AC to AC Converters, Part II: Single phase voltage controller (b), 8/1/2014
Channel: Lutfi Al-Sharif
Date: 2014-01-09

This video looks in more detail at the single phase voltage controller using a pair of anti-parallel (or back to back) silicon controlled rectifiers (thyristors).  It uses an inductive load and find the angle of the load.  It also uses a firing angle (alpha) to delay the pulses that fire the two SCR's.  Note that the firing angle must be larger than the angle of the inductive load.  Otherwise the circuit will not work properly.