Async. motor braking system - uses signal shape at stator winding monitor and L.F. signal filtered out with motor stationary

摘要

A sync. motor braking method using a d.c fed into at least one phase of the stator winding, the d.c being switched off following stoppage of the motor, is now designed so that motor standstill can be sensed without the use of a special revs. measurement instrument. Thus, the signal shape at the stator winding is monitored and a l.f signal is filtered out at or near to the motor standstill point and is used to switch off the in-feed braking d.c More specif. the signal shape is monitored on one phase of the stator winding.