This is a mid-point phase controlled full-wave rectifier that uses two SCRs for controlled rectification of AC to DC and is fed to an RL load. The two series voltage sources are actually supposed to be a centre tapped transformer, but I had issues using EC's wierd transformer so I just used two voltage sources instead.
Unlike a normal diode, an SCR is a partially controllable thyristor, meaning it's turn on can be controlled, but not it's turn off. Using this property, an initial portion of the mains voltage can be cutoff, resulting in a lower effective voltage across the load.
The RC timing circuit allows us to control the turn on of the thyristor; the thyristor turns off automatically when the current through it is zero and does not turn on until it's triggered.
