A Systematic Approach to Extract State-Space Averaged Equations and Small-Signal Model of Partial-Power Converters

An isolated full power (FP) converter can be easily transformed into a partial-power (PP) converter by changing the connections of source and load to the converter. This is known as PP processing technique which can improve voltage gain, power rating, and efficiency of the system. This paper discusses the dynamic behavior of the PP converter. A general procedure is proposed to find the dynamic equations and ac small-signal relations for input-to-output voltage and duty ratio-to-output voltage transfer functions of the PP converter. It requires only the dynamic equations of the FP converter. Therefore, circuit analysis is not necessary. The presented methodology is applicable to the converters with any number of switching states. In order to validate the proposed method, it is applied to PP quasi-Z-source dc-dc converter. Several experimental/simulation tests are performed, and the results are compared to the modeling results. Frequency responses of G(vd) and G(vg) are obtained by simulations, while experiments verify the theoretical predictions.