METHOD OF CONTROLLING ALTERNATING CURRENT DRIVE Russian patent published in 2009 - IPC H02P25/02 H02P27/06 H02P27/08 

FIELD: electrical engineering.

SUBSTANCE: invention relates to electrical engineering, particularly to systems for controlling alternating current drives with frequency converters. In the method of controlling an alternating current drive, the inverter is controlled by a relay regulator, at the input of which given and the measured values of phase currents at the output of the frequency converter are compared. Commutation of the inverter switches takes place if the difference between these values is greater than a threshold level, when current frequency at the output of the inverter is less than 1/3 of the supply frequency. In the region of instantaneous values of phase currents of the stator, less than √3/2 of the given amplitude values, a smooth current component is formed at the output of the frequency converter by toggling the switch of the inverter. In the region of instantaneous values of phase currents of the stator greater than √3/2 of the given amplitude value, the inverter switches in the corresponding phases are left closed until the instantaneous value of phase current at the output of the frequency converter drops to √3/2 of the given amplitude value, and a smooth current component is formed at the output of the frequency converter by regulating the switch-on point of the rectifier switches. This reduces the number of commutations of the inverter switches and as a result, reduces energy loss in the electric drive.

EFFECT: reduced energy loss and improvement of harmonic composition of current in windings of an alternating current synchronous motor.

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