Nonlinear Representation of Two-Stage Power-Factor-Correction AC/DC Circuits

Orabi Mohamed,Ninomiya Tamotsu The Korean Institute of Power Electronics 2004 JOURNAL OF POWER ELECTRONICS Vol.4 No.4

Two-stage Power-Factor-Correction (PFC) converters are the most common circuits for drawing sinusoidal and in phase current waveforms from an ac source with a good regulated output voltage. The first stage is a boost PFC converter with average-current-mode control for achieving the near-unity power factor and the second stage is a forward converter with voltage-mode control to regulate the output voltage. Stability analysis and design methods of two-stage PFC converters have previously been discussed using linear models. Recently, new nonlinear phenomena have been detected in pre-regulator boost PFC circuits and a new nonlinear model has been proposed for pre-regulated PFC converters. Therefore, investigation of two-stage PFC converters from the nonlinear viewpoint becomes important because the second stage DC/DC converter adds more complexity to the circuit. So, this paper introduces a study of the stability of two-stage PFC converters. A novel nonlinear model of two-stage PFC converters is proposed. Then, a stability analysis is made based upon this nonlinear model. The high correspondence between the simulated and experimental results confirms our analysis.

Step-One in Pre-regulator Boost Power-Factor-Correction Converter Design

Orabi, Mohamed,Ninomiya, Tamotsu The Korean Institute of Power Electronics 2004 JOURNAL OF POWER ELECTRONICS Vol.4 No.1

The output storage capacitor of the PFC converters is commonly designed for the selected hold-up time or the allowed output ripple voltage percentage. Nevertheless, this output capacitor is a main contribution factor to the PFC system stability. Moreover, seeking for a minimum output storage capacitor that assures the PFC desired operation under all condition, and providing the advantage of a small size and low cost is the main interesting target for engineering. Therefore, in this issue the design steps of the PFC converter have been discussed depending on three choices, output ripple, hold-up time, and stability. It is cleared that any design must take the minimum required storage capacitor for stability prospective as step-l in deign, then apply for any other specification like hold-up time or ripple percentage.

Step-One in Pre-regulator Boost Power-Factor-Correction Converter Design

Mohamed Orabi,Tamotsu Ninomiya 전력전자학회 2004 JOURNAL OF POWER ELECTRONICS Vol.4 No.1

The output storage capacitor of the PFC converters is commonly designed for the selected hold-up time or the allowed output ripple voltage percentage Nevertheless, this output capacitor is a main contribution factor to the PFC system stability. Moreover, seeking for a minimum output storage capacitor that assures the PFC desired operation under all condition, and providing the advantage of a small size and low cost is the main interesting target for engineering Therefore, in this issue the design steps of the PFC converter have been discussed depending on three choices, output ripple, hold-up time, and stability It is cleared that any design must take the minimum required storage capacitor for stability prospective as step-1 in deign, then apply for any other specification like hold-up time or ripple percentage

Nonlinear Representation of Two-Stage Power-Factor-Correction AC/DC Circuits

Mohamed Orabi,Tamotsu Ninomiya 전력전자학회 2004 JOURNAL OF POWER ELECTRONICS Vol.4 No.4

Two-stage Power-Factor-Correction (PFC) converters are the most common circuits for drawing sinusoidal and in phase current wave forms from an ac source with a good regulated output voltage. The first stage is a boost PFC converter with average-current-mode control for achieving the near-unity power factor and the second stage is a forward converter with voltage-mode control to regulate the output voltage. Stability analysis and design methods of two-stage PFC converters have previously been discussed using linear models. Recently, new nonlinear phenomena have been detected in pre-regulator boost PFC circuits and a new nonlinear model has been proposed for pre-regulated PFC converters. Therefore, investigation of two-stage PFC converters from the nonlinear viewpoint becomes important because the second stage DC/DC converter adds more complexity to the circuit. So, this paper introduces a study of the stability of two-stage PFC converters. A novel nonlinear model of two-stage PFC converters is proposed. Then, a stability analysis is made based upon this nonlinear model. The high correspondence between the simulated and experimental results confirms our analysis.<br/>

Would Polymer Banknotes (Plastic Money) Influence Customer Intention to Buy? An Empirical Study from Jordan

Marwan Mohamed Abu ORABI 한국유통과학회 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.2

The goal of the study was to see how polymer banknotes affected users’ purchasing intention. Variables affecting the properties of polymer banknotes were considered, including security, ease of use, convenience, and durability. To achieve the study’s main goal, quantitative methods were used, and a questionnaire was created and posted online through Google Forms to collect primary data. The questionnaire was completed by 403 people, and the data was screened and analyzed using SPSS.The study found that using Polymer money influenced people’s behavior, particularly in terms of purchase patterns, decisions, and impulsive behavior toward purchases. This was attributed to the security and simplicity of using Polymer money, which appealed to many people. Furthermore, the study found that people lost their feeling of spending, meaning that using polymer money didn’t feel like spending to them, effectively eliminating the moral guilt associated with excessive spending and encouraging more impulsive buying decisions.Based on the findings, the study recommends that a study be conducted to compare the use of Polymer money with tiny and large banknotes to see what kind of difference there is.

