此論文旨在研製一單模組高頻隔離三相變頻器及一史考特T (Scott-T) 模組連接之低頻隔離三相變頻器。二者皆配備三種不同類型式之三相切換式整流器前級,藉由數位信號處理器為主之數位控制,所建變頻器具良好之輸出性能。 首先設計建構一單相變頻器模組,以所提之電流及電壓控制架構使其具有良好及強健之輸出電壓波形追蹤特性。接著應用二組所建單相變頻器透過Scott-T變壓器接成一低頻隔離式三相變頻器,此系統僅需兩個單相變頻器模組及一組史考特變壓器。一些實測結果顯示其優良之操作性能,包括在不平衡及非線性負載下之電壓波形追控特性以及三相不平衡特性等。接著,建構高頻隔離三相變頻器,其包含一個六開關單模組三相變頻器及一LLC共振DC/DC轉換器,建立隔離直流鏈具有良好之電壓調節特性。兩種三相變頻器性能也將予以比較評估。特定言之,高頻隔離三相變頻器在非線性負載下之電壓波形失真較少。不過,由於高頻變壓器之固有限制,其額定之增大較為困難。 最後,本論文從事三種三相切換式整流器之開發,並將其用為所建立三相變頻器之前級。此三種切換式整流器含三相單開關,三相無橋式及零電流轉移切換,具不同型式切換式整流器前級之三相變頻器系統將以一些實測結果進行其性能比較評估。
The major purposes of this thesis are to develop a single-module high-frequency isolated three-phase inverter and a Scott-T modular connected low-frequency isolated three-phase inverter. All are equipped with different types of three-phase switch-mode rectifiers, and proper digital controls using digital signal processor (DSP) are conducted to yield good inverter output performance. First, a single-phase inverter is designed and implemented, which possesses excellent and robust output voltage waveform tracking characteristics via the proposed sophisticated current and voltage control schemes. The established single-phase inverter is then employed to form a low-frequency isolated Scott-T modular connected three-phase inverter, only two inverter modules and a Scott-T transformer bank are employed. Some measured results are provided to demonstrate its operating performances, including voltage waveforms under unbalanced and nonlinear loads, and three-phase imbalance, etc. Second, a high-frequency isolated three-phase inverter is constructed. It consists of a single-module six-switch three-phase inverter and a LLC resonant DC/DC converter to establish the isolated DC-link with well-regulated voltage. The comparative performance evaluation for these two types of three-phase inverters is conducted. Specifically speaking, the high-frequency isolated inverter possesses less output voltage waveform distortion in powering nonlinear loads. However, its rating enlargement is more difficult owing to the inherent limits of high-frequency power transformer. Finally, the development of three types of three-phase switch-mode rectifiers (SMRs) is made, and they are utilized to serve as the front-ends of the developed inverters. These include three-phase single-switch (3P1SW) SMR, three-phase bridgeless SMR and three-phase single-switch zero-current-transition (3P1SW ZCT) SMR. The established different SMR-fed inverter systems are assessed their performances comparatively by measured results.