Performance Evaluation of Medium Voltage DC-DC Converters based on 10kV SiC MOSFETS for Energy Storage Systems
Author
Stathis, Spyridon-Pyrros
Term
4. term
Education
Publication year
2019
Submitted on
2019-05-30
Pages
82
Abstract
Dette projekt undersøger, om et mellemspændings DC-indsamlingsnet kombineret med mellemspændings DC-DC-konvertere kan understøtte fremtidige DC-baserede energiinfrastrukturer og samtidig reducere behovet for tunge filtre og transformere i for eksempel vindparker. To DC-DC-topologier til energilagringssystemer baseret på 10 kV SiC MOSFET-moduler—en faseforskydnings-buck-afledt og en single active bridge—blev analyseret. Der blev udviklet matematiske modeller (med ækvivalente AC-kredsløb, detaljerede ligninger og karakteristiske bølgeformer under kontinuerlig ledning), og der blev implementeret faseforskydnings-PWM til effekttilpasning og bløde omskiftningsbetingelser; desuden diskuteres de driftsområder, hvor soft-switching mistes. Herefter blev hardwaredesignet gennemgået og de præcise parametre anvendt i LTSpice-simuleringer af en 6 kV DC-indgang, fuldbro-inverter, transformer til 800 V, ensretter, filter og en 50 kW belastning. En sammenligning førte til valg af den buck-afledte topologi til laboratorieopbygning. Eksperimenter bekræftede de teoretisk forudsagte bølgeformer og komponentdesignets funktion og viste god overensstemmelse mellem målinger og simuleringer, hvilket understøtter anvendeligheden af de undersøgte koncepter til mellemspændings DC-indsamlingsnet og energilagring.
This thesis examines whether a medium-voltage (MV) DC collector grid combined with MV DC-DC converters can support future DC-based power systems while reducing bulky filters and transformers in applications such as wind parks. Two converter topologies for energy storage systems based on 10 kV SiC MOSFET power modules—the phase-shift buck-derived and the single active bridge—were studied. Mathematical models were developed using equivalent AC circuits, detailed equations, and characteristic waveforms under continuous conduction, and phase-shift PWM was applied to regulate power and enable soft-switching; operating conditions that forfeit soft-switching were also discussed. The hardware design was detailed, and the derived parameters were used in LTSpice simulations of a 6 kV DC input, a full-bridge inverter, a transformer stepping down to 800 V, a rectifier, a filter stage, and a 50 kW load. A comparison led to selecting the buck-derived topology for laboratory prototyping. Experiments confirmed the theoretically predicted waveforms and validated the component design, showing strong agreement between measurements and simulations and supporting the feasibility of the investigated concepts for MV DC collector grids and energy storage.
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