本論文以拓樸-返馳式轉換器為基礎電路，對抑制功率開關元件電壓應力之緩衝器進行研究，如初級側功率開關元件MOSFET(Metal-Oxide-Semiconductor Field-Effect Transistor)的電壓應力，為改善返馳式轉換器MOSFET的耐受電壓並減輕成本壓力，電路設計上常設置緩衝器，包括並聯於激磁電感線圈與MOSFET汲-源極的方式，而不同的並聯位置，緩衝器幾乎都有固定的種類，而輸出整流器的電壓應力，亦為應予重視問題。在常見的RC(電阻-電容)緩衝器結構設計上，本文實際驗證當輸出整流器使用RCD(電阻-電容-二極體)緩衝器時，對降低電壓應力效益不佳，進而分析其中的電路原理。緩衝器的功能是吸收並消耗功率開關元件在切換過程中產生的不利能量，增加緩衝器如未適當設計可能增加損耗、減低效率。
實驗數據顯示，在返馳式轉換器初級側電路中增加適當設計的緩衝器，可降低電壓應力，減少MOSFET關閉時的切換損耗，對轉換器效率提升具助益，本文驗證在增加並聯於激磁電感線圈的RCD緩衝器後，改善了電壓應力，自136.7V下降到122V，效率可從88.55%上升到88.81%。
並提出返馳式轉換器次級側整流器，關斷時電壓應力產生的LC震盪頻率，可透過於迴路增加串聯電感，大幅降低LC震盪頻率，改善電磁輻射干擾。

In this paper, the topology-flyback converter is used as the basic circuit to study the snubber for suppressing the switching stress of the switching power component.
In order to improve the voltage stress of the main MOSFET(Metal-Oxide-Semiconductor Field-Effect Transistor) on the primary side of the flyback converter and reduce the cost pressure of the withstand voltage of the MOSFET, snubbers is often set up in the circuit design, including the method of parallel connection between the excitation inductance coil and the Drain-Source of the main MOSFET, there are almost fixed types of snubbers for different positions, and the voltage stress of the output rectifier is also a problem that should be paid attention to. In the design of the common RC (resistor-capacitor) snubber structure, this paper verifies that when the output rectifier uses an RCD (resistor-capacitor-diode) snubber, it is not helpful to reduce the voltage stress, and then analyzes the circuit.
The function of the snubber is to absorb and consume the unfavorable energy generated by the power component during switching. If the snubber is not properly designed, it may increase the loss and reduce the efficiency.
The data of experiment shows that adding properly designed snubbers in the circuit can reduce the voltage stress and improve the efficiency of the converter. This paper verifies that the voltage stress decrease form 136.7V to 122V,and the efficiency can be increased from 88.55% to 88.81%, after adding an RCD snubber connected in parallel to the exciting inductance coil and improved the voltage stress problem.
And proposed that the rectifier on the secondary side of the flyback converter, the LC oscillation frequency generated by the voltage stress when the rectifier turned off, when increase the series inductance in the loop, can greatly reduce the LC oscillation frequency, and improve the electromagnetic radiation interference.

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