft-switching conditions are easily defined. In addition to the unified analysis of the ZVT PWM converters with RAC, a theoretical comparative analysis addresses the converter current and voltage stresses, as well as the time-delay intervals taken during the main-switch turn-on process. By means of this analysis, the main characteristics and constraints of the converters are identified. Moreover, a novel design methodology is presented. It is based on the soft-switching-condition abacus obtained from the analytical description of the common ZVT-RAC topology. Besides the soft-switching conditions, a set of performance parameters is also plotted into the soft-switching-condition abacus, making it a simple and useful tool for the proper design of a ZVT-RAC converter. An experimental efficiency comparison is also carried out among three ZVT-RAC boost converters. The experimental results have been obtained from ZVT PWM boost prototypes operating at 1 kW and 100 kHz.