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Mahmoud A. Gaafar
Aswan Power Electronics Applications Research Center (APEARC), Faculty of Engineering, Aswan University, Aswan 81542, Egypt

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Journal article
Published: 24 August 2021 in Sustainability
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Switched reluctance machines (SRMs) have received increasing attention for their many potential uses, such as for wind power and electric vehicle (EV) drive systems. The Quasi-Z-source Integrated Multiport Converter (QZIMPC) was recently introduced to improve the reliability of the SRM driver through small capacitance values. It is not possible, however, to simultaneously energize and deenergize two SRM phases in QZIMPC. This phenomenon can significantly increase the commutation period which, in turn, degrades the performance of SRM; in addition, this causes high-voltage ripples on the converter’s capacitors. Two switching algorithms are introduced and applied in this paper, and their performance with SRM is investigated in terms of torque ripple and peak phase current. The algorithms are based on prioritizing the control command in the on-going and off-going phases to fulfill the required load torque, as well as to accelerate the commutation process where possible. This is achieved without the interference of high-level controllers, which include speed controllers and/or torque ripple minimization. Through the simulation results, a comparison between the two switching algorithms is presented to determine their potential to improve the SRM drive system’s performance.

ACS Style

Mahmoud A. Gaafar; Arwa Abdelmaksoud; Mohamed Orabi; Hao Chen; Mostafa Dardeer. Performance Investigation of Switched Reluctance Motor Driven by Quasi-Z-Source Integrated Multiport Converter with Different Switching Algorithms. Sustainability 2021, 13, 9517 .

AMA Style

Mahmoud A. Gaafar, Arwa Abdelmaksoud, Mohamed Orabi, Hao Chen, Mostafa Dardeer. Performance Investigation of Switched Reluctance Motor Driven by Quasi-Z-Source Integrated Multiport Converter with Different Switching Algorithms. Sustainability. 2021; 13 (17):9517.

Chicago/Turabian Style

Mahmoud A. Gaafar; Arwa Abdelmaksoud; Mohamed Orabi; Hao Chen; Mostafa Dardeer. 2021. "Performance Investigation of Switched Reluctance Motor Driven by Quasi-Z-Source Integrated Multiport Converter with Different Switching Algorithms." Sustainability 13, no. 17: 9517.

Journal article
Published: 13 September 2019 in IEEE Transactions on Power Electronics
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This paper proposes a novel single-phase micro-inverter fit to process the power of two photovoltaic (PV) modules; in a modular way. The proposed topology combines a full bridge inverter integrated with two DC-DC boost converters, in addition to a DC link consists of switched capacitor (SC) networks. The operating modes of the proposed topology are illustrated. The voltage stress of all components is identified. A modulation technique along with a control system are developed for proper operation of the proposed topology. A comparative study with other topologies is introduced and shows the following merits for the proposed one: 1) the power of two PV modules can be harvested individually or simultaneously without any circulating current issues, 2) very high gain can be acquired; thus no series connection of PV modules is required for grid-tie applications, 3) Transformer-less operation, 4) multi-level shaping of the output voltage; thus reduced filter size is required, and 5) self-balancing for the DC-link capacitors; thus simple control systems can be used. The performance of the 7-level version of the proposed topology is validated using real-time simulation and experimental prototype under grid-tie and stand-alone conditions, respectively

ACS Style

Eltaib Abdeen D. Ibrahim; Mahmoud A. Gaafar; Mohamed Orabi; Ahmed Sheir; Mohamed Z. Youssef; Eltaib Abedeen. A Novel Dual-Input High-Gain Transformerless Multilevel Single-Phase Microinverter for PV Systems. IEEE Transactions on Power Electronics 2019, 35, 4703 -4714.

AMA Style

Eltaib Abdeen D. Ibrahim, Mahmoud A. Gaafar, Mohamed Orabi, Ahmed Sheir, Mohamed Z. Youssef, Eltaib Abedeen. A Novel Dual-Input High-Gain Transformerless Multilevel Single-Phase Microinverter for PV Systems. IEEE Transactions on Power Electronics. 2019; 35 (5):4703-4714.

