This paper investigates the feasibility of electrical power generation using differently orientat... more This paper investigates the feasibility of electrical power generation using differently orientated photovoltaic (PV) modules attached to vertical surfaces. The global horizontal irradiance (GHI) has been measured to verify the commonly used corresponding mathematical models. However, the solar irradiances on vertical surfaces are calculated concerning directional orientation using recently validated mathematical models of similar climates. A selected case representing the predominant construction style for houses in Kuwait was used to examine the PV configuration proposed on the house's façade at different promising orientations, east, west, and south. The total generated electrical power from the three promising façades (100 MW) is almost twice the roof's amount (57 MW). A detailed economic evaluation using lifecycle cost analysis (LCC) was conducted through a 25 years plan. It includes a suggested investment plan for the annual cash resulted from avoided conventional elec...
Fuel cell based vehicles when compared with conventional vehicles are relatively more efficient i... more Fuel cell based vehicles when compared with conventional vehicles are relatively more efficient in terms of energy conversion and dose not pose any threat to climate due to no emissions of hazardous gases. An implementation of closed loop speed control of a separately excited dc motor for vehicle applications using dSPACE DSP is proposed in this paper. The dc motor is fed by a proton exchange membrane (PEM) fuel cell through boost converter. Experimental verification has been carried out using dSPACE DS1103-based digital signal processor. The system robustness and transient response have also been studied under sudden load changes to prove feasibility.
2017 IEEE International Workshop On Integrated Power Packaging (IWIPP), 2017
The quasi Z-source power factor correction (QZS-PFC) in the range of 36–720W is analyzed for cont... more The quasi Z-source power factor correction (QZS-PFC) in the range of 36–720W is analyzed for continuous conduction mode operation and compared with a classical flyback power factor correction (F-PFC) under the same operation conditions. A very precise closed loop duty ratio control was developed to optimize the performance of the QZS-PFC. The selected topology of QZS-PFC is compared with traditional F-PFC operating in continuous conduction mode (CCM) and the study confirms that it operates better than the F-PFC at different power ratings. The major advantage of QZS-PFC is its high performance, and ability to accommodate higher load than the traditional F-PFC. The total harmonic distortion (THD) for the QZS-PFC was considerably low when load were increasing; the value for the THD% reached the standardized limits of 5% while operation at load of 360 W and above. Moreover, the power factor value is close to one across the range of operation with minimal voltage and current ripple. It w...
Small-signal analysis of boost converter fed permanent magnet DC (PMDC) motor for electric vehicl... more Small-signal analysis of boost converter fed permanent magnet DC (PMDC) motor for electric vehicle applications is performed, and hardware implementation is realized in this paper. Extensive analysis is performed to identify the relevant steady-state and dynamic features of the proposed system with small-signal linearization, and relevant transfer functions are formulated. The nonlinear equations of the system are derived and then linearized around a stable operating point to construct a small-signal model. Transfer functions relating the control of the converter to the motor speed and control to input current are derived symbolically using computerized symbolic algebra in MathCAD. The control-to-output transfer functions are obtained by introducing perturbation in state variables, equating AC and DC quantities and proceeding with AC quantities. The principle of operation, operation modes, small-signal analysis, experimental verification, and the effectiveness of the speed control a...
Twentieth Annual IEEE Applied Power Electronics Conference and Exposition, 2005. APEC 2005.
ABSTRACT This paper presents a two-switch boost-half bridge one stage power conversion circuit to... more ABSTRACT This paper presents a two-switch boost-half bridge one stage power conversion circuit topology of commercial single-phase utility frequency AC fed ZVS-PWM power converter with harmonic current suppression and unity power factor correction functions. This cost effective utility frequency AC (UFAC) to high frequency AC (HFAC) power converter is developed for consumer induction heating (IH) appliances. This two-switch boost-half bridge one stage UFAC to HFAC power converter includes some advantages as simple configuration and control scheme, low cost, utility AC side harmonic current reduction with unity power factor, and constant frequency ZVS-PWM for power regulation. Its operating principle is described and discussed herein. In addition to this, its operating performances are illustrated and estimated on the basis of simulation and experimental results. An active voltage clamped ZVS-PWM high frequency inverter with boost function and its characteristics are also evaluated as compared with two-switch boost-half bridge power converter treated here
... 1 ~~~T 2277kHz (c) Switching voltage and current waveforms ofQs. Current axis: 40 A/div, Volt... more ... 1 ~~~T 2277kHz (c) Switching voltage and current waveforms ofQs. Current axis: 40 A/div, Voltage axis: 100 V/div, Time axis: 10 p/sdiv Figure 8. Measured voltage and current switching waveforms ofQl, Qs &L. 1221 T el I Page 6. PWM-ZVS area 12.5 25 37.5 Duty Cycle ...
