CONVERTER CONTROL PROCESS Russian patent published in 2000 - IPC

FIELD: electrical engineering; frequency-controlled electric drives. SUBSTANCE: electric-drive converter of induction machine connected to off-line voltage inverter with input of the latter connected to plugging control and to filter input is controlled by system built around microprocessor controller such as K1-20 (MS 2702) and coupled with off-line voltage inverter through its output stages. Off-line voltage inverter uses three-phase bridge circuit and has switching members (thyristors) shorted out by back diodes. When machine runs as motor, control is first effected in 180 deg mode, that is λ = 180 deg., by generating six periodic trains of control pulses shifted 60 el. deg apart. Setting negative slip makes induction machine run as generator with field voltage polarity reversed; control angle of switching members (thyristors) equals in this case one sixth of period, that is λ = 60 el. deg.; in addition, each switching member (thyristor) is changed over twice (at and greater) and during intervals between change-over operations at given control angle switching members (thyristors) are synchronously cut in and out in all sides of their phases. Plugging control ensures protection of off-line voltage inverter when its output voltage rises above rated value. Mentioned control process provides for plugging with energy regenerated into supply mains at lower speed and for regulating waveform of output voltage characteristic. EFFECT: enlarged functional capabilities and control range of induction machine. 2 dwg