Modeling and Evaluation of Cycloconverter-Fed Two-Stator-Winding SAG Mill Drive— Part II: Starting Evaluation

A detailed evaluation of a SAG mill starting is presented using three different modeling options. The first option considers a qd0 model of the two-stator winding synchronous motor fed by two six-pulse cycloconverters. The second option considers the qd0 model of an equivalent one-stator winding synchronous motor fed by a 12-pulse cycloconverter. The third option considers the equivalent one-stator winding synchronous motor fed by an ideal, purely sinusoidal signals, converter. To obtain an accurate representation of the dynamic behavior of the mill charge, especially during the first half turn of the SAG mill, a dynamic model of the mill charge is developed. This dynamic model uses the radius and angle position of the mill charge center of mass. The dynamic angle is obtained from starting field records. First, a typical starting is evaluated using the three modeling options, comparing the computational requirements of each evaluation. Then, the effect of the charge volume and the effect of the initial ball charge are presented. Finally, results are compared to field records for three different starts of an 8.2-MW SAG mill, and the effect of the shutdown time period is analyzed.