Multilayers ceramic capacitors (MLCC) presenting non linear behaviours of their
C(V) characteristics may have interesting applications in power electronics. Most of them
have already been described. Nevertheless, the choice of a particular type instead of another
one is all the more so difficult since, on one hand the physical mechanisms able to explain this
behaviour is far from being understood. On the other hand, C(V) characteristics are in general
obtained for low voltage values different from the ones they are going to be involved in. In
this paper, direct in situ characterisations of different BaTiO3 based capacitors commercially
available are achieved. The role of the capacitors' type (X7R,Z5U), of the temperature and of
the voltage waveform (and more particularly its polarity) is demonstrated. Temperature values
up to 200 °C are measured during normal operations in a RCD dissipative snubber without any
alterations of the C(V) characteristics. All these results are discussed as regards the main
physical properties of the constitutive materials in order to reach an optimisation of their use
through an appropriate dimensioning.