Otis Elevator Company

Todd A Simonds

Daryl J Marvin

Mark Eugene Shepard

Alberto Vecchiotti

Vladan Petrovic

A method and apparatus of determining the position of a rotor at standstill relative to a stator in a synchronous motor elevator machine includes injecting an AC current having a predetermined single frequency and a predetermined initial phase angle into a stator coil of the stator, and sampling the injected current and resultant voltage a predetermined number of times per period of the frequency. Subsequently the method calculates a stator inductance from the sampled voltages and currents using a DFT. By incrementing the initial phase angel a predetermined number of times over a 360 degree cycle, and repeating the injecting, sampling, and calculating with each incremented phase angle, the algorithm provides a predetermined number of calculated stator inductances. The position of the d axis relative to the stator is then determined from the minimum of the calculated stator inductances.

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Colchester, CT, United States of America

Todd A Simonds