Abb Daimler-benz Transportation (north America) Inc.

Ajay P Mishra

An electric powered vehicle includes a traction motor powered from a source of switched DC power. The motor includes a tachometer for measuring the rotational velocity of the motor and for providing a tachometer signal indicative thereof. A low pass filter low pass filters the tachometer signal and produces a reference tachometer signal. A summing circuit combines the tachometer signal and the reference tachometer signal to produce a deviation signal. The deviation signal is provided to a signal processing circuit which includes a comparator and a reference value generator. The comparator compares the output of the summing circuit to a reference value provided by the reference value generator and produces a binary changing signal as a function of the comparison. A controller, which controls the rate DC power is switched to the motor, accumulates a count of the comparator signals over a predetermined interval and terminates the provisioning of power to the motor if the accumulated count exceeds a predetermined value.

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Cannonsburg, PA, United States of America

Ajay P Mishra