Three-Phase Fully Magnetically Integrated <i>LCL</i> Filters With Enhanced Ripple Attenuation Capability

High efficiency and high power density are the trends in power electronic converters. However, conventional LCL filters suffer from low core utilization and high volume redundancy. This is one of the key factors limiting the improvement of power density in grid-connected inverters. Three-phase grid-connected inverters require more filtering inductors and the problem of volume redundancy is even more pronounced. However, existing filter magnetic integration techniques suffer from varying degrees of degradation in ripple attenuation capability. To address above problem, a three-phase fully magnetically integrated LCL (TPFMI-LCL) filter with enhanced ripple attenuation capability is proposed in this paper. The proposed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TPFMI-LCL</i> integrates all filter inductors on the same magnetic core, which eliminates the volume redundancy of the filter. In addition, a rational core size parameter design is carried out to achieve the joint optimization of filter volume and loss. Compared with the conventional three-phase <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCL</i> filter, the advantages of the proposed TPFMI-LCL are enhanced ripple attenuation capability and reduced size. Finally, a laboratory prototype is built to verify the effectiveness of the proposed TPFMI-LCL filter.