18-pulse rectification system using a wye-connected autotransformer

摘要

An electrical AC-DC power conversion system featuring 18-pulse rectification and utilizing a low weight wye-connected phase shifting autotransformer (500) supplied from a 3-phase AC source (40) through a 3-phase line reactor (41). The current harmonic distortion is less that 5% and can be further reduced to 3% level by the use of additional suppression devices (eg., chokes) which are often required in aerospace applications. The transformer (500) includes three sections (501) each spaced 120° electrically apart, wherein each section (501) includes a main winding (510) and a pair of phase shift windings (540). The main winding (510) has a neutral end connected to a floating neutral point (502) and a source end (514) is connected to one phase (1, 2, 3) of the three-phase power source (40). The pair of phase shift windings (540) each include a second winding (520) and a third winding (530) connected in series and arranged to generate phase outputs (4-9) of the autotransformer (500). The above-described design results in a low weight/power configuration.