X光機共振式高壓電源供應器之研究

Abstract

本論文主要探討適用於X光機的高功率高壓電源供應器之原理與架構，並且分析高功率轉換器的電路拓樸與控制方法。在高功率輸出的前提下，為了提高電源功率密度，一方面必須要提高開關頻率，另一方面則必須降低開關損失，所以採用柔切方式的共振式轉換器將有助於實現此一目標，因此針對適合X光機的共振式轉換器架構進行詳細的電路分析，並且利用電腦模擬方式說明零電壓切換的原理。應用於X光機的高壓變壓器，其繞組匝數比通常相當高，因此變壓器初級側與次級側繞組之間必須有適當的絕緣距離，如此一來兩繞組磁通耦合的效果變差，漏電感變大，不僅降低輸出功率，同時也降低效率，因此本研究同時以電腦模擬方式分析變壓器漏電感造成之影響。此外，高功率電源模組化也是未來發展趨勢，本文也提出了高壓高功率電源供應器的模組化與控制架構，作為未來數位控制的發展方向。

This thesis makes a research on a theoretic study of high-voltage high-power power supplies for X-Ray generators. We have made a survey of the circuit topologies and control methods for high-power high-voltage converters. In order to enhance the power density of a power converter, we must increase the switching frequency and at the same time to reduce the switching losses. Resonant dc-dc converter employing soft switching techniques can be a feasible solution. Special emphasis has been focused on the study of circuit topologies suitable for high-voltage high-power X-Ray generator. Extensive computer simulation has been applied to the study of the zero voltage switching behaviors of the full-bridge resonant dc-dc converter. The leakage inductance effect of the power transformer on the resonant converter has been studied analytically and by computer simulation, the results can provides us to employ this leakage inductance for resonant switching. Modularized and paralleled of power converters has become a trend in design of high-power converting systems. In this research, we also propose serial and parallel control architectures by using standard power converting modules and these power modules can be digitally controlled by a host digital controller.