A novel integrated AC choke for common-mode voltage suppression in power converter systems

This paper presents a novel three-phase choke that integrates the common-mode (CM) suppression and differential-mode (DM) filtering functions. The proposed choke provides a transformerless solution to issues caused by the switching common-mode voltage (CMV) in power converter systems. The magnetic core involves three bridge legs and a peripheral part on which one set (three-phase) of coils are wound. While the induced CM flux flows in the circumference; the DM flux fills in both the external core and bridge legs through the air gaps. A high CM-to-DM inductance ratio is generated by the mechanical assembly. Despite novelty of the structure, a traditional design method based on magnetic circuit calculation is applicable to the integrated choke, in which not only is the size/weight minimized, but a reasonably small core loss is also achieved. Comparison to separate DM and CM reactors demonstrates the benefits of integration in iron and copper material saving, volume and weight reduction and efficiency improvement. The finite element analysis (FEA) simulation and test results of the prototype are finally supplied to verify the feasibility and effectiveness of the integrated choke.