The effect of change in DC link series resistance on the AC/AC converter operation: Power converters embedded diagnostics

Nowadays health and condition monitoring of the particular elements of the industrial system is a standard requirement. This also applies to power converters which are becoming more and more critical and important parts of the automation systems. That brings an important need for the appropriate solutions for internal diagnostics methods. One of the most important elements of the voltage source converter circuit is the DC capacitor(s). In many of the proposed and available methods the health state of the DC bus capacitor is described by monitoring the equivalent series resistance. This paper presents the method for monitoring the DC link capacitor aging effects. Additionally the article examines the possibility of using the emerging changes in the frequency spectrum of the converter currents for the DC link deterioration. The results are obtained from simulations.