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Goal: 1-develop the whole drive system model: a multiphase PMaSynRM and a multiphase matrix converter. 2-performance improvement via redesign of the main system components: PMaSynRM and matrix converter. 3-demonstrate and study the reliability of the whole drive system.
The torque density and efficiency of synchronous reluctance machines (SynRMs) are greatly affected by the geometry of the rotor. Hence, an optimal design of the SynRM rotor geometry is highly recommended to achieve optimal performance (i.e., torque density, efficiency, and power factor). This paper studies the impact of considering the current angle as a variable during the optimization process on the resulting optimal geometry of the SynRM rotor. Various cases are analyzed and compared for different ranges of current angles during the optimization process. The analysis is carried out using finite element magnetic simulation. The obtained optimal geometry is prototyped for validation purposes. It is observed that when considering the effect of the current angle during the optimization process, the output power of the optimal geometry is about 3.32% higher than that of a fixed current angle case. In addition, during the optimization process, the case which considers the current angle as a variable has reached the optimal rotor geometry faster than that of a fixed current angle case. Moreover, it is observed that for a fixed current angle case, the torque ripple is affected by the selected value of the current angle. The torque ripple is greatly decreased by about 34.20% with a current angle of 45° compared to a current angle of 56.50°, which was introduced in previous literature.
Hegazy Rezk; Kotb B. Tawfiq; Peter Sergeant; Mohamed Ibrahim. Optimal Rotor Design of Synchronous Reluctance Machines Considering the Effect of Current Angle. Mathematics 2021, 9, 344 .
AMA StyleHegazy Rezk, Kotb B. Tawfiq, Peter Sergeant, Mohamed Ibrahim. Optimal Rotor Design of Synchronous Reluctance Machines Considering the Effect of Current Angle. Mathematics. 2021; 9 (4):344.
Chicago/Turabian StyleHegazy Rezk; Kotb B. Tawfiq; Peter Sergeant; Mohamed Ibrahim. 2021. "Optimal Rotor Design of Synchronous Reluctance Machines Considering the Effect of Current Angle." Mathematics 9, no. 4: 344.
The interest in motor drive systems with a number of phases greater than three has increased, mainly in high-power industrial fields due to their advantages compared with three-phase drive systems. In this paper, comprehensive mathematical modeling of a five-phase matrix converter (MC) is introduced. Besides that, the direct and indirect space vector modulation (SVM) control methods are compared and analyzed. Furthermore, a mathematical model for the MC with the transformation between the indirect and direct topology is constructed. The indirect technique is used to control the five-phase MC with minimum switching losses. In this technique, SVM deals with a five-phase MC as a virtual two-stage converter with a virtual DC link (i.e., rectifier and inverter stages). The voltage gain is limited to a value of 0.79. Moreover, to analyze the effectiveness of the control technique and the advantages of the MC, a static R-L load is employed. However, the load can also be an industrial load, such as hospital pumping or vehicular applications. The presented analysis proves that the MC gives a wide range of output frequencies, and it has the ability to control the input displacement factor and the output voltage magnitude. In addition, the absence of the massive DC link capacitors is an essential feature for the MC, resulting in increased reliability and a reduced size converter. Eventually, an experimental validation is conducted on a static load to validate the presented model and the control method. It is observed that good matching between the simulation and the experimental results is achieved.
Kotb B. Tawfiq; Mohamed N. Ibrahim; Hegazy Rezk; Elwy E. El-Kholy; Peter Sergeant. Mathematical Modelling, Analysis and Control of a Three to Five-Phase Matrix Converter for Minimal Switching Losses. Mathematics 2021, 9, 96 .
AMA StyleKotb B. Tawfiq, Mohamed N. Ibrahim, Hegazy Rezk, Elwy E. El-Kholy, Peter Sergeant. Mathematical Modelling, Analysis and Control of a Three to Five-Phase Matrix Converter for Minimal Switching Losses. Mathematics. 2021; 9 (1):96.
Chicago/Turabian StyleKotb B. Tawfiq; Mohamed N. Ibrahim; Hegazy Rezk; Elwy E. El-Kholy; Peter Sergeant. 2021. "Mathematical Modelling, Analysis and Control of a Three to Five-Phase Matrix Converter for Minimal Switching Losses." Mathematics 9, no. 1: 96.
In this paper, a new topology for a shunt active power filter using a matrix converter is proposed. The topology analysis, description of the associated control technique, steady-state and dynamic performance are also presented in this study. The proposed topology doesn’t contain the bulky DC-link capacitor. In addition, the parameters of the proposed filter are robust against the change in the load and the THD percentage is the same under this condition. So, the proposed filter parameters don’t require to be retuned with load change. Moreover, a simple and compact form can be realized. The reference currents are calculated using a synchronous reference frame theory. Space vector modulation and hysteresis current control are used to control the rectifier and inverter stages in the indirect matrix converter to obtain the required injected filter current. Finally, a simulation model and an experimental prototype are implemented using Matlab/Simulink program and DSP1104, respectively with a detailed analysis to the obtained results which confirm the effectiveness and the high accuracy performance of the proposed topology.
