| Summary: | 碩士 === 國立臺灣科技大學 === 電機工程系 === 101 === Two LLC converters LLC with Taiwan Tech center-tapped rectifier (LLC-TCT) and current ripple reduction LLC-TCT are proposed in the thesis. In addition to having zero-voltage switching operation on the MOSFETs and zero-current switching on the rectifier diodes inherited from their predecessors, both converters have several additional features. For instance, the rectifier diodes are clamped to the output voltage due to the absence of filter inductor, the utilization of the clamping series-diode technique, and the recovery of the transformer secondary leakage energy. Moreover, the load current is shared by the output filter capacitor and the L-C-L filter cell constructed by the leakage inductance of the secondary windings and one clamping capacitor. As a result, the required high-voltage output filter capacitor can be reduced.
To reduce input current ripple, moreover, an input current ripple reduction LLC-TCT converter (RR-LLC-TCT) is proposed. It features low di/dt on the input current waveform. As a result, the required high-voltage input filter capacitor can be reduced.
These characteristics make it desirable for high frequency, high efficiency and high input-voltage and output-voltage power conversion applications such as solar power conversion or larger size LCD TV back light driver. In addition to the descriptions of the operation principle, theoretical analysis, and design considerations, three high frequency converters, LLC-CT, LLC-TCT, and RR-LLC-TCT, with 300-400-V input and 200-V/400-W output specification are built and tested to demonstrate their feasibility.
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