A Comparative Study of AC/DC Converters Used in High Current Applications

This paper is dedicated to a comparative study between prevailing schematics of rectifiers employed in industry for high current uses. Different configurations are introduced so far but the most common ones are thyristor- controlled rectifiers (ANSI 25-26 and ANSI 45-46). This paper proposes another configuration that is a combination of AC/AC converter, transformer and paralleled diode rectifiers. As an illustration, a comparison is made between the proposed converter and double bridge rectifier (ANSI 45-46) from viewpoint of reactive and harmonic powers and power losses. Current harmonics, harmonic loss factor (FHL), apparent, active, reactive, and distortion powers are extracted for different operating modes of the two converters. It is shown that for the proposed rectifier, RMS value of the current and its harmonics, current THD, and losses including switching, DC and eddy current losses of windings reduce as the firing angle increases. Finally, two descriptive experiments are conducted to verify the theoretical results.

Keywords:

AC/AC regulator , ANSI 45-46 , eddy current losses , high current rectifiers , reactive and distortion powers