# Rectified signal from three phase rectifier circuit

I'm trying to simulate this circuit

This is the implementation

I'm getting this output signal, that is close to what you would expect from a rectifier. In this image α = 0, α1 = π/6, α2 = 5π/6 and α3 = 3π/2. The α is the turn on angle for the thyristors.

But there's a negative part that shouldn't exist, The same happens for bigger alpha, for example α = π/2 would result in this:

What would be the reason for this drop down in voltage ? The output signal should only have positive voltages.

What changes can be done to get a better output signal?

Is there something else I'm missing in the circuit?

• SE supports the use of HTML entities including all the Greek letters such as &alpha; and &pi; (but they don't work in the comments). It also supports MathJAX so you can do $\alpha \frac {\pi} 6$. Jul 7, 2021 at 14:03
• This question appears very similar to your previous two on the same topic. Can you explain the differences? Jul 7, 2021 at 14:05
• In my first question I asked about the design of the isolation circuit. In my second question the subject was the behavior of the circuit resulting in a wrong signal according to the alfa turn on angle. In this one the output signal is close to what is expected for the given alfa, but now it has some sort of negative part that shouldn't be there. Jul 7, 2021 at 14:12
• Seems that the duration pulse for triggering not enough ? Add the picture for pulses. 100 us min to 1 ms. Jul 11, 2021 at 18:32