Chicago/Turabian Style

Eltaib Abdeen D. Ibrahim; Mahmoud A. Gaafar; Mohamed Orabi; Ahmed Sheir; Mohamed Z. Youssef; Eltaib Abedeen. 2019. "A Novel Dual-Input High-Gain Transformerless Multilevel Single-Phase Microinverter for PV Systems." IEEE Transactions on Power Electronics 35, no. 5: 4703-4714.

Journal article
Published: 25 May 2019 in Energies
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This paper presents a multi-input Ćuk-derived Buck-Boost voltage source inverter (CBBVSI) for Photovoltaic (PV) systems. The proposed topology consists of a single-stage DC-AC inverter that combines both DC-DC and DC-AC stages. The DC-DC stage is used for stepping-up the voltage from the PV generator. Simultaneously, the DC-AC stage is used for interfacing the PV source with the AC grid. The topology allows three sources to utilize the antiparallel diodes for each inverter leg for transferring the energy. The proposed system exhibits several features such as a reduction of the number of components compared to typical two-stage structures, and Split-Source Inverter (SSI), and Z-Source Inverter (ZSI) topologies. Moreover, the power of each PV source can be harvested either simultaneously or separately since independent Maximum Power Point Tracking (MPPT) is performed. The system was simulated using MATLAB/SIMULINK software and a 1 kW laboratory prototype was implemented to verify the operation of the proposed CBBVSI. The numerical simulations are presented together with the experimental results, showing a good agreement.

ACS Style

Eltaib Abdeen; Mahmoud A. Gaafar; Mohamed Orabi; Emad M. Ahmed; Abdelali El Aroudi. Multi-Input Ćuk-Derived Buck-Boost Voltage Source Inverter for Photovoltaic Systems in Microgrid Applications. Energies 2019, 12, 2007 .

AMA Style

Eltaib Abdeen, Mahmoud A. Gaafar, Mohamed Orabi, Emad M. Ahmed, Abdelali El Aroudi. Multi-Input Ćuk-Derived Buck-Boost Voltage Source Inverter for Photovoltaic Systems in Microgrid Applications. Energies. 2019; 12 (10):2007.

Chicago/Turabian Style

Eltaib Abdeen; Mahmoud A. Gaafar; Mohamed Orabi; Emad M. Ahmed; Abdelali El Aroudi. 2019. "Multi-Input Ćuk-Derived Buck-Boost Voltage Source Inverter for Photovoltaic Systems in Microgrid Applications." Energies 12, no. 10: 2007.

Proceedings article
Published: 01 May 2019 in 2019 IEEE International Symposium on Predictive Control of Electrical Drives and Power Electronics (PRECEDE)
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This paper presents a model predictive control (MPC) system for multi-level microinverter operated for the applications of module-based Photovoltaic (PV) configurations. A microinverter topology consists of switched capacitor (SC) networks, boost converter and single-phase inverter; all are integrated in one power stage and connected to single PV module. In this paper, a model predictive control system is introduced to reduce the steady state error of the grid-injected current and assure harvesting the maximum power from the PV module. In addition to enhance the response time during the transient condition and reduce the total harmonic distortion (THD) without using any modulation schemes. The proposed control on the multilevel microinverter topology is verified using MATLAB-Simulink and OPAL-RT LAB tools.

ACS Style

Eltaib Abdeen; Mahmoud A. Gaafar; Mohamed Orabi; Fengxiang Wang. Predictive Control of Multi-Level Single Phase Microinverter. 2019 IEEE International Symposium on Predictive Control of Electrical Drives and Power Electronics (PRECEDE) 2019, 1 -5.

AMA Style

Eltaib Abdeen, Mahmoud A. Gaafar, Mohamed Orabi, Fengxiang Wang. Predictive Control of Multi-Level Single Phase Microinverter. 2019 IEEE International Symposium on Predictive Control of Electrical Drives and Power Electronics (PRECEDE). 2019; ():1-5.

Chicago/Turabian Style

Eltaib Abdeen; Mahmoud A. Gaafar; Mohamed Orabi; Fengxiang Wang. 2019. "Predictive Control of Multi-Level Single Phase Microinverter." 2019 IEEE International Symposium on Predictive Control of Electrical Drives and Power Electronics (PRECEDE) , no. : 1-5.

