An Overview of Capacitive DC-Links-Topology Derivation and Scalability Analysis

Abstract

Capacitive DC links are widely used in Voltage Source Converters (VSC) for power balance, voltage ripple limitation, and short-term energy storage. A typical solution which uses Aluminum Electronic Capacitors (E-cap) for such applications is assumed to be one of the weakest links in power electronic systems, therefore, also becoming one of the lifetime bottlenecks of power electronic systems. Various passive and active capacitive DC-link solutions have been proposed intending to improve the reliability of the DC links qualitatively, making great effort to diverting the instantaneous pulsating power into extra reliable storage components. In this publication, a generic topology derivation method for single-phase power converters with active capacitive DC link integrated has been proposed, which can derive all existing topologies, and identify a few new topologies. According to the synthesis results, the main achievements in research on capacitive DC-link solutions are reviewed and presented chronologically as well as thematically ordered. Further more, the reliabilityoriented design procedure is applied to size the chip area of active switching devices and the passive components to fulfill a specific lifetime target and system specification, as well as compare the overall capacitive energy storage, energy buffer ratio, and the cost of different solutions. The cost comparisons are performed with a scalable lifetime target and power rating. It reveals that different conclusions can be drawn with different lifetime targets in terms of cost-effectiveness.

An Overview of Condition Monitoring Techniques for Capacitors in DC-Link Applications

“…According to the model, the dissipation factor (DF) is defined as tanδ = ωRESRC. The impedance ZC of capacitors is expressed as (1) Using (1), Fig. 2(b) shows the impedance characteristics of capacitors [103].…”

“…C-LINK capacitors are an important part in the majority of electronic converters, which contribute to suppressing dc-link voltage ripple, absorbing harmonics, and balance the instantaneous power difference between the front-end and rear-end of converter systems [1], [2]. In some applications, they are also served to provide sufficient energy for transient and abnormal operations [3], [4].…”

Single-Phase Current Source Inverter with Reduced Ground Leakage Current for Photovoltaic Applications

“…This represents the main drawback for the use in actual PV microinverters of single-phase CSI topologies-to keep the small dimensions and weight, there is the need to manage the output pulsating power through a capacitor. However, different solutions, based on active capacitors [19], can be employed.…”

Analytical Expressions for Voltage Controller Coefficients to Attain Desired Values of Total Harmonic Distortion and DC Link Voltage Undershoot in Power Factor Correction Rectifiers

“…Bulk (typically electrolytic) capacitors, connected across the DC link of the power conversion system are typically utilized for this purpose [6]. Pulsating power components, absorbed by the short-time energy storage element, generate DC link voltage ripple proportional to system power rating and inversely correlated to the DC link capacitance value [7] (with the exception of balanced three-phase system, where DC link-side pulsating power component is zero [8], [9]). Moreover, DC link voltage deviation from its nominal value caused by load variations is also inversely related to the DC link capacitance value.…”