International Journal of Electrical Power & Energy Systems, 2013
Selective harmonic elimination-pulse width modulation techniques offer a tight control of the har... more Selective harmonic elimination-pulse width modulation techniques offer a tight control of the harmonic spectrum of a given voltage waveform generated by a power electronic converter along with a low number of switching transitions. Traditional optimization methods suffer from various drawbacks, such as prolonged and tedious computational steps and convergence to local optima; thus, the more the number of harmonics to be eliminated, the larger the computational complexity and time. This paper presents a novel method for output voltage harmonic elimination and voltage control of PWM AC/AC voltage converters using the principle of hybrid Real-Coded Genetic Algorithm-Pattern Search (RGA-PS) method. RGA is the primary optimizer exploiting its global search capabilities, PS is then employed to fine tune the best solution provided by RGA in each evolution. The proposed method enables linear control of the fundamental component of the output voltage and complete elimination of its harmonic contents up to a specified order. Theoretical studies have been carried out to show the effectiveness and robustness of the proposed method of selective harmonic elimination. Theoretical results are validated through simulation studies using PSIM software package. Finally, these results are verified by means of an experimental prototype.
IEE Proceedings - Electric Power Applications, 2006
Page 1. Boost-half-bridge edge resonant soft switching PWM high-frequency inverter for consumer i... more Page 1. Boost-half-bridge edge resonant soft switching PWM high-frequency inverter for consumer induction heating appliances NA Ahmed and M. Nakaoka Abstract: A novel soft-switching PWM utility frequency AC to high-frequency ...
This paper describes a new drive for single-phase induction motors. This new drive employs a sing... more This paper describes a new drive for single-phase induction motors. This new drive employs a single controlled device to operate as a d.c. chopper switch which may be a GTO or a thyristor. The chopper switch is actuated to effect integral-cycle control for the voltage applied on the motor. The proposed drive is not only suitable for-integral-cycle control but it is also suitable for frequency control as well as phase-angle control. With such a scheme, the single-phase induction motor is able to exhibit a wide speed range; a property which it does not normally possess. The study includes theoretical and experimental results. 0 1997 Elsevier Science S.A.
This article proposes a hybrid energy system combining solar photovoltaic and wind turbine as a s... more This article proposes a hybrid energy system combining solar photovoltaic and wind turbine as a small-scale alternative source of electrical energy where conventional generation is not practical. A simple and cost-effective control technique has been proposed for maximum ...
This paper presents a novel circuit topology of a high efficiency single-phase power conditioner.... more This paper presents a novel circuit topology of a high efficiency single-phase power conditioner. This power conditioner is composed of time-sharing sinewave absolute pulse width modulated boost chopper with a bypass diode in the first power processing stage and time-sharing sinewave pulse width modulated full-bridge inverter in the second power processing stage operated by time-sharing dual mode pulse pattern control scheme. The unique operating principle of the two power processing stage with time-sharing dual mode sinewave modulation scheme is described with a design example. This paper proposes also a sinewave tracking voltage controlled soft switching PWM boost chopper with a passive auxiliary edge-resonant snubber. The new conceptual operating principle of this novel power conditioner related to new energy utilization system is presented and discussed through the experimental results.
2017 IEEE 6th International Conference on Renewable Energy Research and Applications (ICRERA), 2017
In this paper a new electric power structure for solar powered unmanned aircraft system is propos... more In this paper a new electric power structure for solar powered unmanned aircraft system is proposed. The presented topology is a prospective improvement to both Solong and Zyphyr models. The proposed UAS model utilized Zyphry UAS by using ac bus-line instead of dc bus-line to supply the propellers. The system involves PV array, lithium sulfur based energy management system, dc bus-line, inverter, active output filter (AOF) and ac bus-line. AOF topology is utilized to reduce the power conversion system size. The system is investigated under nonlinear load condition with closed-loop control strategy. Active compensation resistance technique control is deployed to ensure high quality sinusoidal line voltages. It introduces an emulated resistance in series with H-bridges stage, this active resistance will create an injected voltage across it to damp unwanted harmonics created from the nonlinear load. The obtained simulation results of voltage and current waveforms prove the feasibility and the accuracy of the proposed system.
