  This paper addresses stability issues of DC networks with constant power
loads (CPL). Common DC networks, such as automotive electrical systems and DC
microgrids, typically have a step-up/down converter connected in one side to
the main bus and, on the other, to the load. When load is constant power it can
generate destabilizing effects if not proper controlled. This paper shows that
converters driving CPLs can make the system unstable, even if they are
individually stable, depending on network parameters. We mitigate this problem
by means of passive components externally connected to the converter/CPL
subsystem. The analysis is verified through simulations. We are able to show
that certain converter circuit configurations achieve the so called
plug-and-play property, which stabilizes the interconnected system for all
network parameters. This property is desirable since it is does not require the
knowledge of detailed system topology and parameters, which can be time varying
and difficult to obtain. This method also contrasts to existing practices of
load augmentation, which can lead to severe efficiency losses.
