Apparatus and method for detecting abnomality in a position detection device

摘要

An abnormality detection apparatus for a position detection device is provided which is capable of performing abnormality detection accurately and inexpensively. The position detection device has a primary winding and a secondary winding, and at least one excitation signal each having a predetermined periodic waveform is supplied to the primary winding to thereby generate at least one output signal each in the form of a phase modulated signal corresponding to a rotational position of a rotating member from the secondary winding directly or after having been subjected to phase shifting and appropriate arithmetic operations. The apparatus is provided with an abnormality detection section for determining an abnormality of the position detection device when the phase modulated signal has a peak value which is outside a predetermined range.