Performance comparison of conventional synchronous reluctance machines and PM-assisted types with combined star-delta winding

This paper compares four prototype Synchronous Reluctance Motors (SynRMs) having an identical geometry of iron lamination stacks in the stator and rotor. Two different stator winding layouts are employed: a conventional three-phase star connection and a combined star-delta winding. In addition, two rotors are considered: a conventional rotor without magnets and a rotor with ferrite magnets. The performance of the four SynRMs is evaluated using a two-dimensional (2D) Finite Element Model (FEM). For the same copper volume and current, the combined star-delta-connected stator with Permanent Magnets (PMs) in the rotor corresponds to an approximately 22% increase in the output torque at rated current and speed compared to the conventional machine. This improvement is mainly thanks to adding ferrite PMs in the rotor as well as to the improved winding factor of the combined star-delta winding. The torque gain increases up to 150% for low current. Moreover, the rated efficiency is 93.60% compared to 92.10% for the conventional machine. On the other hand, the impact on the power factor and losses of SynRM when using the star-delta windings instead of the star windings is merely negligible. The theoretical results are experimentally validated using four identical prototype machines with identical lamination stacks but different rotors and winding layouts

Performance evaluation of synchronous reluctance motors with and without permanent magnets

Nowadays, a growing interest in the efficiency and the cost of electrical machines has been noticed. Therefore, Synchronous Reluctance Motors (SynRMs) have become more attractive, thanks to their higher efficiency and nevertheless acceptable cost compared to induction machines. The rotor design of SynRMs with or without permanent magnets (PMs) has a huge effect on the motor efficiency, torque density and power factor. This paper introduces an evaluation for the performance of SynRMs with and without PMs in terms of efficiency, torque and power factor maps. Three different rotor designs for the same machine have been compared. For one machine, the experimental measurements have been obtained and the validation of the simulation results have been confirme

Hybrid photovoltaic-thermoelectric generator powered synchronous reluctance motor for pumping applications

The interest in photovoltaic (PV) pumping systems has increased, particularly in rural areas where there is no grid supply available. However, both the performance and the cost of the whole system are still an obstacle for a wide spread of this technology. In this article, a hybrid photovoltaic (PV)-thermoelectric generator (TEG) is investigated for pumping applications. The electric drivetrain comprises a synchronous reluctance motor and an inverter. A control strategy for the drivetrain is employed to execute two main tasks: 1) driving the motor properly to achieve a maximum torque per Ampere condition and 2) maximizing the output power of the PV system at different weather conditions. This means that the conventional DC-DC converter is not used in the proposed system. Moreover, batteries, which are characterized by short life expectancy and high replacement cost, are also not used. It is found that the motor output power and the pump flow rate are increased by about 9.5% and 12% respectively when the hybrid PV-TEG array is used compared to only using PV array. Accordingly, the performance, cost and complexity of the system are improved. Measurements on an experimental laboratory setup are constructed to validate the theoretical results of this work

Energy management control strategy for renewable energy system based on spotted hyena optimizer

Hydrocarbons, carbon monoxide and other pollutants from the transportation sector harm human health in many ways. Fuel cell (FC) has been evolving rapidly over the past two decades due to its efficient mechanism to transform the chemical energy in hydrogen-rich compounds into electrical energy. The main drawback of the standalone FC is its slow dynamic response and its inability to supply rapid variations in the load demand. Therefore, adding energy storage systems is necessary. However, to manage and distribute the power-sharing among the hybrid proton exchange membrane (PEM) fuel cell (FC), battery storage (BS), and supercapacitor (SC), an energy management strategy (EMS) is essential. In this research work, an optimal EMS based on a spotted hyena optimizer (SHO) for hybrid PEM fuel cell/BS/SC is proposed. The main goal of an EMS is to improve the performance of hybrid FC/BS/SC and to reduce the amount of hydrogen consumption. To prove the superiority of the SHO method, the obtained results are compared with the chimp optimizer (CO), the artificial ecosystem-based optimizer (AEO), the seagull optimization algorithm (SOA), the sooty tern optimization algorithm (STOA), and the coyote optimization algorithm (COA). Two main metrics are used as a benchmark for the comparison: the minimum consumed hydrogen and the efficiency of the system. The main findings confirm that the minimum amount of hydrogen consumption and maximum efficiency are achieved by the proposed SHO based EMS

Solar array fed synchronous reluctance motor driven water pump : an improved performance under partial shading conditions

