A study on behavioural changes on high voltage capacitors in power electronics applications

Inhalt:
The aim of this paper is to research and study suitable mathematical models of capacitors for high voltage applications, such as DC link in a power converter circuit, and to compare the results with data obtained from the manufacturer datasheet. For a DC link capacitor, stable values of capacitance and low ESR are some of the most important parameters. A real capacitor consists of its intended capacitance in combination with parasitic components, such as resistance and inductance. Due to the presence of these parasitic components, especially the ESR, the electrical properties of a capacitor are influenced by various factors, such as change in temperature, frequency, DC bias voltage etc. In this paper, the changes of capacitance and ESR with respect to temperature, frequency and DC bias voltage are studied. Several mathematical models are investigated for aluminum electrolytic capacitors, film capacitors and ceramic capacitors. The research is concluded by adopting a mathematical model for the effect of DC bias voltage on capacitance change to a broader voltage range and by comparing the results obtained with the model with manufacturer datasheets.