Abstract
Usage of conventional bridge type rectifiers for obtaining DC power from AC grid results in injection of unwanted current harmonics into the grid. Due to standards such as IEEE 519-1992 [1] which limit the amount of harmonic injection into the mains, the bridge type rectifiers are being replaced by improved power quality converters which have reduced harmonic injection into the mains along with a host of other advantages. This project deals with the hardware development and control of a 3-phase, 3-level UPF rectifier which is a variant of an improved power quality converter named vienna rectifier [2]. The 3-phase, 3-level rectifier is characterised by its input currents being almost sinusoidal, reduced input current ripple, controllable output DC voltage, high power density and UPF operation. Further, reduced losses and a lesser component count of the 3-phase, 3-level rectifier compared to the vienna rectifier indicate a greater scope for reduction in the size of the rectifier along with reduced packaging effort. In this work, the necessary hardware for the 3-phase, 3-level UPF rectifier has been developed, assembled and tested for a power level of 2kW and a DC bus voltage of 750V. A carrier based control strategy has been proposed for the control of the rectifier and its operation is validated on the hardware setup. Based on the results obtained from simulation and hardware implementation, a comparison has been done between the already existing hysteresis based control strategy [2] and the proposed carrier based control strategy. Overall, the project work involves the building of the 3-phase, 3-level UPF rectifier setup, design of the controller parameters, validation of the proposed carrier based control strategy both in simulation/hardware and comparison of the proposed control strategy with an originally existing hysteresis based control strategy.
LINK ORIGINAL COMPLETE THESIS
http://www.ee.iisc.ac.in/new/people/faculty/vjohn/pdf/ME2012_KrishnaKumarMJ.pdf
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