Kotb B. Tawfiq; Arafa S. Mansour; Mohamed N. Ibrahim; E. E. El-Kholy; Peter Sergeant. Design, implementation and performance analysis of shunt active filter based on a matrix converter. International Journal of Electronics 2020, 108, 395 -410.
AMA StyleKotb B. Tawfiq, Arafa S. Mansour, Mohamed N. Ibrahim, E. E. El-Kholy, Peter Sergeant. Design, implementation and performance analysis of shunt active filter based on a matrix converter. International Journal of Electronics. 2020; 108 (3):395-410.
Chicago/Turabian StyleKotb B. Tawfiq; Arafa S. Mansour; Mohamed N. Ibrahim; E. E. El-Kholy; Peter Sergeant. 2020. "Design, implementation and performance analysis of shunt active filter based on a matrix converter." International Journal of Electronics 108, no. 3: 395-410.
This paper investigates the performance of 3-phase synchronous reluctance machines (SynRMs) when upgrading their stator to 5-phase, keeping the same rotor. The design of the 5-phase stator has been optimized to select the optimal dimensions of the slots and teeth. Moreover, a combined star-pentagon winding is employed to further improve the machine performance. Different winding configurations have been studied and compared using 2D Ansys Maxwell transient simulations. It is observed that at optimal current angle and rated current, the average torque is increased by 17.41% when changing the 3-phase stator with the proposed 5-phase one. In addition, the efficiency of the 5-phase SynRM is increased by about 0.8% compared to 3-phase SynRM. At 3 times the rated speed, the torque and efficiency are significantly increased by around 33% and 3.5% respectively. Moreover, the 5-phase SynRM shows a superior performance in the faulty case with one phase opened. It works at 98.84% of the rated torque of the healthy 3-phase machine, whereas the 3-phase machine works at only 43.35% with huge torque ripple (228%). Finally, an experimental validation using the reference 3-phase machine has been done.
Kotb B. Tawfiq; Mohamed N. Ibrahim; E. E. El-Kholy; Peter Sergeant. Performance Improvement of Existing Three Phase Synchronous Reluctance Machine: Stator Upgrading to 5-Phase With Combined Star-Pentagon Winding. IEEE Access 2020, 8, 143569 -143583.
AMA StyleKotb B. Tawfiq, Mohamed N. Ibrahim, E. E. El-Kholy, Peter Sergeant. Performance Improvement of Existing Three Phase Synchronous Reluctance Machine: Stator Upgrading to 5-Phase With Combined Star-Pentagon Winding. IEEE Access. 2020; 8 (99):143569-143583.
Chicago/Turabian StyleKotb B. Tawfiq; Mohamed N. Ibrahim; E. E. El-Kholy; Peter Sergeant. 2020. "Performance Improvement of Existing Three Phase Synchronous Reluctance Machine: Stator Upgrading to 5-Phase With Combined Star-Pentagon Winding." IEEE Access 8, no. 99: 143569-143583.
Refurbishing electrical machines to have a higher performance and/or reliability is a clear trend in the circular economy. This paper investigates the gain in efficiency, torque density and reliability with replacing the windings and the iron of the stator of existing three-phase synchronous reluctance machines (SynRMs), resulting in a multiphase machine. The stator housing, shaft, bearings and the rotor are not changed, to keep the cost of refurbishing low. As the housing and rotor are kept, logical constraints are to have the same inner and/or outer stator diameters, air gap length and axial length. In the new windings, an identical copper volume is considered as a constraint. An optimization technique is coupled to 2D finite element method to select the optimal slot dimensions. Case studies showed that it is possible to replace the stator of existing three-phase SynRMs with a better performance multiphase one. It is found that the average torque, efficiency and power factor of the five-phase SynRM are increased by 11.78%, 0.72% and 5.54%, respectively, compared to a three-phase SynRM at rated conditions. At higher speeds (three times rated value), the efficiency and average torque are greatly improved by about 3.64% and 33.67%, respectively, compared to the three-phase SynRM. Moreover, a faulty case of one phase opened is also investigated. The five-phase SynRM works at 75.45% of the healthy rated torque of the three-phase SynRM, whereas the three-phase SynRM works at only 43%. Measurements on an existing 5.5-kW, three-phase SynRM confirm the observed results.
Kotb B. Tawfiq; Mohamed N. Ibrahim; E. E. El-Kholy; Peter Sergeant. Refurbishing three-phase synchronous reluctance machines to multiphase machines. Electrical Engineering 2020, 103, 139 -152.
AMA StyleKotb B. Tawfiq, Mohamed N. Ibrahim, E. E. El-Kholy, Peter Sergeant. Refurbishing three-phase synchronous reluctance machines to multiphase machines. Electrical Engineering. 2020; 103 (1):139-152.
