Importance

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Abstract

A method is presented for detecting the position and the direction of motion of a movably mounted part on an electric motor that makes provision not only for a single-channel sensor but also a measuring arrangement for the motor current and the rectified motor current by means of which the motor current is activated after operating switching devices to reverse the polarity of the voltage applied to the motor to cause a reversal of the direction of motion. The measuring arrangement establishes from the variation of the motor current over time the point of time of the motor current maximum and transmits this to the evaluation logic. The point of time of the actual reversal of the direction of motion is derived from the point of time of the motor current. Preferably, the current is measured as a reference current value even before falling through the zero crossing. By means of a calculating unit that simulates a motor state model, the measured values of motor current, motor voltage and motor speed can also be used to ascertain by calculation the time of reversal of the direction of motion and the current threshold value.

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First Claim