METHOD FOR CONTROLLING FREQUENCY CONVERTER Russian patent published in 2006 - IPC H02M5/44 

FIELD: converter engineering; control systems for ozonizers.

SUBSTANCE: proposed method for controlling frequency converter that has rectifier and push-pull inverter built around fully controlled diodes and connected to output leads through filter choke operating into inductive load involves generation of control pulses across controlled diodes and their sequential supply to controlled diodes shaping forward and backward current half-waves across load. In the process rectangular pulses are produced, their period being 0.5 T, where T is output ac current period; leading edges of these pulses specify turn-on moment of controlled diodes. Current level is set. Instant value of current through inverter diodes shaping forward and backward current half-waves across load is measured. Instant value of current through inverter controlled diodes is compared with desired current level. Moment when instant current through inverter controlled diodes is equalized with desired current level is determined. Controlled diodes are turned off as soon as current through their circuits becomes equal to desired current level. Time interval is set. Time interval whose origin is set by rectangular-pulse cutoff and its end, by moment of controlled diode turn-off is measured. Measured time interval is compared with desired value. Rectifier is turned off when measured time interval exceeds desired value.

EFFECT: enhanced operating reliability of frequency converter.

1 cl, 2 dwg