| 摘要 |
The invention relates to a method and to an apparatus for the failsafe monitoring of an electromotive drive (10) without additional sensors. The apparatus comprises a drive having a three-phase control of an electric motor, means (20) for detecting the current and voltage profiles of each of the three phases (U, V, W), as they are forwarded to the motor (10) by drive electronics (12), means (26) for determining the load speed (nL) while using the detected current and voltage values, wherein the determination of the load speed (nL) takes place by calculating an observer model with reference to the detected current, to the detected voltage, to the frequency fFU preset by the control and to the characteristic data of the motor (10) and means (28) for generating a failsafe switch signal (30) for the motor (10) when the calculated load speed (nL) does not correspond to a preset desired speed within the framework of preset tolerances. The load torque (ML) can also be determined and monitored with reference to the observer model.
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