Conference paper
Published: 01 March 2019 in 2019 IEEE Applied Power Electronics Conference and Exposition (APEC)
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This paper proposes a transformer-less high gain multi-level single phase micro-inverter. The proposed topology integrates full-bridge inverter into DC link consists of switched capacitors network. By a proper connection of the DC link capacitors, the output voltage levels can be generated. A proper modulation and control algorithms have been developed for the proposed topology. Compared to other micro-inverters, the proposed one offers much higher gain along with multi-level shaping of the output voltage. The operating modes of the proposed topology are illustrated. The voltage stress of all components is identified. Simulation and experimental validation for the proper operation of the 7-level version of the proposed topology are carried out.

ACS Style

Eltaib Abdeen; Mahmoud A. Gaafar; Mohamed Orabi; Mohamed Youssef. A Novel High Gain Single-phase Transformer-less Multi-level Micro-inverter. 2019 IEEE Applied Power Electronics Conference and Exposition (APEC) 2019, 3263 -3268.

AMA Style

Eltaib Abdeen, Mahmoud A. Gaafar, Mohamed Orabi, Mohamed Youssef. A Novel High Gain Single-phase Transformer-less Multi-level Micro-inverter. 2019 IEEE Applied Power Electronics Conference and Exposition (APEC). 2019; ():3263-3268.

Chicago/Turabian Style

Eltaib Abdeen; Mahmoud A. Gaafar; Mohamed Orabi; Mohamed Youssef. 2019. "A Novel High Gain Single-phase Transformer-less Multi-level Micro-inverter." 2019 IEEE Applied Power Electronics Conference and Exposition (APEC) , no. : 3263-3268.

Conference paper
Published: 01 December 2017 in 2017 Nineteenth International Middle East Power Systems Conference (MEPCON)
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Conventional LED drive has a limited lifetime due to present of bulky electrolytic output capacitor (E-Cap) which is essential to make the power difference balancing between the constant output power and the pulsating input power. In fact, LED chip has a longer lifetime than E-Cap. Therefore, it is insufficient to use this type of capacitors in LED driver. Increasing the LED lamp lifetime can be achieved through changing the E-Cap with Film or Ceramic one. But the LED current peak will be double as a result of using low energy density capacitors. However, the LED can be driven by a pulsating current with a defined peak value. Peak to average ratio (PTAR) of LED current has to be limited (less than 1.4) to save LED from overdriven, failure and flux saturation. Recently, the methodology of injecting a predefined value of harmonics to limit the PTAR is costly and complex to be used in interior and exterior LED applications. This paper will present an optimization methodology for the LED driver control circuitry to be simpler and more cost-effective. Three major parameters will constrain the design of the control circuitry are cost reduction, lifetime expansion and simplicity in implementation. The feasibility of the proposed control circuit has been verified by simulation and real prototyping as well.

ACS Style

Mahmoud Nassary; Mohamed Orabi; Emad M. Ahmed; El-Sayed Hasaneen; Mahmoud Gaafar. Modified harmonic injection technique for electrolytic capacitor-less LED driver. 2017 Nineteenth International Middle East Power Systems Conference (MEPCON) 2017, 1459 -1464.

AMA Style

Mahmoud Nassary, Mohamed Orabi, Emad M. Ahmed, El-Sayed Hasaneen, Mahmoud Gaafar. Modified harmonic injection technique for electrolytic capacitor-less LED driver. 2017 Nineteenth International Middle East Power Systems Conference (MEPCON). 2017; ():1459-1464.

Chicago/Turabian Style

Mahmoud Nassary; Mohamed Orabi; Emad M. Ahmed; El-Sayed Hasaneen; Mahmoud Gaafar. 2017. "Modified harmonic injection technique for electrolytic capacitor-less LED driver." 2017 Nineteenth International Middle East Power Systems Conference (MEPCON) , no. : 1459-1464.

