高功率密度、小尺寸和高效率是電源轉換器的趨勢。傳統返馳式轉換器由於漏感的問題較適用於低功率的應用。錯相半橋返馳式的架構可以提供較高的輸出功率且可回收漏感能量降低功率開關的跨壓並箝位於輸入電壓。然而，主功率開關仍然承受高切換損失，而限制了轉換器的操作頻率。本論文針對錯相半橋返馳式轉換器提出了二種柔切的架構。藉由二組外加的輔助開關，使改良後的錯相半橋返馳式轉換器可以操作在零電壓切換，並經由輔助開關的反向並接二極體回收變壓器的漏感能量。而藉由外加的輔助電路，使改良後的錯相半橋返馳式轉換器其功率開關可以在寬負載範圍內達到零電流切換。
本論文中針對所提出之兩款改良型錯相半橋返馳式轉換器，其操作原理做一詳細的分析，並對達成零電壓切換和零電流切換條件做一詳細的推導。最後實作完成具零電壓切換及具零電流切換的錯相半橋返馳式轉換器原型電路，驗證理論分析並與現有的技術進行比較。實驗結果顯示所提出的零電壓及零電流架構在滿載時可以分別提升傳統的錯相半橋返馳式轉換器0.52% 和1.17%的效率。本論文所提出的零電壓切換及零電流切換錯相半橋返馳式轉換器可工作於超高切換頻率以提升轉換器之功率密度。

High power density, small size, and high efficiency are the trend of the power converters. The conventional flyback converter is the topology favored for low power applications because of the constraint of the leakage inductance. The interleaved structures can provide higher output power by recycling the leakage energy to clamp the voltage on power switches. However, the main power switches suffer from higher switching losses, which will limit operating frequency of the converter.
This dissertation proposes two soft-switching mechanisms for interleaved half-bridge flyback converters. By adding two additional auxiliary switches, the interleaved half-bridge flyback converter can operate with zero-voltage switching (ZVS), moreover, the anti-parallel diodes of the auxiliary switches can be used to recycle the leakage energy of the transformers. With additional auxiliary circuits, the power switches of the interleaved half-bridge flyback converter can be turned off with zero-current switching (ZCS) for wide range applications. The operating principles of the proposed ZVS and ZCS interleaved flyback converters are described. Finally, experimental prototypes of the interleaved flyback converters with ZVS and ZCS are implemented to verify the theoretical analyses and compare with state of art technologies. The experimental results show that the proposed ZVS and ZCS mechanisms can improve the efficiency of the conventional interleaved flyback converter by 0.52% and 1.17% at full load condition, respectively. The future of the proposed ZVS and ZCS interleaved flyback converters is for very high switching frequency applications to increase the power density of the converter.

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