| 摘要 |
PURPOSE:To carry out the commutation certainly and to make the stable operation available in all the operation range when there is no counterelectromotive force detected in all the operation range and to make the high-efficiency operation available when the load fluctuates. CONSTITUTION:This equipment is provided with a counterelectromotive force detecting circuit 6 that detects a counterelectromotive force of a stator winding, a rotation judging circuit 6 that detects the number of rotations due to the output of the counterelectromotive force detecting circuit 5, and a phase judging circuit 7 that determines a commutation timing based on the outputs of the circuits 5 and 6. The phase judging circuit 7 temporarily stores the output of the counter electromotive force detecting circuit 5 sequentially and when there is not output from the circuit 5, it judges the commutation timing due to the output it has stored immediately before. Because of this structure, an accurate commutation is available even when no counterelectromotive force is detected in a high rotation range. This equipment is also provided with a load torque judging device that determines the load torque to correspond with the control duty ratio and the number of rotations due to the preliminarily mapped data and a phase shift selecting device that selects a phase shift suitable for the load torque and the number of rotations based on the preliminarily set correction table. Because of these devices, a high-efficiency operation is available. |
