零電壓切換全橋轉換器轉態與輸出電感的實現

Abstract

本論文研究相移式零電壓切換脈波寬調變全橋轉換器(PS-ZVS-PWM FB Converter)之動態特性分析的新詮釋，尤其針對圈數比 大於1的情況下。本文提出在半個開關週期內轉換器的五種動態模式，依次為能量傳輸狀態(Energy-delivery-state, )，領前側第一共振狀態(First-resonant-state, )，能量保持狀態(Energy-holding-state, )，落後側第二共振狀態(Second-resonant-state, )，以及能量轉向狀態(Energy-transition-state, )等。值得注意的是，轉換器之轉態電感 只在能量轉向狀態時為主要參數，其餘四種狀態則以反射至初級側之輸出電感 為主，因此兩個共振狀態均受制於共振電感 和功率開關之輸出電容的共振表現。此外，本論文並提出共振電感 對應於初級電流 的3-D動態能量分佈情形，以做為功率開關達到零電壓切換條件的參考能量準則。根據理論的推導結果，我們提出實現PS-ZVS-PWM FB轉換器之轉態電感 和輸出電感 的搭配設計及選用準則。最後，經由MATLAB軟體模擬以驗證理論推導之正確性後，實際製作一部1KW相移式零電壓切換脈波寬調變全橋轉換器，並針對各種不同的負載變化作實務的量測，以評估系統之動態表現及驗證理論與實務的一致性。

This thesis proposes a new description of the phase-shifted zero-voltage-switching pulse-width modulated full-bridge (PS-ZVS-PWM FB) converter, in particular for the turns-ratio greater than one. Five dynamic conversion models are introduced, including energy-delivery state, first resonant state, energy-holding state, second resonant state, and energy-transition state etc. Interestingly, the transition inductor is only dominant in energy-transition period and the other four dynamics are mainly subject to the output inductor when the turns-ratio of the main transformer is greater than one. Both two resonant states are dependent on the resonant inductance and the power MOSFETs’ output capacitances. Besides, a 3-D dynamic-energy distribution for describing the energy in the resonant inductor versus the primary current is explored, which is as reference to achieving ZVS at the power switches. According to the theoretical derivation, we suggest a design consideration for selecting the and in system realization. Finally, a simulation by MATLAB is implemented for verifying the theoretical description. A 1-KW PS-ZVS-PWM FB converter is realized with the derived parameters and examined with versatile loads to assess the system performance, which is quite the same as the predicted dynamics.