PSIM: thyristor acting as a diode in a full bridge rectifier with C filter
The problem is with the capacitor. You see, when using a controlled rectifier, if a Capacitor is present, it will charge the capacitor with the input voltage source with the maximum value of \$v_{i}(t)\$, after it is cut by the switching. Since your angle is bellow 90 degrees, you will always pass through the maximum value.
As such, I would suggest you to stick with switching angles between 90 and 180 degrees.
Here are some curves showing the behaviour.
Simulated rectifier:

Curves with \$\alpha=90^\circ\$:

Curves with \$\alpha=135^\circ\$:

P.S.: The curves were obtained with PSIM 2020 demo.
P.S.S.: As a bonus, it is recomended to, after switching the thyristors, to remove the gattling signal.