Розробка двигуна постійного струму з безобмотковим ротором для застосування в електротранспорті

Modern electric vehicles typically exploit synchronous motors with magnetoelectric excitation as traction engines. While possessing a series of undeniable advantages, the synchronous motor has one significant drawback ‒ the high cost predetermined by the high price of permanent magnets. In addition, the impossibility to disable a magnetic field in case of engine malfunction can lead to an emergency on the road. Given this, there is a need to design new structures of electrical machines with electromagnetic excitation. The structure of a DC traction motor with electromagnetic excitation involving the rotor or stator segmentation makes it possible to considerably weaken the field of the armature transverse reaction by decreasing magnetic conductivity of the magnetic circuit in the transverse direction. Therefore, such a structure lacks commutating poles and a compensation winding. There are no permanent magnets in the structure, all windings are stationary, an electronic switch is used instead of a collector, and a windingless low-inertia rotor does not require additional measures to remove heat. That all has made it possible to significantly reduce the cost of active materials for the traction engine and improve its reliability. To test the performance of the new design, a full-size model of the engine and a working experimental prototype were fabricated. Applying a synchronous jet engine with magnetization for the BMW i3 electric car as an analog, the engine calculations were performed and its simulation was carried out. The results of the analysis show that the mass of the new engine is 35 % greater than the mass of the analog but the cost of active materials is less than that of the analog by 63 %. The results testify to the possibility of implementing a given structure industriallyКак правило, в современных электромобилях в качестве тяговых используют синхронные двигатели с магнитоэлектрическим возбуждением. Обладая рядом неоспоримых достоинств, синхронный двигатель имеет один существенный недостаток – высокую стоимость, обусловленную высокой ценой на постоянные магниты. Кроме этого, невозможность отключить магнитное поле при неисправности двигателя может привести к возникновению аварийной ситуации на дороге. В связи с этим возникает необходимость в разработке новых конструкций электрических машин с электромагнитным возбуждением. Конструкция тягового двигателя постоянного тока с электромагнитным возбуждением за счет сегментации статора или ротора позволяет существенно ослабить поле поперечной реакции якоря путем снижения магнитной проводимости магнитопровода в поперечном направлении. Поэтому в данной конструкции нет дополнительных полюсов и компенсационной обмотки. В конструкции отсутствуют постоянные магниты, все обмотки неподвижны, вместо коллектора используется электронный коммутатор, а безобмоточный малоинерционный ротор не требует дополнительныых мер по отводу тепла. Все это позволило существенно уменьшить стоимость активных материалов тягового двигателя и повысить его надежность. Для проверки работоспособности новой конструкции были созданы полноразмерный макет двигателя и рабочий экспериментальный образец. Приняв в качестве аналога синхронный реактивный двигатель с подмагничиванием для электромобиля BMW i3, были проведены расчеты двигателя и его моделирование. Результаты анализа показывают, что масса нового двигателя больше массы аналога на 35 %, но при этом стоимость активных материалов меньше, чем у аналога, на 63 %. Полученные результаты позволяют говорить о возможности внедрения данной конструкции в промышленное производствоЗазвичай у сучасних електромобілях у якості тягових електродвигунів використовують синхронні двигуни з магнітоелектричним збудженням. Маючи ряд переваг серед інших типів електричних машин, цей двигун має один істотний недолік – високу вартість, обумовлену високою ціною на постійні магніти. Крім цього, неможливість відключити магнітне поле при несправності двигуна може призвести до виникнення аварійної ситуації на дорозі. У зв'язку із цим виникає необхідність у розробці нових конструкцій електричних машин з електромагнітним збудженням. Конструкція тягового двигуна постійного струму з електромагнітним збудженням за рахунок сегментації статора або ротора дозволяє суттєво послабити поле поперечної реакції якоря шляхом зниження магнітної провідності магнітопроводу в поперечному напрямку. Тому в даній конструкції немає необхідності в установці додаткових полюсів і компенсаційної обмотки. У конструкції відсутні постійні магніти, усі обмотки нерухомі, замість колектора використовується електронний комутатор, а безобмотковий малоінерціїний ротор не потребує додаткових мір по відводу тепла. Усе це дозволило суттєво зменшити вартість активних матеріалів тягового двигуна й підвищити його надійність. Для перевірки працездатності нової конструкції були створені повнорозмірний макет двигуна та робочий експериментальний зразок. Прийнявши в якості аналога синхронний реактивний двигун з підмагнічуванням для електромобіля BMW i3, були проведені розрахунки двигуна і його моделювання. Результати аналізу показують, що маса нового двигуна більше маси аналога на 35 %, але при цьому вартість активних матеріалів менше, ніж у аналога, на 63 %. Отримані результати дають підстави щодо можливості втілення даної конструкції у реальне промислове виробництв

