以MathCAD為基礎之邊界模式功率因數修正轉換器與EMI濾波器設計

Abstract

本文主要探討用於100W 電源級AC-DC 功率因數改善電路，具功率因數修正之臨界導通模式升壓式功率因數修正轉換器及EMI 濾波器之設計與功率損失分析。文中將針對採用臨界導通模式控制之升壓式功率因數修正轉換器說明電壓控制模式的原理及電路控制架構、電路設計與差模EMI 濾波器設計並透過MathCAD 軟體作完整連貫性的計算與 設計程序，藉以探討在不同負載工作點與輸入電壓下，各個主要零件的功率損失與切換頻率的變化。再探討輸入電壓,電流,電感電流,導通時間,關閉時間與開關切換頻率對不同輸入電壓相位角度的分析比較。而設計加入一個差模EMI 濾波器以提升系統電路的功率因數並降低總電流諧波量以符合相關的規範。再用PSIM 軟體模擬開關控制、輸出入電壓及電流的波形與加入EMI 濾波器後的整體功率因數校正結果，最後再由MathCAD 整合基本計算、理論分析、模擬資料與量測資料。將計算、模擬、與實驗結果互相比對驗證。

This paper presents a practical design method for the critical-conduction-mode (CRM) power-factor-correction (PFC) converter with EMI filter design by using an interactive mathematical computation and documentation software, the MathCAD. The design of CRM PFC converter is an involved process and there is a need for practical design engineers to follow an interactive and intuitive design procedure. The selection of major power components with loss analysis of the CRM PFC converter has been described. The design of input differential-mode (DM) EMI filter for the reduction of total-harmonic-distortion (THD) for line current has been developed in considerations of practical design limitations. Computer simulations have been carried out by using power electronic system simulation software, the PSIM, to verify the design results such as power factor and THD. An illustrated design rocedure and analysis are presented with given design example by using the MathCAD to combine and analyze the results of design, simulation .and experiment.