This paper introduces an interleaved buck-boost converter with reduced power electronics devices ... more This paper introduces an interleaved buck-boost converter with reduced power electronics devices count in comparison with the conventional topology. The proposed converter consists of a single buck converter followed by n parallel interleaved boost converters. The buck switch is gated only if any of the boost switches is gated. In addition to the reduced switches count, the proposed converter offers the following advantages, soft start-up and shutdown capabilities. In addition, the buck stage gives the ability to protect the power electronic devices and to isolate the supply during load failure or overload. Moreover, the proposed converter performs as an interleaved boost converter for high voltage gain requirements with the same switching scheme. Furthermore, it offers fast dynamic performance with smooth transition from the buck mode to the boost mode. This paper investigates the eight different operating zones of the proposed three-phase interleaved buck-boost converter for non-overlapping gate signals operation. The detailed analysis and zones of operation are presented and experimentally validated. In addition, a simple control system is presented to operate the proposed converter as dc-dc converter or ac-dc converter. More study cases are carried out to evaluate the different capabilities of the proposed converter. INDEX TERMS Interleaved buck-boost converter, ac-dc converter, and dc-dc converter.
2019 IEEE 6th International Conference on Engineering Technologies and Applied Sciences (ICETAS), 2019
This paper presents the optimal distributed generators (DG) placement and sizing in a power syste... more This paper presents the optimal distributed generators (DG) placement and sizing in a power system using genetic algorithm (GA) and particle swarm optimization (PSO) techniques. GA and PSO optimization techniques are modeled to be suitable for the application to any real power system and used to solve the optimal load flow, where the objective function is performed to minimize system losses. The correctness and effectiveness of both methods are analyzed and compared. The effect of optimal DG location and sizing on power system losses, voltage profile and voltage stability are studied. The presented optimization algorithms are investigated and examined on the standard IEEE 33 bus system and the advantage and reliability of the proposed approach will be discussed in detail.
This paper presents a novel three-phase utility frequency to high frequency soft switching power ... more This paper presents a novel three-phase utility frequency to high frequency soft switching power conversion circuit with dual mode pulse width modulation and pulse density modulation for high power induction heating applications as melting of steel and non ferrous metals, annealing of metals, surface hardening of steel and cast iron work pieces and hot water producers, steamers and super heated steamers. This high frequency power conversion circuit can operate from three-phase systems to produce high current for high power induction heating applications under the principles of ZVS and it can regulate its ac output power from the rated value to a low power level. A dual mode modulation control scheme based on high frequency PWM in synchronization with the utility frequency positive and negative half cycles for the proposed high frequency conversion circuit and utility frequency pulse density modulation is produced to extend its soft switching operating range for wide ac output power ...
This paper proposes to enhance the execution requirements of the solar photovoltaic (PV) street l... more This paper proposes to enhance the execution requirements of the solar photovoltaic (PV) street lighting system in Kuwait. A strength, weakness, opportunity and threat (SWOT) analysis was performed...
In this paper, a comparative study assessing net metering and feed-in tariffs is proposed for gri... more In this paper, a comparative study assessing net metering and feed-in tariffs is proposed for grid-connected photovoltaic (PV) systems in the Kuwaiti market. This study measures the impact of the two mechanisms as well as a mechanism combining both approaches in deploying solar energy systems in residential areas. The advantages and disadvantages of each approach are inspected to determine the optimal approach for Kuwaiti market conditions. A feasibility study on installing a roof-mounted PV system in a typical Kuwaiti residential building is utilized to validate the optimum solar electricity mechanism. The proposed study intends to reduce the peak load demand in Kuwait’s electric grid as a solution to the shortage of electric production capacity by encouraging investors and house owners to invest in solar energy. PV*Sol premium 2018 (R10) and RETScreen software packages are utilized to perform the assessment and study analysis.
