Otis Elevator Company

Jost-Ingo Eichberger

Herbert K Horbruegger

The invention concerns an open-look speed control device for an induction motor to drive an elevator cabin, approaching a premarked where braking must be initiated point in advance of stopping at a marked point at a floor level to be approached at a creep speed, and for a VVVF inverter, which supplies current to the induction motor. The current supplied to the induction motor, is measured when the cabin travels at constant speed prior to reaching the premarked point. A slippage compensation unit determines a pertinent slippage frequency from the measured active current, and from it derives the frequency specification for the upcoming creep phase. A memory stores a function that indicates creep time as a function of the measured active current. A computer unit calculates a delay time for the next run from the measured creep time. The start of the cabin's deceleration process is delayed, according to a lookup function, and after the car stops a new virtual updated creep time is again 'measured' by turning from the stopping of dictated deceleration until the actual end of the creep process.

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Berlin, Germany

Jost-Ingo Eichberger