Bhowmik, Pankaj Kumar
DESIGN, ANALYSIS AND EXPERIMENTAL VERIFICATION OF CENTER-POINT-CLAMPED AC-AC CONVERTER
1 online resource (158 pages) : PDF
University of North Carolina at Charlotte
With the increasing use of electronic loads by the consumers, the utilities are facing more and more power quality issues. The advancement in semiconductor industry has led to introduction of power electronic devices as solutions to the power quality issues. But the implementation of these devices at utility scale voltage still remains challenging due to lack of power semiconductor devices rated at utility scale voltages. This thesis proposes a novel topology of power converter that uses semiconductor devices rated at about half the magnitude of utility scale voltage. This novel converter topology would help realizing a power electronic converter for utility scale voltages with easily available semiconductor devices that are rated at half the utility scale voltages.This thesis investigates a center point clamped ac-ac topology for direct ac-ac power conversion. This converter topology introduces a unique methodology to clamp the voltage to the mid-point of the input transformer thus reducing the voltage blocking requirements on the bi-directional switches employed in such direct ac-ac converter. This thesis also discusses the considerations that are taken into account while designing an input filter for Center-Point-Clamped AC-AC Converter. The switched mode regulators due to their switching action feed in unwanted harmonic currents to the input side. These switching harmonics are attenuated by the designed input filter. But the addition of an input filter changes the transfer functions associated with the converter, which may degrade the performance of the converter and may even destabilize the system. The dynamic analysis of the Center-Point-Clamped AC-AC Converter with an input filter has been discussed in the thesis. A feedback controller has been designed for closed loop control of the converter. Simulation results presented in the paper verify that the proposed converter offers high power transfer efficiency compared to conventional ac-dc-ac converters, and smaller output voltage ripple along with reduced voltage stress on the bi-directional switches when compared to other direct ac-ac converters. Also, it is seen that the designed input filter reduces the harmonic distortion of the input current, maintains the stability of the system as well as does not degrade the performance of the Center-Point-Clamped AC-AC converter. Experimental results demonstrating the Center-Point-Clamped mechanism of the converter as well as closed loop control of the AC-AC Converter are also presented in the paper.
AC-AC CONVERTERCENTER-POINT-CLAMPEDDYNAMIC ANALYSISMULTILEVEL POWER CONVERTERPOWER SYSTEM CONTROL
Cox, RobertChowdhury, Badrul
Thesis (M.S.)--University of North Carolina at Charlotte, 2015.
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