678772 event 1733437814 1733437911 <![CDATA[Ph.D. Proposal Oral Exam - Aniruddh Marellapudi]]> Title:  Medium Voltage AC to Low Voltage DC Building Block Using Inertialess Isolated Converters

Committee: 

Dr. Divan, Advisor         

Dr. Graber, Chair

Dr. Saeedifard

]]> The objective of the proposed research is to develop a novel medium voltage (MV) AC to DC (MV2DC) solid-state transformer (SST) that enables a scalable, efficient, and cost-effective interface for the more than 2000 GW of DC resources seeking grid connection over the next decade. The global shift towards a decarbonized energy system is propelled by significant advancements in fast-growing sectors including PV solar, energy storage, DC fast charging of EVs, data centers, and green hydrogen electrolysis. These inherently DC resources, operating at 400-1500 VDC and 0.5-3 MW, are aggregated into larger plants rated at 1-500 MW, and must exchange energy with the MV AC grid at 13 kV to 34 kV. State-of-the-art approaches for MVAC-LVDC conversion are based on series-cascaded, modular converters with high-frequency (HF) isolation, enabling a drastic increase in power density relative to traditional solutions based on low-frequency transformers. However, the need for bulky intermediate energy storage elements and complex multi-stage control complicate achievement of practical system level requirements, such as basic insulation level, fault and transient mode behavior, and meeting cost and size targets, limiting commercial adoption at scale. This dissertation proposes a novel, bidirectional MV AC to DC (MV2DC) SST based on the Inertialess Isolated Converter (IIC), a single-stage, HF isolated topology enabling high power density and simple control. Consisting of a voltage-sourced DC bridge, a four-quadrant-switch AC bridge, and an ultra-low-leakage HF MV transformer, the IIC achieves DC-AC conversion without intermediate passive components or multi-stage control typical of state-of-the-art SSTs. This work will present the design and experimental validation of the MV2DC SST, including advancements in MV transformer design, stacked converter control under steady-state and transient conditions, and optimization of system efficiency and cost, culminating in a robust MVAC-LVDC interface for the future grid.

]]> <![CDATA[]]> https://teams.microsoft.com/l/meetup-join/19%3ameeting_YjA5OWIxNzUtOGNjYy00YTBmLWE1OWMtMTlkMjM5NzAzN2Vh%40thread.v2/0?context=%7b%22Tid%22%3a%22482198bb-ae7b-4b25-8b7a-6d7f32faa083%22%2c%22Oid%22%3a%22b3f8cb03-0461-425c-a33d-557b66b609f5%22%7d 434371 1788 102851 1808