ESR Estimation Schemes of Output Capacitor for Buck Converter from Capacitor Perspective

Abstract

The aluminum electrolytic capacitor (AEC) is one of the most vulnerable parts in power electronic converters and its reliability is crucial to the whole system. With the growth of service time, the equivalent series resistance (ESR) increases and the capacitance (C) decreases due to the loss of electrolytes, which will result in extra power loss and even damage to transistors. To prevent significant damages, the AEC must be replaced at an optimal period and online health monitoring is indispensable. Through the analysis of degradation parameters (ESR and C), ESR is proved to be a better health indicator and therefore is determined as the monitoring parameter for AEC. From the capacitor perspective, ESR estimation schemes of output capacitors for a Buck converter are studied. Based on the voltage–current characteristics, two ESR calculation models are proposed, which are applicable for both continuous conduction mode (CCM) and discontinuous conduction mode (DCM). From the point of implementation view, the advantages and disadvantages of the two estimation schemes are pointed out, respectively. A Buck prototype is built and tested, and simulation and experimental results are provided to validate the proposed ESR estimation schemes.

Advanced Fault-Detection Technique for DC-Link Aluminum Electrolytic Capacitors Based on a Random Forest Classifier

“…It is available in various sizes and capacities [11]. However, AECs must be connected in series and require safety resistors to maintain the necessary high voltage in power networks, leading to a more complex system that may result in additional damage when they fail [12,13]. AEC failure can be caused by several thermal and electrical issues, leading to the vaporization of its electrolyte and degradation of the oxide layer.…”

“…AEC failure can be caused by several thermal and electrical issues, leading to the vaporization of its electrolyte and degradation of the oxide layer. This results in a significant decrease in capacitance (C) and an increase in equivalent series resistance (ESR) rates [6,[13][14][15][16].…”

“…Experimental techniques have been utilized to evaluate the condition of aluminum electrolytic capacitors (AECs) in converters [13][14][15][16]18,20,21]. Some approaches require the presence of a current sensor connected in series with the capacitor [14,15,18,20], which could increase the stray inductance and alter the capacitor voltage, as previously reported [20].…”

“…Some approaches require the presence of a current sensor connected in series with the capacitor [14,15,18,20], which could increase the stray inductance and alter the capacitor voltage, as previously reported [20]. However, there are alternative methods that can replace the current sensor in the DC link [13,16,19,21]. These methods rely on the circuit relationship and the capacitor current to assess the AEC's condition.…”

A Feature Engineering-Assisted CM Technology for SMPS Output Aluminium Electrolytic Capacitors (AEC) Considering D-ESR-Q-Z Parameters

“…ESR, DF, and Q are all elements of a capacitor's performance that impact its durability and efficiency. However, for capacitors used in power supplies, ESR and DF are essential since a high ESR and dissipation factor, DF, will result in a considerable quantity of power being dissipated in the capacitor [14,19,20].…”