Magnetic Integration for Parallel Interleaved VSCs Connected in a Whiffletree Configuration

The voltage source converters (VSCs) are often connected in parallel to realize a high current rating. In such systems, the harmonic quality of the output voltage can be improved by interleaving the carrier signals of the parallel VSCs. However, an additional inductive filter is often required to suppress the circulating current that flows between the parallel interleaved VSCs. One of the ways to deal with the circulating current problem is to use the coupled inductors in a whiffletree configuration. This paper proposes the integration of the line filter inductor and the circulating current filter inductor in a single magnetic component for such systems. The fundamental frequency component of the flux is mostly confined to the limbs around which the coils are placed, whereas other parts of the magnetic structure only experiences high-frequency flux excitation. As a result, the integrated inductor can be made smaller and the power density of the overall converter system can be increased. The magnetic structure of the integrated inductor is analyzed and performance is verified by simulation and experimental studies.