具倍流輸出架構之全橋相移電路零電壓切換特性之研究

Investigation of Zero-Voltage-Switching characteristics of Phase-Shifted Full Bridge with Current Doubler circuit

曾成德(Jerry Tseng)

指導教授 ： 陳德玉

國立臺灣大學/電機資訊學院/電機工程學研究所/碩士(2006年)

https://doi.org/10.6342/NTU.2006.02319

摘要

全橋相移電路一般都是使用在中高功率的應用場合，本文重點是將其應用在低電壓大電流的環境，因此在二次側電路上改為倍流架構。再者，內容中會針對ZVS達成的條件加以仔細的分析，並提出對應的計算公式，然後透過模擬軟體針對全橋電路加上倍流整流電路作閉迴路模擬，同時也針對全橋電路加上中間抽頭式整流電路作閉迴路模擬來對計算公式作為驗證。
在本文中也提到使用倍流整流電路的ZVS範圍比中間抽頭式整流電路還要大，其中則是與變壓器上所流過的激磁電流的大小還有其負載電流有關，而這部份在內容裡所提出的計算公式中可以明顯的看出來。最後在附上一5V/20A、100W的實作電路作為佐證。

關鍵字

全橋相移電路 ； 零電壓切換 ； 倍流輸出

並列摘要

The phase-shift full-bridge converter with current-doubler circuit in the output is often used in medium- power high-current low-output voltage applications. The research reported in this thesis is to investigate the soft-switching characteristics of the main switches. It’s well known that the main switches in the “leading leg” can be zero-voltage turned on without much of a problem, but not necessary so for those in the “lagging leg”. The focus of the thesis is to investigate the conditions affecting the zero-voltage turn on of the main switches of the lagging leg.
In the thesis, equations will be derived to show mathematically how the converter design and the operating condition affect the ZVS switching. Software simulations were run to confirm the conditions derived. A comparison was also made between the current doubler secondary circuit and the center-tapped secondary circuit working in conjunction with the phase-shifted primary was made.
It’s found out that although the magnetizing inductance never gets involved in the resonance to achieve ZVS, the magnetizing current indirectly affect the primary current which plays a dominant role in determining if ZVS can be achieved. It’s also found out that current doubler circuits, compared to the center-tapped circuit, make it easier to achieving ZVS condition even at light-load condition. This is because the current in the output chokes in the current doubler always operates in the continuous mode even at light-load condition, unlike that of the center-tapped counter part. Therefore, the conduction duty cycle stays about the same for the full range of load which causes a larger magnetizing current and makes it easier to achieve ZVS condition at light load. The information obtained in the thesis is valuable for designing such a converter for high efficiency.

並列關鍵字

Zero-Voltage-Switching ； Phase-Shifted ； Full Bridge ； Current Doubler

參考文獻

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