A Series Chain-Link Modular Multilevel DC-DC Converter For High Voltage and High Power Applications

In high voltage and high-power applications, many modular multilevel DC-DC converter topologies have been proposed for DC voltage scaling applications. In most of those proposed a three phase transformer is required. The construction of a three-phase transformer at high power and high voltages can be challenging. For example, in multi-terminal HVDC applications, several hundred kilo volts of isolation may be required. Additionally, a high number of submodules is required in most of the high voltage modular multilevel DC-DC converters. In this paper, a new modular multilevel DC-DC converter is proposed for high voltage applications, which aims to significantly reduce the number of submodules and achieve a more compact stored energy distribution. Furthermore, a number of lower voltage rated transformers are used to replace a single high voltage component. A simulation system for a 10MW, 20kV-20kV Series Chain-Link DC-DC converter, simulated in PLECS to verify the proposed topology.