| 摘要 |
PROBLEM TO BE SOLVED: To prevent the components of a motor from being damaged by correctly recognizing the state of the motor by forcibly functioning burn up prevention means by discriminant signals from the number of revolutions discriminant means. SOLUTION: A burn up prevention circuit detects the loss of magnetic pole switching in a detection signal of rotation position detecting means during rotation control, and performs feeding with an intermittent current having a constant duty ratio to phase coils L1 and L2 thereby preventing the burning up of coil L1 and L2. The number of revolutions discriminant means 26 detects the number of revolutions of a rotor based on the magnetic pole switching of detecting signals from the rotation position detecting means, and judges that the number of revolutions dropped below a specified value lower than the number of revolutions during ordinary rotating state. And by this discriminant signal of this number of revolutions discriminant means 26, the burn up prevention means is forcibly functioned. By doing this, rotating state of a rotor can be correctly recognized even in a vibrating state, and the rotation control can be performed without giving damages to the portions of the motor. |
