Taylor series expansion based repetitive controllers for power converters, subject to fractional delays

Nazir, Rabia

doi:10.1016/j.conengprac.2017.03.013

Cited by 20 publications

(10 citation statements)

References 16 publications

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“…In this application a fractional delay filter of order M = 2 is used. The N th order sub-filters (P k (z)) in the fractional delay filter can be designed using the criteria given in [10]. Usually first/second order sub-filters are sufficient in almost all applications in the field of power systems.…”

Section: ) Advanced Repetitive Controllermentioning

confidence: 99%

“…An Advanced Repetitive Controller (ARC) scheme aimed at maintaining a constant performance of the repetitive controller in variable frequency environment has been earlier proposed by Nazir [10]. We describe in [10] the design and analysis of an ARC, which is a Taylor series expansion based digital repetitive controller. In this control scheme, non-integer N is divided into two components; integer part N i = N and fractional part F = N − N i .…”

Section: Introductionmentioning

confidence: 99%

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Low THD Grid Connected Converter Under Variable Frequency Environment

2019

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This paper is aimed at achieving unity power factor and low total harmonic distortion (THD) at the input side of a grid connected three-phase rectifier in a variable grid frequency environment. Variable grid frequency results in performance degradation of the digital controllers. Advanced repetitive control (ARC) scheme is an internal model principal-based digital control scheme, capable of tracking a variable frequency signal with nearly constant and very low (nearly zero) steady-state error. The ARC is a Taylor series expansion-based digital repetitive controller whose parameters can be tuned online with reasonably fast transient response to track the signal with an updated frequency. In this paper, the ARC has been applied to a three-phase grid connected rectifier where the reference frequency is variable. Controller coefficients are calculated and updated online. The experimental results demonstrate that the ARC tracks a variable frequency signal very effectively and results in very low THD of input current under steady state.INDEX TERMS Three-phase rectifier, advanced repetitive control, total harmonic distortion, unity power factor.

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Section: ) Advanced Repetitive Controllermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Low THD Grid Connected Converter Under Variable Frequency Environment

2019

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“…Whereas a controller based on the universal signal generator (16), assuming γ = 0 and taking into account (18) and (19), can be rewritten in the form of…”

Section: Are They Equivalent or Just Similar?mentioning

confidence: 99%

“…where: unless an additional adaptive fractional delay filter is implemented, which has already been demonstrated in the case of grid converters [2,19,20,21,22]; † very good if the oscillatory terms are of an adaptive type, which is fairly easy to achieve because the grid frequency is already available thanks to the PLL; ‡ by modifying (24) into x(k, p) = Q(z)x(k − 1, p) + k RC e(k − 1, p + p 0 ) and setting a proper value of p 0 [2,19]; § unless oscillatory terms are individually modified to obtain the phase lead [23,16,24] (with corrections in [25]).…”

Section: Periodic Disturbance Feedforward In the Context Of Repetitivmentioning

confidence: 99%

On the similarity and challenges of multiresonant and iterative learning current controllers for grid converters and why the disturbance feedforward matters

Ufnalski¹

2018

ELECTROTECHNICAL REVIEW

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There are two main techniques to solve the reference tracking problem for repetitive references and under repetitive disturbances, namely multiresonant (a.k.a. multioscillatory) controllers and iterative learning controllers. Nevertheless, neither of the approaches is a definitive winner, which is to be demonstrated herein. Both have their strengths, weaknesses and challenges. A grid-tie converter will be the case study here. The goal is to draw or inject sinusoidal currents under distorted grid voltage conditions. The supporting feedforward controller will be addressed within the context of the discussed repetitive control task. The case will be illustrated using numerical simulations. Our main goal is to make practitioners familiar with the relationships between these two control methods. Streszczenie. Istnieją dwia główne sposoby rozwiązywania zadania regulacji nadążnej dla powtarzalnego sygnału zadanego w obecności powtarzalnego zakłócenia, jest to zastosowanie regulatorów wielorezonansowych (zwanych też wielooscylacyjnymi) oraz regulatorów z uczeniem iteracyjnym. Jednakżadnego z tych rozwiązań nie można uznać za jednoznacznie lepsze, co zostanie tutaj pokazane. Oba cechują zarówno mocne strony, jak i pewne słabości oraz wyzwania implementacyjne. Przekształtnik sieciowy posłuży tutaj za przykład. Celem jest pobieranie lub oddawanie sinusoidalnego prądu sieci pomimo odkształconego napięcia. Omówione zostanie również sprzężenie w przód od zakłócenia w kontekście zadania sterowania powtarzalnego. Zagadnienie zostanie zilustrowane przy użyciu symulacji komputerowych. Naszym głównym celem jest pokazanie praktykom związków pomiędzy tymi dwiema metodami sterowania. (O podobieństwach i wyzwaniach regulatorów wielorezonansowych i regulatorów z uczeniem iteracyjnym dla przekształtników sieciowych oraz dlaczego sprzężenie w przód ma znaczenie)

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“…Deadbeat control technique in comparison to other modern control techniques (e.g resonant control, repetitive control) is simple, quick and achieves the steady state in minimum number of time steps. However, performance of deadbeat control is highly sensitive to parameter uncertainties and unmodelled dynamics of the system [7][8][9][10]. Unmodelled dynamics may cause unexpected delay in the systems.…”

Section: Introductionmentioning

confidence: 99%

Comprehensive analysis and synthesis of time delay compensated deadbeat control strategy

Nazir

Shabbir

et al. 2020

SN Appl. Sci.

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This research comprehensively investigates the effect of uncertain time delay on performance of the deadbeat control. A solution based on a non-integer order Smith predictor has been proposed and analyzed to compensate uncertain time delays occurring in a stable closed loop system. Deadbeat control has been widely and conveniently used in the control of linear and non-linear systems. However, this control technique is severely sensitive to unmodeled dynamics and parameter uncertainties. Thus the performance of system may deviate significantly and hence lead to instability in practical cases. Time delay in a closed loop control system is a common source of unmodeled dynamics, which severely deteriorates control accuracy and results in reduced stability margin of the deadbeat control system. Physical system considered in this research work is a single-phase inverter. The simulation results indicate that the Smith predictor based deadbeat control scheme offers accurate time delay compensations and thus enhances the robustness and stability margin. Application example comprehensively illustrates effectiveness of the proposed control technique.

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Taylor series expansion based repetitive controllers for power converters, subject to fractional delays

Cited by 20 publications

References 16 publications

Low THD Grid Connected Converter Under Variable Frequency Environment

Low THD Grid Connected Converter Under Variable Frequency Environment

On the similarity and challenges of multiresonant and iterative learning current controllers for grid converters and why the disturbance feedforward matters

Comprehensive analysis and synthesis of time delay compensated deadbeat control strategy

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