無橋式升壓電路轉換器之功率因數校正

Abstract

本文主要是探討功率因數校正器之交、直流轉換前緣電路，以升壓型轉換器做為主要架構，採用固定切換頻率200kHz下的平均電流控制模式，使用單晶片TMS320F28035在連續電流導通模式下控制電路中的功率開關，利用調整每個切換頻率的責任週期，可將輸入電流波形重塑，使其接近輸入電壓的正弦波形並使電流相位跟電壓相位一致，以達成高功率因數。有別於傳統的功率因數修正電路，文中使用滿載300W之無橋式升壓型電路架構，以並聯兩組升壓電路的方式取代以二極體做全波整流再提供給後端電路的傳統功率因數電路架構。無橋式功率因數校正器的優點在於，電路中二極體的數量比傳統式功率因數校正電路少，相對之下其導通損耗及電流之扭曲率也會小很多。本文的無橋式功率因數架構在滿載下轉換效率為93.39%，電流總諧波失真率為3.4%，功率因數達0.9994。

This paper presents the AC to DC Power Factor Correction converter with boost topology, using average current mode in fixed 200kHz switching frequency, and using microcontroller TMS320F28035 to control the PWM duty ratio in continuous conduction mode to re-shape the input current waveform and in phase with the input voltage. Typically, the PFC stage is a bridge rectifier followed by a boost circuit. However, the current distortion and power losses in the diode bridge cannot be ignored, so the conventional PFC topology is replaced by bridgeless PFC topology. This paper using the full-load 300W with two boost circuits in parallel whitch operates alternately in positive and negative half cycle of AC input voltage, so the conduction loss and current shape distortion can be improved due to the reduction of the number of diodes compare to the conventional PFC topology. The experiment results show in full-load the power efficiency is 93.39% and the power factor reaches to 0.9994.