Sliding Mode Control of a New Wind-Based Isolated Three-Phase Induction Generator System with Constant Frequency and Adjustable Output Voltage

Moradian, Mohammadreza,Soltani, Jafar The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.2

This paper presents a new stand-alone wind-based induction generator system with constant frequency and adjustable output voltage. The proposed generator consists of a six-phase cage-rotor induction machine with two separate three-phase balanced stator windings and a three-phase space vector pulse width modulation inverter that operates as a static synchronous compensator (STATCOM). The first stator winding is fed by the STATCOM and used to excite the machine while the second stator winding is connected to the generator external load. The main frequency of the STATCOM is determined to be constant and equal to the load-requested frequency. The generator output frequency is independent of the load power demand and its prime mover speed because the frequency of the induced emf in the second stator winding is the same as this constant frequency. A sliding mode control (SMC) is developed to regulate the generator output voltage. A second SMC is used to force the zero active power exchanged between the machine and the STATCOM. Some simulation and experimental results are presented to prove the validity and effectiveness of the proposed generator system.

Sliding Mode Control of a New Wind-Based Isolated Three-Phase Induction Generator System with Constant Frequency and Adjustable Output Voltage

Mohammadreza Moradian,Jafar Soltani 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.2

This paper presents a new stand-alone wind-based induction generator system with constant frequency and adjustable output voltage. The proposed generator consists of a six-phase cage-rotor induction machine with two separate three-phase balanced stator windings and a three-phase space vector pulse width modulation inverter that operates as a static synchronous compensator (STATCOM). The first stator winding is fed by the STATCOM and used to excite the machine while the second stator winding is connected to the generator external load. The main frequency of the STATCOM is determined to be constant and equal to the load-requested frequency. The generator output frequency is independent of the load power demand and its prime mover speed because the frequency of the induced emf in the second stator winding is the same as this constant frequency. A sliding mode control (SMC) is developed to regulate the generator output voltage. A second SMC is used to force the zero active power exchanged between the machine and the STATCOM. Some simulation and experimental results are presented to prove the validity and effectiveness of the proposed generator system.

Whole genome detection of recent selection signatures in Sarabi cattle: a unique Iranian taurine breed

Hasan Moradian,Ali Esmailizadeh Koshkoiyeh,Mohammadreza Mohammadabadi,Masood Asadi Fozi 한국유전학회 2020 Genes & Genomics Vol.42 No.2

Background The identification of genomic regions under selection can potentially permit a better understanding of the biology of the specific phenotypes which are useful for the development of tools designed to increase selection efficiency. Objective The aim of this study was to detect any traces of recent selection signatures as well as to identify corresponding genes and QTLs underlying these selection signatures in Sarabi cattle. Methods Samples from 20 animals were genotyped for 777,962 SNPs across the genome using the Illumina BovineHD BeadChip. Selection signatures analysis was performed using the integrated haplotype score (iHS) methodology. Results A total of eight significant regions (P < 0.0001) of possible recent selection signatures were detected on BTA14 and BTA17. In addition, nine genes were identified in regions harboring selection signatures, such as KCNQ3, HHLA1, OC90, EFR3A, ADCY8, ASAP1, TMEM132B, and TMEM132C. Study of the reported QTLs in these regions of the bovine genome has showed that they are associated with important traits such as milk, reproduction and production traits. Conclusion The results revealed multiple genomic regions as well as multiple new genes under positive selection on BTA14 and BTA17. Moreover, candidate selected regions that overlap with QTL reported in the cattle QTL database provided additional evidence for the significance of the detected regions under selection. This study provides a foundation for detailed analysis of the identified putative selection signatures in the cattle genome particularly of the indigenous and locally-developed cattle breeds and provides an avenue for a well-structured breed improvement.

Excess Deaths During the COVID-19 Pandemic in Southern Iran: Estimating the Absolute Count and Relative Risk Using Ecological Data

Zakeri Mohammadreza,Mirahmadizadeh Alireza,Azarbakhsh Habibollah,Dehghani Seyed Sina,Janfada Maryam,Moradian Mohammad javad,Moftakhar Leila,Sharafi Mehdi,Heiran Alireza 대한예방의학회 2024 예방의학회지 Vol.57 No.2

Objectives: The coronavirus disease 2019 (COVID-19) pandemic led to increased mortality rates. To assess this impact, this ecological study aimed to estimate the excess death counts in southern Iran.Methods: The study obtained weekly death counts by linking the National Death Registry and Medical Care Monitoring Center repositories. The P-score was initially estimated using a simple method that involved calculating the difference between the observed and expected death counts. The interrupted time series analysis was then used to calculate the mean relative risk (RR) of death during the first year of the pandemic.Results: Our study found that there were 5571 excess deaths from all causes (P-score=33.29%) during the first year of the COVID-19 pandemic, with 48.03% of these deaths directly related to COVID-19. The pandemic was found to increase the risk of death from all causes (RR, 1.26; 95% confidence interval [CI], 1.19 to 1.33), as well as in specific age groups such as those aged 35-49 (RR, 1.21; 95% CI, 1.12 to 1.32), 50-64 (RR, 1.38; 95% CI, 1.28 to 1.49), and ≥65 (RR, 1.29; 95% CI, 1.12 to 1.32) years old. Furthermore, there was an increased risk of death from cardiovascular diseases (RR, 1.17; 95% CI, 1.11 to 1.22).Conclusions: There was a 26% increase in the death count in southern Iran during the COVID-19 pandemic. More than half of these excess deaths were not directly related to COVID-19, but rather other causes, with cardiovascular diseases being a major contributor.

Torque pulsation reduction in five‑phase PMASyncRMs

Hamidreza Ghorbani,Mohammadreza Moradian 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.1

This paper investigates two rotor configurations for five-phase permanent magnet assisted synchronous reluctance motor (PMASyncRM) in which the Ns/Np ratio remains equal to the number of phases and the minimization of torque pulsation, mainly cogging torque (Tcog), is desired. The proposed initial models have three layers of flux barriers per pole and are categorized as either A-type or B-type. The A-type has three layers of flux barriers where two of them are filled with PMs and the third one is left empty. The B-type has PMs inserted into all three layers of the flux barriers. Accordingly, based on torque analyses of the proposed models, the candidate that produces the lowest Tcog is selected for in-depth study. Thus, a sensitivity analyze is performed considering the length of the stator slot opening (Lso), the length of the air-gap (Lg), and the length of the 3rd flux barrier (Lb) as analysis parameters that are simultaneously taken into account. The outputs demonstrate that for the resultant values of Lso-Opt, Lg-Opt, and Lb-Opt, the value of Tcog declined considerably when compared with that of the initial motors. Finally, the optimized model is studied using 2-D finite element analysis (FEA) and the torque characteristics were compared with the initial model. The obtained results show that the optimized model provides much lower torque vibrations.