Patent ID: 7015840

Claim:
A Resolver/Digital (R/D) converter configured to find an angle of a rotor axis of a resolver, the R/D converter comprising: a first converter configured to convert a sine wave output and a cosine wave output of said resolver to a digitized sine wave and digitized cosine wave; and a digital signal processor including a calculator configured to calculate a tangent from the digitized sine wave and the digitized cosine wave, and directly perform a digital calculation of the angle of said rotor axis of said resolver by calculating an arc tangent from the calculated tangent, the calculated angle being between 0 and 90 degrees, wherein: said digital signal processor further includes a discriminator for determining to which one of four quadrants formed by dividing an angle space of said resolver into four, said rotor axis of said resolver belongs, and said calculator finds a final angle of said rotor axis of said resolver by setting an offset value of the calculated angle of said rotor axis based on the one of four quadrants determined by said discriminator.