Control systems of alternating current motors
First Claim
1. In a control system of an alternating current motor which is energized by a current type frequency converter including a serially connected rectifier and inverter wherein the output direct current voltage of said rectifier is controlled by a phase controller which is controlled by a phase control signal, the output frequency of said inverter and a speed reference signal, the improvement which comprises a power factor detector which differentiates said phase control signal, and means for adding the output of said power factor detector to said speed reference signal so as to suppress low frequency oscillations of the torque of said motor.
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Abstract
In a control system of an alternating current motor energized by serially connected rectifier and inverter wherein the output DC voltage of the rectifier is controlled by a phase controller which is controlled by a phase control signal and the output frequency of the inverter is controlled by a speed reference signal there is provided a power factor detector which differentiates the phase control signal or the DC voltage and the output of the phase detector is added to the speed reference signal so as to suppress low frequency oscillations of the torque of the motor.
31 Citations
4 Claims
- 1. In a control system of an alternating current motor which is energized by a current type frequency converter including a serially connected rectifier and inverter wherein the output direct current voltage of said rectifier is controlled by a phase controller which is controlled by a phase control signal, the output frequency of said inverter and a speed reference signal, the improvement which comprises a power factor detector which differentiates said phase control signal, and means for adding the output of said power factor detector to said speed reference signal so as to suppress low frequency oscillations of the torque of said motor.
- 3. In a control system of an alternating current motor which is energized by a current type frequency converter including a serially connected rectifier and inverter wherein the output direct current voltage of said rectifier is controlled by a phase controller which is controlled by a phase control signal, the output frequency of said inverter and a speed reference signal, the improvement which comprises a power factor detector which differentiates the output direct current voltage of said rectifier, and means for adding the output of said power factor detector to said speed reference signal so as to suppress low frequency oscillations of the torque of said motor.
Specification