CM Noise Reduction of Isolated Convertor by Balancing Technique

Authors: Cobb, J. and Nasir, N.

Journal: IEEE Power and Energy Conference

Abstract:

Common mode (CM) Electromagnetic interference (EMI) noise in an isolated converter is mainly due to parasitic capacitance occurring within the SMPS (Switch-mode Power Supply). It flows through transformer coupling capacitance and the parasitic capacitance of MOSFETs and diodes. Several techniques have been proposed in the literature to mitigate the common mode noise flowing through transformer windings.

Transformer shielding is one of the most effective methods to reduce EMI noise between the primary and secondary windings, however. However, further improvement should be possible by developing more precise models. In this paper, we develop an EMI noise model for an isolated converter that allows detailed performance analysis. It incorporates the parasitic elements of the converter components and also the coupling capacitance of the transformer. Using this model we propose a new balancing technique to mitigate the CM noise of the isolated converter with modified transformer. The proposed method is applied to an isolated converter and experimental results are provided to verify the novel balancing technique.

https://eprints.bournemouth.ac.uk/33347/

Source: Manual

CM noise reduction of isolated converter by balancing technique

Authors: Nasir and Cobb, J.E.

Abstract:

Common mode (CM) EMI noise in an isolated converter is mainly due to parasitic capacitance occurring within the SMPS. It flows through the transformer coupling capacitance and the parasitic capacitance of switching MOSFETs and rectification diodes. Several techniques have been proposed in the literature to reduce CM noise. The most common techniques are compensation, shielding, and the balancing-shielding technique. In this paper, a new balancing technique is described to reduce the noise of both parasitic capacitances of MOSFETs and transformer inter-winding capacitance. Analysis is presented to demonstrate the efficacy of the compensation method and the resultant reduction in EMI noise. Finally, the practical measurement results obtained from a practical implementation of the new technique in a flyback converter topology, are presented as verification of the benefits of the approach in comparison to the conventional method.

https://eprints.bournemouth.ac.uk/33347/

Source: BURO EPrints