A controlled half-wave rectifier is a type of rectifier circuit that uses a controlled switching device and an external control signal to convert AC power into DC power. It is called a "controlled" rectifier because it uses an external control signal to regulate the output DC voltage or current.
There are several types of controlled half-wave rectifiers, including phase-controlled rectifiers and pulse-width modulated rectifiers.
Phase-controlled rectifiers use a thyristor as the control element, and the output DC voltage can be varied by adjusting the firing angle of the control element. The firing angle is the point in the AC waveform at which the control element begins to conduct, and it determines the amount of the AC waveform that is utilized.
Pulse-width modulated rectifiers use an electronic switch (such as MOSFET transistor ) as the control element, and the output DC voltage is varied by modulating the width of the pulses applied to the control element.
One of the main advantages of controlled half-wave rectifiers over uncontrolled rectifiers is the ability to control the power delivered to the load. In an uncontrolled rectifier, the output DC voltage and current are fixed and cannot be adjusted. In contrast, a controlled rectifier allows the output power to be precisely regulated by adjusting the firing angle or pulse width of the control element. This can be useful in applications where the load requires a stable DC power supply, such as in a DC motor drive system or a battery charging system.
Resistive Load
Figure (1) show a single phase controlled half wave rectifier with resistive load circuits and its input output voltage wave forms relations.
The rms and average output voltage and current relations can be computed as following :
