A Novel Method to Estimate Primary Inductance for Transformer Saturation in Flyback Converters

This paper presents a novel technique for estimating the transformer’s primary inductance of a QR or DCM-operated flyback converter, which does not require additional dedicated external sensing circuitry. By using signals already available on the primary side of the flyback converter and combining them with an innovative technique, the primary inductance value can be monitored during steady-state operations to detect transformer saturation. This information is used by the converter’s control logic to determine whether to activate specific countermeasures to prevent malfunctions. This paper provides a theoretical analysis of the new method, explaining the operating principle and the steady-state equations. Additionally, the significant practical implications of this methodology will be explored in detail. Finally, the simulation results will demonstrate the feasibility benefits of the method