| 摘要 |
PURPOSE:To detect abnormal rotation of the rotor in a position sensorless type brushless motor. CONSTITUTION:An induced voltage detecting circuit 27 produces position detection signals PSU, PSV and PSW based on comparison between therminal voltages UV, VV and WV of stator windings 21U, 21V and 21W for respective phases of a brushless motor 20 and a voltage reference VR. A conduction timing signal forming circuit 28 produces a base signal based on these position detection signals PSU, PSV and PSW and delivers thus produced base signal to a drive circuit 2. On the other hand, the induced voltage detecting circuit 27 outputs a state detection signal SI corresponding to the state of voltages induced in the stator windings 21U, 21V and 21W and an abnormality detecting circuit 29 makes a decision whether the rotation of a rotor 22 is normal or abnormal based on the state detection signal SI. If a decision is made that the rotation is abnormal, the abnormality detecting circuit 29 outputs an abnormality detection signal SA. The conduction timing signal forming circuit 28 stops operation based on the abnormality detection signal SA and an alarm 30 is actuated. |
