Abstract:
In high voltage direct current (HVDC) power transmission of offshore wind power systems,
DC/DC converters are applied to transfer power from wind generators to HVDC terminals, and they
play a crucial role in providing a high voltage gain, high efficiency, and high fault tolerance. This paper
introduces an innovative multi-port DC/DC converter with multiple modules connected in a scalable
matrix configuration, presenting an ultra-high voltage step-up ratio and low voltage/current rating
of components simultaneously. Additionally, thanks to the adoption of active clamping current-fed
push–pull (CFPP) converters as sub-modules (SMs), soft-switching is obtained for all power switches,
and the currents of series-connected CFPP converters are auto-balanced, which significantly reduce
switching losses and control complexity. Furthermore, owing to the expandable matrix structure,
the output voltage and power of a modular converter can be controlled by those of a single SM,
or by adjusting the column and row numbers of the matrix. High control flexibility improves fault
tolerance. Moreover, due to the flexible control, the proposed converter can transfer power directly
from multiple ports to HVDC terminals without bus cable. In this paper, the design of the proposed
converter is introduced, and its functions are illustrated by simulation results.
