THYRISTOR CONTROLLED 14- HALF-WAVE  RECTIFIER - PSCAD

AIM:

To illustrate the use of the thyristor components in Converter Circuits

THEORY:

As shown, a simple half-wave, thyristor controlled rectifier has been constructed. The voltage source is an externally controlled, dc source, where the control signal is a sinusoid generated by the VCO below. The firing pulse control circuit is also shown. It consists of the "Interpolated Firing Pulse" component, which compares a high (H) and a low (L) input. When (H) goes higher than (L), a firing pulse is ordered (FP1).

This example utilizes "Interpolated Switching" - a feature exclusive to EMTDC. If firing pulse occurs between time steps, EMTDC will interpolate the switching time, allowing for much more accurate results. In A.C. circuits, the SCR can be turned "on" by the gate at any angle, with respect to the applied voltage. This firing angle is measured with respect to a given reference, at which the firing pulses are applied to the thyristor gates. The reference, at which the firing pulses are application of the gate pulses results in the maximum mean positive D.C.-terminal voltage of which the converter is capable.

In its simplest form, phase control can be described by considering the half-wave thyristor circuit. In a half- wave single-phase controlled rectifier only one SCR is employed in the circuit. It is included in between the A.C. source and the load. The performance of the controlled rectifier very much depends upon the type and parameters of the output (load) circuit.

RESULT:

The single phase rectifier circuit was simulated using PSCAD.