High Precision Modeling of Saturable Transformers used as Voltage Regulators

We bring in attention the almost missed magnetic device used as voltage regulator. It´s about a partially saturable transformer, having four legs, two main and two controlling legs. The controlling legs work as a saturable magnetic shunt, while the main legs are never saturated. Thus, the secondary magnetic flux, respectively the secondary voltage can be rigorously controlled. The paper describes the principle of this application and uses the most modern tools that permit a rigorous study. The study is based on an accurate modeling and numerical simulation of the ferromagnetic core, respectively the primary/secondary/control circuit that permits a rigorous analysis in any working regime, including switching regime at any frequency. The modeling is made through an equivalent electric circuit described by the same differential-algebraic equation system as the studied device in transient regime. An example is given, that treats a 1 kVA low voltage regulator, using a SPICE simulation