Non-Linear State-Space Modeling and Electromagnetic Analysis of Three-Phase High-Frequency Magnetic Links for Power Converter Applications

Most distributed renewable energy sources are nowadays connected to the utility through emerging power converter circuits. The interconnecting magnetic link in the power converters provides galvanic isolation and increases the fault-tolerant capability of the converters. Compared to single-phase high-frequency magnetic links (SPHFMLs), three-phase high-frequency magnetic links (TPHFMLs) can handle more power and offers better reliability of operation. Due to the different excitation waveforms in the magnetic link of the dual-active bridge converters, an appropriate design of the magnetic links is required to analyze the magnetic field and voltage distributions in balanced and unbalanced cases. The state-space model can be applied to analyze the frequency spectrum of magnetic flux and induced voltages. In this paper, a non-linear state-space modeling of the TPHFMLs is proposed considering the non-linear characteristics of the core. The model has been validated with frequency spectrum analysis for TPHFML with three different core geometries such as 5-limb, 3-limb, and matrix cores. By comparing the magnitude spectrum and pole-zero plots of these three types of TPHFMLs, the results show that matrix core-based TPHFML provides better operation in terms of output magnitude for particular frequency regions. Experimental prototypes have been developed and tested to obtain the B-H curves with 50 V, 10 kHz three-phase excitations. A dc-dc converter is successfully tested with the proposed matrix core based-TPHFML with 50 V dc input and 65.2 W output power.