| 摘要 |
PURPOSE:To effectively prevent the increase of the shaft loss of the motor by performing a preliminary stepping process for supplying an exciting current having a frequency higher than the frequency which is nearly the same as the natural vibration of the rotating system of the motor before a stepping process. CONSTITUTION:A control circuit has a preliminary stepping signal oscillator 1, stepping signal oscillator 2, timer 3, stepping timing generation circuit 4, conduction switching logic 5, output driver 6, and counter-electromotive voltage detection circuit 7 and the three-phase coils (u), (v), and (w) of a stator coil 26 are connected to the output side of the output driver 6. When a start signal is inputted to the timer 3, the coils (u), (v), and (w) are excited by a set period of time based on the output signal of the oscillator 1. After a prescribed period of downtime, a stepping process in which an exciting current of a frequency which is nearly the same as the natural vibration of the rotating system of a motor is executed. As a result, the shaft loss of the motor can be remarkably reduced at the starting time of the motor, since a rotor is floated by small vibrations generated in the preliminary stepping process. |
