Topic

# Filter capacitor

About: Filter capacitor is a research topic. Over the lifetime, 5986 publications have been published within this topic receiving 65712 citations.

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TL;DR: In this article, the fundamental principles, performance, characteristics, present and future applications of electrochemical capacitors are presented in this communication, and different applications demanding large ECs with high voltage and improved energy and power density are under discussion.

4,175 citations

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TL;DR: Graphene nanosheets have a preponderance of exposed edge planes that greatly increases charge storage as compared with that of designs that rely on basal plane surfaces, and capacitors constructed with these electrodes could be smaller than the low-voltage aluminum electrolyte capacitors that are typically used in electronic devices.

Abstract: Electric double-layer capacitors (DLCs) can have high storage capacity, but their porous electrodes cause them to perform like resistors in filter circuits that remove ripple from rectified direct current. We have demonstrated efficient filtering of 120-hertz current with DLCs with electrodes made from vertically oriented graphene nanosheets grown directly on metal current collectors. This design minimized electronic and ionic resistances and produced capacitors with RC time constants of less than 200 microseconds, in contrast with ~1 second for typical DLCs. Graphene nanosheets have a preponderance of exposed edge planes that greatly increases charge storage as compared with that of designs that rely on basal plane surfaces. Capacitors constructed with these electrodes could be smaller than the low-voltage aluminum electrolyte capacitors that are typically used in electronic devices.

1,233 citations

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TL;DR: This review serves to provide a clear picture of the state-of-the-art research in this area and to identify the corresponding challenges and future research directions for capacitors and their dc-link applications.

Abstract: DC-link capacitors are an important part in the majority of power electronic converters which contribute to cost, size and failure rate on a considerable scale. From capacitor users' viewpoint, this paper presents a review on the improvement of reliability of dc link in power electronic converters from two aspects: 1) reliability-oriented dc-link design solutions; 2) conditioning monitoring of dc-link capacitors during operation. Failure mechanisms, failure modes and lifetime models of capacitors suitable for the applications are also discussed as a basis to understand the physics-of-failure. This review serves to provide a clear picture of the state-of-the-art research in this area and to identify the corresponding challenges and future research directions for capacitors and their dc-link applications.

882 citations

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Sanyo

^{1}TL;DR: In this paper, a three-stage switched capacitor DC-DC converter capable of generating an output boosted voltage in increments of less than power supply voltage is described, where the two capacitors are connected in series when charging by turning one of the switches ON, and are connected parallel when discharging by turning the other two switches ON.

Abstract: A three-stage switched capacitor DC-DC converter capable of generating an output boosted voltage in increments of less than power supply voltage. A first stage of the DC-DC converter comprises two capacitors and three switches, which alternate a connection of the two capacitors. The two capacitors are connected in series when charging by turning one of the switches ON, and are connected in parallel when discharging by turning the other two of the switches ON.

642 citations

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TL;DR: In this article, a capacitor-current-feedback active damping with reduced computation delay is proposed, which is achieved by shifting the capacitor current sampling instant towards the PWM reference update instant.

Abstract: This paper investigates the capacitor-current-feedback active damping for the digitally controlled LCL-type grid-connected inverter. It turns out that proportional feedback of the capacitor current is equivalent to virtual impedance connected in parallel with the filter capacitor due to the computation and pulse width modulation (PWM) delays. The LCL-filter resonance frequency is changed by this virtual impedance. If the actual resonance frequency is higher than one-sixth of the sampling frequency (fs/6), where the virtual impedance contains a negative resistor component, a pair of open-loop unstable poles will be generated. As a result, the LCL-type grid-connected inverter becomes much easier to be unstable if the resonance frequency is moved closer to fs/6 due to the variation of grid impedance. To address this issue, this paper proposes a capacitor-current-feedback active damping with reduced computation delay, which is achieved by shifting the capacitor current sampling instant towards the PWM reference update instant. With this method, the virtual impedance exhibits more like a resistor in a wider frequency range, and the open-loop unstable poles are removed; thus, high robustness against the grid-impedance variation is acquired. Experimental results from a 6-kW prototype confirm the theoretical expectations.

598 citations