本論文主旨在研製一台獨立運轉(Stand-alone)的單相二極體箝位式五階換流器，利用多階的架構來分散降低在功率開關上的跨壓。為提供適當的電流路徑及功率開關的電壓箝位，此架構需要相當數量的二極體。雖然五階電壓輸出的電壓諧波已較方波或三階電壓輸出低，仍需透過輸出二階低通濾波器，以減少輸出的諧波分量。在控制方面，開關控制信號採用正弦脈波寬度調變信號(Sinusoidal Pulse-Width-Modulation, SPWM)，透過振幅調變指數來達到所需的輸出電壓，而頻率調變指數及取樣週期的考量則會影響輸出波形的失真狀況。由於換流器的動作會使得輸入電容電壓不平衡，所以本文也採用電容電壓平衡技術來改善。
本論文實際完成一台輸出功率630 W具有電容電壓平衡技術的原型電路，輸入端電壓為800 V，輸出端電壓為230 V，並以數位信號處理器來實現數位控制，在不同負載下效率均在90%以上。

In this thesis, a stand-alone single-phase diode-clamped five-level inverter is studied and implemented. This prototype circuit makes the input voltage shared by series-connected switching devices. Besides, this topology needs clamped diodes to clamp the voltage on the MOSFETs. Although the output voltage harmonics of five-level inverter are much lower than those of three-level or square wave output inverters, a second-order low pass filter is still necessary to attenuate the switching harmonics. On the other hand, the control signals of the power devices are generated by sinusoidal pulse-width-modulation (SPWM). The desired output voltage can be modulated by the amplitude modulation index; while the frequency modulation index as well as the sampling period will influence the distortion factor of the output waveform. The circuit operation naturally causes the input capacitor voltages unbalance. Accordingly, a switched-capacitor charge equalization technique is implemented to solve the imbalance problem.
A prototype circuit with the switched-capacitor equalizer has been built and tested successfully in this thesis. The circuit is with rated power of 630 W, 800 V input voltage, and 230 V output voltage. A digital-signal processor chip is used to realize the controller of this inverter. The measured efficiency is always higher than 90% within the overall range of load conditions.

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