A gate drive circuit (a forward converter) for a thyristor is shown. In the on-state the thyristor on the secondary side can be modeled as a diode with a constant voltage drop. This can be seen as the DC source in the equivalent circuit (click the red box around the transformer symbol). During the on-state the load current i2 is equal to the primary side current i1 reduced by the magnetizing current iu of the non-ideal transformer. With higher relative permeability of the transformer core material, the magnetizing current iu would be smaller. If the core material saturates, iu rises significantly and reduces the secondary load current i2 accordingly.

• Click the red box around the transformer symbol to see the equivalent circuit of the transformer (and also the thyristor shown as DC voltage source).
• Move the red time slider to visualize the current paths. The actual state of the transformer magnetization is shown accordingly on the B(H) characteristic of the non-ideal transformer core material.
• Change the frequency by dragging the red point of the horizontal arrow. Show that with higher frequency core saturation can be avoided.
• Change the on-time of the switch by dragging the red point on the signal curve.
• Change the input voltage u0 by dragging the red point on the voltage source symbol. According to the equivalent circuit, the transformer voltage is defined by the load-side diodes. Therefore, changing the input voltage u0 will mainly effect the current amplitudes i1 and i2.