Abstract
This thesis develops some DSP-based isolated single- and three-phase inverters with switch-mode rectifier (SMR) front-end. The adequate control is conducted to yield good inverter output performance and satisfactory line drawn power quality. In the development of inverter systems, the designs, implementations and controls for the following plants are performed: (i) single-phase low-frequency (LF) and high-frequency (HF) isolated inverters; (ii) three-phase single-module LF and HF isolated inverters; (iii) three-phase LF isolated Y and Δ/V modular connected inverters. Some major features of these developed inverters lie in: (i) the robust current and voltage waveform controls are proposed to yield good and robust inverter output performance under changing and nonlinear loads; (ii) the HF isolation is achieved by an isolated intermediate DC/DC series resonant converter; (iii) the Δ-connected inverter can become V-connected one automatically as one constituted module is faulted. As generally recognized, SMR is an indispensable power electronic equipment for AC to DC conversion with good power quality, and the three-phase one is a natural choice for higher power rating. This thesis develops a three-phase single-switch (3P1SW) and a three-phase Vienna SMR front-ends for the established inverters, and their comparative performance evaluation is made. The 3P1SW SMR operating in discontinuous conduction mode (DCM) is simpler in circuit and control scheme, but it suffers from having limited power quality characteristics. As to the Vienna SMR, it employs three power switches and operates under continuous conduction mode (CCM). Hence it possesses much better power conditioning control capability and power quality than those of 3P1SW SMR. Key words: Single-phase inverter, three-phase inverter, modular connection, resonant converter, isolated DC-link, digital control, DSP, waveform control, transformer flux imbalance, switch-mode rectifier, power factor correction.