Online health monitoring of metallized polymer film capacitors for avionics applications

Metallized polymer film capacitors, assuming a special position among the various types of capacitors thanks to their capabilities to self-heal, became the components of choice for critical power electronics applications requiring optimized performances such as, avionics, automotive and railways equipment's. However, as a result of the increasingly growing demand for guaranteeing safety and enhancing reliability, a greater interest has been devoted to the health monitoring of power electronics devices. In this paper, an online health monitoring approach for metallized film capacitors is proposed based on the estimation of their precursor parameters. The proposed technique makes use of the already existing current, voltage and temperature sensors for the power drive command/control purposes, and do not need the injection of additional external signals. To demonstrate and validate the effectiveness of such technique, the resulting algorithm was simulated on a set of capacitors at different degradations rates with Matlab/Simulink software. In this paper is also presented a novel “PEN type” polymer. This high-temperature polymer has great advances over the standard polymers films providing excellent self-healing capability with an enhanced energy density, making it one of the most compact film capacitors on the market.