A PWM Strategy for Cascaded H-bridges to Reduce the Loss Caused by Parasitic Capacitances of Medium Voltage Dual Active Bridge Transformers

Conference · Sun Oct 09 04:00:00 EDT 2022 · 2022 IEEE Energy Conversion Congress and Exposition (ECCE)

DOI:https://doi.org/10.1109/ecce50734.2022.9947550· OSTI ID:1974600

Li, Haiguo ^[1]; Gao, Zihan ^[2]; Wang, Fred ^[2]

---

1. University of Tennessee, Knoxville,Min H. Kao Department of Electrical Engineering and Computer Science,Knoxville,TN,USA; University of Tennessee
2. University of Tennessee, Knoxville,Min H. Kao Department of Electrical Engineering and Computer Science,Knoxville,TN,USA

In this paper, to reduce the power loss caused by the parasitic capacitances of medium voltage medium frequency transformers in a two-stage dc/ac converter, including a dual active bridge (DAB)-based dc/dc stage and a cascaded H-bridge (CHB)-based dc/ac stage, a PWM strategy is proposed for the dc/ac stage. For each H-bridge, by shifting the high switching frequency to one half-bridge and having the other half-bridge switching at the fundamental frequency of the ac voltage, equivalent frequencies of transformer terminal-to-ground voltages are reduced. As a result, the frequencies of charging and discharging current to the parasitic capacitance are reduced, and therefore the loss caused by the parasitic capacitances is reduced. Compared to the conventional phase-shift PWM, the proposed PWM strategy can reduce the parasitic capacitance loss by about 75%. Experimental test results of one phase in the 13.8 kV/ 100 kW converter prototype are provided to validate the approach.

• Research Organization: University of Tennessee
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Energy Efficiency Office. Advanced Materials & Manufacturing Office (AMMTO)
• DOE Contract Number: EE0008410
• OSTI ID: 1974600
• Report Number(s): DOE-UTK-08410-7
• Conference Information: Journal Name: 2022 IEEE Energy Conversion Congress and Exposition (ECCE)
• Country of Publication: United States
• Language: English