Induction motor drive unit, motor drive system, and elevating system
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United States of America Patent
Stats
-
Mar 8, 2011
Grant Date -
Dec 25, 2008
app pub date -
Jun 19, 2008
filing date -
Jun 19, 2007
priority date (Note) -
In Force
status (Latency Note)
Importance
Abstract
A slip frequency is estimated from a current instruction or detected currents in an induction motor. Acceleration impossibility in an induction motor drive unit is determined, when the slip frequency exceeds the maximum torque generating slip frequency for the predetermined interval or the time integrating result exceeds a predetermined value; when the q-axis magnetic flux exceeds the maximum torque generating q-axis magnetic flux or exceeds for a predetermined interval; when the estimated rotational speed is under a predetermined value; when the rotational speed variation rate is negative; and when the rotational speed instruction value or the estimated rotational speed is equal to or smaller than a predetermined value. An induction motor drive system and an elevating system including the induction motor drive unit are also disclosed.
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