Wide Input Local Power Supply with Variable Frequency Adaptive On-time Modulator for Modular Solid State Transformer

Research efforts for realizing local power supply (LPS) for modular solid state transformer (SST) have largely been focused on solving the problem of high input voltage. Challenges associated with wide input voltage, switching nodes, component count, solution size, cost, and complexity are still unaddressed. This has hindered the adoption of LPS for a long time. This paper presents a wide input (200–2100 V) 3.3 kV SiC-based LPS which proactively solves all the above-mentioned key challenges. A unique variable frequency adaptive on-time modulator is proposed to tackle the wide input voltage, along with a clamped gating circuit that takes care of switching nodes, cost, and voltage sharing. Comprehensive theoretical analyses are presented to show the proposed modulator’s ability to impart robust wide-input operation, reduce system complexity, and effectively handle input voltage and load disturbances. A detailed design procedure is presented to elucidate component selection. Experimental results verify the proposed LPS’ ability to produce stable 12 V output across 200–2100 V input, 2–20 W output, possess reliable startup-shutdown behavior, and reduce the switching nodes to just one. Finally, extensive comparative analyses are presented to highlight the electrical and cost advantages of the proposed LPS, emphasizing its potential as a cost-effective, technically superior LPS.