A novel online ESR and C identification method for output capacitor of buck converter

Abstract

As electrolytic capacitor is apt to fail in power circuits, it is very important to monitor its electrical parameters, mainly the equivalent series resistance (ESR) and capacitance (C). A novel non-invasive online monitoring method of capacitor's ESR and C for CCM buck converter is proposed in this paper. Based on the ac component of capacitor voltage, the calculation model is founded. By sampling the PWM signal and output voltage, the method needs no current sensor and is effective for the CCM buck converter operating at different conditions. Implementation of the monitoring system is presented. The experimental results validate the effectiveness of the method.

Review of Health Monitoring Techniques for Capacitors Used in Power Electronics Converters

“…Regarding the sampling waveforms, the sampling frequency of the large-signal transient voltage need not be higher than that of the steady state voltage in order to achieve the same quality of sampling waveforms [49]. Hence, instead of sampling the steady voltage and current, the large-signal transient voltage and current are sampled and utilized to estimate the capacitor parameters, without requiring a duty cycle signal as in [43,44]. However, this technique is only applicable to transient states with large signals.…”

“…In [43][44][45], online monitoring methods for the buck converter are proposed. The primary advantage of these methods is that, instead of measuring both current and voltage capacitors, only two values of the capacitor voltage at two specific moments within a switching period need to be measured.…”

“…These methods offer a health monitoring solution without requiring current sensors. However, these methods are only effective in the CCM of buck converters [43].…”

“…Several existing methods for buck converters [38,43,44] are capable of applying boost converters [39,51,52]. Monitoring techniques for the fly-back converter and the isolating DC-DC converter are proposed in [54][55][56].…”

A Low-Cost, High-Precision Method for Ripple Voltage Measurement Using a DAC and Comparators

“…According to differences in data acquisition, the current research achievement of using ripple to evaluate the health state of AECs can be summarized as the indirect calculation of ripple through simulation software [9][10][11], the offline computing from sampled data [12], AEC parameter calculation based on the mathematical model of a particular topology and some specific measurement value (voltage or current) [13][14][15][16][17][18][19], and direct measurement of ripple through high-cost oscilloscopes, data acquisition cards, or high-speed analog-to-digital converters (ADCs) [20][21][22][23]. Nevertheless, the developed methods are rarely adopted in practical industry applications due to the increased cost, complexity, and other relevant issues [8,24].…”