| 摘要 |
PURPOSE:To control the speed of a snychronous motor while operating the motor in a high power-factor by a method wherein the phase of the induced voltage of the motor and the phase of the output voltage of an inverter are detected and the phase of the output voltage of the inverter is controlled on the basis of the phase difference. CONSTITUTION:When a torque reference is given from a torque reference circuit 35, a torque angle set instrument 34 operates a torque angle theta corresponding to the torque characteristics of a synchronous motor 13, and the operational phase of a self-excited inverter 24 is advanced or delayed by means of a phase controller 36 according to a fact that phase difference detected by means of a phase difference detector 33 is smaller than theta or larger than that. Consequently, the voltage phase of the inverter 24 becomes to advanced phase only by theta to the internal induced voltage of the motor 13, and torque is generated. Thus, the motor can continually be operated in a high power-factor by properly selecting a voltage reference of a voltage reference circuit 37 because a power-factor can be controlled by altering the magnitude of terminal voltage. |
