| 摘要 |
PROBLEM TO BE SOLVED: To provide a circuit for driving a sensorless motor smoothly from start to steady rotation without requiring the switching operation between a circuit operating only at the time of steady rotation of rotor and a circuit being actuated at the time of starting and low rotation. SOLUTION: The drive circuit for sensorless motor comprises a starter section 30 for adding an analog voltage SO to a DC voltage MP at the neutral of a motor thus forming a starter signal WP, and a comparison circuit 12 for comparing the starter signal WP with the counter electromotive forces U, V, W from exciting coils CU, CV, CW of respective phase to produce comparison voltage signals Uin, Vin, Win. The drive circuit further comprises a delay circuit 14 for delaying the comparison voltage signals from the comparison circuit 12 by predetermined electrical angles T1, T2, T3 to produce a signal PC for switching the conduction pattern of exciting coil CU, CV, CM of a plurality of phases. |