Conference paper
Published: 22 September 2016 in 2015 IEEE International Telecommunications Energy Conference (INTELEC)
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Active damping of grid-connected LCL filter resonance by means of an observer loop to estimate the capacitor current is a well-known method. However, with variation of the grid side inductance due to grid conditions, the system robustness has to be checked. This work discusses the effect of the observer design on the system robustness against grid side inductance variation. Different values of resonant frequency, lower and higher than a critical value of one-sixth of the sampling frequency, are considered to clarify the system robustness at different resonant frequencies. Simulation and experimental results are presented to confirm the system operation at specific values of grid side inductance and resonant frequency.

ACS Style

Mahmoud A. Gaafar; Gamal M. Dousoky; Masahito Shoyama. Robustness analysis for observer based active damping of LCL filter at different resonant frequencies. 2015 IEEE International Telecommunications Energy Conference (INTELEC) 2016, 1 -6.

AMA Style

Mahmoud A. Gaafar, Gamal M. Dousoky, Masahito Shoyama. Robustness analysis for observer based active damping of LCL filter at different resonant frequencies. 2015 IEEE International Telecommunications Energy Conference (INTELEC). 2016; ():1-6.

Chicago/Turabian Style

Mahmoud A. Gaafar; Gamal M. Dousoky; Masahito Shoyama. 2016. "Robustness analysis for observer based active damping of LCL filter at different resonant frequencies." 2015 IEEE International Telecommunications Energy Conference (INTELEC) , no. : 1-6.

Journal article
Published: 20 July 2016 in Journal of Power Electronics
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ACS Style

Mahmoud A. Gaafar; Emad M. Ahmed; Masahito Shoyama. A Two State Feedback Active Damping Strategy for the LCL Filter Resonance in Grid-Connected Converters. Journal of Power Electronics 2016, 16, 1587 -1597.

AMA Style

Mahmoud A. Gaafar, Emad M. Ahmed, Masahito Shoyama. A Two State Feedback Active Damping Strategy for the LCL Filter Resonance in Grid-Connected Converters. Journal of Power Electronics. 2016; 16 (4):1587-1597.

Chicago/Turabian Style

Mahmoud A. Gaafar; Emad M. Ahmed; Masahito Shoyama. 2016. "A Two State Feedback Active Damping Strategy for the LCL Filter Resonance in Grid-Connected Converters." Journal of Power Electronics 16, no. 4: 1587-1597.

Conference paper
Published: 01 March 2016 in 2016 IEEE Applied Power Electronics Conference and Exposition (APEC)
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Two feedback active damping technique for LCL filter resonance is proposed using the capacitor voltage and the grid current. The proposed method is derived in continuous time domain with discussion for its discrete implementation. Based on the proposed method, excitation of un-stable open loop pools, which implies non-minimum phase behavior, can be avoided over a wide range of resonant frequencies; Co-design procedures for both the active damping loops along with the fundamental current regulator are presented. Numerical example and simulation work are presented to confirm the performance of the proposed method at different resonant frequencies.

ACS Style

Mahmoud Gaafar; Gamal M. Dousoky; Masahito Shoyama. New active damping method for LCL filter resonance based on two feedback system. 2016 IEEE Applied Power Electronics Conference and Exposition (APEC) 2016, 2735 -2741.

AMA Style

Mahmoud Gaafar, Gamal M. Dousoky, Masahito Shoyama. New active damping method for LCL filter resonance based on two feedback system. 2016 IEEE Applied Power Electronics Conference and Exposition (APEC). 2016; ():2735-2741.

Chicago/Turabian Style

Mahmoud Gaafar; Gamal M. Dousoky; Masahito Shoyama. 2016. "New active damping method for LCL filter resonance based on two feedback system." 2016 IEEE Applied Power Electronics Conference and Exposition (APEC) , no. : 2735-2741.

Conference paper
Published: 01 November 2015 in IECON 2015 - 41st Annual Conference of the IEEE Industrial Electronics Society
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This paper proposes a new active damping method for LCL filter resonance. The proposed method employs a dual feedback loop of the capacitor voltage and the grid current. Based on the proposed method, non-minimum phase behavior can be avoided over a wide range of resonant frequencies. Co-design procedures for both the active damping loops along with the fundamental current regulator are introduced. The proposed method is derived in continuous time domain as well as discussed in discrete form for digital implementation. The performance of the proposed method is verified numerically at different values of resonant frequency. Moreover, simulation work is presented to confirm the numerical results.