This paper investigates the feasibility of electrical power generation using differently orientat... more This paper investigates the feasibility of electrical power generation using differently orientated photovoltaic (PV) modules attached to vertical surfaces. The global horizontal irradiance (GHI) has been measured to verify the commonly used corresponding mathematical models. However, the solar irradiances on vertical surfaces are calculated concerning directional orientation using recently validated mathematical models of similar climates. A selected case representing the predominant construction style for houses in Kuwait was used to examine the PV configuration proposed on the house's façade at different promising orientations, east, west, and south. The total generated electrical power from the three promising façades (100 MW) is almost twice the roof's amount (57 MW). A detailed economic evaluation using lifecycle cost analysis (LCC) was conducted through a 25 years plan. It includes a suggested investment plan for the annual cash resulted from avoided conventional elec...
Fuel cell based vehicles when compared with conventional vehicles are relatively more efficient i... more Fuel cell based vehicles when compared with conventional vehicles are relatively more efficient in terms of energy conversion and dose not pose any threat to climate due to no emissions of hazardous gases. An implementation of closed loop speed control of a separately excited dc motor for vehicle applications using dSPACE DSP is proposed in this paper. The dc motor is fed by a proton exchange membrane (PEM) fuel cell through boost converter. Experimental verification has been carried out using dSPACE DS1103-based digital signal processor. The system robustness and transient response have also been studied under sudden load changes to prove feasibility.
2017 IEEE International Workshop On Integrated Power Packaging (IWIPP), 2017
The quasi Z-source power factor correction (QZS-PFC) in the range of 36–720W is analyzed for cont... more The quasi Z-source power factor correction (QZS-PFC) in the range of 36–720W is analyzed for continuous conduction mode operation and compared with a classical flyback power factor correction (F-PFC) under the same operation conditions. A very precise closed loop duty ratio control was developed to optimize the performance of the QZS-PFC. The selected topology of QZS-PFC is compared with traditional F-PFC operating in continuous conduction mode (CCM) and the study confirms that it operates better than the F-PFC at different power ratings. The major advantage of QZS-PFC is its high performance, and ability to accommodate higher load than the traditional F-PFC. The total harmonic distortion (THD) for the QZS-PFC was considerably low when load were increasing; the value for the THD% reached the standardized limits of 5% while operation at load of 360 W and above. Moreover, the power factor value is close to one across the range of operation with minimal voltage and current ripple. It w...
Small-signal analysis of boost converter fed permanent magnet DC (PMDC) motor for electric vehicl... more Small-signal analysis of boost converter fed permanent magnet DC (PMDC) motor for electric vehicle applications is performed, and hardware implementation is realized in this paper. Extensive analysis is performed to identify the relevant steady-state and dynamic features of the proposed system with small-signal linearization, and relevant transfer functions are formulated. The nonlinear equations of the system are derived and then linearized around a stable operating point to construct a small-signal model. Transfer functions relating the control of the converter to the motor speed and control to input current are derived symbolically using computerized symbolic algebra in MathCAD. The control-to-output transfer functions are obtained by introducing perturbation in state variables, equating AC and DC quantities and proceeding with AC quantities. The principle of operation, operation modes, small-signal analysis, experimental verification, and the effectiveness of the speed control a...
Twentieth Annual IEEE Applied Power Electronics Conference and Exposition, 2005. APEC 2005.
ABSTRACT This paper presents a two-switch boost-half bridge one stage power conversion circuit to... more ABSTRACT This paper presents a two-switch boost-half bridge one stage power conversion circuit topology of commercial single-phase utility frequency AC fed ZVS-PWM power converter with harmonic current suppression and unity power factor correction functions. This cost effective utility frequency AC (UFAC) to high frequency AC (HFAC) power converter is developed for consumer induction heating (IH) appliances. This two-switch boost-half bridge one stage UFAC to HFAC power converter includes some advantages as simple configuration and control scheme, low cost, utility AC side harmonic current reduction with unity power factor, and constant frequency ZVS-PWM for power regulation. Its operating principle is described and discussed herein. In addition to this, its operating performances are illustrated and estimated on the basis of simulation and experimental results. An active voltage clamped ZVS-PWM high frequency inverter with boost function and its characteristics are also evaluated as compared with two-switch boost-half bridge power converter treated here
... 1 ~~~T 2277kHz (c) Switching voltage and current waveforms ofQs. Current axis: 40 A/div, Volt... more ... 1 ~~~T 2277kHz (c) Switching voltage and current waveforms ofQs. Current axis: 40 A/div, Voltage axis: 100 V/div, Time axis: 10 p/sdiv Figure 8. Measured voltage and current switching waveforms ofQl, Qs &L. 1221 T el I Page 6. PWM-ZVS area 12.5 25 37.5 Duty Cycle ...
