{"659827":{"#nid":"659827","#data":{"type":"event","title":"Ph.D. Dissertation Defense - Liran Zheng","body":[{"value":"\u003Cp\u003E\u003Cstrong\u003ETitle\u003C\/strong\u003E\u003Cem\u003E:\u0026nbsp; \u003C\/em\u003E\u003Cem\u003EMedium-Voltage Current-Source Solid-State Transformer\u003C\/em\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003ECommittee:\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDr. Deepak Divan, ECE, Chair, Advisor\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDr. Maryam Saeedifard, ECE\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDr. Thomas Habetler, ECE\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDr. Santiago Grijalva, ECE\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDr. Prasad Enjeti, Texas A\u0026amp;M\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDr. Lukas Graber, ECE\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EAbstract:\u0026nbsp;\u003C\/strong\u003EThe objective of this research is to develop circuit topologies, control methods, and medium-voltage (MV) prototypes of the current-source solid-state transformer (SST). Recent years have witnessed significant growth in renewable energy and electrified transportation resources. The MV SST is a promising solution to replace the conventional line-frequency transformer and integrate these resources into DC or AC power grids with reduced footprint and power loss. The MV SST prototypes in the literature are based on voltage-source topologies. The voltage-source SST topologies have the drawbacks of complex multi-stage conversion, high dv\/dt, high volume, and low efficiency. In this dissertation, single-stage current-source SST topologies are proposed for higher efficiency and density, including universal circuits and reduced-switch circuits. Based on 3.3 kV SiC reverse-blocking modules, a 5 kV DC and a 7.2 kV AC multiport current-source SST prototype are developed to verify the proposed circuit topologies. A grounding method is also developed to mitigate the additional device voltage stress from ground leakage current. Significantly, it is the first time that MV current-source SST experimental prototypes and results have been reported. Conventional voltage-source SST has bulky DC-link, which enables the use of proportional-integral controller. However, the modular current-source SST has fast dynamics from reduced DC-link. Such modular reduced DC-link converter is proposed as stacked low-inertia converter (SLIC). A model predictive priority-shifting (MPPS) control method is proposed for the SLIC. The performance is analyzed and verified under parameter mismatches, low-inertia DC-link, and time delay. A clamping modulation is also proposed to address the voltage sharing of reverse-blocking devices. Besides these control methods for basic operation, control methods are proposed for advanced metrics. First, a direct DC-link predictive control method for active power decoupling and higher density is proposed. Second, a partial-power control method is proposed for higher efficiency of the multiport configuration. Third, a dynamic DC-link minimization control method is proposed for higher efficiency. These control concepts are verified on the 5 kV and the 7.2 kV SST prototypes.\u003C\/p\u003E\r\n","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":"","field_summary_sentence":[{"value":"Medium-Voltage Current-Source Solid-State Transformer "}],"uid":"28475","created_gmt":"2022-08-01 19:28:44","changed_gmt":"2022-08-01 19:29:47","author":"Daniela Staiculescu","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2022-08-11T15:00:00-04:00","event_time_end":"2022-08-11T17:00:00-04:00","event_time_end_last":"2022-08-11T17:00:00-04:00","gmt_time_start":"2022-08-11 19:00:00","gmt_time_end":"2022-08-11 21:00:00","gmt_time_end_last":"2022-08-11 21:00:00","rrule":null,"timezone":"America\/New_York"},"extras":[],"groups":[{"id":"434381","name":"ECE Ph.D. Dissertation Defenses"}],"categories":[],"keywords":[{"id":"100811","name":"Phd Defense"},{"id":"1808","name":"graduate students"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[{"id":"1788","name":"Other\/Miscellaneous"}],"invited_audience":[{"id":"78771","name":"Public"}],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[],"email":[],"slides":[],"orientation":[],"userdata":""}}}