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Syed Rahman
Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX 77843, USA

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Journal article
Published: 25 July 2021 in Electronics
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This paper presents a novel, scalable, and modular multiport power electronic topology for the integration of multiple resources. This converter is not only scalable in terms of the integration of multiple renewable energy resources (RES) and storage devices (SDs) but is also scalable in terms of output ports. Multiple dc outputs of a converter are designed to serve as input to the stacking modules (SMs) of the modular multilevel converter (MMC). The proposed multiport converter is bidirectional in nature and superior in terms of functionality in a way that a modular universal converter is responsible for the integration of multiple RES/SDs and regulates multiple dc output ports for SMs of MMC. All input ports can be easily integrated (and controlled), and output ports also can be controlled independently in response to any load variations. An isolated active half-bridge converter with multiple secondaries acts as a central hub for power processing with multiple renewable energy resources that are integrated at the primary side. To verify the proposed converter, a detailed design of the converter-based system is presented along with the proposed control algorithm for managing power on the individual component level. Additionally, different modes of power management (emulating the availability/variability of renewable energy sources (RES)) are exhibited and analyzed here. Finally, detailed simulation results are presented in detail for the validation of the proposed concepts and design process.

ACS Style

Syed Rahman; Irfan Khan; Khaliqur Rahman; Sattam Al Otaibi; Hend Alkhammash; Atif Iqbal. Scalable Multiport Converter Structure for Easy Grid Integration of Alternate Energy Sources for Generation of Isolated Voltage Sources for MMC. Electronics 2021, 10, 1779 .

AMA Style

Syed Rahman, Irfan Khan, Khaliqur Rahman, Sattam Al Otaibi, Hend Alkhammash, Atif Iqbal. Scalable Multiport Converter Structure for Easy Grid Integration of Alternate Energy Sources for Generation of Isolated Voltage Sources for MMC. Electronics. 2021; 10 (15):1779.

Chicago/Turabian Style

Syed Rahman; Irfan Khan; Khaliqur Rahman; Sattam Al Otaibi; Hend Alkhammash; Atif Iqbal. 2021. "Scalable Multiport Converter Structure for Easy Grid Integration of Alternate Energy Sources for Generation of Isolated Voltage Sources for MMC." Electronics 10, no. 15: 1779.

Review
Published: 20 June 2021 in Electronics
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The development of offshore wind farms (WF) is inevitable as they have exceptional resistance against climate change and produce clean energy without hazardous wastes. The offshore WF usually has a bigger generation capacity with less environmental impacts, and it is more reliable too due to stronger and consistent sea winds. The early offshore WF installations are located near the shore, whereas most modern installations are located far away from shore, generating higher power. This paradigm shift has forced the researchers and industry personnel to look deeper into transmission options, namely, high voltage AC transmission (HVAC) and high voltage DC transmission (HVDC). This evaluation can be both in terms of power carrying capability as well as cost comparisons. Additionally, different performance requirements such as power rating, onshore grid requirements, reactive power compensation, etc., must be considered for evaluation. This paper elaborately reviews and explains the offshore wind farm structure and performance requirements for bulk offshore power transfer. Based on the structure and performance requirements, both HVDC and HVAC transmission modes are compared and analyzed critically. Finally, a criterion for selection and increasing popularity of HVDC transmission is established.

ACS Style

Syed Rahman; Irfan Khan; Hend Alkhammash; Muhammad Nadeem. A Comparison Review on Transmission Mode for Onshore Integration of Offshore Wind Farms: HVDC or HVAC. Electronics 2021, 10, 1489 .

AMA Style

Syed Rahman, Irfan Khan, Hend Alkhammash, Muhammad Nadeem. A Comparison Review on Transmission Mode for Onshore Integration of Offshore Wind Farms: HVDC or HVAC. Electronics. 2021; 10 (12):1489.

Chicago/Turabian Style

Syed Rahman; Irfan Khan; Hend Alkhammash; Muhammad Nadeem. 2021. "A Comparison Review on Transmission Mode for Onshore Integration of Offshore Wind Farms: HVDC or HVAC." Electronics 10, no. 12: 1489.

