Buck converter output capacitor switching frequency point esr and c monitoring method

Abstract

The invention discloses a monitoring method of a Buck converter output capacitor switching frequency point ESR and C monitoring method. The steps of the method are as follows: the first step, the inductor current i Lf vs. output voltage v o Obtain AC component i through high-pass filter unit and synchronous sampling Lf_ac (t) and v o_ac (t); the second step, calculate i respectively Lf_ac (t), v o_ac (t) and sin(2πf s t), cos(2πf s t) Integer multiple switching period n / f s The definite integral on , where f s is the switching frequency of the converter, n is a positive integer; the third step, according to A u , B u 、A i , B i value to calculate the loss angle δ; the fourth step, according to A u , B u 、A i , B i , δ values ​​were calculated ESR and C values. The method provided by the present invention does not need to add additional sampling points, does not affect the normal operation of the converter, is applicable to CCM and DCM modes at the same time, and can accurately monitor the values ​​of ESR and C at the switching frequency point of the output capacitor of Buck type direct-to-direct converters , to provide a basis for the health monitoring of capacitors.

Description

technical field [0001] The invention relates to a method for monitoring the health of an output filter capacitor of a Buck type direct-to-direct converter, in particular to a method for monitoring ESR and C of a switching frequency point of a Buck converter output capacitor. Background technique [0002] Due to the advantages of high efficiency, small size, and low noise, power electronic converters have been widely used in military, aerospace, and industrial fields. In power electronic converters, in order to obtain higher quality output voltage, capacitors must be used to filter out high-frequency noise, among which electrolytic capacitors are most commonly used. According to surveys, electrolytic capacitors are power devices with the highest failure rate in power electronic converters. After the electrolytic capacitor is used for a period of time, the equivalent series resistance ESR of the capacitor will increase, and the capacitance C of the capacitor will decrease. Wh...

AI Technical Summary

Problems solved by technology

However, the existing Buck DC-DC converter output capacitor ESR and C monitoring methods mostly use switching ripple, and the switching ripple contains multiple harmonics, so that the identification results are all affected by harmonics, and the reference value of the results affected

Moreover, most of the existing methods need to judge the discontinuous current mode (DCM) and the continuous current mode (CCM) mode, so it is impossible to provide a more general and effective capacitor health monitoring method

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