An improved performance of a photovoltaic (PV) pumping system employing a synchronous reluctance motor (SynRM) under partial shading conditions is proposed. The system does not include the dc-dc converter that is predominantly being utilized for maximizing the output power of the PV array. In addition, storage batteries are also not contained. A conventional inverter connected directly to the PV array is used to drive the SynRM. Further, a control strategy is proposed to drive the inverter so that the maximum output power of the PV array is achieved while the SynRM is working at the maximum torque per Ampere condition. Consequently, this results in an improved system efficiency and cost. Moreover, two maximum power point tracking (MPPT) techniques are compared under uniform and partial shadow irradiation conditions. The first MPPT algorithm is based on the conventional perturbation and observation (P&O) method and the second one uses a differential evolution (DE) optimization technique. It is found that the DE optimization method leads to a higher PV output power than using the P&O method under the partial shadow condition. Hence, the pump flow rate is much higher. However, under a uniform irradiation level, the PV system provides the available maximum power using both MPPT techniques. The experimental measurements are obtained to validate the theoretical work

Knowledge and Attitude of Medical Students of Cairo University, Cairo, Egypt About National DNA Database

Background: DNA database is used to identify individuals based on their specific DNA profiles. In Egypt, a definitive law describing and legalizing DNA related issues is absent; however, the Egyptian courts frequently deal with these issues. The legal authorities strongly suggest the impending need for detailed decrees in this regard that guard the safety of the whole Egyptian community. This paper aimed to assess the knowledge and attitude of Medical students about Egyptian National DNA Database (END). Methods: Data of this study were collected from 272 participants in the Faculty of Medicine, Cairo University using interviewer administered questionnaire. Results: The participants were 136 males and 136 females with mean (SD) age of 27(9) years. Majority of the participants (89.7%) were aware about national database out of their medical textbooks. Personal identification was the most chosen END benefit and database usefulness was the main motivation for them. About 29% suggested to start END with the detected crime scene stains and forensic doctors should freely access END. Conclusion: These collective points of views might be useful in preparing some international and common ethical standards for the development of DNA databases framework

Parameter estimation of electric power transformers using Coyote Optimization Algorithm with experimental verification

In this work, the Coyote Optimization Algorithm (COA) is implemented for estimating the parameters of single and three-phase power transformers. The estimation process is employed on the basis of the manufacturer's operation reports. The COA is assessed with the aid of the deviation between the actual and the estimated parameters as the main objective function. Further, the COA is compared with well-known optimization algorithms i.e. particle swarm and Jaya optimization algorithms. Moreover, experimental verifications are carried out on 4 kVA, 380/380 V, three-phase transformer and 1 kVA, 230/230 V, single-phase transformer. The obtained results prove the effectiveness and capability of the proposed COA. According to the obtained results, COA has the ability and stability to identify the accurate optimal parameters in case of both single phase and three phase transformers; thus accurate performance of the transformers is achieved. The estimated parameters using COA lead to the highest closeness to the experimental measured parameters that realizes the best agreements between the estimated parameters and the actual parameters compared with other optimization algorithms

Spektrofluorimetrijsko određivanje ciklopiroks olamina prevođenjem u ternarni kompleks s Tb(III) i EDTA

A highly sensitive and selective spectrofluorimetric method was developed for the determination of ciclopirox olamine in raw material and in dosage forms. The proposed method is based on the formation of a ternary complex with Tb(III) in the presence of ethylenediaminetetraacetic acid. It was found that this complex manifests intense fluorescence at λem 489 and 545 nm with excitation at 295 nm. Different experimental parameters affecting the fluorescence intensity of the complex were carefully studied and incorporated into the procedure. Under the described conditions, the method is applicable over the concentration range of 30150 and 1070 ng mL-1 with minimum detectability of 6.7 and 0.9 ng mL-1 at λem 489 and 545 nm, respectively. The mean percentage recovery at λem 489 and λem 545 nm ranged between 98.7 and 100.2 for the pure substance, solution, and cream. Relative error of 0.10.4% and RSD up to 0.9% were estimated at λem 489 and 545 nm. A proposal of the reaction pathway is given.Razvijena je vrlo osjetljiva i selektivna spektrofluorimetrijska metoda za određivanje antimikotika ciklopiroks olamina, kao čiste supstancije i u ljekovitim oblicima. Metoda se temelji na stvaranju kompleksa s Tb(III) u prisutnosti etilendiamintetraoctene kiseline. Nakon ekscitacije pri 295 nm taj kompleks intenzivno fluorescira pri λem 489 i 545 nm. Proučavani su različiti eksperimentalni parametri koji utječu na intenzitet fluorescencije kompleksa. Za opisane uvjete metoda se može primijeniti u koncentracijskom području 30150 i 10 70 ng mL-1. Minimalna koncentracija koja se može odrediti je 6,7, odnosno 0,9 ng mL-1 na λem 489, odnosno 545 nm. Analitički povrat pri λem 489 i λem 545 nm iznosio je 98,7100,2% za čistu supstanciju, otopinu i kremu. Relativna pogreška metode je 0,10,4%, a relativna standardna devijacija 0,9%. Predložena je jednažba kemijske reakcije