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Highly Integrated Monolithic Filter Building Block for Silicon Carbide based Three-Phase Interleaved Converters

System Schematic
Fig. 1. System Schematic.
  Three-phase interleaved converters provide lower harmonic content due to multi-level output voltage generation at the point of common coupling (PCC) at the expense of circulating current. Magnetic interphase coupling between converters is a well-known technique to mitigate the problem of inter-channel circulation due to interleaved carriers.

  But such magnetically coupled inductors contribute to additional volume and loss. Since interleaving does not cancel the Nth order harmonics, where N is the number of parallel converters, consequently an additional boost inductor is added after the PCC to meet the power quality standards. In conjunction, the total filter volume defeats the purpose of interleaving. Thanks to the use of SiC devices, the switching frequency barrier can be extended, and the size of magnetics can be reduced dramatically. Herein lies the benefit of using a magnetically coupled structure with an integrated boost inductor as per Fig. 1.

  A hybrid core structure as shown in Fig. 2 using a combination of amorphous and nanocrystalline materials has been proposed to maximize the power density of a Monolithic Filter Building Block (M-FBB) compared to a conventional Si-Steel counterpart for IGBT applications. A complete experimental evaluation using a 45-kW 3-L NPC converter is presented for a comprehensive
design verification.
Fig. 2. Monolithic block and system assembly.

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