In situ characterisation of non linear capacitors

¹ Laboratoire de Génie Électrique de Toulouse - Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 4, France
² Laboratoire d'Électrotechnique et d'Électronique Industrielle INP-ENSEIIHT, 2 rue Camichel, 31062 Toulouse Cedex, France
³ Laboratoire d'Analyse et d'Architecture des Systèmes du CNRS, 7 avenue du Colonel Roche, 31077 Toulouse Cedex 4, France

Corresponding author: lebey@lget.ups-tlse.fr

Received: 27 October 2000
Revised: 19 March 2001
Accepted: 19 March 2001
Published online: 15 May 2001

Abstract

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.