A Novel Array-Type Symmetrical CI for Multiphase Interleaved DC-DC Converters

For conventional parallel multiphase coupled inductor (CI), it is difficult to achieve full symmetrical coupling. A novel multiphase array CI is proposed, along with the analysis of the relevant symmetry principle, topology combination, and design method. Planar design and exploration are performed, which are then generalized to design a universal n-phase symmetrical CI and ring-type array CI with head and tail sequence coupling. The universal design criteria for multiphase symmetrical CI are summarized. Finally, soft switching mechanism is investigated under symmetrical inductance, thereby alleviating the problem of low efficiency at light load. The experimental results prove that the multiphase symmetrical array CI theory is valid and practical.