零電壓切換之高導通週期升壓－順向式直流∕直流轉換器

Zero-Voltage-Switching for High Duty Cycle Boost-Forward DC/DC Converter

本文提出一零電壓切換 （zero-voltage-switching, ZVS） 之高導通週期升壓－－順向式直流／直流轉換器。電路架構是結合順向式轉換器和升壓型轉換器之輸出電壓做疊接方式，藉此提高轉換器之升壓比與電源轉換效率，利用漏電感和磁化電感對切換開關寄生電容之充放電，使得主開關和輔助開關都能達到零電壓切換，且輔助開關具有同步整流功能可降低導通損失。並將變壓器之磁化電感電流回送至正電端，藉此使變壓器之磁化電感可重置，則此升壓－－順向式轉換器之導通週期可至80%，以提高升壓比。最後，將實作一組輸入電壓48 V，輸出電壓400 V，輸出功率100 W之電路雛型，並由實驗結果驗證所提轉換器電路架構之可行性與性能。

This study proposed zero-voltage-switching (ZVS) for a high dutycycle boost-forward DC/DC converter. The circuit topology of theproposed converter is composed of boost converters and a forward converterwith cascaded output connection. The proposed converter canachieve high step-up voltage gain and improve conversion efficiency. Inorder to achieve the main switch and auxiliary switch operating at zerovoltage switching, leakage inductance and magnetizing inductance are usedto charge and discharge the parasitic capacitance of the switch. Meanwhile,the auxiliary switch can synchronize rectification and reduceconduction losses. The current of the magnetizing inductance of theforward transformer can be transferred to the input, thus the magnetizing inductance of the transformer can be reset. The duty cycle of the proposedboost-forward converter can achieve 80% high step-up voltage gain.Finally, a prototype of a high duty cycle boost-forward DC/DC converterwith an input voltage of 48 V, output voltage of 400 V, and output powerof 100 W was developed. The experimental results verify the feasibilityand performance of the proposed high duty cycle boost-forward DC/DCconverter.