A novel design methodology for low pass filter stage of a voltage source inverter

Purpose This paper aims to propose a novel grid current control strategy for grid-connected voltage source converters (VSCs) under unbalanced grid voltage conditions. Design/methodology/approach A grid voltage dynamic model is represented in symmetrical positive and negative sequence reference frames. A proportional controller structure with a first-order low-pass filter disturbance observer (DOB) is designed for power control in unbalanced voltage conditions. This controller is capable of meeting the positive sequence power requirements, and it also eliminates negative sequence power components which cause double-frequency oscillations on power. The symmetrical components are calculated by using the second-order generalized integrator-based observer, which accurately estimates the symmetrical components. Findings Proportional current controllers are sufficient in this study in a wide range of operating conditions, as DOB accurately estimates and feed-forwards nonlinear terms which may be deteriorated by physical and operating conditions. This is the first reported scheme which estimates the VSC disturbances in terms of symmetrical component decomposition and the DOB concept. Originality/value The proposed method does not require any grid parameter to be known, as it estimates nonlinear terms with a first-order low-pass filter DOB. The proposed control system is implemented on a dSPACE ds1103 digital controller by using a three-phase, three-wire VSC.

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A Compact Planar Low-Pass Filter Based on SRR-Metamateria

International Journal of Electrical and Computer Engineering (IJECE) ◽

10.11591/ijece.v8i6.pp4972-4980 ◽

2018 ◽

Vol 8 (6) ◽

pp. 4972

Author(s):

Badr Nasiri ◽

Ahmed Errkik ◽

Jamal Zbitou ◽

Abdelali Tajmouati ◽

Larbi El Abdellaoui ◽

...

Keyword(s):

Cutoff Frequency ◽

Total Surface Area ◽

Ring Resonators ◽

Split Ring ◽

Pass Filter ◽

Low Pass Filter ◽

Attenuation Level ◽

Low Pass ◽

Novel Design ◽

Good Agreement

In this work, a novel design of a Microstrip Low-pass filter based on metamaterial square split ring resonators (SRRs) is proposed. The SRRs has been added to obtain a reduced size and high performances. The filter is designed on an FR-4 substrate having a thickness of 1.6mm, a dielectric constant of 4.4 and loss tangent of 0.025. The proposed low-pass filter is characterized by a cutoff frequency of 2.4 GHz and an attenuation level below than -20dB in the stopband. The LPF is designed, simulated and optimized by using two electromagnetic solvers CST microwave studio and ADS. The computed results obtained by both solvers are in good agreement. The total surface area of the proposed circuit is 18x18mm2 excluding the feed line, its size is miniaturized by 40% compared to the conventional filter. The experimental results illustrate that the filter achieves very good electrical performances in the passband with a low insertion loss of 0.2 dB. Moreover, a suppression level can reach more than 35 dB in the rejected band.

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MATHEMATICAL MIXER MODEL WITH FORMATION OF HETERODYNE ANTIPHASE SIGNAL

Herald of Dagestan State Technical University Technical Sciences ◽

10.21822/2073-6185-2019-46-3-97-107 ◽

2019 ◽

Vol 46 (3) ◽

pp. 97-107

Author(s):

Z. N. Mirzaev ◽

M. S. Guseynov ◽

T. G. Aigumov

Keyword(s):

Power Level ◽

Voltage Source ◽

Simultaneous Increase ◽

Pass Filter ◽

Low Pass Filter ◽

Topological Parameters ◽

Nonlinear Distortions ◽

Noticeable Improvement ◽

Low Pass ◽

Intermodulation Distortions

Objectives To carry out calculations involved in the design of a microwave mixer with a diplexer with the formation of the antiphase heterodyne signal using a slot resonator.Method In order to calculate and optimise the characteristics, design and topological parameters of microwave mixers, the results of the design bandpass filter PF and low-pass filter (LPF) mixers of through-feed type were used. The characteristics of mixers and their structural elements were calculated using the Serenade software package intended for the automated calculation of microwave devices. A distinct feature of designing mixers (with a diplexer) involves the need to optimise the topology of the diplexer before optimising the mixer characteristics.Results The characteristics of nonlinear distortions show that the maximum power level at the mixer inlet should not exceed -15 – -20 dBm. In order to attenuate the intermodulation distortions of the 3rd order, this level should be higher that 50 dBs. The relatively low level of compression and suppression of harmonic and intermodulation distortions associated with the minimisation of the heterodyne power level at the calculation of characteristics of mixers of the required heterodyne power level (Rh ~ 5-7 dBm) is due to the minimum expenses at the realisation of sources of heterodyne signals. A noticeable improvement in the characteristics of mixers by nonlinear distortions can be achieved by shifting the operating point at the points on the current-voltage characteristic (VAC) diodes by an external voltage source with a simultaneous increase in Ph by several dB (up to Ph = 10 dBm).Conclusion A mode of increased nonlinear distortion suppression can be practically realised by switching on diodes through resistive-capacitive circuits (auto-shift) or using diodes with an increased potential barrier. The calculation shows that it is possible to realise sufficiently small conversion losses of 6.6-8.0 dB at low levels of Rh ~ 5-7 dBm.