A NOTE ON CERTAIN TRANSFORMATION FORMULAS RELATED TO APPELL, HORN AND KAMPÉ DE FÉRIET FUNCTIONS

Asmaa Orabi Mohammed,Medhat Ahmed Rakha,Arjun K. Rathie Korean Mathematical Society 2023 대한수학회논문집 Vol.38 No.3

In 2019, Mathur and Solanki [7, 8] obtained a few transformation formulas for Appell, Horn and the Kampé de Fériet functions. Unfortunately, some of the results are well-known and very old results in literature while others are erroneous. Thus the aim of this note is to provide the results in corrected forms and some of the results have been written in more compact form.

Modified Finite Control Set-Model Predictive Controller (MFCS-MPC) for quasi Z-Source Inverters based on a Current Observer

Abualkasim Bakeer,Mohamed A. Ismeil,Mohamed Orabi 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.3

The Finite Control Set-Model Predictive Controller (FCS-MPC) for quasi Z-Source Inverters (qZSIs) is designed to reduce the number of sensors by proposing a current observer for the inductor current. Unlike the traditional FCS-MPC algorithm, the proposed model removes the inductor current sensor and observes the inductor current value based on the deposited prior optimized state as well as the capacitor voltage during this state. The proposed observer has been validated versus a typical MPC. Then, a comparative study between the proposed Modified Finite Control Set-Model Predictive Controller (MFCS-MPC) and a linear PID controller is provided under the same operating conditions. This study demonstrates that the dynamic response of the control objectives by MFCS-MPC is faster than that of the PID. On the other hand, the PID controller has a lower Total Harmonic Distortion (THD) when compared to the MFCS-MPC at the same average switching. Experimental results validate both methods using a DSP F28335.

Modified Finite Control Set-Model Predictive Controller (MFCS-MPC) for quasi Z-Source Inverters based on a Current Observer

Bakeer, Abualkasim,Ismeil, Mohamed A.,Orabi, Mohamed The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.3

The Finite Control Set-Model Predictive Controller (FCS-MPC) for quasi Z-Source Inverters (qZSIs) is designed to reduce the number of sensors by proposing a current observer for the inductor current. Unlike the traditional FCS-MPC algorithm, the proposed model removes the inductor current sensor and observes the inductor current value based on the deposited prior optimized state as well as the capacitor voltage during this state. The proposed observer has been validated versus a typical MPC. Then, a comparative study between the proposed Modified Finite Control Set-Model Predictive Controller (MFCS-MPC) and a linear PID controller is provided under the same operating conditions. This study demonstrates that the dynamic response of the control objectives by MFCS-MPC is faster than that of the PID. On the other hand, the PID controller has a lower Total Harmonic Distortion (THD) when compared to the MFCS-MPC at the same average switching. Experimental results validate both methods using a DSP F28335.

Fuzzy Logic Speed Controller of 3-Phase Induction Motors for Efficiency Improvement

Emad Abdelkarim,Mahrous Ahmed,Mohamed Orabi,Peter Mutschler 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.2

The paper presents an accurate loss model based controller of an induction motor to calculate the optimal air gap flux. The model includes copper losses, iron losses, harmonic losses, friction and windage losses, and stray losses. These losses are represented as a function of the air gap flux. By using the calculated optimal air gap flux compared with rated flux for speed sensorless indirect vector controlled induction motor, an improvement in motor efficiency is achieved. The motor speed performance is improved using a fuzzy logic speed controller instead of a PI controller. The fuzzy logic speed controller was simulated using the fuzzy control interface block of MATLAB/SIMULINK program. The control algorithm is experimentally tested within a PC under RTAI-Linux. The simulation and experimental results show the improvement in motor efficiency and speed performance.

Fuzzy Logic Speed Controller of 3-Phase Induction Motors for Efficiency Improvement

Abdelkarim, Emad,Ahmed, Mahrous,Orabi, Mohamed,Mutschler, Peter The Korean Institute of Power Electronics 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.2

The paper presents an accurate loss model based controller of an induction motor to calculate the optimal air gap flux. The model includes copper losses, iron losses, harmonic losses, friction and windage losses, and stray losses. These losses are represented as a function of the air gap flux. By using the calculated optimal air gap flux compared with rated flux for speed sensorless indirect vector controlled induction motor, an improvement in motor efficiency is achieved. The motor speed performance is improved using a fuzzy logic speed controller instead of a PI controller. The fuzzy logic speed controller was simulated using the fuzzy control interface block of MATLAB/SIMULINK program. The control algorithm is experimentally tested within a PC under RTAI-Linux. The simulation and experimental results show the improvement in motor efficiency and speed performance.