I am required to simulate a three-phase full wave thyristor converter using MATLAB Simulink. The circuit I have so far is given below:
The three input sources are 230V each at 50Hz, the first having a phase of 0, the second 120, and the third -120.
The thyristors come with resistance-capacitance snubbers which I eliminated by setting the resistance to infinity. But in doing this I had to add a high-value resistance in parallel to the second thyristor in order to get the circuit to run. For the thyristors:
Thyristor resistance = 0.001 ohms
Thyristor inductance = 0 henry
Forward current = 0V
Snubber resistance = infinity
Snubber capacitance = 1e-12 F
In order to trigger the thyristors at 45 degrees, I have set the frequency to 50Hz (the same as the sources) and the phase delay (seconds) to (1/50)*(45/360).
The output I get is the following:
As you can see, the waveform has been rectified. But I'm looking for the ideal output from a controlled rectifier and this output has several ripples as you can see. I tried several different values for the thyristor parameters, but couldn't change much.
Could anyone tell me what's wrong with the circuit?