Heretofore, a hybrid electric vehicle and an electric vehicle use a high-power brushless motor. To control the brushless motor of the hybrid electric vehicle, it is necessary to accurately ascertain the rotation position (angle) of a motor rotating shaft. This is because, for switching control of energization to each coil of the motor stator, the rotation position of a motor rotor has to be accurately ascertained. In vehicles, specifically, drivability is apt to deteriorate due to motor cogging. Reducing the cogging is therefore desired. Accordingly, there is a large demand for accurate switching of coil energization.
Herein, for detection of the position of the rotating shaft of each motor mounted in the hybrid electric vehicle and the electric vehicle, a resolver is used to satisfy such functions as high-temperature resistance, noise resistance, vibration resistance, and high-humid resistance. The resolver is built in the motor and directly mounted to the motor rotating shaft.
FIG. 33 is a cross sectional view of a motor 200 with rotation detector disclosed in JP 2007-124757A. A motor stator 202 is fixed on the inner periphery of a motor casing 208. A bus bar 201 is connected to one end of the motor stator 202. A resolver stator 203 is fixed to the inner peripheral end face of the bus bar 201. The resolver stator 203 includes a resolver stator coil 204 in a wound form.
On the other hand, a pair of bearings 209 are fixed in the motor casing 208 and rotatably support a rotating shaft 205 of the motor rotor 206. On the rotating shaft 205, a resolver rotor 207 is fixedly mounted so as to face the resolver stator 203. The resolver stator 203 and the resolver rotor 207 constitute a resolver serving as a rotation detector.
JP 9(1997)-65617A also discloses a similar invention to JP 2007-124757A. A difference between the '617 invention and the '757 invention is that the resolver stator 203 of the '757 invention is attached to the bus bar 201 while the resolver stator of the '617 invention is fixed to a casing.
On the other hand, JP 2000-292205A discloses an invention using an exciting signal modulated onto a high frequency carrier, thereby reducing the number of turns of a coil in the resolver stator to achieve cost reduction. This invention enables a reduction in the number of turns of a coil and thus can use a sheet coil without using a winding coil. The resolver therefore can be made compact.