Modeling, analysis and design of fixed frequency series-parallel resonant DC/DC converters using the extended describing function method

Abstract

The fixed frequency series-parallel resonant de/de converter is used in high current and low voltage power supplies in telecommunication applications. The frequency domain analysis technique has been the preferred method for the modeling and analysis of the converter. However, the modeling and analysis technique results in a complex set of equations from which it is difficult to establish systematic design procedure for selecting the component values of the converter. -- This thesis proposes a generalized modeling, analysis and design approach of the fixed frequency series-parallel resonant de/de converter. A systematic approach to modeling the behavior of the converter based on extended describing function technique is presented. By employing this technique, both continuous-time large-signal and small-signal models of the converter are developed. A new set of design criterion and procedure aimed at minimizing the cost and size of the converter is developed from the large-signal model A design example is presented to illustrate the use of the design procedure. Finally, a Pspice implementation of the converter is provided to validate the extended describing function technique.