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Authors = Gabriel Ekemb

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25 pages, 13060 KiB  
Article
Instantaneous Electromagnetic Torque Components in Synchronous Motors Fed by Load-Commutated Inverters
by Gabriel Ekemb, Fouad Slaoui-Hasnaoui, Joseph Song-Manguelle, P. M. Lingom and Issouf Fofana
Energies 2021, 14(11), 3223; https://doi.org/10.3390/en14113223 - 31 May 2021
Cited by 10 | Viewed by 3289
Abstract
This paper proposes time-domain analytical expressions of the instantaneous pulsating torque components in a synchronous machine air gap when supplied by a load-commutated-inverter (LCI) system. The LCI technology is one of the most used variable frequency drives when very high power and low [...] Read more.
This paper proposes time-domain analytical expressions of the instantaneous pulsating torque components in a synchronous machine air gap when supplied by a load-commutated-inverter (LCI) system. The LCI technology is one of the most used variable frequency drives when very high power and low speed are required in applications such as pipeline recompression and decompression, as well as liquefied natural gas compression. In such applications, synchronous motors are used because of their high efficiency resulting from a separated supply of the current to their rotor through the excitation circuit. These applications usually have long and flexible shafts, which are very sensitive to torsional vibration excitation when their natural frequencies interact with any external torque applied to the shaft. A torsional analysis is required by international standards to assess the survivability of the shaft through the overall speed range of the motor. Therefore, the magnitude and frequencies of the motor air-gap torque are needed for such evaluation. The proposed developments are supported by numerical simulations of LCI systems in a large range of operation range. From the simulation results, torque harmonic families are derived and expressed in a parametric form, which confirm the accuracy of the proposed relationships. Full article
(This article belongs to the Special Issue Design, Analysis and Application of Power Electronics, Motor Drives and Renewable Energy Systems)
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20 pages, 5325 KiB  
Article
Electric Circuit Model for the Aerodynamic Performance Analysis of a Three-Blade Darrieus-Type Vertical Axis Wind Turbine: The Tchakoua Model
by Pierre Tchakoua, René Wamkeue, Mohand Ouhrouche, Ernesto Benini and Gabriel Ekemb
Energies 2016, 9(10), 820; https://doi.org/10.3390/en9100820 - 14 Oct 2016
Cited by 2 | Viewed by 8692
Abstract
The complex and unsteady aerodynamics of vertical axis wind turbines (VAWTs) pose significant challenges for simulation tools. Recently, significant research efforts have focused on the development of new methods for analysing and optimising the aerodynamic performance of VAWTs. This paper presents an electric [...] Read more.
The complex and unsteady aerodynamics of vertical axis wind turbines (VAWTs) pose significant challenges for simulation tools. Recently, significant research efforts have focused on the development of new methods for analysing and optimising the aerodynamic performance of VAWTs. This paper presents an electric circuit model for Darrieus-type vertical axis wind turbine (DT-VAWT) rotors. The novel Tchakoua model is based on the mechanical description given by the Paraschivoiu double-multiple streamtube model using a mechanical‑electrical analogy. Model simulations were conducted using MATLAB for a three-bladed rotor architecture, characterized by a NACA0012 profile, an average Reynolds number of 40,000 for the blade and a tip speed ratio of 5. The results obtained show strong agreement with findings from both aerodynamic and computational fluid dynamics (CFD) models in the literature. Full article
(This article belongs to the Special Issue Wind Turbine 2017)
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34 pages, 1338 KiB  
Article
A New Approach for Modeling Darrieus-Type Vertical Axis Wind Turbine Rotors Using Electrical Equivalent Circuit Analogy: Basis of Theoretical Formulations and Model Development
by Pierre Tchakoua, René Wamkeue, Mohand Ouhrouche, Tommy Andy Tameghe and Gabriel Ekemb
Energies 2015, 8(10), 10684-10717; https://doi.org/10.3390/en81010684 - 25 Sep 2015
Cited by 24 | Viewed by 16578
Abstract
Models are crucial in the engineering design process because they can be used for both the optimization of design parameters and the prediction of performance. Thus, models can significantly reduce design, development and optimization costs. This paper proposes a novel equivalent electrical model [...] Read more.
Models are crucial in the engineering design process because they can be used for both the optimization of design parameters and the prediction of performance. Thus, models can significantly reduce design, development and optimization costs. This paper proposes a novel equivalent electrical model for Darrieus-type vertical axis wind turbines (DTVAWTs). The proposed model was built from the mechanical description given by the Paraschivoiu double-multiple streamtube model and is based on the analogy between mechanical and electrical circuits. This work addresses the physical concepts and theoretical formulations underpinning the development of the model. After highlighting the working principle of the DTVAWT, the step-by-step development of the model is presented. For assessment purposes, simulations of aerodynamic characteristics and those of corresponding electrical components are performed and compared. Full article
(This article belongs to the Special Issue Wind Turbine 2015)
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36 pages, 943 KiB  
Review
Wind Turbine Condition Monitoring: State-of-the-Art Review, New Trends, and Future Challenges
by Pierre Tchakoua, René Wamkeue, Mohand Ouhrouche, Fouad Slaoui-Hasnaoui, Tommy Andy Tameghe and Gabriel Ekemb
Energies 2014, 7(4), 2595-2630; https://doi.org/10.3390/en7042595 - 22 Apr 2014
Cited by 547 | Viewed by 43160
Abstract
As the demand for wind energy continues to grow at exponential rates, reducing operation and maintenance (OM) costs and improving reliability have become top priorities in wind turbine (WT) maintenance strategies. In addition to the development of more highly evolved WT designs intended [...] Read more.
As the demand for wind energy continues to grow at exponential rates, reducing operation and maintenance (OM) costs and improving reliability have become top priorities in wind turbine (WT) maintenance strategies. In addition to the development of more highly evolved WT designs intended to improve availability, the application of reliable and cost-effective condition-monitoring (CM) techniques offers an efficient approach to achieve this goal. This paper provides a general review and classification of wind turbine condition monitoring (WTCM) methods and techniques with a focus on trends and future challenges. After highlighting the relevant CM, diagnosis, and maintenance analysis, this work outlines the relationship between these concepts and related theories, and examines new trends and future challenges in the WTCM industry. Interesting insights from this research are used to point out strengths and weaknesses in today’s WTCM industry and define research priorities needed for the industry to meet the challenges in wind industry technological evolution and market growth. Full article
(This article belongs to the Special Issue Wind Turbines 2014)
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