| Summary: | 碩士 === 國立雲林科技大學 === 電機工程系 === 107 === In this thesis, a LLC resonant converter with a wide output voltage range is proposed. The proposed converter adopts a full-bridge resonant converter on the primary side and an AC switch which can change full-bridge rectifier mode to voltage double rectifier mode on the secondary side. With the voltage gain changing, it can achieve a wide output voltage range. Besides, it utilizes the characteristics of zero voltage switching to achieve high efficiency. During the experiment, though the efficiency has been raised up, there is still a disadvantage of the LLC resonant converter. The excitation current will become larger when the converter is operated at low frequency, which would increase obvious conduction loss. In order to effectively utilize the advantages of LLC resonant converter which has zero-voltage switching and the low conduction loss over the wide range, this thesis presents a new LLC resonant converter with an AC power switch. With the help of the AC switch, it allows the variable output voltage to be expanded by more than three to four times and reach high efficiency. It effectively improves the wide output voltage range of the LLC resonant converter in a single stage.
Finally, the proposed converter is deeply analyzed by simulation software and the feasibility of the proposed converter is verified by a laboratory prototype. The practical electric specifications under the test are Vin = 400V, Vo. = 120~360V, Io = 8.333A and Po = 1kW.
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