Noncovalent Interactions in Extended Systems Described by the Effective Fragment Potential Method: Theory and Application to Nucleobase Oligomers

The implementation of the effective fragment potential (EFP) method within the Q-CHEM electronic structure package is presented. The EFP method is used to study noncovalent π−π and hydrogen-bonding interactions in DNA strands. Since EFP is a computationally inexpensive alternative to high-level ab initio calculations, it is possible to go beyond the dimers of nucleic acid bases and to investigate the asymptotic behavior of different components of the total interaction energy. The calculations demonstrated that the dispersion energy is a leading component in π-stacked oligomers of all sizes. Exchange-repulsion energy also plays an important role. The contribution of polarization is small in these systems, whereas the magnitude of electrostatics varies. Pairwise fragment interactions (i.e., the sum of dimer binding energies) were found to be a good approximation for the oligomer energy

Advances in Molecular Quantum Chemistry Contained in the Q-Chem 4 Program Package

A summary of the technical advances that are incorporated in the fourth major release of the Q-Chem quantum chemistry program is provided, covering approximately the last seven years. These include developments in density functional theory methods and algorithms, nuclear magnetic resonance (NMR) property evaluation, coupled cluster and perturbation theories, methods for electronically excited and open-shell species, tools for treating extended environments, algorithms for walking on potential surfaces, analysis tools, energy and electron transfer modelling, parallel computing capabilities, and graphical user interfaces. In addition, a selection of example case studies that illustrate these capabilities is given. These include extensive benchmarks of the comparative accuracy of modern density functionals for bonded and non-bonded interactions, tests of attenuated second order Møller–Plesset (MP2) methods for intermolecular interactions, a variety of parallel performance benchmarks, and tests of the accuracy of implicit solvation models. Some specific chemical examples include calculations on the strongly correlated Cr2 dimer, exploring zeolite-catalysed ethane dehydrogenation, energy decomposition analysis of a charged ter-molecular complex arising from glycerol photoionisation, and natural transition orbitals for a Frenkel exciton state in a nine-unit model of a self-assembling nanotube

Thermodynamics of Binding of Di- and Tetrasubstituted Naphthalene Diimide Ligands to DNA G‑Quadruplex

Naphthalene diimide ligands have the potential to stabilize human telomeric G-quadruplex DNA via noncovalent interactions. Stabilization of G-quadruplex high order structures has become an important strategy to develop novel anticancer therapeutics. In this study four naphthalene diimide based ligands were analyzed in order to elucidate the principal factors determining contributions to G-quadruplex-ligand binding. Three possible modes of binding and their respective Gibbs free energies for two naphthalene diimide based di-<i>N</i>-alkylpyridinium substituted ligands have been determined using a molecular docking technique and compared to experimental results. The structures obtained from the molecular docking calculations, were analyzed using the ab initio based fragment molecular orbital (FMO) method in order to determine the major enthalpic contributions to the binding and types of interactions between the ligand and specific residues of the G-quadruplex. A computational methodology for the efficient and inexpensive ligand optimization as compared to fully ab initio methods based on the estimation of binding affinities of the naphthalene diimide derived ligands to G-quadruplex is proposed

Effective fragment potential method in Q-CHEM: A guide for users and developers

A detailed description of the implementation of the effective fragment potential (EFP) method in the Q-CHEM electronic structure package is presented. The Q-CHEM implementation interfaces EFP with standard quantum mechanical (QM) methods such as Hartree-

Noncovalent Interactions in Extended Systems Described by the Effective Fragment Potential Method: Theory and Application to Nucleobase Oligomers

The implementation of the effective fragment potential (EFP) method within the Q-CHEM electronic structure package is presented. The EFP method is used to study noncovalent π−π and hydrogen-bonding interactions in DNA strands. Since EFP is a computationally inexpensive alternative to high-level ab initio calculations, it is possible to go beyond the dimers of nucleic acid bases and to investigate the asymptotic behavior of different components of the total interaction energy. The calculations demonstrated that the dispersion energy is a leading component in π-stacked oligomers of all sizes. Exchange-repulsion energy also plays an important role. The contribution of polarization is small in these systems, whereas the magnitude of electrostatics varies. Pairwise fragment interactions (i.e., the sum of dimer binding energies) were found to be a good approximation for the oligomer energy.Reprinted (adapted) with permission from Journal of Physical Chemistry A 114 (2010): 12739, doi:10.1021/jp107557p. Copyright 2010 American Chemical Society.</p

Accurate Prediction of Noncovalent Interaction Energies with the Effective Fragment Potential Method: Comparison of Energy Components to Symmetry-Adapted Perturbation Theory for the S22 Test Set

