Five-Terminal Switched Transformer Average Modeling and AC Analysis of PFC Converters

Abstract

A simple and accurate five-terminal switched transformer average model is proposed and its generalized equations are derived. The proposed model is capable of both time domain and ac analysis of dc-dc, ac-dc, and is especially suitable for single-stage power factor correction (PFC) converters. Unlike other models presented in literature, the proposed switching cell includes the transformer leakage inductance, an intermediate bus input, and still addresses both continuous and discontinuous conduction modes. The model was applied to two topologies, the bi-flyback and the flyboost parallel/series forward converters. The time domain results show great accuracy when compared with the slower and time consuming switching simulation. The ac analysis is also predicted with greater accuracy exposing the dynamics of such converters, a task that was not as easily addressed before when the unique characteristics of single-stage are considered. The frequency domain analysis was also verified with experimental results for the bi-flyback converter. The model is very relevant to isolated flyback converters including the PFC examples provided, which are not as easily or as accurately modeled by other approaches.Index Terms-Average modeling, modeling and simulation of power factor correction (PFC) converters.

A switched-winding transformer with low quiescent loss to meet the level VI efficiency standard at high power density

“…When imposed along with the increase in loaded efficiency requirements this greatly limits the achievable power density. However, this new efficiency standard opens new design opportunities to apply switched transformer and inductor techniques that have previously been utilized in dc-dc converter applications [2], [3], VCOs in integrated circuits [4], [5], energy harvesting [6], and PFC converters [7], to enhance traditionally fully-passive line-frequency transformers. This paper explores a cost-effective approach to improving the performance of line-frequency transformers, resulting in larger power capability for a given transformer size while meeting no-load loss and average efficiency requirements.…”

Zero‐voltage switching current‐fed flyback converter for power factor correction application

“…To overcome the shortcomings of the two-stage PFC converters, many studies on the single-stage PFC converters have been conducted [6][7][8]. The single-stage approach combines the PFC stage and the isolated DC-DC converter stage into one power stage, which is typically controlled by only one pulse width modulation integrated circuit (IC).…”

Extension of minimum separable switching configuration modelling to single-stage AC/DC converters with direct power transfer

“…However, the prerequisite of using the model is to identify three-terminal network in the circuit. It is hard to conceptualise a complex single-stage AC/DC converter with direct power transfer path into three-terminal cell because the converter usually contains more than one inductive element and passive switch [22]. In addition, it is also difficult to realise the three-terminal network in the situation where, for example, shifting inductor to the power returning path in a boost converter.…”

“…Rustom et al [22] and Uan-Zo-li et al [25] presented the methods in developing equivalent average circuit model for single-stage AC/DC converters. However, the papers did not give systematic guidelines in simplification and analysis of complex single-stage AC/DC converters.…”