AC small signal modeling of PWM Y-source converter by circuit averaging and averaged switch modeling technique

© 2016 IEEE and EPE Association. Magnetically coupled Y-source impedance network is a newly proposed structure with versatile features intended for various power converter applications e.g. in the renewable energy technologies. The voltage gain of the Y-source impedance network rises exponentially as a function of turns ratio, which is inherited from a special coupled inductor with three windings. Due to the importance of modeling in the converter design procedure, this paper is dedicated to dc and ac small signal modeling of the PWM Y-source converter. The derived transfer functions are presented in detail and have been verified through simulation and experimental results

A Classification of Single-Phase Transformerless Inverter Topologies for Photovoltaic Applications

© 2018 IEEE. In Photovoltaic (PV) applications, a transformer is often used to provide galvanic isolation and voltage ratio transformations. However, a transformer based inverter is bulky and has high conduction losses, therefore lead to a reduction in the inverter efficiency. To overcome this issue, the transformerless inverter topologies are addressed widely, but the main challenge of a transformerless inverter is common mode issue. Numerous topological modifications with their control and modulation techniques makes them difficult to follow, generalize and highlight the advantages and disadvantages. To address the issue, this paper gives an overview on transformerless inverter and classify them into subsection to discuss the merit and demerit of some of the major topologies. Five subsections based on common mode behavior, voltage clamping and decoupling techniques have been demonstrated (i.e., common ground, mid-point clamping, AC-decoupling, DC-decoupling and AC+DC decoupling). To verify the finding and for general consensus, major transformerless topologies are simulated using PLECS. A general summary is presented at the end to stimulate readers to acknowledge the problems and identify solutions

Free vibration analysis and design optimization of SMA/Graphite/Epoxy composite shells in thermal environments

Composite shells, which are being widely used in engineering applications, are often under thermal loads. Thermal loads usually bring thermal stresses in the structure which can significantly affect its static and dynamic behaviors. One of the possible solutions for this matter is embedding Shape Memory Alloy (SMA) wires into the structure. In the present study, thermal buckling and free vibration of laminated composite cylindrical shells reinforced by SMA wires are analyzed. Brinson model is implemented to predict the thermo-mechanical behavior of SMA wires. The natural frequencies and buckling temperatures of the structure are obtained by employing Generalized Differential Quadrature (GDQ) method. GDQ is a powerful numerical approach which can solve partial differential equations. A comparative study is carried out to show the accuracy and efficiency of the applied numerical method for both free vibration and buckling analysis of composite shells in thermal environment. A parametric study is also provided to indicate the effects of like SMA volume fraction, dependency of material properties on temperature, lay-up orientation, and pre-strain of SMA wires on the natural frequency and buckling of Shape Memory Alloy Hybrid Composite (SMAHC) cylindrical shells. Results represent the fact that SMAs can play a significant role in thermal vibration of composite shells. The second goal of present work is optimization of SMAHC cylindrical shells in order to maximize the fundamental frequency parameter at a certain temperature. To this end, an eight-layer composite shell with four SMA-reinforced layers is considered for optimization. The primary optimization variables are the values of SMA angles in the four layers. Since the optimization process is complicated and time consuming, Genetic Algorithm (GA) is performed to obtain the orientations of SMA layers to maximize the first natural frequency of structure. The optimization results show that using an optimum stacking sequence for SMAHC shells can increase the fundamental frequency of the structure by a considerable amount

Extended Ideals in MV-Algebras

In this paper, we introduce the notion of extended of an ideal associated to a subset of an [Formula: see text]-algebra [Formula: see text] and investigate the related properties. A characterization of this extended ideal is given. We show that [Formula: see text] is stable ideal relative to [Formula: see text] such that [Formula: see text] if and only if [Formula: see text] is chain [Formula: see text]-algebra. Finally, the class [Formula: see text] of all stable ideals relative to [Formula: see text] is also a complete Heyting algebra, for an [Formula: see text]-algebra [Formula: see text]. </jats:p

Non-linear dynamic analysis of automotive suspension system incorporating rubber bump stops

Rubber bump stops are used in automotive suspension systems to absorb energy, limit the motion of wheels, and reduce vibrations. They are made from elastomeric materials that are non-linear and exhibit large deformation under loading. In the present paper, the bump stop used in a double-wishbone suspension system was analysed numerically to obtain the load–displacement curve and compared with experimental test data. The numerical analysis was done with a non-linear finite element (FE) model using ABAQUS software. The results showed good agreement between numerical and experimental data, with a difference of less than 2 per cent between them. Then dynamic analysis of the suspension system with the bump stop was done to recognize the stress and acceleration effects arising from use of this part in the system. For different vehicle velocities, the comparison between von Mises stress curves in two cases, with and without a bump stop on the lower control arm, showed higher stresses in the lower control arm in the presence of the bump stop and the comparison between acceleration curves showed lower acceleration in the lower control arm with the bump stop. Thus automotive engineers must pay attention to these effects to design suspension components correctly. </jats:p

Some results in types of extensions of MV-algebras

We introduce the notions of zero divisor and extension, contraction of ideals in MV-algebras and several interesting types of extensions of MV-algebras. In particular, we show what kinds of extensions MV-algebras will lead in a homeomorphism of the spectral topology and inverse topology on minimal prime ideals. Finally, we investigate the relations among types of extensions of MV-algebras.</jats:p

Reflectional Topology in Residuated Lattices

In this paper, we introduce soaker filters in a residuated lattice, give some characterizations and investigate some properties of them. Then we define a topology on the set of all the soaker filters, which we call reflectional topology, show it is an Alexandrov topology and give a basis for it. We introduce the notion of join-soaker filters and prove that when the residuated lattice is a join-soaker filter, then the reflectional topology is compact. We also give a characterization of connectedness of the reflectional topology. Finally, we prove the reflectional topology is [Formula: see text], give necessary and sufficient conditions under which it is [Formula: see text] and prove that being [Formula: see text] is equivalent to being [Formula: see text]. Several illustrative examples are given. </jats:p