| 摘要 |
In a control system for a power converter driving a synchronous motor, comprising a controllable rectifier and an inverter of a load commutation type, a speed target is passed through a variation rate limiter for limiting the variation rate to produce a speed reference varied to follow the speed target but within a limited rate. A speed controller is responsive to the speed reference and the detected speed of the motor for producing a current reference. A current control circuit is responsive to the current reference and the detected current of the rectifier for adjusting the average current through the rectifier thereby to reduce the deviation of the detected speed from the speed reference. The current control means comprises means for causing intermission of the current through the rectifier for intermission commutation of the inverter when the detected speed is below a predetermined threshold. A phase angle controller is responsive to the detected rotary position of the motor and determines the firing phase angle of the inverter, and causes load commutation of the inverter when the detected speed is higher than the predetermined threshold. The speed controller resets the current reference at zero when the detected speed exceeds the predetermined threshold. |
