As for a hybrid electric vehicle and an electric vehicle, a high-power brushless motor is used. Furthermore, a higher power motor will be expected. To control the brushless motor of a hybrid electric vehicle, it is necessary to accurately ascertain the rotation angle of an output shaft of the motor. This is because the rotation position (angle) of a rotor needs to be correctly ascertained in order to control switching of energization of coils of a stator.
Accordingly, the motor preferably includes a resolver to accurately detect the angle. Such resolver used in a drive mechanism of a vehicle is required to provide high accuracy in addition to environment resistance because of the high number of revolution of the drive mechanism. As with other in-vehicle components, the resolver is also demanded to achieve size reduction and cost reduction.
For increasing the accuracy of the resolver, a method using “skew” as disclosed in Patent Literature 1 (JP 5 (1993)-312590A) is conceivable. Specifically, in the prior art section of Patent Literature 1 for preventing distortion of a sine wave output from a magnetic resolver, there are disclosed a method of changing magnetic pole pitches of a rotor core and a stator core and a skew method of placing a stator core in an oblique position with respect to a rotor core.
On the other hand, a printed circuit has been known to reduce the size of a resolver. Patent Literature 2 (JP 7 (1995)-211537A) discloses that a pattern pitch in an arranging direction of a sheet coil to be provided on a base plate is adjusted to an irregular pitch, thereby preventing a higher harmonic wave from overlapping an electromotive waveform to enhance detection accuracy.
USPTO Backgrounds
USPTO Backgrounds