Digital control of four quadrant regulating element connected to AC voltage mains transformer - sampling control magnitudes at frequency time that of semiconductor switch pulse frequency

摘要

The four-quadrant final control or regulatory element is connected via a mains trnasformer to an a.c. voltage mains network and requires initial switching of the semiconductor switch of the regulating element in a pulse-pattern synchronised with the mains voltage. The control magnitudes required for digital control are sampled at a frequency for digital control are sampled at a frequency twice that of the semiconductor switch pulse frequency. The digital control is influenced by a fixed carrier frequency fuel control voltage, so as to hold the terminal d.c. voltage of the four-quadrant regulatory element constant. The semi-conductor switches (T1-T4) used in the regulating element are e.g. GTO-thyristors with a free-wheel diode connected in parallel opposition across them. USE - For three-phase current locomotive drive.