  Grid-tied photovoltaic (PV) installations with Distributed Maximum Power
Point Tracking (DMPPT) architectures include a DC-DC Module Integrated
Converter (MIC) for managing each PV panel, isolating it from the others,
reducing the mismatching effect and maximizing the harvested power. In this
paper, the Autotransformer Forward converter with type-Zeta resonant reset
(AFZ) is proposed as a DMPPT architecture MIC candidate. The main
characteristics of the AFZ converter are the high versatility due to its
voltage step-up and step-down capability; the use of an optimized
autotransformer with only two windings, reducing the complexity and power
losses of this component; the good dynamic performances, like the Forward
converter ones; the low number of components and the simplicity and high
feasibility associated to the use of just one active switch. Besides, soft
switching transitions are achieved thanks to the autotransformer type-Zeta
resonant reset. The steady-state theoretical analysis, considering the effect
of the autotransformer leakage inductance, is presented. The converter is also
studied in the frequency domain, obtaining the small-signal transfer functions.
A design procedure based on the requirements of a 100 kW grid-tied photovoltaic
installation is described, yielding in a 225 W prototype with efficiencies up
to 95.6 %. Experimental results validate the theoretical analysis.
