Ripple analysis-based electrolytic capacitor life calculation method

Abstract

The invention relates to the technical field of power electronics, in particular to a ripple analysis-based electrolytic capacitor life calculation method. The method comprises the steps of solving current ripples of an electrolytic capacitor under different frequencies by utilizing double Fourier series, and solving electrolytic capacitor life in combination with impedance characteristics of the electrolytic capacitor and an inner temperature rise-based electrolytic capacitor model. Specifically, the method comprises the steps of A, calculating an effective value of each harmonic current in a buck circuit; B, giving out the electrolytic capacitor model and performing calculation through the effective value of the harmonic current and equivalent series resistance (ESR) of the electrolytic capacitor at a harmonic frequency by utilizing an iterative algorithm to obtain an inner temperature rise of the electrolytic capacitor; and C, substituting the inner temperature rise of the electrolytic capacitor into an electrolytic capacitor life formula and performing calculation to obtain the electrolytic capacitor life. According to the method, the electrolytic capacitor life model is combined with system parameters, so that the influence of inductance in a main circuit on the electrolytic capacitor life is analyzed; and the life calculation of the electrolytic capacitor is closely combined with the impedance properties of the electrolytic capacitor, so that the electrolytic capacitor life can be accurately solved.

Description

technical field [0001] The invention belongs to the technical field of power electronics, in particular to a method for calculating the life of an electrolytic capacitor based on ripple analysis. Background technique [0002] With the development of power electronics technology, DC converters are playing an increasingly important role in applications such as renewable energy power generation, smart grid, and aerospace and navigation. Due to the function of the switching device in the DC conversion device, the output voltage contains the switching frequency and its integer multiple harmonics, so the output side of the DC conversion device needs to install a filter circuit, such as LC filter circuit, LCL filter circuit, etc. Capacitors are indispensable for filter circuits, and electrolytic capacitors have the advantages of large capacitance, high energy density, and low cost, making them widely used in the design of filter circuits on the output side of DC converters. [000...

AI Technical Summary

Problems solved by technology

However, the equivalent resistance ESR of an electrolytic capacitor changes with its operating frequency and internal temperature. Since this type of electrolytic capacitor model ignores the impedance characteristics of the electrolytic capacitor, the accuracy of the calculated life of the electrolytic capacitor is low.

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