本論文主旨在於研製一無電解電容之七階換流器，以解決傳統換流器架構中，分壓電容上之電壓不平衡所造成的波形失真，與電解電容使用壽命較短之問題；故本架構應用兩組變壓器取代電解電容分壓電源之架構，產生七階電壓輸出，能避免電容電壓不平衡、提升電路壽命、且具備電氣隔離效果。

本論文中將會說明本架構之動作原理及控制流程，最後採用TI公司所生產之TMS32F28335數為訊號處理器為核心，研製一輸入電壓300V，輸出電壓220V 60Hz，輸出功率3kW之實驗室雛形電路，以驗證本文架構之正確性即可行性，並測試其電路效能。

In this thesis, a novel single-phase seven-level electrolytic capacitor-less inverter topology is proposed. In conventional inverter topologies, the problems of voltage unbalance of capacitor induce distortion of output voltage. And, the life time of capacitors is shorter than semiconductor components. Due to, the proposed topology which is composed of two transformers can achieve seven multi-level output without electrolytic capacitor. hence, it would not have the question of voltage unbalance of electrolytic capacitors, the longer life time and electric isolation are achieved.

The operating principle, mode analysis, control method and modulation method are introduced. Finally, a 220 Vrms / 3 kW laboratory prototype of seven-level inverter with input voltage 300 Vdc is implemented to verify the theoretical analysis and the performance. The control scheme is presented by DSP (Digital Signal Processor ) TMS320F28335.

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