US 5,476,158 A · Rotor time constant adaptation for induction motor in vector controlled elevator drive

Abstract

Torque current reference I.sub.Tref and reference acceleration a.sub.ref are sampled in a vector controlled induction motor drive for developing a quality criterion by which an estimated rotor time constant .tau..sub.2 may be adapted to the actual rotor time constant .tau..sub.2. More specifically, the torque current reference I.sub.Tref and reference acceleration a.sub.ref are sampled and then a slope of I.sub.Tref versus a.sub.ref is plotted against the offset of that line, which offset is proportional to the lead torque T.sub.LOAD. The no-load slope is then determined from this plot and subtracted from an ideal no-load slope and the difference passed through a proportional-integral circuit for providing an estimated rotor time constant .tau..sub.2 which is adapted to the actual rotor time constant .tau..sub.2.

Claims14

Dependent claims

A method for providing an estimated rotor time constant of an induction machine, operated by a vector control, for driving an elevator, comprising:

running the elevator up while empty and sampling an acceleration reference and a torque current reference provided by said vector control;
running the elevator down while empty and sampling said acceleration reference and said torque current reference;
determining the slope of a linear relationship between said sampled acceleration references and said sampled torque current references;
subtracting said slope from an ideal slope associated with the actual rotor time constant of said machine and providing a difference signal;
providing said estimated rotor time constant in response to said difference signal;
and
controlling an output torque of said induction machine by providing said estimated motor time constant to said vector control of said induction machine.

4 more elements

Dependencies are inferred from the claim text.

Rotor time constant adaptation for induction motor in vector controlled elevator drive

Life of this patent

Rotor time constant adaptation for induction motor in vector controlled elevator drive

Life of this patent

Abstract

Claims14