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A motor control system controls to be constant a reactive power consumed by a motor load equipment having a motor to be driven by power supplied from an AC power source and a couple of thyristor converters for regulating the power supplied to the motor. To this end, the motor control system is compr

A motor control system controls to be constant a reactive power consumed by a motor load equipment having a motor to be driven by power supplied from an AC power source and a couple of thyristor converters for regulating the power supplied to the motor. To this end, the motor control system is comprised of a reactor power detector for detecting the reactive power of the motor load equipment, a command circuit for issuing a command to specify the rated reactive power consumed in the rated load running of the motor load equipment, and a reactive power control unit which receives an output signal from the command circuit and an output signal from the reactive power detector to produce a firing phase command signal depending on a difference between them. The firing phase command signal from the reactive power control unit is applied to an automatic pulse phase shifter to control the firing phase of the thyristor converters.

대표청구항 ▼

A motor control system comprising: a motor load equipment connected to an AC power source having a motor consuming power supplied from the AC power source and means connected to said motor including first and second converters connected in series for controlling the power to be consumed by the motor

A motor control system comprising: a motor load equipment connected to an AC power source having a motor consuming power supplied from the AC power source and means connected to said motor including first and second converters connected in series for controlling the power to be consumed by the motor through control of the firing angle of said first and second converters; phase modifying equipment connected to the power source and consuming a leading reactive power for compensating for a lagging reactive power at rated load running consumed by said motor load equipment; a speed detector for detecting the speed of the motor; a speed command circuit for providing a speed command signal for controlling the speed of the motor; a speed adjustor for producing a current command value in accordance with a signal representing the difference between the speed detector output and the speed command signal; a current detector for detecting the current flowing through said first and second converters; a current adjustor for producing a first firing phase command signal in accordance with a signal representing the difference between the output of said current detector and the current command value; a first automatic pulse phase shifter for controlling the firing phase of said first converter in response to said first firing command signal; a second automatic pulse phase shifter for controlling the firing phase of said second converter; a reactive power detector for producing an electrical signal corresponding to the reactive power consumed by said motor load equipment and/or said phase modifying equipment; a reactive power command circuit for providing an electrical signal of a reactive power command value corresponding to that consumed by said motor load equipment in the rated load operation; a reactive power control unit for applying a second firing phase command signal to said second automatic pulse phase shifter in accordance with a signal representing the difference between an electrical signal corresponding to said reactive power and said lagging reactive power command; and phase detector means for detecting a reference phase synchronized with the induced voltage of said motor, said second automatic pulse phase shifter being connected to receive the outputs of said reactive power control unit and said phase detector means to control the firing phase of said second converter.