High-Efficiency Step-Up DC/DC Converter for Renewable Energy Power Applications

• Main Authors: Ming-Hui Li, 李明輝
• Other Authors: Ching-Shan Leu
• Format: Others
• Language: en_US
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/00901082403417926753

碩士 === 國立臺灣科技大學 === 電機工程系 === 97 === Developing a clean, high efficiency alternative energy power system has become an urgent matter. Fuel cells and photovoltaic solar cells are considered two of the alternative energy sources for the future. However, both fuel cell and solar cell produce wide-range low DC output voltage and cannot directly support AC or DC electrical appliances. Therefore, this necessitates a step-up converter. Among various step-up converter topologies, current-fed configuration is more suitably than voltage-fed configuration due to high output impedance of these cells. Furthermore, current-fed configuration has a non-pulsating input current, no output inductor, and a smaller turns-ratio in the high voltage transformer design. However, a full-wave rectification circuit and filter circuit are essentially required on the secondary side of the transformer to generate high DC output voltage. Two key issues of concern have to be dealt with in these two stages. 1. Employing center-tapped or bridge-type rectification circuit, there is a voltage spikes caused by transformer leakage inductance resulting in using high voltage-rating rectifier diode. 2. The output current suffers from high current ripple due to the absence of an output inductor. Consequently, turn-off snubber circuit, and larger output capacitor are needed. These components decrease converter efficiency and power density. To alleviate these two problems, two rectification circuits: a full-wave rectification circuit with output current ripple reduction and a full-wave rectification circuit with output current ripple cancellation, are proposed in this thesis. Both circuits feature minimum of the voltage spike on the rectifier diode and small current ripple of the output capacitor. Applying the proposed rectification circuits, three converters, a boost converter with output current ripple reduction (BCRR), a dual-inductor boost converter with output current ripple reduction (DI-BCRR), and a dual-inductor boost converter with output current ripple reduction (DI-BCRC), are presented. In addition to the description of the operation principle, theoretical analysis, and design considerations, circuits are implemented and tested with 150 kHz, 24-34V input and 200V/600W output specifications.