中文摘要 本文提出了一種新型相移脈波寬度調變的切換控制方式，並實現應用在交流穩壓器的換流器上，以提升交流穩壓器的性能。有別於傳統的脈波寬度調變切換方式，本文所提出來的切換方式，是將傳統的切換訊號做相位移控制的改變，並使得每個開關的切換頻率相同，而換流器的輸出脈波寬度調變切換頻率為開關切換頻率的兩倍，這將可降低交流穩壓器的輸出總諧波失真，並縮小輸出濾波器的規格，進而降低成本。本文所提出來的新型交流穩壓器是由一個具有電壓極性可逆的交流/交流轉換器與一個串聯補償變壓器所組成的，並藉由所提出來的切換方式，只需簡單地控制開關切換的責任週期，就可以得到與輸入市電同極性或反極性的電壓，進而補償或抑制市電的變動。本系統也將使用一個定點式數位訊號處理器（TMS320F240）來實現控制法則，以提高本系統的可靠度與系統響應。本文最後也將提出模擬與實驗的結果，來證明所提出的理論與切換方式可以改善交流穩壓器的性能。 Abstract In this paper, a novel pulse width modulation (PWM) switching strategy for single-phase inverter is proposed. It is applied to the automatic voltage regulator (AVR) to improve its performance. In contrast with conventional PWM switching strategy of the inverter, the proposed strategy uses phase-shifted control to the PWM switching signals. Though those switches have the same switching frequency, the output switching frequency in the inverter is doubled due to the phase-shifted control. It reduces the total harmonic distortions and the filter size for system output. The novel AVR is made up of an AC chopper with reversible voltage control and a compensation transformer in series with AC line. To obtain an inphase or reverse voltage with respect to AC line to compensate the variations, one only needs to control the duty ratio of switches by using the proposed phase-shifted PWM. The AVR uses a fully digital controller, which is implemented by a fixed-point digital signal processor(DSP) (TMS320F240). Therefore, the proposed AVR gives high efficiency and reliability. It is also shown via some experimental results that the presented novel AVR gives fast response for high quality control of the output voltage.
