| 摘要 |
PURPOSE:To detect the lock of a motor in a rapid responding time without erroneous operation by detecting the presence of a counterelectromotive force generated in a drive winding. CONSTITUTION:When a permanent magnet rotor is rotated, a counterelectromotive voltage is generated at the drive winding of the side not energized, a reverse bias is applied to a transistor Tr4, Tr3 become monoperative states. Accodingly, drive windings L1, L2 are alternately excited in response to the switching of position detecting means H. When a permanent magnet becomes locked state, a counterelectromotive force is not generated at the drive winding of the side not energized, and the transistor Tr4 becomes operative state. The collector current flowed to the transistor Tr4 is regulated by a resistor R4, and inputted to the base of the transistor Tr3. Here the transistor Tr5 becomes operative state, saturated voltage between the collector and the emitter of the transistor Tr3 is outputted to an alarm signal output terminal (a), and warning means B is operated. |