Journal article
Published: 01 December 2020 in IEEE Transactions on Power Electronics
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A new Interleaved Multilevel Boost Converter is presented with minimal Voltage Multiplier (VM) cells for high voltage step-up applications. The Interleaved-MBC is derived in such a way that maximum utilization of the voltage multiplier (VM) circuit operation can be achieved by the interleaved structure. Furthermore, compared to existing multilevel interleaved converters, the reduced number of capacitors and diode with equal voltage rating makes more attractive. Similar to existing multilevel converter, the feature of the Interleaved-MBC provides the extension of the number of levels to achieve the necessary voltages just by adding similar capacitor-diode stages (single capacitor and diode required to increase the stage by 1). The continuous input current, low input ripples, high voltage conversion ratio, reduced stress on devices,possible to feed from a single or double source, makes this more suitable for the voltage step-up applications, such as DC Link, hybrid Distribution Systems (DS), hybrid photovoltaic (PV) systems. The detailed analysis of the converter carried out by considering the non-idealities in the power circuit. The detail operation of the Interleaved-MBC is presented for Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM) with boundary conditions. Experimental results are provided to validate the proposed circuit.

ACS Style

Mohammad Meraj; Mahajan Sagar Bhaskar; Atif Iqbal; Nasser Al-Emadi; Syed Rahman. Interleaved Multilevel Boost Converter With Minimal Voltage Multiplier Components for High-Voltage Step-Up Applications. IEEE Transactions on Power Electronics 2020, 35, 12816 -12833.

AMA Style

Mohammad Meraj, Mahajan Sagar Bhaskar, Atif Iqbal, Nasser Al-Emadi, Syed Rahman. Interleaved Multilevel Boost Converter With Minimal Voltage Multiplier Components for High-Voltage Step-Up Applications. IEEE Transactions on Power Electronics. 2020; 35 (12):12816-12833.

Chicago/Turabian Style

Mohammad Meraj; Mahajan Sagar Bhaskar; Atif Iqbal; Nasser Al-Emadi; Syed Rahman. 2020. "Interleaved Multilevel Boost Converter With Minimal Voltage Multiplier Components for High-Voltage Step-Up Applications." IEEE Transactions on Power Electronics 35, no. 12: 12816-12833.

Journal article
Published: 20 August 2020 in IEEE Transactions on Power Electronics
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Phase Shifted Pulse Width Modulation (PS-PWM) is a well-known switching technique for Quasi Z Source (qZS) based Cascaded Multilevel Inverters (qZS-CMI). PS-PWM ensures equal power distribution (among operating modules) and equal switchings in all the semiconductors of the every given module, however this technique suffers from higher number of switchings. On the other hand, Level Shifted Pulse Width Modulation (LS-PWM) ensures optimal switching but suffers from uneven distribution of power among the all the operating modules and also the all the semiconductors of the same module, of qZSI. This article proposes a novel switching technique which combines the advantages of both PS-PWM and LS-PWM such as equal power distribution (among operating modules) and optimal switching sequence along with equal switch utilization. The proposed method is Phase Opposed Disposed, Phase Shifted Pulse Width Modulation (PODPS-PWM). The paper details the switching technique, along with switching loss analysis and compares it with the PS-PWM technique to show its superiority. Simulation results are carried out to study the CMLI performance. Experimental prototype is developed to validate the performance of the proposed modulation.

ACS Style

Mohammad Meraj; Syed Rahman; Atif Iqbal; Lazhar Ben-Brahim; Haitham A. Abu-Rub. Novel Level-Shifted PWM Technique for Equal Power Sharing Among Quasi-Z-Source Modules in Cascaded Multilevel Inverter. IEEE Transactions on Power Electronics 2020, 36, 4766 -4777.

AMA Style

Mohammad Meraj, Syed Rahman, Atif Iqbal, Lazhar Ben-Brahim, Haitham A. Abu-Rub. Novel Level-Shifted PWM Technique for Equal Power Sharing Among Quasi-Z-Source Modules in Cascaded Multilevel Inverter. IEEE Transactions on Power Electronics. 2020; 36 (4):4766-4777.

Chicago/Turabian Style

Mohammad Meraj; Syed Rahman; Atif Iqbal; Lazhar Ben-Brahim; Haitham A. Abu-Rub. 2020. "Novel Level-Shifted PWM Technique for Equal Power Sharing Among Quasi-Z-Source Modules in Cascaded Multilevel Inverter." IEEE Transactions on Power Electronics 36, no. 4: 4766-4777.