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Control Strategy for Grid Connected Inverters Under Unbalanced Network Conditions - A DOb Based Decoupled Current Approach

10.20944/preprints201706.0088.v1 ◽

2017 ◽

Author(s):

Emre Ozsoy ◽

Sanjeevikumar Padmanaban ◽

Lucian Mihet-Popa ◽

Viliam Fedák ◽

Fiaz Ahmad ◽

...

Keyword(s):

Control Strategy ◽

Current Approach ◽

Current Control ◽

Positive Sequence ◽

Voltage Source ◽

Renewable Sources ◽

Pass Filter ◽

Low Pass Filter ◽

Negative Sequence ◽

Low Pass

Penetration of grid connected inverters (GCI) has arisen in power systems due to increasing integration of renewable sources. However, restrictive grid codes require that renewable sources connected to the grid with power electronic systems must be properly connected and appropriate currents must be injected to support stability of the grid under grid faults. Simultaneous injection of symmetrical positive and negative sequence currents is mandatory to support stabilization of grid at the instant of grid faults. Conventional synchronously rotating frame dq current controllers are insufficient under grid faults due to low bandwidth of PI controllers. This paper proposes a new grid current control strategy for grid connected voltage source inverters under unbalanced grid voltage conditions. A proportional current controller with a first order low pass filter disturbance observer (DOb) is proposed which establishes positive sequence power requirements and independently control negative sequence current components under unbalanced voltage conditions. The method does not need any parameter, since it estimates nonlinear terms with low pass filter DOb. Simulations are implemented in Matlab/Simulink platform demonstrating the effectiveness of proposed method.

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Low-pass filter with deep and wide stop band and controllable rejection bandwidth

International Journal of Microwave and Wireless Technologies ◽

10.1017/s1759078714000555 ◽

2014 ◽

Vol 7 (2) ◽

pp. 141-149

Author(s):

Dusan A. Nesic ◽

Branko M. Kolundzija ◽

Dejan V. Tošić ◽

Dario S. Jeremic

Keyword(s):

Transmission Lines ◽

Stop Band ◽

Design Procedure ◽

Pass Filter ◽

Low Pass Filter ◽

Cell Parameters ◽

Unit Cells ◽

Low Pass ◽

Novel Design ◽

Identical Unit

Novel design of low-pass microwave filters based on cascading of identical unit cells is proposed. Dispersion relation is used to determine the cell parameters for a given relative stop-band width. For a filter consisting of two cells, each made of single- or two-section transmission lines, the design formulas and curves are presented. Based on them typical filters are designed, fabricated, and measured. The presented filters feature a deep stop band and a wide rejection band, which can be controlled within the proposed design procedure. The design procedure and the simulation results are verified experimentally by measurement of the fabricated structures containing two and three cells.

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Miniaturized ultra-wideband coplanarwaveguide lowpass filter with extended stop band

Indonesian Journal of Electrical Engineering and Computer Science ◽

10.11591/ijeecs.v19.i3.pp1415-1419 ◽

2020 ◽

Vol 19 (3) ◽

pp. 1415

Author(s):

Elmahjouby Sghir ◽

Ahmed Errkik ◽

Jamal Zbitou ◽

Otman Oulhaj ◽

Ahmed Lakhssassi ◽

...

Keyword(s):

Stop Band ◽

Wide Band ◽

Ultra Wideband ◽

Pass Filter ◽

Entire Area ◽

Low Pass Filter ◽

Planar Circuits ◽

Low Pass ◽

Band Pass ◽

Novel Design

<p class="Default">In this article, we propose a novel design of large rejected band of miniaturized ultra wide band (UWB) of a planar CPW low pass filter “LPF” based on the use of periodic elements of ‘e’ slots. The goal of this work is to develop a new structure of Low Pass Filter with the following criterion: Miniature, Compact and Easy for Fabrication. The Miniaturization of this structure is achieved by entering the 'e' slot in etching area in the ground of CPW line, to save the standard gap of the adapted coplanar line. The designed coplanar LPF is a compact filter having a large band pass and extended stop band, with the possibility to associate easily with others RF and microwave planar circuits. The entire area of the proposed structure of CPW LPF is 14.3x20 mm<sup>2</sup>.</p>

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Damping techniques for grid-connected converters with LCL filter: an overview

Semina Ciências Exatas e Tecnológicas ◽

10.5433/1679-0375.2021v42n2p227 ◽

2021 ◽

Vol 42 (2) ◽

pp. 227

Author(s):

Arthur de Abreu Romão ◽

Newton Da Silva

Keyword(s):

Renewable Energy Sources ◽

Design Procedure ◽

Voltage Source ◽

Third Order ◽

Pass Filter ◽

Low Pass Filter ◽

Resonant Behavior ◽

Low Pass ◽

Grid Connected Converters ◽

Low Pass Filters

Distributed generation systems, based on renewable energy sources, are typically connected to the main grid by a voltage-source inverter with a low-pass filter. The need for improved efficiency led to the use of third order low-pass filters, such as the LCL configuration, which has resonant behavior. In order to meet energy quality requirements and ensure the systems stability it is necessary to suppress the LCL filters resonance through damping techniques. Therefore, this paper presents an overview of some damping strategies found in literature and its design procedure, applied to a simulated single-phase grid-tied inverter. The comparison of each presented damping methodology characteristics is described, with analysis of advantages and drawbacks for each case.

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