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Article
Publication date: 1 December 2004

Konrad Urbański and Krzysztof Zawirski

This paper deals with the problem of rotor speed and position detection in sensorless permanent magnet synchronous motor (PMSM) drives. A concept based on detecting the back EMF…

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Abstract

This paper deals with the problem of rotor speed and position detection in sensorless permanent magnet synchronous motor (PMSM) drives. A concept based on detecting the back EMF induced in stator windings was developed and modified. A general structure of an adaptive observer with the proportional‐integral function of a corrector is introduced. The non‐stationary character of the observer presented in this paper requires an adaptive change of observer corrector settings. Such observer structure was implemented on a DSP system and verified experimentally. Both simulation and experimental results show good properties of the proposed observer structure.

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COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 23 no. 4
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 5 May 2015

Konrad Urbanski

The purpose of this paper is to develop the Permanent Magnet Synchronous Motors drive which has possibility to work in sensorless mode at low speed based on back EMFs estimation…

376

Abstract

Purpose

The purpose of this paper is to develop the Permanent Magnet Synchronous Motors drive which has possibility to work in sensorless mode at low speed based on back EMFs estimation.

Design/methodology/approach

Estimation uses modified Luenberger observer and the preprocessing of the EMFs before calculating the speed, using derivative and the Kalman filter (KF) to obtain smooth waveform of the estimated speed. This modification is needed because of the nonlinear change of the estimated back EMFs amplitude as a function of speed, in low-speed range.

Findings

How to use back EMF observer to estimate a speed in the low-speed range was found in the course of the work. Simple and effective algorithm uses KF and can work even with a relatively big deformation of the estimated back EMF.

Practical implications

Such sensorless drive may be used in low-cost constant or variable speed drive in domestic use or industrial application. Such drive may work properly where there is no initial load torque and the sign of the speed does not change.

Originality/value

Presented results challenge the view that at low-speed range (not the standstill), the back EMF-based method of position estimation is very difficult or impossible. However, the problem lays in proper speed estimation, not the position estimation.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 34 no. 3
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 December 1999

Krzysztof Zawirski, Konrad Urbański and Jacek Ferenc

In the paper an application of fuzzy logic controller (FLC) for control of thyristor DC drive is presented. During synthesis of the FLC a robustness against variation of structure…

503

Abstract

In the paper an application of fuzzy logic controller (FLC) for control of thyristor DC drive is presented. During synthesis of the FLC a robustness against variation of structure of the current control plant was taken into account. Comparison between the fuzzy control system and an ordinary digital control system, carried out by simulation method, proved that FLC as a robust controller gives better performance in the range where non‐linearity and parameter variation is observed. The simulation results were confirmed by the laboratory experiment.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 18 no. 4
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 January 2006

Tomasz Pajchrowski, Konrad Urbański and Krzysztof Zawirski

The aim of the paper is to find a simple structure of speed controller robust against drive parameters variations. Application of artificial neural network (ANN) in the controller…

475

Abstract

Purpose

The aim of the paper is to find a simple structure of speed controller robust against drive parameters variations. Application of artificial neural network (ANN) in the controller of PI type creates proper non‐linear characteristics, which ensures controller robustness.

Design/methodology/approach

The robustness of the controller is based on its non‐linear characteristic introduced by ANN. The paper proposes a novel approach to neural controller synthesis to be performed in two stages. The first stage consists in training the ANN to form the proper shape of the control surface, which represents the non‐linear characteristic of the controller. At the second stage, the PI controller settings are adjusted by means of the random weight change (RWC) procedure, which optimises the control quality index formulated in the paper. The synthesis is performed using simulation techniques and subsequently the behaviour of a laboratory speed control system is validated in the experimental set‐up. The control algorithms of the system are performed by a microprocessor floating point DSP control system.

Findings

The proposed controller structure with proper control surface created by ANN guarantees expected robustness.

Originality/value

The original method of robust controller synthesis was proposed and validated by simulation and experimental investigations.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 25 no. 1
Type: Research Article
ISSN: 0332-1649

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Available. Open Access. Open Access
Article
Publication date: 27 September 2022

Olusegun Emmanuel Akinwale and Olusoji James George

The mass exodus of the professional healthcare workforce has become a cankerworm for a developing nation like Nigeria, and this worsens the already depleted healthcare systems in…

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Abstract

Purpose

The mass exodus of the professional healthcare workforce has become a cankerworm for a developing nation like Nigeria, and this worsens the already depleted healthcare systems in underdeveloped nation. This study investigated the rationale behind medical workers' brain-drain syndrome and the quality healthcare delivery in the Nigerian public healthcare sector.

Design/methodology/approach

To stimulate an understanding of the effect of the phenomenon called brain drain, the study adopted a diagnostic research design to survey the public healthcare personnel in government hospitals. The study administered a battery of adapted research scales of different measures to confirm the variables of interest of this study on a probability sampling strategy. The study surveyed 450 public healthcare sector employees from four government hospitals to gather pertinent data. The study used a structural equation model (SEM) and artificial neural networks (ANNs) to analyse the collected data from the medical personnel of government hospitals.

Findings

The findings of this study are significant as postulated. The study discovered that poor quality worklife experienced by Nigerian medical personnel was attributed to the brain-drain effect and poor healthcare delivery. The study further demonstrated that job dissatisfaction suffered among the public healthcare workforce forced the workforce to migrate to the international labour market, and this same factor is a reason for poor healthcare delivery. Lastly, the study discovered that inadequate remuneration and pay discouraged Nigerian professionals and allied healthcare workers from being productive and ultimately pushed them to the global market.

Originality/value

Practically, this study has shown three major elements that caused the mass movement of Nigerian healthcare personnel to other countries of the world and that seems novel given the peculiarity of the Nigerian labour market. The study is original and novel as much study has not been put forward in the public healthcare sector in Nigeria concerning this phenomenon.

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Book part
Publication date: 19 March 2024

Rose Cardarelli and Harley Pomper

Abstract

Details

Children and the Climate Migration Crisis: A Casebook for Global Climate Action in Practice and Policy
Type: Book
ISBN: 978-1-80455-910-9

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Book part
Publication date: 15 December 2015

Jared Friedman, Anthony Ian Jack, Kylie Rochford and Richard Boyatzis

Recent neuroscience research shows that two large-scale cortical networks are involved in organizational behavior. These two networks are naturally antagonistic – when one is…

Abstract

Recent neuroscience research shows that two large-scale cortical networks are involved in organizational behavior. These two networks are naturally antagonistic – when one is active the other tends to be suppressed. The focus of the chapter is to apply the opposing-domains hypothesis to problems associated with: (1) trying to balance creative thinking and global processing with analytic reasoning and focused attention; (2) avoiding ethical dangers associated with an imbalance in task positive network (TPN) and default mode network (DMN) thinking; and (3) properly motivating and incentivizing employees so as not to lead to an imbalance between the TPN and DMN. We contend that the opposing-domains hypothesis can inform organizational and leadership theory in areas where single-dimensional dual-process models are inadequate.

Details

Organizational Neuroscience
Type: Book
ISBN: 978-1-78560-430-0

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