In a DAB converter, power transfer is realized through the phase shift between the bridge voltages on the primary and secondary sides of a transformer. As a result, the transformer current typically exhibits a piecewise-linear triangular or trapezoidal waveform. This inherently introduces a certain amount of reactive or circulating current, which does not contribute to active power transfer but still flows through the devices, thereby causing additional power loss. In contrast, near the resonant frequency, the LLC converter presents an approximately resistive input characteristic, and the net reactive power seen from the source is minimized, resulting in lower RMS current and conduction loss. Therefore, LLC converters are generally more favorable for achieving higher peak efficiency under optimized operating conditions.
Based on these considerations, this master thesis focuses on the design and simulation of an LLC resonant converter as an alternative to DAB topologies, with a particular emphasis on efficiency and hardware implementation. The work includes a comprehensive study of LLC converters, a literature review of high-peak-efficiency designs, and system simulations in PLECS. Furthermore, a 30 kW reference design will be developed, covering magnetic components, electronic hardware and control software. The project concludes with the realization and experimental validation of a prototype.
Bearbeiter: Yucheng Ye
Betreuer: Ara Bissal (Alpitronic)
Verantwortlicher: Prof. Dr.-Ing. Martin März