Modelling and performance evaluation of diode-assisted impedance source networks

This paper deals with a family of two- and three-windings coupled inductor-based impedance source networks. They have been basically derived from the successful quasi-Y-source network (q-YSN) by replacing one of its capacitors with a diode with different combinations of coupled inductors and called diode assisted impedance source networks (DA-ISNs). The general three-windings version, called diode-assisted Y-source network (DA-YSN), as the origin of all other simplified versions, is thoroughly investigated from various points of view. From the voltage gain characteristics aspect, it offers a higher voltage gain with the same number of elements as the conventional q-YSN. Lower magnetizing and input current ripples show the higher power density of DA-YSN in comparison to q-YSN. The effectively reduced voltage stress and the total value of capacitors, and a considerable decreased conversion loss of the magnetic element are the other attractive features of DA-YSN. With the advantages of a low input current ripple and a high voltage gain, DA-ISNs can be suitable choices for renewable energy and distributed power generation systems. Operating principle, circuit analysis, and parameters design guidelines for DA-YSN are thoroughly investigated. Also, the small-signal modelling, analysis and the controller design are presented in this paper. Finally, the theoretical properties of DA-YSN are scrutinized by performing extensive experiments on a 200 W laboratory prototype.