Mobile QR Code QR CODE : The Korean Institute of Power Electronics
Title Low-Cost High-Efficiency Two-Stage Cascaded Converter of Step-Down Buck and Tapped-Inductor Boost for Photovoltaic Micro-Inverters
Authors Jong-Ho Jang ; Jong-Hyun Shin ; Joung-Hu Park
DOI 10.6113/TKPE/2014.19.2.157
Page pp.157-163
ISSN 1229-2214
Keywords high efficiency; tapped-inductor; cascaded converter; low frequency inverter; micro-inverter
Abstract This paper proposes a two-stage step-down buck and a tapped-inductor boost cascaded converter for high efficiency photovoltaic micro-inverter applications. The proposed inverter is a new structure to inject a rectified sinusoidal current into a low-frequency switching inverter for single-phase grid with unity power factor. To build a rectified-waveform of the output current. the converter employs both of a high efficiency step-up and a step-down converter in cascade. In step-down mode, tapped inductor(TI) boost converter stops and the buck converter operates alone. In boost mode, the TI converter operates with the halt of buck operation. The converter provides a rectified current to low frequency inverter, then the inverter converts the current into a unity power-factor sinusoidal waveform. By applying a TI, the converter can decrease the turn-on ratios of the main switch in TI boost converter even with an extreme step-up operation. The performance validation of the proposed design is confirmed by an experimental results of a 120W hardware prototype.