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While comprehensive researches have been conducted on modeling the electromechanical stability of wide-enough beam-plate nano-switches, few researchers have focused on modeling the electromechanical instability of narrow-width nano-switches. For such systems, considering the coupled effects of surface stresses and size dependency of material characteristics is crucial as well as applying appropriate force models. In this paper, Gurtin-Murdoch surface theory incorporating with strain gradient elasticity is employed to study the pull-in instability of narrow-width beam-type nano-switch with small width to height ratio. The model accounts for the force corrections, i.e. the impact of finite dimensions on the fringing field, Casimir attraction and van der Waals force. Furthermore, a modified gas damping model has been incorporated in the governing equation. The nonlinear governing equation was solved using analytical Rayleigh-Ritz method. The influences of the above-mentioned corrections on the static and dynamic pull-in parameters, phase planes and stability threshold of the switch are demonstrated. The modified model is compared with conventional parallel beam-plate models in the literature. [ABSTRACT FROM AUTHOR]

Multilevel inverters have recently been received more attention in the power industry. Two traditional types of multilevel inverters are multilevel voltage-source inverter and multilevel current-source inverter. Despite this widespread use, multilevel Z-source inverter (ML-ZSI) has not been regarded enough, because a unique approach to voltage control of ML-ZSI has not yet been presented. Besides, the phase voltage and its total harmonic distortion (THD) have not been calculated for ML-ZSI so far. This study proposes two new methods for the formulation of phase voltage in ML-ZSI. The first method is based on Fourier series analysis of the phase-voltage waveform, and the second utilises the staircase waveform of the phase voltage. In addition, two new methods are introduced for computing the phasevoltage THD in ML-ZSI: approximate method and waveform-integration method. Although the waveform-integration method leads to the accurate answer, using this method is more difficult than an approximate method. The detailed description of suggested methods and comparison with each other are presented in this study. Simulation and experimental results are also given to demonstrate the new features of the proposed methods. [ABSTRACT FROM AUTHOR]

Phase-shift control is a common approach to voltage control of traditional H-bridge inverters, but this method has not been used to voltage control of H-bridge Z-source inverter (ZSI) so far. This study proposes a new phase-shift control method for H-bridge ZSI, which its main difference with phase-shift control of traditional H-bridge inverters is existence of four shoot-through states (short circuit of the H-bridge) in each switching cycle. One of the advantages of the proposed method is simultaneous elimination of several harmonics by choosing the appropriate switching angles. Moreover, by using this phase-shift control method, the amplitude of low-order harmonics for many values of switching angles is less than the amplitude of low-order harmonics in traditional H-bridge voltage source inverter (VSI). Total harmonic distortion and distortion factor, as two important indexes for quantifying the merits of the proposed method, are calculated and compared with their values in traditional H-bridge VSI. A detailed description of suggested method and comparison with the traditional method are presented in this study. Simulation and experimental results are also given to demonstrate the new features of the proposed method. [ABSTRACT FROM AUTHOR]

Two techniques for the control of flux switching motors in the low and high-speed ranges of operation are presented in this paper. Because of the motor construction, torque production at some rotor positions is low, which leads us into not exciting the windings in those regions. Using this method will improve the efficiency by reducing the losses but, in high-speed range of operation there exist some aspects that affect the above technique. This paper introduces the proper control strategies for flux switching motors in low and high-speed ranges of operation, and presents the simulation results. The results that are obtained based on mathematical relations and not on computer aided simulations, show the advantages of the proposed control schemes. In order to verify the current relations, experiments were performed with similar conditions. The experimental results confirm that the current relations are adequate for control purposes. [ABSTRACT FROM AUTHOR]