Browse Prior Art Database

Arrangement and Method to Detect End-of-Life of Large-Size Aluminum Electrolytic Capacitors

IP.com Disclosure Number: IPCOM000235515D
Publication Date: 2014-Mar-05
Document File: 7 page(s) / 361K

Publishing Venue

The IP.com Prior Art Database

Abstract

One of the distinctive features of power electronics converters is a presence of energy storage component on the DC side. For energy storage, it is common to use aluminum electrolytic capacitors. Often considerable energy storage requirements are present, so large-size aluminum electrolytic capacitors are used. The limited current capability parallel connected capacitors in capacitor bank (further called DC-link). Also, for applications with DC voltage levels >400V, series connection of the capacitors is required. Therefore, generally, DC-link contains a number of capacitors connected as in parallel, so in series. The current stress and pronounced ageing behavior pose a challenge for reliability of the DC-link design. Therefore, complimentary to significant design and qualification effort, DC-link parameters monitoring must be applied. Implementation- and feasibility-wise, the total DC-link capacitance is the parameter of choice for the monitoring. However, total DC-link capacitance gives no indication on the individual state of each capacitor in the bank. The total DC-link capacitance has a very low sensitivity to the large capacitance drop of an individual capacitor. The cause of the latter could be for example a manufacturing (intrinsic) defect resulting in a much faster ageing for this very capacitor. The inability to detect this condition early enough could lead to the much faster ageing of the individual capacitor with potential to damage adjacent electronic components. In this paper, a solution is proposed to overcome this problem. The idea of the method is to monitor pressure formed in the capacitor housing to detect potential future failure. A simple pressure sensing arrangement with a low number of components is used. By using this method and its proposed implementation, information on individual capacitor state is obtained. These data close the gap in the existing monitoring information allowing it to make the right decision on converter maintenance actions. This method can also be applied to other aluminum electrolytic capacitors that are critical for the converter operation. This method can also be applied to film capacitors.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 22% of the total text.

Page 01 of 7



Date: March 5, 2014 Page: 1/7

Arrangement and Method to Detect End-of-Life of Large- Size Aluminum Electrolytic Capacitors


1.Abstract

One of the distinctive features of power electronics converters is a presence of energy storage component on the DC side. For energy storage, it is common to use aluminum electrolytic capacitors. Often considerable energy storage requirements are present, so large-size aluminum electrolytic capacitors are used. The limited current capability parallel connected capacitors in capacitor bank (further called DC- link). Also, for applications with DC voltage levels >400V, series connection of the capacitors is required. Therefore, generally, DC-link contains a number of capacitors connected as in parallel, so in series. The current stress and pronounced ageing behavior pose a challenge for reliability of the DC-link design. Therefore, complimentary to significant design and qualification effort, DC-link parameters monitoring must be applied. Implementation- and feasibility-wise, the total DC-link capacitance is the parameter of choice for the monitoring. However, total DC-link capacitance gives no indication on the individual state of each capacitor in the bank. The total DC-link capacitance has a very low sensitivity to the large capacitance drop of an individual capacitor. The cause of the latter could be for example a manufacturing (intrinsic) defect resulting in a much faster ageing for this very capacitor. The inability to detect this condition early enough could lead to the much faster ageing of the individual capacitor with potential to damage adjacent electronic components.

In this paper, a solution is proposed to overcome this problem. The idea of the method is to monitor pressure formed in the capacitor housing to detect potential future failure. A simple pressure sensing arrangement with a low number of components is used. By using this method and its proposed implementation, information on individual capacitor state is obtained. These data close the gap in the existing monitoring information allowing it to make the right decision on converter maintenance actions. This method can also be applied to other aluminum electrolytic capacitors that are critical for the converter operation. This method can also be applied to film capacitors.
2.Background

Having excellent energy/voltage ratio, the aluminum electrolytic capacitors become a natural choice for the DC-link design. The practical DC-link capacitance realization also takes into account current rating, capacitor lifetime, voltage rating and thermal design. As a result, often, the DC-link capacitance is realized with a large number of individual large-size aluminum electrolytic capacitors connected in series and parallel. © Copyright 2014 ABB Technology Ltd, Affolternstrasse 44, CH-8050 Zurich, Switzerland. All rights reserved.


Page 02 of 7



Date: March 5, 2014 Page: 2/7 Aluminum electrolytic capacitors have a domin...