Experimental Test of 3.6 kW Totem-Pole Converter Using State of the Art SiC MOSFETs
Author
Sørensen, Benjamin Spragg
Term
4. term
Education
Publication year
2025
Abstract
This thesis investigates improving the efficiency of an existing converter in a Migatronic welding machine by adopting a 3.6 kW totem-pole topology using state-of-the-art SiC MOSFETs. The converter was designed, simulated, and experimentally validated, with analyses of component losses, topology selection, and transistor choice to meet Migatronic’s requirements. Two FPGA-based controllers were implemented: a 100 kHz DC-DC mode with dead time and an inverter mode that synthesizes a 50 Hz sinusoidal duty cycle at 100 kHz; both were validated in laboratory tests. C3M0045065K devices were used in the high-frequency leg and C3M0025065K in the low-frequency leg. Simulations predicted up to 98.9% efficiency; in DC-DC configuration boosting to about 397 V was demonstrated, and in inverter mode 228.9 Vrms and 15.48 Arms at 50 Hz were achieved. A two-layer PCB prototype confirmed the concept: DC-DC tests covered 39–415 V with estimated efficiencies of 99.1% at 2.3 kW and 99.3% at 3.6 kW; in inverter tests, adding a 3.3 µF capacitor enabled conversion of 329 V DC to 168 Vrms with an estimated 98.9% efficiency at 1.86 kW. The results indicate that a SiC-based totem-pole stage can meet very high efficiency targets for welding applications.
Denne afhandling undersøger, hvordan effektiviteten af en eksisterende konverter i en Migatronic-svejsemaskine kan forbedres ved at anvende en 3,6 kW totempæl-topologi baseret på moderne SiC‑MOSFET’er. Konverteren er designet, simuleret og eksperimentelt valideret, med fokus på komponenttab, konfigurationsvalg og transistorvalg for at opfylde Migatronics krav. Der er udviklet to FPGA-baserede styresystemer: en DC‑DC-tilstand ved 100 kHz med dead-time og en invertertilstand, der genererer en 50 Hz sinusformet duty-cycle ved 100 kHz; begge er afprøvet i laboratoriet med dokumenteret funktion. I designet anvendes C3M0045065K i højfrekvensbenet og C3M0025065K i lavfrekvensbenet. Simulationer forudsiger op til 98,9 % virkningsgrad; i DC‑DC konfiguration blev der bl.a. vist boost til ca. 397 V, og i invertertilstand opnåedes 228,9 V rms og 15,48 A rms ved 50 Hz. En prototype på et tolags PCB bekræfter konceptet: DC‑DC-tests viser konvertering over 39–415 V med estimerede virkningsgrader på 99,1 % ved 2,3 kW og 99,3 % ved 3,6 kW; i invertertests muliggjorde en 3,3 µF kondensator konvertering af 329 V DC til 168 V rms med estimeret 98,9 % virkningsgrad ved 1,86 kW. Resultaterne indikerer, at en SiC‑baseret totempæl kan nå meget høj effektivitet i svejseanvendelser.
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