Patent ID: 8589105

Claim:
A rotating field sensor for detecting an angle that a direction of a rotating magnetic field in a reference position forms with respect to a reference direction, the rotating field sensor comprising: a signal generation unit that includes a plurality of magnetic detection elements for detecting the rotating magnetic field, and generates a first signal and a second signal based on output signals of the plurality of magnetic detection elements, the first and second signals being associated with intensities of components of the rotating magnetic field in mutually different directions; and an angle detection unit that calculates, based on the first and second signals generated by the signal generation unit, a detected angle value that has a correspondence relationship with the angle that the direction of the rotating magnetic field in the reference position forms with respect to the reference direction, wherein: the first signal includes a first ideal component and a first error component; the second signal includes a second ideal component and a second error component; the first ideal component and the second ideal component vary periodically with the same signal period in an ideal sinusoidal manner; the second ideal component differs from the first ideal component in phase; the sum of the square of the first ideal component and the square of the second ideal component takes on a constant value; the first error component and the second error component vary in synchronization with each other, each with a period of ⅓ the signal period; and the angle detection unit includes: a first arithmetic unit that generates a sum of squares signal, the sum of squares signal being made up of the sum of the square of the first signal and the square of the second signal, and having a period of ½ the signal period; a second arithmetic unit that calculates a first error component estimate and a second error component estimate based on the sum of squares signal, the first error component estimate being an estimated value of the first error component, the second error component estimate being an estimated value of the second error component; and a third arithmetic unit that generates a first corrected signal by subtracting the first error component estimate from the first signal, generates a second corrected signal by subtracting the second error component estimate from the second signal, and calculates the detected angle value based on the first and second corrected signals.