| Summary: | 碩士 === 國立清華大學 === 電機工程學系 === 93 === This thesis is mainly concerned with the development of various three-phase inverters constructed using two or three single-phase modules, and the study of their waveform controls. First, the single-phase inverter module with robust voltage waveform control is designed and implemented. In its control aspect, a two-degrees-of-freedom (2DOF) current- controlled PWM scheme is first designed to let the filter inductor current closely follow its command. Then a robust 2DOF voltage robust waveform control scheme is developed. The nominal plant dynamic model is first estimated, and it is employed to design its feedback controller and command feedforward controller. Then an observer-based robust disturbance feedforward controller and a robust waveform controller are designed to yield improved voltage waveform control under unknown, varying and nonlinear loads.
Having established the single-phase inverter module with good voltage waveform control performance, three modules are connected to form a Y-connected and a -connected three-phase inverters. And a V-connected and a Scott-T connected three-phase inverters are constructed using two modules. In order to improve the three-phase output voltage waveforms of V-connected three-phase inverter, a robust balance waveform controller is further proposed. The weighted and phase shifted robust compensation signals are yielded from the voltage waveform tracking error of the third phase, and they are added to the waveform commands of the two modules for performing the imbalance compensation control. The performance evaluation for established inverters includes: sinusoidal waveforms and power quality characteristics under various types of loads, step magnitude response of sinewave, swept-sine waveform tracking response and arbitrary waveform tracking response, etc.
Key words: Inverter, single-phase, three-phase, modular connection, waveform control, two-degrees-of-freedom, robust control.
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