CIRCUIT OPERATION
A fully-controlled rectifier circuit contains only controlled-rectifiers, whereas a semi-controlled rectifier circuit is made up of both controlled and uncontrolled rectifiers. Due to presence of diodes, free-wheeling operation takes place without allowing the bridge output voltage to become negative. In a semi-controlled rectifier, control is effected only for positve output voltage, and no control is possible when its output voltage tends to become negative since it is clamped at zero volt. This page describes the operation of a single-phase half-controlled rectifier.
A semi-controlled full-wave bridge rectifier can be configured in a few ways. They are shown below.