Modeling and evaluation of cycloconverter-fed, two-stator windings SAG mill drive. Part I: Modeling options

Typical drive configurations of high-capacity SAG mills uses a two-stator windings vector controlled synchronous motor, with 30^o shift between the two windings, fed by a two secondary´s delta-delta-wye power transformer and two 6-pulse cycloconverters. Paper presents and evaluates three different modeling options for the SAG mill drive. First option considers a complete model in phase and qd0 variables of the two-stator winding synchronous motor fed by two 6-pulse cycloconverters. The second option develops a winding rotation transformation to obtain an equivalent one-stator winding synchronous motor, which is fed by a 12-pulse cycloconverter. The third model considers the equivalent one-stator synchronous motor fed by an ideal converter that produces purely sinusoidal voltage and current waveforms. Each model is evaluated during steady state, and during step speed commands and step load disturbances. Responses are compared to field records of an 8.2 MW SAG mill, confirming the accuracy of the developed models.