Systems, apparatus, and methods for soft starting large AC motors with a variable frequency drive

摘要

A system for soft starting a large AC motor may include a variable frequency drive (VFD) having a much lower voltage rating than the rated voltage of the AC motor. The VFD's voltage rating may be in a range of about 33% to about 67% of the AC motor's rated voltage. The AC motor may be coupled to a utility power source via conventional connections to leads of the AC motor's windings. The VFD may be connected to the AC motor via tapped connections within the windings of the AC motor such that the tap voltages are much less than the AC motor's rated voltage. A less expensive VFD may therefore be used to soft start the AC motor instead of a VFD having the same rated voltage as the AC motor. Methods of starting large AC motors with a VFD are also provided, as are other aspects.