International Journal of Electrical Power & Energy Systems, 2013
Selective harmonic elimination-pulse width modulation techniques offer a tight control of the har... more Selective harmonic elimination-pulse width modulation techniques offer a tight control of the harmonic spectrum of a given voltage waveform generated by a power electronic converter along with a low number of switching transitions. Traditional optimization methods suffer from various drawbacks, such as prolonged and tedious computational steps and convergence to local optima; thus, the more the number of harmonics to be eliminated, the larger the computational complexity and time. This paper presents a novel method for output voltage harmonic elimination and voltage control of PWM AC/AC voltage converters using the principle of hybrid Real-Coded Genetic Algorithm-Pattern Search (RGA-PS) method. RGA is the primary optimizer exploiting its global search capabilities, PS is then employed to fine tune the best solution provided by RGA in each evolution. The proposed method enables linear control of the fundamental component of the output voltage and complete elimination of its harmonic contents up to a specified order. Theoretical studies have been carried out to show the effectiveness and robustness of the proposed method of selective harmonic elimination. Theoretical results are validated through simulation studies using PSIM software package. Finally, these results are verified by means of an experimental prototype.
IEE Proceedings - Electric Power Applications, 2006
Page 1. Boost-half-bridge edge resonant soft switching PWM high-frequency inverter for consumer i... more Page 1. Boost-half-bridge edge resonant soft switching PWM high-frequency inverter for consumer induction heating appliances NA Ahmed and M. Nakaoka Abstract: A novel soft-switching PWM utility frequency AC to high-frequency ...
This paper describes a new drive for single-phase induction motors. This new drive employs a sing... more This paper describes a new drive for single-phase induction motors. This new drive employs a single controlled device to operate as a d.c. chopper switch which may be a GTO or a thyristor. The chopper switch is actuated to effect integral-cycle control for the voltage applied on the motor. The proposed drive is not only suitable for-integral-cycle control but it is also suitable for frequency control as well as phase-angle control. With such a scheme, the single-phase induction motor is able to exhibit a wide speed range; a property which it does not normally possess. The study includes theoretical and experimental results. 0 1997 Elsevier Science S.A.
This article proposes a hybrid energy system combining solar photovoltaic and wind turbine as a s... more This article proposes a hybrid energy system combining solar photovoltaic and wind turbine as a small-scale alternative source of electrical energy where conventional generation is not practical. A simple and cost-effective control technique has been proposed for maximum ...
This paper presents a novel circuit topology of a high efficiency single-phase power conditioner.... more This paper presents a novel circuit topology of a high efficiency single-phase power conditioner. This power conditioner is composed of time-sharing sinewave absolute pulse width modulated boost chopper with a bypass diode in the first power processing stage and time-sharing sinewave pulse width modulated full-bridge inverter in the second power processing stage operated by time-sharing dual mode pulse pattern control scheme. The unique operating principle of the two power processing stage with time-sharing dual mode sinewave modulation scheme is described with a design example. This paper proposes also a sinewave tracking voltage controlled soft switching PWM boost chopper with a passive auxiliary edge-resonant snubber. The new conceptual operating principle of this novel power conditioner related to new energy utilization system is presented and discussed through the experimental results.
2017 IEEE 6th International Conference on Renewable Energy Research and Applications (ICRERA), 2017
In this paper a new electric power structure for solar powered unmanned aircraft system is propos... more In this paper a new electric power structure for solar powered unmanned aircraft system is proposed. The presented topology is a prospective improvement to both Solong and Zyphyr models. The proposed UAS model utilized Zyphry UAS by using ac bus-line instead of dc bus-line to supply the propellers. The system involves PV array, lithium sulfur based energy management system, dc bus-line, inverter, active output filter (AOF) and ac bus-line. AOF topology is utilized to reduce the power conversion system size. The system is investigated under nonlinear load condition with closed-loop control strategy. Active compensation resistance technique control is deployed to ensure high quality sinusoidal line voltages. It introduces an emulated resistance in series with H-bridges stage, this active resistance will create an injected voltage across it to damp unwanted harmonics created from the nonlinear load. The obtained simulation results of voltage and current waveforms prove the feasibility and the accuracy of the proposed system.
