Converter-Level Packaging and Optimization for a SiC-Based Grid-Interface Converter Using Discrete Devices

Grid integration of renewables through power electronic grid-interface converters (GICs) is essential for achieving a sustainable grid. This mission involves developing compact, efficient converters with standardized interfaces to minimize redundancy. In line with this objective, this article presents an electromechanical-thermal design and packaging of two-stage silicon carbide (SiC)-based 75-kVA GIC using TO-247 discrete devices with two times lower cost-to-power ratio than power modules. The power stage is 3-D packaged on a cylindrical-hole-based three-face utilized heat sink to achieve 5.5-kW/L power density, including passive components. For the dc-ac stage, two-level split-phase (2L-SP) topology is employed, owing to its lower switching loss and output dv/d and increased crosstalk immunity compared with simple two-level (2L) topology. An equivalent switching transition circuit is derived for optimal sizing of split inductors in 2L-SP. Furthermore, for device interconnection, an optimized printed circuit board (PCB) layout with flux cancellation and minimum board parasitic capacitance is developed for optimal device switching with minimum voltage overshoot. Moreover, for magnetics, the split-direct winding technique is employed to achieve minimum winding capacitance. Finally, the developed GIC is systematically tested at rated system voltage with an RL load at 10 kVA.