| 摘要 |
PURPOSE:To safely operate an AC motor without commutation failuer even if abruptly accelerated or decelerated and to enhance the operating power factor and efficiency by deciding the superposing angle in response to the magnitude of the accelerating/decelerating rate, the amplitude of a current or the magnitude of the change rate of the current. CONSTITUTION:A control lead angle (beta) controller 21 controls the control lead angle (beta) by the detection signal of a superposing angle detector 23 and the voltage detection signal of a voltage detector 22 irrespective of the rotating speed of an AC motor 15 for the commutation margin time of an inverter 14 when the acceleration/deceleration rate detected by an acceleration/deceleration detector 25 is the prescribed value or lower. If the acceleration/deceleration rate becomes the prescribed value or higher, the angle (beta) is so controlled that the commutation margin angle (beta) of the inverter 14 becomes substantially constant by using superposing angle (u) set by a superposing angle setter 26. When the angle (beta) is thus set, the operating power factor is improved to reduce the current of the motor 15 and to improve the operating efficiency. |
