AC DRIVE CONTROL PROCESS Russian patent published in 1998 - IPC

FIELD: adjustable ac drives with frequency changers. SUBSTANCE: in shaping currents at outputs of frequency changer that feeds electric motor and has two inverting rectifiers of which one is built around fully controlled diodes, both interconnected through smoothing reactor, with output current controlled depending on desired amplitude of smooth current components at frequency changer output, diodes of each inverting rectifier are changed over depending on its desired current distribution through ac conductors, and high-frequency components of current are filtered off at output of frequency changer; inverting rectifier diodes are changed over also depending on desired amplitude of smooth components of current in its ac conductors and separately of output current. EFFECT: improved power factor of electric drive and harmonic content of currents at low speed. 7 cl 13 dwg