This paper introduces an interleaved buck-boost converter with reduced power electronics devices ... more This paper introduces an interleaved buck-boost converter with reduced power electronics devices count in comparison with the conventional topology. The proposed converter consists of a single buck converter followed by n parallel interleaved boost converters. The buck switch is gated only if any of the boost switches is gated. In addition to the reduced switches count, the proposed converter offers the following advantages, soft start-up and shutdown capabilities. In addition, the buck stage gives the ability to protect the power electronic devices and to isolate the supply during load failure or overload. Moreover, the proposed converter performs as an interleaved boost converter for high voltage gain requirements with the same switching scheme. Furthermore, it offers fast dynamic performance with smooth transition from the buck mode to the boost mode. This paper investigates the eight different operating zones of the proposed three-phase interleaved buck-boost converter for non-overlapping gate signals operation. The detailed analysis and zones of operation are presented and experimentally validated. In addition, a simple control system is presented to operate the proposed converter as dc-dc converter or ac-dc converter. More study cases are carried out to evaluate the different capabilities of the proposed converter. INDEX TERMS Interleaved buck-boost converter, ac-dc converter, and dc-dc converter.
2019 IEEE 6th International Conference on Engineering Technologies and Applied Sciences (ICETAS), 2019
This paper presents the optimal distributed generators (DG) placement and sizing in a power syste... more This paper presents the optimal distributed generators (DG) placement and sizing in a power system using genetic algorithm (GA) and particle swarm optimization (PSO) techniques. GA and PSO optimization techniques are modeled to be suitable for the application to any real power system and used to solve the optimal load flow, where the objective function is performed to minimize system losses. The correctness and effectiveness of both methods are analyzed and compared. The effect of optimal DG location and sizing on power system losses, voltage profile and voltage stability are studied. The presented optimization algorithms are investigated and examined on the standard IEEE 33 bus system and the advantage and reliability of the proposed approach will be discussed in detail.
This paper presents a novel three-phase utility frequency to high frequency soft switching power ... more This paper presents a novel three-phase utility frequency to high frequency soft switching power conversion circuit with dual mode pulse width modulation and pulse density modulation for high power induction heating applications as melting of steel and non ferrous metals, annealing of metals, surface hardening of steel and cast iron work pieces and hot water producers, steamers and super heated steamers. This high frequency power conversion circuit can operate from three-phase systems to produce high current for high power induction heating applications under the principles of ZVS and it can regulate its ac output power from the rated value to a low power level. A dual mode modulation control scheme based on high frequency PWM in synchronization with the utility frequency positive and negative half cycles for the proposed high frequency conversion circuit and utility frequency pulse density modulation is produced to extend its soft switching operating range for wide ac output power ...
This paper proposes to enhance the execution requirements of the solar photovoltaic (PV) street l... more This paper proposes to enhance the execution requirements of the solar photovoltaic (PV) street lighting system in Kuwait. A strength, weakness, opportunity and threat (SWOT) analysis was performed...
In this paper, a comparative study assessing net metering and feed-in tariffs is proposed for gri... more In this paper, a comparative study assessing net metering and feed-in tariffs is proposed for grid-connected photovoltaic (PV) systems in the Kuwaiti market. This study measures the impact of the two mechanisms as well as a mechanism combining both approaches in deploying solar energy systems in residential areas. The advantages and disadvantages of each approach are inspected to determine the optimal approach for Kuwaiti market conditions. A feasibility study on installing a roof-mounted PV system in a typical Kuwaiti residential building is utilized to validate the optimum solar electricity mechanism. The proposed study intends to reduce the peak load demand in Kuwait’s electric grid as a solution to the shortage of electric production capacity by encouraging investors and house owners to invest in solar energy. PV*Sol premium 2018 (R10) and RETScreen software packages are utilized to perform the assessment and study analysis.
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Papers by Nabil Ahmed