Journal article
Published: 16 December 2019 in IEEE Transactions on Industry Applications
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This paper presents the design and implementation of solar powered V/f controlled single phase capacitor start induction motor. Multi Level Quasi Impedance Source Inverter (MLqZSI) controls the power flowing from PV array to single - phase induction motor. In solar powered drive systems, main concern is stable intended operation of drive when subjected to variations in power generation of PV array. For same environmental conditions, PV power extraction is different at different torques for constant speed application. Due to this, extraction of maximum power with MPPT algorithm is not achieved with only motor load. To address this concern, concept of battery storage system is introduced in the system which helps in achieving maximum power when PV power generation capability exceeds rated motor input power. In addition to this, battery storage system can supply power to the load when PV power generation is less than the rated motor input power. Conclusively, design of control algorithm must address issues of MPPT algorithm, control of battery storage system and stable operation of V/f - controlled induction motor drive operation. MATLAB®/ Simulink model of the proposed system with 4kW PV array rating is developed. Proposed Control Algorithm achieves satisfactory operation of single - phase motor drive in all the three operation modes (depending upon PV power generation). Variation of solar irradiation and temperature are simultaneously considered for introducing perturbation in the PV power generation. Hardware results for this system are also presented which validates the effectiveness of the control algorithm for the proposed system.

ACS Style

Syed Rahman; Mohammad Meraj; Atif Iqbal; Mohd Tariq; Ali Iftekhar Maswood; Lazhar Ben-Brahim; Rashid Al-Ammari; Rahman Syed; Meraj Mohammad. Design and Implementation of Cascaded Multilevel qZSI Powered Single-Phase Induction Motor for Isolated Grid Water Pump Application. IEEE Transactions on Industry Applications 2019, 56, 1907 -1917.

AMA Style

Syed Rahman, Mohammad Meraj, Atif Iqbal, Mohd Tariq, Ali Iftekhar Maswood, Lazhar Ben-Brahim, Rashid Al-Ammari, Rahman Syed, Meraj Mohammad. Design and Implementation of Cascaded Multilevel qZSI Powered Single-Phase Induction Motor for Isolated Grid Water Pump Application. IEEE Transactions on Industry Applications. 2019; 56 (2):1907-1917.

Chicago/Turabian Style

Syed Rahman; Mohammad Meraj; Atif Iqbal; Mohd Tariq; Ali Iftekhar Maswood; Lazhar Ben-Brahim; Rashid Al-Ammari; Rahman Syed; Meraj Mohammad. 2019. "Design and Implementation of Cascaded Multilevel qZSI Powered Single-Phase Induction Motor for Isolated Grid Water Pump Application." IEEE Transactions on Industry Applications 56, no. 2: 1907-1917.

Journal article
Published: 07 November 2019 in IEEE Journal of Emerging and Selected Topics in Power Electronics
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ACS Style

Mohammad Meraj; Syed Rahman; Atif Iqbal; Nasser Al Emadi. Novel Level Shifted PWM Technique for Unequal and Equal Power Sharing in Quasi Z-Source Cascaded Multilevel Inverter for PV Systems. IEEE Journal of Emerging and Selected Topics in Power Electronics 2019, 9, 937 -948.

AMA Style

Mohammad Meraj, Syed Rahman, Atif Iqbal, Nasser Al Emadi. Novel Level Shifted PWM Technique for Unequal and Equal Power Sharing in Quasi Z-Source Cascaded Multilevel Inverter for PV Systems. IEEE Journal of Emerging and Selected Topics in Power Electronics. 2019; 9 (1):937-948.

Chicago/Turabian Style

Mohammad Meraj; Syed Rahman; Atif Iqbal; Nasser Al Emadi. 2019. "Novel Level Shifted PWM Technique for Unequal and Equal Power Sharing in Quasi Z-Source Cascaded Multilevel Inverter for PV Systems." IEEE Journal of Emerging and Selected Topics in Power Electronics 9, no. 1: 937-948.

