Patent attributes
An abnormality judging apparatus of a rotation angle detecting apparatus generating a sine wave signal and a cosine wave signal according to the rotation angle of a rotor is provided with an interface which receives the sine wave signal, an interface which receives the cosine wave signal, a signal arithmetic circuit which successively calculates the sum of each square of the received sine wave signal and cosine wave signal, a memory which stores as a threshold value the value of the sum of each square of the sine wave signal and cosine wave signal received from the rotation angle detecting apparatus at a predetermined point in time, and a judging circuit which judges that abnormality has occurred at the rotation angle detecting apparatus when the difference between the value calculated by the signal arithmetic circuit and the value stored in the memory is out of a predetermined range.
