Abstract:
In this thesis an active filtering scheme for input current wave shaping of the
transformers used in a 12-pulse rectifier system has been proposed, analyzed and
compared with passive filtering technique. Both ac and dc filter have been designed
and the most appropriate position of the ac filter has been checked and determined in
passive filtering scheme. With the active filtering scheme high switching frequency
PWM Boost converter has been used at the output of the ac to dc rectifier to shape
the input currents by eliminating high frequency harmonic components with small
sized filters. The number of Boost stages and its/their position at the output stage
have been found out to get a good solution to the problem. With the proposed
method the transformers as well as the rectifier draw near sinusoidal currents from
the utility. Performance evaluation of the proposed scheme has been carried out and
compared with the passive filtering scheme under similar conditions. The outcome is
expected to provide a better solution to harmonic mitigation of input current in
transformers of a twelve-pulse rectifier.
