臺灣博碩士論文加值系統

台灣地區小型單相電力用戶功因及諧波的管制，並無明確之規範，導致低
功因及高諧波對電力及通訊系統的嚴重污染。針對此一問題，本文提出一
種主動式功因修正電路，可同時解決低功因與高諧波的問題，又兼具負載
電壓調節的功能。它是以升壓式轉換器為基礎，使用可變磁滯電流控制法
，來控制開關的切換。此為一種固定開關導通時間，可變切換頻率的控制
法。本文首先利用ＰＷＭ平均法求得功率電路參數，再配合切換模式模擬
實際波形，以求得功率因數與總諧波失真的最佳值。另一方面，本文也對
效率預估與電源內阻抗效應問題作了探討。最後經由實作與模擬的比較，
証實此一功因修正電路，滿載功因在0.99以上運轉，總諧波失真低於
10%，且滿載效率也高達93%以上。

The ac line current of the rectifier circuit with a bulk
capacitor is notoriously with poor power factor and serious
harmonic distortion. This thesis explores a power factor
correction circuit using active devices with variable-
hysteresis-control to solve these problems. In addition,
incorporating with a PWM-controlled boost converter the active
filter can serve as the preregulator to retain a required
load voltage level. At first, the power circuit parameters
can be determined by PWM-averaging model. Employing the
derived parameters on switching-mode circuits, the voltage
and the current waveforms on the converter circuit as well
as the ac line suorce are calculated by the computer
simulations and then the system perfor- mance can be
evaluated. Finally, the prototype is built and the
experimental results are provided to validate the
theoretical analysis and to demonstrate the feasibility
of the designed circuit. It is proved that the proposed
active filter can achieve almost unity power factor
(>0.99) and very low total harmonic distortion (<10%).