| Summary: | 碩士 === 國立雲林科技大學 === 電機工程系碩士班 === 90 === Power electronic products have been widely used in the industry. But these products produce the serious power pollution. The power pollution problems results in low power quality and low efficiency. The power quality include the cases of under-voltage, over-voltage, outage, surge, dip, voltage sag, voltage swell, harmonics, electromagnetic inference (EMI), flicker, voltage frequency variation and unbalance. In the recent market products, we can not find a perfect and low cost product to solve above mentioned problems for power pollution. Large current harmonics, low power factor and low efficiency are the main drawbacks of diode or phase-controlled rectifier. In this thesis, a multilevel pulse width modulation (PWM) converter used in the medium voltage and high power applications is proposed to replace the conventional power converter. With the advantages of low harmonic distortion, low EMI, low voltage rating of the switching devices, power reversible and reduction in size and weight, the neutral-point switch-clamped converter is proposed. The proposed neutral-point-clamped converter can be operated as an active power filter, power factor corrector, on line uninterruptible power supply and voltage regulator. To verify the proposed operation scheme, performance characteristics are given by the computer simulation and experimental results.
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