Siemens SINAMICS PERFECT HARMONY GH180 Function Manual page 191

Using neutral shift after loss of five cells
This example shows a 15 cell drive: five cells remain in phase A; two cells have failed in phase B;
three cells have failed in phase C.
Without neutral shift, one functional cell would be bypassed in phase B, and three functional
cells would be bypassed in phase A. Only 40% of the original cells would remain in use, and only
40% of the original voltage would be available.
With neutral shift only the failed cells are bypassed. The phase angles of the cell voltages have
been adjusted so that phase A is displaced from phase B by 61.1° and from phase C by 61.6°. The
star-point of the cells is far removed from the neutral of the motor voltages, but the motor
voltage is balanced. 67% of the cells are in use, and 50% of full voltage is available.
Figure 7-8
NXGPro+ Control Manual
Operating Manual, A5E50491925A
Drive Output after loss of 5 Cells
Operating the Control
7.4 Cell Bypass
189