LLC諧振轉換器之整合磁件耦合效應分析與設計

Abstract

由於高效率與高功率密度之特性，LLC諧振轉換器已廣泛被採用在不同應用之中。為了改善轉換器之功率密度，諧振電感與變壓器整合在同一個鐵芯之整合磁件常被使用。諧振電感與變壓器之間之耦合效應會改變LLC轉換器之穩態特性，並引發如增益曲線偏移與元件應力過大等問題。但是，LLC轉換器之耦合效應從未被分析。 本論文旨在分析LLC諧振轉換器之整合磁件耦合效應，包括時域分析、電壓增益分析、諧振槽之輸入阻抗分析，亦計算了元件上之電壓與電流應力，以分析開關零電壓切換 (ZVS) 條件和能量損耗。此外，三種不同繞線方法之整合磁件設計亦展現與分析，並由Ansys Maxwell與Simplorer模擬所提出之磁件設計。具有400 V 輸入和 20 V/10 A 輸出之轉換器原型的實驗結果驗證了所提出分析之準確性。所提出之分析如在正規化頻率為1之增益曲線與諧振電感電流峰值，與實驗結果相比分別只有11.25%誤差與1.99%誤差，與傳統分析相比分別減少55%與81.6%。

LLC resonant converter has been widely adopted in different applications due to its high efficiency and high-power density characteristics. To improve the power density of the converter, an integrated magnetic combining resonant inductor and transformer into the same core is often adopted. The coupling effects between resonant inductor and transformer change the LLC converter’s steady-state characteristics and induce issues such as gain curve shift, and component overstress. However, the coupling effects have never been analyzed for LLC converter. This thesis aims to analyze the coupling effects of the integrated magnetic for the LLC resonant converter, including time-domain analysis, voltage gain analysis, and the input impedance analysis of the resonant tank. Voltage and current stress on components are also calculated to analyze the zero-voltage switching conditions of switches and power loss. In addition, magnetic designs of integrated magnetic with three different winding structures are also performed and analyzed. The characteristics of the proposed magnetic designs are simulated by ANSYS Maxwell and Simplorer. Experimental results of a prototype converter with 400 V input and 20 V/10 A output verify the accuracy of the proposed analysis. The proposed analysis such as gain curve when the normalized frequency is 1 and peak value of resonant inductor current only have 11.25% mismatch and 1.99% mismatch respectively, compared with the experimental results, and reduce by 55% and 81.6% respectively compared with traditional analysis.