電漿火炬電力供應系統之開發

Abstract

電力系統模組化的優點在於: (1)提供較可靠的電源供應，具有備用模組者可靠度更高。(2) 模組元件的標準化，容易設計且減少製造成本及時間。(3) 可以線上更換模組。(4) 對整個系統而言，可以帶來較高的功率和功率密度。(5) 減少組件的應力，各模組零件均勻老化因而壽命延長。為了解決傳統電漿火炬電源系統的缺點，開發高效率、低成本、高可靠度之電漿火炬電力系統模組，我們將以小功率電源轉換器為基礎實現高功率之電力模組，並驗證其擴充的可行性，同時符合IEEE以及IEC對輸入電流諧波(Current Harmonic)污染之規範。此外，為了符合低成本、高功率的需求，我們採用全橋式單級交/直流轉換器做為電源系統的基本模組；此外，欲降低轉換器的切換損失，提升轉換器的效率以降低工作溫度及延長元件使用壽命，我們在轉換器的設計上，加上了柔性切換(Soft Switching)。在設計一新型轉換器架構時，我們將針對轉換器的能量傳遞與電路工作效能觀點做分析，目的在達到單級式交/直流轉換器的最佳化設計。電漿火炬的設計和操作方式有許多種類，所需之電源供應器的電壓和電流需求也因此有很大的分佈，故在設計時應考量極大功率負載需求時，該如何擴充轉換器模組。為此，針對輸入/輸出高電壓及輸出高電流型式之電漿火炬負載，其電源模組的設計採用單級交/直流轉換器的串聯組合，使用電壓共享技術以達成負載所要求的輸入/輸出高電壓規格；而輸出高電流的需求則以模組間並聯連接的方式來實現。在實作方面，每個交/直流轉換器模組設計成定電流輸出，且輸入與輸出端具有與其他模組串聯的電壓共享功能，模組最高電壓輸出為50V、電流最大為10A。

The advantages of modularizing the power system are: (1) better reliability and even much better if using redundant modules, (2) easy to design so that the manufacturing period can be lowered down, and so is the cost because that the components will bear lower stress, (3) on-line replacement possibility for the power modules, (4) higher efficiency and power density comparing to the power systems without using modules, (5) longer life time due to the lower stress on components.To improve the traditional plasma torch, high efficiency, low cost, and high reliability power modules should be used. The modularization technology provides a good solution for this target. Therefore, we consider to design a 500W single-stage AC/DC converter as the basic power system module, and also to develop the power expansion technology by using multiple proposed power modules. Simultaneously, the input current harmonic of power system will also be designed in meeting IEEE and IEC power standards.A single-stage AC/DC full-bridge converter with soft switching is considered in this project in approaching lower cost, high power, and high efficiency requirements. The switching loss can be reduced by using soft-switching design. Thus, the working temperature will be drawn down. Moreover, to help us to develop a new single-stage AC/DC converter, we analysis the power flow and work efficiency on many type single-stage AC/DC converter to obtain an optimized design of converter topology.Since the voltage/current curve characteristics of power system for plasma torch spreads in a wide range, owing to the difference of circuit structures and the use of operating gases, the design should consider the method how to expand the output power level of the power system to meet the high power requirements. Therefore, this project is to design a power system which can operates in a high line voltage input and produce a high current and high voltage output. For operating in a high line voltage input, the power modules are allowed connected in series in the input line power side. For producing a high voltage output, the power modules can be connected in series in the output side. The whole integration power sets can also be connected in parallel in both the input and output sides to produce high current output. For the practical consideration, each power module is designed as the current-source that can produce 50V maximum output voltage and 10A maximum output current. The power module also has the voltage sharing capability both in the input and output sides