SIMextrix is great and SIMPLIS being part of it makes dealing with power-electronics easier
http://microe.udea.edu.co/~alince/recursos/software/simetrix/SIMPLIS_Reference.pdf
In the analysis of a switching piecewise-linear system, the
steady-state solution is essential. For example, in the study of the
line/load regulation of a regulated switching power system, the
relevant information is the steady-state load voltage over a range of
line/load conditions. Although carrying important information in its
own right, the transient information on how the system settles to the
new steady-state under the new line/load condition is not the focus of
such a study. To carry out such a study, the load voltage is measured
after the system has settled to new steady-state operations under new
line/load conditions. Depending on the damping and the regulation
circuitry of the system, it may take the system hundreds to thousands
of switching cycles before settling to a new steady-state operation
after each change in the line/load condition. While carrying out such
a study with a brute-force simulation is possible, it can be
time-consuming. Hence, there is a need for a special analysis tool
that can "accelerate" the convergence of the system towards its
steady-state operating condition without going through the actual
transient.
The Periodic Operating Point Analysis tool in SIMPLIS is able to speed
up the convergence to the steady-state solution of a switched
piecewise-linear system that is either self-oscillating or driven by
one or more periodic sources that are commensurate in their periods.
To invoke such an analysis, the user only needs to add a few lines in
the input file. “Statements Relating to POP Analysis” on page 139
explains in detail the format of the input statements related to the
Periodic Operating Point analysis. “Synopsis of the Periodic Operating
Point Analysis” on page 146 explains what happens during a Periodic
Operating Point analysis. After reading this section, a user will
understand the internal workings of this analysis tool and, as a
result, will be able to use the analysis tool more productively. An
example in “Example of Applying the Chapter 10 Simplis-POP 139 POP
Analysis Tool” on page 154 illustrates the application of the POP
analysis to a closed-loop regulated switching power system
What does that mean? in short power electronics always results in switching current and ringing around the edges. This slows down simulation packages immensely as they suddenly reduce their stepsize in an attempt to resolve the present step.
Now some packages to get around then just "overlook" switching transients (Simulink does this) to facilitate a reasonable simulation time.
SIMPLIS have some ... lets call it "voodoo" to manage this that produces fast but accurate simulations for switching characteristics.