Chicago/Turabian StyleKotb B. Tawfiq; Mohamed N. Ibrahim; E. E. El-Kholy; Peter Sergeant. 2020. "Refurbishing three-phase synchronous reluctance machines to multiphase machines." Electrical Engineering 103, no. 1: 139-152.
In this article, different matrix converter (MC) control strategies are comprehensively explained. Further, an ultra-modified space vector modulation (UMSVM) of the MC is proposed. The total harmonic distortion for both output voltage and current is reduced, when the proposed UMSVM technique is applied. Moreover, a modified indirect space vector modulation with feed forward controller (MISVMFC) of the MC is also proposed in order to obtain a fixed output voltage and frequency for different wind speeds. The advantages of the MC are introduced in this article. These advantages include the wide range of the output frequency of MC, which may be greater than the input frequency and the control of both the output voltage magnitude and input displacement factor (IDF). Extensive theoretical and simulation results about conventional and proposed control techniques for the MC are presented. Experimental test bench is constructed and several experimental results are obtained. The experimental results validate the simulation ones.
Kotb B. Tawfiq; Arafa S. Mansour; Mohamed N. Ibrahim; Elwy El-Kholy; Peter Sergeant. Implementation of Matrix Converter in Wind Energy Conversion System with Modified Control Techniques. Electric Power Components and Systems 2019, 47, 1316 -1331.
AMA StyleKotb B. Tawfiq, Arafa S. Mansour, Mohamed N. Ibrahim, Elwy El-Kholy, Peter Sergeant. Implementation of Matrix Converter in Wind Energy Conversion System with Modified Control Techniques. Electric Power Components and Systems. 2019; 47 (14-15):1316-1331.
Chicago/Turabian StyleKotb B. Tawfiq; Arafa S. Mansour; Mohamed N. Ibrahim; Elwy El-Kholy; Peter Sergeant. 2019. "Implementation of Matrix Converter in Wind Energy Conversion System with Modified Control Techniques." Electric Power Components and Systems 47, no. 14-15: 1316-1331.
Sources of renewable energy such as wind energy are indigenous and can help in decreasing the reliance on non-renewable energy sources. After introducing the history of wind energy production in Egypt and worldwide besides its techno-economic importance, this paper presents a comparative review on the wind energy conversion systems (WECS). The horizontal and vertical types of wind turbines with their mathematical dynamic models are discussed. Different types of electrical generators used in WECS in addition to their advantages and disadvantages are illustrated. The various AC-AC converters topologies for WECS are explained with a detailed discussion for their features.
Kotb B. Tawfiq; Arafa S. Mansour; Haitham S. Ramadan; Mohamed Becherif; E.E. El-Kholy. Wind Energy Conversion System Topologies and Converters: Comparative Review. Energy Procedia 2019, 162, 38 -47.
AMA StyleKotb B. Tawfiq, Arafa S. Mansour, Haitham S. Ramadan, Mohamed Becherif, E.E. El-Kholy. Wind Energy Conversion System Topologies and Converters: Comparative Review. Energy Procedia. 2019; 162 ():38-47.
Chicago/Turabian StyleKotb B. Tawfiq; Arafa S. Mansour; Haitham S. Ramadan; Mohamed Becherif; E.E. El-Kholy. 2019. "Wind Energy Conversion System Topologies and Converters: Comparative Review." Energy Procedia 162, no. : 38-47.
Keeping in mind the end goal to address energy issues, considering financial and natural variables, a Wind Energy Conversion System (WECS) is bit-by-bit gaining interest as the suitable source of renewable energy. In this chapter, a direct AC-AC Matrix Converter (MC) is utilized to interface an isolated static load fed from the WECS. Due to the advantage of lower cost, maintenance simplicity and short circuit self-protection, the self-excited induction generator is used to generate electric energy. The MC is used instead of the conventional rectifier-inverter converter because it does not contain the bulky size capacitor, the ability of controlling the input displacement factor and the unity factor can be achieved. Moreover, the MC can be provided in a simple construction, and gives a wide range of output frequency. In comparison with cycloconverter, the MC can give an output frequency that may be equal, less or greater than input frequency. This chapter introduces a modified algorithm for space vector modulation that reduces the total harmonic distortion of the output voltage so the size and cost of the required filter can be reduced. Moreover, a modified open loop control of matrix converter with indirect space vector modulation is introduced to provide constant frequency and output voltage even if the wind speed changed.
Kotb B. Tawfiq; A. F. Abdou; E. E. El-Kholy. Wind Energy System with Matrix Converter. Energy Internet and We-Energy 2017, 143 -174.
AMA StyleKotb B. Tawfiq, A. F. Abdou, E. E. El-Kholy. Wind Energy System with Matrix Converter. Energy Internet and We-Energy. 2017; ():143-174.
Chicago/Turabian StyleKotb B. Tawfiq; A. F. Abdou; E. E. El-Kholy. 2017. "Wind Energy System with Matrix Converter." Energy Internet and We-Energy , no. : 143-174.