ACS Style

Mahmoud A. Gaafar; Gamal M. Dousoky; Masahito Shoyama. Dual feedback active damping method for grid-connected LCL filter resonance. IECON 2015 - 41st Annual Conference of the IEEE Industrial Electronics Society 2015, 003821 -003826.

AMA Style

Mahmoud A. Gaafar, Gamal M. Dousoky, Masahito Shoyama. Dual feedback active damping method for grid-connected LCL filter resonance. IECON 2015 - 41st Annual Conference of the IEEE Industrial Electronics Society. 2015; ():003821-003826.

Chicago/Turabian Style

Mahmoud A. Gaafar; Gamal M. Dousoky; Masahito Shoyama. 2015. "Dual feedback active damping method for grid-connected LCL filter resonance." IECON 2015 - 41st Annual Conference of the IEEE Industrial Electronics Society , no. : 003821-003826.

Conference paper
Published: 01 September 2014 in 2014 IEEE Energy Conversion Congress and Exposition (ECCE)
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LCL filters are widely used for grid-connected converters because its superiority over L and LC filters, however the resonance problem produced by these filters requires a more effort in the design process to damp it. Active damping techniques which use the sensed capacitor current are widely used in this regard to solve this problem; however this requires an increase in the number of sensors. Based on the optimum design for PI controller, this paper introduces an active damping method based on the capacitor estimated current without increase in the number of sensors. This is achieved by using an additional observer loop as a feedback in the controller loop to estimate the capacitor current. The simulation results for the proposed control algorithm are introduced in this work.

ACS Style

Mahmoud A. Gaafar; Masahito Shoyama. Active damping for grid-connected LCL filter based on optimum controller design using injected grid current feedback only. 2014 IEEE Energy Conversion Congress and Exposition (ECCE) 2014, 3628 -3633.

AMA Style

Mahmoud A. Gaafar, Masahito Shoyama. Active damping for grid-connected LCL filter based on optimum controller design using injected grid current feedback only. 2014 IEEE Energy Conversion Congress and Exposition (ECCE). 2014; ():3628-3633.

Chicago/Turabian Style

Mahmoud A. Gaafar; Masahito Shoyama. 2014. "Active damping for grid-connected LCL filter based on optimum controller design using injected grid current feedback only." 2014 IEEE Energy Conversion Congress and Exposition (ECCE) , no. : 3628-3633.

Conference paper
Published: 01 September 2014 in 2014 IEEE 36th International Telecommunications Energy Conference (INTELEC)
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PWM converters are widely used to connect the distributed energy sources to the grid. LCL filters are widely used for these converters because its superiority over L and LC filters, however the resonance problem produced by these filters requires a more effort in the design process to damp it. Active damping techniques which use the sensed capacitor current are widely used in this regard to solve this problem; however this requires an increase in the number of sensors. Based on the optimum design for proportional plus resonant (P+R) controller, this paper introduces an active damping method based on the capacitor estimated current without increase in the number of sensors. This is achieved by using an additional observer loop as a feedback in the controller loop to estimate the capacitor current. The simulation results and the experimental verification for the proposed control algorithm are introduced in this work.

ACS Style

Mahmoud A. Gaafar; Masahito Shoyama. Active damping for grid-connected LCL filter based on optimum P+R controller design using injected grid current feedback only. 2014 IEEE 36th International Telecommunications Energy Conference (INTELEC) 2014, 1 -6.

AMA Style

Mahmoud A. Gaafar, Masahito Shoyama. Active damping for grid-connected LCL filter based on optimum P+R controller design using injected grid current feedback only. 2014 IEEE 36th International Telecommunications Energy Conference (INTELEC). 2014; ():1-6.

Chicago/Turabian Style

Mahmoud A. Gaafar; Masahito Shoyama. 2014. "Active damping for grid-connected LCL filter based on optimum P+R controller design using injected grid current feedback only." 2014 IEEE 36th International Telecommunications Energy Conference (INTELEC) , no. : 1-6.