Computer Aided Small-Signal Analysis for PWM DC-DC Converters Operated in Continuous Conduction Mode and its Application for a Flyback Converter

A computer analysis PWM dc-dc converters operated in continuous conduction mode CCM is presented. The analysis is based on a linearized small-signal model of the ideal converter switching-cell (ISC), which is used as a sub-circuit inside the computer program. This sub-circuit is composed of controlled voltage and current sources. Parasitic resistances of the converter are kept outside this sub-circuit and this makes the ISC model general and suitable for the analysis of most of the dc-dc PWM power converters. True rms values of the parasitic resistances are considered. A symbolic approach for PWM dc-dc converters analysis, generating the symbolic expressions, root locus and Bode plots of the several network functions, is utilized. Many are the advantages of the proposed method. First, the converter models are generated by the program; moreover the program derives symbolic expressions starting from the circuit scheme and this allows for converter parasitic components to be taken into account with no need to derive cumbersome expressions. Finally a good understanding of the frequency domain behavior of power converters is achieved.