MMC-Autotransformer : Impact of the Control on the Design and Efficiency

To increase flexibility and reliability of HVDC links and MTDC, it is likely that DC-DC converter will be employed. This paper specifically focuses on the DC-Auto-transformer. This study investigates its performance in relation to its parameters including: AC voltages, frequency and waveform characteristics. The analysis presented in this paper demonstrates that increasing the AC voltage within the converter reduces losses and minimizes capacitor size requirements. While, increasing the frequency reduces the losses as well as required size of capacitors. Furthermore, the results indicate that adopting a trapezoidal waveform improves both efficiency and capacitor size.