Modelling and Analysis of a Novel Transformer with Ability to Suppress Conducted interference

A novel transformer with ability to suppress conduction-interference, named as interference-free transformer (IFT), is proposed in this paper. Comparing with the traditional transformers, it has a special magnetic structure, namely magnetic air-gap shunt, and adds a resonance coil on the secondary side. The modelling and analysis indicate that the magnetic air-gap shunt can be equivalent to a step-down inductor between the primary and secondary coils. It is in series with the parallel resonance-circuit to construct a filter-network, which makes the difference-mode (DM) interferences be attenuated obviously, while nearly doesn´t affect the fundamental signal. In order to suppress the common-mode (CM) interferences, two coils with few turns and opposite direction, which are in series with the primary coil, are also added. A prototype of the IFT has been implemented in the lab. The simulation and experimental results prove the modelling, analysis and conclusion are right