Journal article
Published: 18 September 2019 in IEEE Access
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Inherent buck–boost capability, reduced component count, controlled power injection and multilevel operation are some of the advantages which makes cascaded qZSI popular for integrating the generated solar energy with the utility grid. Phase– Shifted Carrier PWM (PSCPWM) and Pulse Width Amplitude Modulation (PWAM) are the most popular techniques for achieving multilevel qZSI operation. Generally, closed loop control implementation of three – phase qZSI system consists of large number of slave controllers (placed locally for voltage control) and one centralized master controller (for grid integration or load current control). Since the aim is to control single system with this highly distributed control structure, issues of clock pulse and interrupt signal synchronization, hardware and software redundancy are common in these implementations. This limits the utilization factor and step size of these control boards. To address these issues, either more optimized solutions must be suggested, or distribution of control structure must be reduced. In this paper, closed loop control of nine – level three – phase qZSI system is implemented using single FPGA control board thereby eliminating above said problems. Since, PWAM control algorithm is more complex than PSCPWM, FPGA based implementation for PWAM control is discussed. Critical implementation processes consisting of DAC – ADC interfacing, FPGA code per unitization, PI Controller realization and different clock pulse utilization are presented. For highlighting and comparing the resource consumption, PWAM and PSCPWM modulation are compared in terms of device utilization. Transient analysis and control algorithm are presented and validated during both starting and load transient conditions by means of simulation results. Finally, hardware results of these modulation methods are discussed and analyzed.

ACS Style

Syed Rahman; Mohammad Meraj; Atif Iqbal; Lazhar Ben-Brahim. Optimized FPGA Implementation of PWAM-Based Control of Three—Phase Nine—Level Quasi Impedance Source Inverter. IEEE Access 2019, 7, 137279 -137290.

AMA Style

Syed Rahman, Mohammad Meraj, Atif Iqbal, Lazhar Ben-Brahim. Optimized FPGA Implementation of PWAM-Based Control of Three—Phase Nine—Level Quasi Impedance Source Inverter. IEEE Access. 2019; 7 (99):137279-137290.

Chicago/Turabian Style

Syed Rahman; Mohammad Meraj; Atif Iqbal; Lazhar Ben-Brahim. 2019. "Optimized FPGA Implementation of PWAM-Based Control of Three—Phase Nine—Level Quasi Impedance Source Inverter." IEEE Access 7, no. 99: 137279-137290.

Journal article
Published: 12 September 2019 in IEEE Transactions on Industry Applications
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Requirement of large number of levels with lower number of switching devices has made asymmetrical converters more popular than the symmetrical ones. Asymmetrical cascaded multilevel inverters (ACMLI) can achieve high efficiency by combining switching devices with different voltage ratings and technologies. The proposed ACMLI cascades two or more units of packed U-Cell (PUC) inverters using two or more isolated DC link supplies. In this paper, one of the PUC unit is controlled using high switching frequency while the other PUCs are operated in a step mode at low switching frequencies, thus operating them in a variable frequency control mode. The cascading of two 7-level PUC inverters with DC link voltage ratios of 1:7 can produce an output voltage with 49 (7x7) levels. The multi-level output voltage waveform is nearly sinusoidal with very low THD content, and the low switching frequency operation leads to lower power dissipation and greater system efficiency. However, each PUC module requires two dc voltage sources. To address this concern, in this manuscript, each PUC module consists of one dc voltage source and one dc bus capacitor. With the cascaded PUC topology and proposed control algorithm, load current and dc bus capacitor voltage control is achieved simultaneously. The proposed converter and its control technique lead to the breaking of the design trade-off rule between switching frequency (efficiency) and filter size. This is very useful in various applications such as Uninterruptible Power Supplies (UPS), and grid-tie inverters. The converter and its control technique are simulated using MATLAB/Simulink software and simulation results for both open loop and closed loop are discussed. Hardware results are obtained by developing a 1-KW experimental prototype. Simulation and experimental results confirm the usefulness and effectiveness of the proposed topology and its control technique.

ACS Style

Mohammad Meraj; Syed Rahman; A. Iqbal; Mohd Tariq; Kaif Ahmed Lodi; Lazhar Ben-Brahim. A New Variable Frequency Control of 49-Level Cascaded Packed U-Cell Voltage Source Inverter. IEEE Transactions on Industry Applications 2019, 55, 7537 -7548.

