Patent ID: 6333614
Filing Date: 2001-12-25
Classification: G05B,H02H

Abstract:
A method for monitoring the operational state of an electric motor, comprising:changing a torque current of an electric motor;performing a first evaluation of an output signal of an angle encoder during a testing interval, wherein said angle encoder is connected to said electric motor, wherein said output signal is representative of the number of revolutions of said angle encoder;simultaneously and independently performing a second evaluation of said output signal a second time during said testing interval;determining a first change in number of revolutions of said angle encoder during said testing interval based on said first evaluation;determining a second change in number of revolutions of said angle encoder during said testing interval based on said second evaluation;detecting a safe operational state for said electric motor if the magnitude of each of said first and second changes in number of revolutions lies above a minimum value; andperforming steps for producing a safe operational state for said electric motor if either of said first and second changes in number of revolutions lies below a predetermined value.