Abstract:
The continued commissioning of DC microgrids in an effort to achieve net-zero carbon
levels in the atmosphere demands the large-scale deployment of converters to make the power from
renewable energy sources, such as solar PV, usable. To control these inherently non-linear converters
using classical linear control methods, averaged modelling techniques are employed. These methods
are laborious and easily become intractable when applied to converters with increased energy storage
elements. A modular modelling approach is proposed. This approach is based on the synthesis of
converters using refined basic building blocks. The refined basic building blocks are independently
modelled as two-port networks and used in a circuit synthesis-oriented manner to derive power
stage models of commonly used DC-DC converters. It is found that most of the converters considered
in the study can be described as a cascade combination of these basic building blocks. As such,
transmission parameters are mainly used to model the two-port networks. Moreover, it is also found
that using this modelling technique enables the computation of generalized expressions for all power
stage models of interest. The use of two-port networks curtails the size of the matrices describing
the basic building blocks to 2 2, and thus simplifies the entire modelling procedure. Additionally,
two-port network analysis makes this modelling technique modular, thus making it more suited to
be employed in DC microgrids. The independence of the two-port models on the circuit topology
and functionality makes it possible to even model new converters containing the described basic
building blocks solely based on circuit connection.