AMA Style

Mohammad Meraj, Syed Rahman, A. Iqbal, Mohd Tariq, Kaif Ahmed Lodi, Lazhar Ben-Brahim. A New Variable Frequency Control of 49-Level Cascaded Packed U-Cell Voltage Source Inverter. IEEE Transactions on Industry Applications. 2019; 55 (6):7537-7548.

Chicago/Turabian Style

Mohammad Meraj; Syed Rahman; A. Iqbal; Mohd Tariq; Kaif Ahmed Lodi; Lazhar Ben-Brahim. 2019. "A New Variable Frequency Control of 49-Level Cascaded Packed U-Cell Voltage Source Inverter." IEEE Transactions on Industry Applications 55, no. 6: 7537-7548.

Journal article
Published: 15 July 2019 in IEEE Access
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In energy efficient system designs, LED lighting leads to reduction in global energy demand. This paper proposes a high brightness, high efficiency, dimmable LED driver based on linear current regulator technology for DC grid distribution systems. The proposed driver has excellent characteristics like highest lumen per watt, long lifetime, high reliability, compact, low cost, both environmental and user friendly which makes it suitable for lighting applications. Steady state and small signal model of the proposed driver are performed which helps in minimizing ground current and accurate compensator design, respectively. These two modelling approaches result in the optimization of both footprint and cost of the driver. The performance of the proposed 20W driver is modeled using real-time simulation in spice software. Experimental prototype is developed to validate the performance of the proposed driver for different dimming levels and achieves a maximum efficiency of 97%.

ACS Style

Mohammad Meraj; Syed Rahman; Atif Iqbal; Lazhar Ben-Brahim. High Brightness and High Voltage Dimmable LED Driver for Advanced Lighting System. IEEE Access 2019, 7, 95643 -95652.

AMA Style

Mohammad Meraj, Syed Rahman, Atif Iqbal, Lazhar Ben-Brahim. High Brightness and High Voltage Dimmable LED Driver for Advanced Lighting System. IEEE Access. 2019; 7 ():95643-95652.

Chicago/Turabian Style

Mohammad Meraj; Syed Rahman; Atif Iqbal; Lazhar Ben-Brahim. 2019. "High Brightness and High Voltage Dimmable LED Driver for Advanced Lighting System." IEEE Access 7, no. : 95643-95652.

Journal article
Published: 18 January 2019 in Electronics
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Multiphase (more than three) power system has gained popularity due to their inherent advantages when compared to three-phase counterpart. Multiphase power supply is extensively used in AC/DC multi-pulse converters, especially supply with multiple of three-phases. AC/DC converter with multi-pulse input is a popular solution to reduce the ripple in the DC output. Single-phase and three-phase transformers and phase transformation from single to multiphase are employed in variable speed drives application to feed the multi-cell H-Bridge converters and multi-pulse AC-DC converters. Six-phase system is extensively discussed in the literature for numerous applications ranging from variable speed drives to multiphase wind energy generation system. This paper shows the systematic phase transformation technique from three-phase to six-phase (both symmetrical and asymmetrical) for both understanding and teaching purposes. Such an approach could help students understand a promising advanced concept in their undergraduate courses. When phase difference between the two consecutive phases of six phases has a phase difference of 60, it is called a symmetrical six-phase system; while an asymmetrical or quasi, six-phase has two set of three-phase with a phase shift of 30 between the two sets. Simulation and experimental results are also presented.

ACS Style

Rashid Al-Ammari; Atif Iqbal; Amith Khandakar; Syed Rahman; Sanjeevikumar Padmanaban. Systematic Implementation of Multi-Phase Power Supply (Three to Six) Conversion System. Electronics 2019, 8, 109 .

AMA Style

Rashid Al-Ammari, Atif Iqbal, Amith Khandakar, Syed Rahman, Sanjeevikumar Padmanaban. Systematic Implementation of Multi-Phase Power Supply (Three to Six) Conversion System. Electronics. 2019; 8 (1):109.

Chicago/Turabian Style

Rashid Al-Ammari; Atif Iqbal; Amith Khandakar; Syed Rahman; Sanjeevikumar Padmanaban. 2019. "Systematic Implementation of Multi-Phase Power Supply (Three to Six) Conversion System." Electronics 8, no. 1: 109.