Evaluation and Design of Symmetrical Winding Configurations for Improved Common Mode Noise Reduction in Full Bridge Converters

Changing voltages due to switching transitions across parasitic grounding impedances, for example in motor windings, lead to common mode noise currents. With synchronized opposing switching transitions in full bridge converters, opposing common mode noise currents can be generated, which reduce the overall noise by superimposition. To generate the opposing noise current, consisting of the same frequency components, the effective grounding impedances at the nodes, where the switching transitions occur, should be equal. The paper shows that a commonly used orthocyclic winding has unsymmetric grounding impedances leading to a non-ideal reduction of the common mode currents. To improve the common mode noise reduction, symmetric winding configurations are designed and evaluated on the example of a full bridge converter.