Wideband impedance characterization and modeling of power electronic capacitors under high bias voltage variation

Passive components, in particular capacitors, are widely used in power electronics, especially in EMC filters. Their impedance variation with respect to operating conditions (frequency, temperature, operating voltage) is very significant and shouldn´t be neglected. In this paper, we aim to characterize the influence of bias voltage variations on capacitor parameters (C and ESR) over a wide frequency range. The characterization is performed for DC bias voltage range up to 1 kilo Volt. This first step enables to define how to include these operating conditions in the development of “high-frequency electric model” of capacitors, which consider the bias voltage dependence of each electric parameter. To do this, a test bench based on vector network analyzer and two current probes is used.