A unified analysis of multi-resonant converters

The method developed by S. Freeland and R.D. Middlebrook (1987) to analyze the DC and AC behavior of quasi-resonant DC/DC converters is applied to multiresonant converters with a single controlled power switch. From PWM converter generic characteristics, rules for inclusion of three resonant elements are given to achieve a multiresonant topology with zero voltage switching in both semiconductor devices. From these rules, equations that describe the voltages across the transistor and diode are obtained. There are significant differences from quasi-resonant converters. These differences mean that a closed-form solution for several important quantities cannot be found analytically. An algorithm for finding the solution numerically is developed. The method developed can be applied to the most isolated DC/DC converter topologies