| 摘要 |
PURPOSE:To provide a driver for brushless motor employing a starting system for making a switch from synchronous operation to position detecting operation in which ultra low speed operation can be realized by making a switch again to the synchronous operation if ultra low speed operation takes place during position detecting operation. CONSTITUTION:At the time of starting a motor, synchronous operation is performed until a voltage induced in an armature winding 4 exceeds a predetermined level and a position detecting operation is performed based on a position detection signal of a rotor 5 when the voltage induced in the armature winding 4 exceeds the predetermined level. If ultra low speed operation takes place during the position detecting operation, switching is made again to synchronous operation. If the phase of voltage to be applied on the motor immediately after switching is lagged, stability can be enhanced at the time of switching. |
