Process for detecting ageing of a dc bus capacitor of a power converter

Abstract

A method to estimate a remaining of useful life of a DC link capacitor of a converter through determination of a minimum value Clim of its capacitance C under which performances of the converter are considered as insufficient. The method includes implementing a real time model including a motor drive model and a capacitor model using decreasing capacitor values to calculate a forecasted minimum capacitance Clim sufficient for keeping at least one of DC voltage ripple, motor current ripple, speed ripple or torque ripple under a specified value. The method further includes calculating a time difference between a time Tactual, for which the capacitor has an estimated capacitance based on an ageing curve Ccurve, and a time Tlim for which the capacitor will have the forecasted minimum capacitance Clim, with the use of an ageing curve Ccurve of the capacitor and estimating the remaining useful life of the capacitor Tactual-Tlim.

Dependencies are inferred from the claim text.