MODES OF OPERATION IN PARALLEL-CONNECTED 12-PULSE UNCONTROLLED BRIDGERECTIFIERS WITHOUT AN INTERPHASE TRANSFORMER

Parallel operation of two 6-n prepulse uncontrolled bridge rectifiers, to obtain a IZ-pulse rectification, without an interphase transformer connected on the de sides is investigated in this paper, The mechanis m of interactions between the two six-pulse bridges is analyzed. As th e load current varies from no-load to the complete short-circuit value , seven modes of operation are recognized, Equations describing the me an output voltage and various operating angles of the rectifier circui t are given in terms of a reactance factor, Voltage regulation and var iations of the ignition angle and the commutation overlap angle for re ctifiers with and without an interphase transformer are also compared.