Patent ID: 7263452

Claim:
A resolver-to-digital converting apparatus for calculating a resolver rotational angle from two-phase sampling values that are the result of sampling output signals of two phases, which are obtained from a single-phase-excited, two-phase output resolver, at peak timings of a waveform, comprising: a determination unit for determining whether each of the two-phase sampling values has deviated from a prescribed path of rotation by more than a predetermined amount when the two-phase sampling values are represented by orthogonal coordinates; a correction processing unit, responsive to a determination by said determination unit that the predetermined amount has been exceeded, for applying a correction to the two-phase sampling values using an equation of a tangent to the path of rotation at a point on the path of rotation at which the previous resolver rotational angle was obtained; and an angle calculation unit for obtaining a resolver rotational angle at the corrected two-phase sampling values obtained by said correction processing unit.