Author ORCID Identifier:
Date of Graduation
12-2025
Document Type
Dissertation
Degree Name
Doctor of Philosophy in Engineering (PhD)
Degree Level
Graduate
Department
Electrical Engineering
Advisor/Mentor
Zhao, Yue
Committee Member
Mantooth, Alan
Second Committee Member
Hu, Han
Third Committee Member
Song, Xiaoqing
Keywords
Dual Active Bridge DC/DC Converter; High Frequency; Optimization; SiC MOSFET; Solid State Transformer (SST); wide-bandgap (WBG) devices
Abstract
High frequency Dual Active Bridge (DAB) converters have become a key enabling technology in medium- and high-power applications such as renewable energy integration, electric vehicle fast charging, and emerging DC power distribution systems. However, when operating at high power and high frequency, DAB converters face critical challenges including limited soft-switching range, uneven semiconductor loss distribution, deadtime-induced resonance, switching-frequency constraints of wide-bandgap (WBG) devices, and transformer DC bias during dynamic transitions. This dissertation addresses these challenges through advancements in modulation strategies and converter architecture. First, an enhanced triple-phase-shift (E-TPS) modulation scheme is proposed to achieve balanced switching and conduction losses across all devices, thereby reducing peak thermal stress and extending the soft-switching operating region. A deadtime-induced resonance mechanism is analytically modeled, and a phase-shift-based suppression method is developed to eliminate waveform distortion under high-frequency operation. Second, a high-frequency interleaving DAB converter employing interleaving switching modulation (ISM) is introduced. This architecture enables the transformer to operate at high switching frequency while maintaining a lower effective switching frequency on semiconductor devices and gate drivers, significantly reducing switching loss on each semiconductor device and improving the operating frequency of transformer. A 150 kHz and 1.5 kV prototype is built and experimentally validated. Finally, an intermediate phase-shift (IPS) modulation strategy is proposed to eliminate transient DC bias in isolated active-bridge converters, enhancing magnetic reliability and ensuring stable operation across dynamic conditions. Overall, the methods developed in this dissertation provide a practical and scalable foundation for efficient, reliable, high frequency and high-power density DAB converters in next-generation renewable energy, transportation electrification, and DC grid systems.
Citation
Cao, H. (2025). Design and Optimization of High-Frequency Medium-Voltage Dual Active Bridge DC/DC Converter Using SiC Device. Graduate Theses and Dissertations Retrieved from https://scholarworks.uark.edu/etd/6005