Noncovalent interactions play an important role in the stabilization of biological molecules. The effective fragment potential (EFP) is a computationally inexpensive ab initio-based method for modeling intermolecular interactions in noncovalently bound systems. The accuracy of EFP is benchmarked against the S22 and S66 data sets for noncovalent interactions [Jurečka, P.; Šponer, J.; Černý, J.; Hobza, P. <i>Phys. Chem. Chem. Phys.</i> <b>2006</b>, <i>8</i>, 1985; Řezáč, J.; Riley, K. E.; Hobza, P. <i>J. Chem. Theory Comput.</i> <b>2011</b>, <i>7</i>, 2427]. The mean unsigned error (MUE) of EFP interaction energies with respect to coupled-cluster singles, doubles, and perturbative triples in the complete basis set limit [CCSD­(T)/CBS] is 0.9 and 0.6 kcal/mol for S22 and S66, respectively, which is similar to the MUE of MP2 and SCS-MP2 for the same data sets, but with a greatly reduced computational expense. Moreover, EFP outperforms classical force fields and popular DFT functionals such as B3LYP and PBE, while newer dispersion-corrected functionals provide a more accurate description of noncovalent interactions. Comparison of EFP energy components with the symmetry-adapted perturbation theory (SAPT) energies for the S22 data set shows that the main source of errors in EFP comes from Coulomb and polarization terms and provides a valuable benchmark for further improvements in the accuracy of EFP and force fields in general

Extension of the Effective Fragment Potential Method to Macromolecules

The effective fragment potential (EFP) approach, which can be described as a nonempirical polarizable force field, affords an accurate first-principles treatment of noncovalent interactions in extended systems. EFP can also describe the effect of the environment on the electronic properties (e.g., electronic excitation energies and ionization and electron-attachment energies) of a subsystem via the QM/EFP (quantum mechanics/EFP) polarizable embedding scheme. The original formulation of the method assumes that the system can be separated, without breaking covalent bonds, into closed-shell fragments, such as solvent and solute molecules. Here, we present an extension of the EFP method to macromolecules (mEFP). Several schemes for breaking a large molecule into small fragments described by EFP are presented and benchmarked. We focus on the electronic properties of molecules embedded into a protein environment and consider ionization, electron-attachment, and excitation energies (single-point calculations only). The model systems include chromophores of green and red fluorescent proteins surrounded by several nearby amino acid residues and phenolate bound to the T4 lysozyme. All mEFP schemes show robust performance and accurately reproduce the reference full QM calculations. For further applications of mEFP, we recommend either the scheme in which the peptide is cut along the C_α–C bond, giving rise to one fragment per amino acid, or the scheme with two cuts per amino acid, along the C_α–C and C_α–N bonds. While using these fragmentation schemes, the errors in solvatochromic shifts in electronic energy differences (excitation, ionization, electron detachment, or electron-attachment) do not exceed 0.1 eV. The largest error of QM/mEFP against QM/EFP (no fragmentation of the EFP part) is 0.06 eV (in most cases, the errors are 0.01–0.02 eV). The errors in the QM/molecular mechanics calculations with standard point charges can be as large as 0.3 eV

Conformationally Locked Chromophores as Models of Excited-State Proton Transfer in Fluorescent Proteins

Members of the green fluorescent protein (GFP) family form chromophores by modifications of three internal amino acid residues. Previously, many key characteristics of chromophores were studied using model compounds. However, no studies of intermolecular excited-state proton transfer (ESPT) with GFP-like synthetic chromophores have been performed because they either are nonfluorescent or lack an ionizable OH group. In this paper we report the synthesis and photochemical study of two highly fluorescent GFP chromophore analogues: <i>p</i>-HOBDI-BF2 and <i>p</i>-HOPyDI:Zn. Among known fluorescent compounds, <i>p</i>-HOBDI-BF₂ is the closest analogue of the native GFP chromophore. These irrreversibly (<i>p</i>-HOBDI-BF₂) and reversibly (<i>p</i>-HOPyDI:Zn) locked compounds are the first examples of fully planar GFP chromophores, in which photoisomerization-induced deactivation is suppressed and protolytic photodissociation is observed. The photophysical behavior of <i>p</i>-HOBDI-BF2 and <i>p</i>-HOPyDI:Zn (excited state p<i>K</i>_a’s, solvatochromism, kinetics, and thermodynamics of proton transfer) reveals their high photoacidity, which makes them good models of intermolecular ESPT in fluorescent proteins. Moreover, <i>p</i>-HOPyDI:Zn is a first example of “super” photoacidity in metal–organic complexes