The circuit demonstrates the use of ARTEMiS zigzag-Y transformer with Switched Saturable Core.
The ARTEMiS zigzag-Y transformer with Switched Saturable Core implements a zigzag-Y saturable transformer with a core that is switched from unsaturated to saturated mode. This is observable by looking inside the model: the primary leakage and magnetization branches have been put outside SPS transformer and a flux-dependant switched L branch is used to model saturation.
It can increase the stability of the simulation with the saturable transformer when compared to the SPS native method of saturation which is to use a current injection with delay.
For example, this model simulates accurately and in a stable manner at 30 µs time step. If you replace the transformer with an SPS transformer (and with no algebraic loop option and no RLC core snubber), it becomes unstable at 0.1 µs.
Alternatively, the model comes with an option to put a series RLC snubber branch directly across the transformer cores. This also helps to stabilize the simulation.
ARTEMiS also includes similar models for Y-Delta and Y-Y configurations.
The ARTEMiS zigzag-Y transformer with Switched Saturable Core must be used with the ARTEMiS Guide option named Use ARTEMiS transformer saturation method turned ON. This method modifies the way SPS computes the fluxes by inserting the non-saturated magnetization inductance directly in the ABCD state-space equations. By comparison, SPS normally computes this flux by the integration of the core voltage.