The paper presents a new transformer-less step-up multilevel inverter structure with a single DC source. The concept was based on cascaded connection of bipolar T-type 5-level modules. Proper charging and discharging of capacitors across the load in prearranged time durations would make a nearly sinusoidal staircase voltage. The output voltage amplitude was several times greater than the DC input depending on the number of modules and charging mode of the capacitors. Multiplying the input voltage, self-balancing, generating bipolar voltage waveform, easy circuit expansion and considerably low THD (Total Harmonic Distortion) were found to be the advantages of the proposed topology. The paper also adds operating principle, simulation and experimental results of a 29-level prototype based on the presented inverter structure.

A new structure of switched capacitor multilevel inverter (SCMLI) capable of voltage boosting and with self-balancing ability is introduced in this article. This advantage is the result of a step by step rise of capacitor voltages in each module, supplied by just one DC voltage source. The proposed topology generates a sinusoidal output waveform with a magnitude several times greater than the input one. Higher output staircase AC voltage is obtained by applying a nearest level control (NLC) modulation technique. The most significant features of this configuration can be mentioned as: fewer semiconductor devices, remarkably low total harmonic distortion (THD), desirable operating under high /low frequency, high efficiency, inherent bipolar voltage production, easy circuit expansion, ease of control and size reduction of the circuit thanks to utilizing neither bulky transformer nor inductor. Moreover, the proposed SCMLI is comprehensively surveyed through theoretical investigation and a comparison of its effectiveness to recent topologies. Eventually, the operating principle of a 25-level prototype of the suggested SCMLI is validated by simulation in the MATLAB SIMULINK environment and experimental results.

In this paper, a step-up seven-level inverter supplied by a single DC source suitable for renewable energy application is presented. Forming the desired output is realized by charging capacitors and synthesizing them based on switched-capacitor concept. This structure is praised for the ability of sensor-less voltage balancing of the capacitors, reducing control complexity to produce a bipolar staircase waveform. It also benefits from regenerative performance, avoiding unwanted capacitors overvoltage. Phase Disposition Pulse Width Modulation (PD-PWM) technique is utilized to control the circuit operation. Furthermore, a comparison with other recent topologies reveals that losses, number of semiconductor devices, and gate driver circuits are reduced. Theoretical analysis is verified through a laboratory prototype implementation. Experimental results under various types of loads approve the performance of the proposed inverter and validity of the design. Finally, maximum experimental efficiency of 94.3% (115 V, 250 W load) was reached.

Evaluation of liquefaction potential of soils is an important step in many geotechnical investigations in regions susceptible to earthquake. For this purpose, the use of site shear wave velocity (Vs) provides a promising approach. The safety factors in the deterministic analysis of liquefaction potential are often difficult to interpret because of uncertainties in the soil and earthquake parameters. To deal with the uncertainties, probabilistic approaches have been employed. In this research, the Jointly Distributed Random Variables (JDRV) method is used as an analytical method for probabilistic assessment of liquefaction potential based on measurement of site shear wave velocity. The selected stochastic parameters are stress-corrected shear-wave velocity and stress reduction factor, which are modeled using a truncated normal probability density function and the peak horizontal earthquake acceleration ratio and earthquake magnitude, which are considered to have a truncated exponential probability density function. Comparison of the results with those of Monte Carlo Simulation (MCS) indicates very good performance of the proposed method in assessment of reliability. Comparison of the results of the proposed model and a Standard Penetration Test (SPT)-based model developed using JDRV shows that shear wave velocity (Vs)based model provides a more conservative prediction of liquefaction potential than the SPT-base model.

This paper aims to present a novel switched-capacitor multi-level inverter. The presented structure generates a staircase near sinusoidal AC voltage by using a single DC source and a few capacitors to step-up the input voltage. The nearest level control (NLC) strategy is used to control the operation of the converter. These switching states are designed in a way that they always ensure the self-voltage balancing of the capacitors. Low switching frequency, simple control, and inherent bipolar output are some of the advantages of the presented inverter. Compared to other existing topologies, the structure requires fewer circuit elements. Bi-directional power flow ability of the proposed topology, facilitates the operation of the circuit under wide range of load behaviors which makes it applicable in most industries. Besides, a 13-level laboratory prototype is implemented to realize and affirm the efficacy of the MATLAB Simulink model under different load conditions. The simulation and experimental results accredit the appropriate performance of the converter. Finally, a theoretical efficiency of 92.73% is reached.