| 摘要 |
PROBLEM TO BE SOLVED: To prevent a generation of an extra pulse signal even when a rotor moves in a reverse direction at the excitation completion time of an electric motor.SOLUTION: The relationship between a rotation angle &thetas; of an electric motor 11 and a magnetic flux density Bs detected by a hole IC device 22 is such that a difference Ab between a first magnetic flux density BS1 when a pulse signal is switched from an ON level to an OFF level and a second magnetic flux density BS2 when the pulse signal is switched from the OFF level to the ON level according to the magnetic flux density from permanent magnets 21, 21B for rotation detection making a reverse rotation CCW is greater than a variation of the magnetic flux density caused by the rotation of the permanent magnet for rotation detection through a cogging torque. |
