脈寬調變換流器之諧波消除

Abstract

本文是對於單相式脈寬調變型換流器進行討論。事實上，在輸出端的電壓諧波可視為一種干擾，儘管其中較高頻的諧波成分可以透過濾波器將其濾除，但由市電基頻所引起之低頻諧波卻難以透過濾波器濾除，進而造成流入市電之系統輸出電流扭曲、失真。另外，真實系統中的不確定性對輸出的影響也是要考慮的問題。 將由實驗室所開發之”雙互質分解干擾觀測器(DCFDOB)”用於換流器中，在不需要繁雜及加入額外電子元件的情況下，可以降低低頻諧波及系統不確定性對系統輸出的影響。 實作部分使用德州儀器DSP單晶片(Piccolo TMS320F28035)控制板，介紹其軟體部分:運作程序、函式方塊、主程式、類比數位轉換器、中斷及系統完整之運作架構。在其運作架構中找到加入DCFDOB之位置，利用學長所做出之模擬數據進行離散化，將其數據藉由宣告變數、指標、改寫程式碼來實現於系統中加入DCFDOB。最後實驗各種模式及有無DCFDOB控制架構情況下之輸出情形，並藉由頻譜分析(FFT)輸出電流來進行比較。

In this thesis, we discuss about a single-phase DC-AC pulse-width modulated (PWM) inverter system. Actually, the harmonics in the PWM inverter output voltage are often generated as a result of voltage source disturbances. The high-frequency harmonics will filter out by the system itself; nevertheless, the low-frequency harmonics induced by the fundamental component can cause the output ac current to be distorted. A Doubly Coprime Factorization Disturbance Observer (DCFDOB) structure is applied to the DC-AC inverter. This structure can reduce the influence between low-frequency harmonic、system uncertainties and output current without complicated calculations or adding extra circuit components. In implementation, we use the TI Piccolo TMS320F28035 DSP control card. Then the software part including operating procedure, function block, main code, analog-to-digital converter(ADC), interrupt service routine(ISR) and the complete software structure will be introduced. Find the place where DCFDOB control structure is added in the software structure. At last, the result of different condition will be shown and analyze the output current by FFT .