應用於馬達驅動器之可變輸出電壓無橋式SEPIC功率因數校正轉換器之研製

Abstract

本文主要提出應用於馬達驅動器具可變輸出電壓功率因數校正VOPFC (Variable Output Voltage Power Factor Correction)無橋式SEPIC，改善馬達離心負載效率。VOPFC電路採用無橋式SEPIC降低橋式整流所造成的導通損失，其中上下臂功率開關採同步脈波寬度調變訊號達到電路控制，且電路設計操作在不連續導通模式具有零電流功率開關導通，零電流輸出二極體關閉使效率提升，由於電路操作在不連續導通時具有高功因特性，使控制迴路大幅簡化。藉由計算、模擬求得VOPFC無橋式SEPIC電路損失分析，證實轉換器具可變輸出電壓的優勢。本文最後使用STM32F0518發展版，以數位控制方式完成40W無橋式SEPIC VOPFC電路，輸出電壓穩壓迴路、可變輸出電壓控制。實驗結果驗證相較於傳統橋式整流電路和固定直流鏈電壓效率皆有改善。

This thesis proposes the variable output voltage power factor correction (VOPFC) bridgeless SEPIC converter for efficiency improvement in applications to motor drives with centrifugal loads. The VOPFC converter is a bridgeless SEPIC with low conduction losses, in which both high side and low side switches are applying the same PWM and topologies are designed to work in discontinuous conduction mode (DCM) with zero-current turn-on in the switch and zero-current turn-off in the output diode to achieve almost unity power factor. By Calculation and simulation circuit loss analysis of the VOPFC bridgeless SEPIC, it will be shown that this converter has advantages for the variable output voltage application. The digital control of VOPFC SEPIC bridgeless is implemented using STM32F0518 to provide a 40W bridgeless SEPIC power factor converter with voltage control loop and variable output voltage control. The experimental results show the efficiency improvement over conventional constant DC link voltage with bridge rectifier.