Trans Z-source-based half-bridge inverter: A method for achieving high voltage gain

This article offers a modified trans Z-source-based half-bridge inverter topology. A suitable pulse width modulation (PWM)-based control method is applied on the proposed inverter. Regarding this control technique, the state of switches in each of the operational states is obtained, and their equivalent control circuits are demonstrated and examined in depth. With the help of the results of these analyses, the boost factor for the proposed structure can be calculated. Additionally, the necessary equations for designing the passive components, as well as the power ratings of the active components, are found. Then, in order to evaluate the advantages and disadvantages of the proposed topology, a comparative study is conducted in several aspects, including the boost factor, the voltage stresses on capacitors, and the voltage stresses on passive devices. This comparison demonstrates that the proposed topology provides a high boost factor while minimizing voltage stresses on the devices, resulting in a smaller volume and size and a lower cost. Once the proposed topology has been thoroughly analyzed, the total power losses and the percentages of power losses consumed by each component device are calculated to obtain efficiency. Finally, an experimental prototype based on the equations for passive and active components is developed. Experiments are used to verify the validity of the proposed topology and the accuracy of the equations.     

RQAR: Location-free reliable and QoS-aware routing protocol for mobile sink underwater wireless sensor networks

Underwater Wireless Sensor Networks (UWSNs) have attracted attention from academics and industries due to many applications such as pollution monitoring, military, tsunami warning, and underwater exploration. One of the effective factors in these applications is efficient communication between underwater sensors. But this process is very challenging in UWSNs due to special conditions and underwater harsh environments. Therefore, designing routing protocols for efficient communication between sensors and sink is an important issue in UWSNs. In this context, this paper proposed a location-free Reliable and QoS-Aware Routing (RQAR) protocol for mobile sink UWSNs. RQAR designed using Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) and does not require the position information of the sensor nodes, which is cumbersome and difficult to obtain. Proposed protocol considers multiple parameters including link quality, hop count, congestion, and residual energy for qos support, and reliable data delivery RQAR also minimizes the effects of hole occurrence by increasing the transmission range as much as possible and ensures communication stability. The simulation results using NS2 showed the superiority of RQAR in improving end-to-end delay, packet delivery ratio, and network throughput compared to the previous methods.     

Evolution of a new surface water quality index for Karoon catchment in Iran

Water quality standards are developed worldwide by national and international agencies for pollution control decision-making. Use-based water quality classification criteria and Water Quality Indices (WQIs) also play an important role in the assessment of the suitability of water resources for various applications. The present study proposes a better overall index for water quality in Iran and its application in Karoon River by exploring the behavior and limitations of conventional methods for quality evaluation. For this purpose, six variables were employed. Water quality determinants of the new index include Dissolved Oxygen, Total Dissolved Solids, Turbidity, Nitrate, Fecal coliform and pH. Besides, the mathematical equations applied to transform the actual concentration values into quality indices have been formulated. This study compares a new index called the Iranian Water Quality Index with other pre-existing indices such as NSFWQI, Oregon, CPCB WQI, MDOE WQI, Kaurish and Younos WQI, and Ahmed Said WQI. Results revealed that the overall quality of the surface water falls under the 'good' class. A case study of Karoon River is made to illustrate the application of this new index system.     

A general approach to approximate solutions of nonlinear differential equations using particle swarm optimization

A general algorithm is presented to approximately solve a great variety of linear and nonlinear ordinary differential equations (ODEs) independent of their form, order, and given conditions. The ODEs are formulated as optimization problem. Some basic fundamentals from different areas of mathematics are coupled with each other to effectively cope with the propounded problem. The Fourier series expansion, calculus of variation, and particle swarm optimization (PSO) are employed in the formulation of the problem. Both boundary value problems (BVPs) and initial value problems (IVPs) are treated in the same way. Boundary and initial conditions are both modeled as constraints of the optimization problem. The constraints are imposed through the penalty function strategy. The penalty function in cooperation with weighted-residual functional constitutes fitness function which is central concept in evolutionary algorithms. The robust metaheuristic optimization technique of the PSO is employed to find the solution of the extended variational problem. Finally, illustrative examples demonstrate practicality and efficiency of the presented algorithm as well as its wide operational domain.     

A new switched-capacitor/switched-inductor–based converter with high voltage gain and low voltage stress on switches

In this paper, a nonisolated transformerless switched-capacitor/switched-inductor–based dc-dc converter with high voltage gain is proposed. The proposed converter has low voltage stress on switches and diodes which leads to decrease the switching losses. The voltage gain of the proposed converter can be increased by adding more diode-capacitor modules at output side; therefore, the proposed converter has expandable structure. The proposed converter has higher voltage gain and lower voltage stress on switches comparing with the other similar switched-capacitor–based converters. The proposed converter uses two switches with the same switching pattern. Therefore, its switching pattern is not complicated. In this paper, the proposed converter is analyzed during a switching period which has two operating modes. Moreover, the average current through the switches, diodes, and inductors; voltage stress on switches and diodes; voltage gain; maximum and minimum current of switches and diodes; and the efficiency curve are calculated. Finally, in order to verify the accuracy performance of the proposed converter, a 530-W 40 to 920-V prototype is implemented practically.     

Expandable interleaved high voltage gain boost DC-DC converter with low switching stress

In this paper, an interleaved DC-DC step-up boost converter with high voltage conversion ratio and low voltage stresses on switches and diodes is proposed. The proposed converter has low average current passing through the diodes and switches and low input current ripple as a feature of interleaved converters. The voltage gain of the proposed converter can be increased by adding more diode-capacitor modules; therefore, the proposed converter has expandable structure. In addition, by implementing more diode-capacitor modules, the switching stresses would be more decreased. Also, to evaluate the performance of the proposed converter, it is compared with other similar presented circuits in the literature. The proposed converter is not only able to provide higher voltage gain but also has lower voltage stresses on switches and diodes. Consequently, switches and diodes with low voltage ratings can be selected. Theoretical analysis is provided in this study for each operation mode and the average current through the switches, diodes and inductors, voltage stresses on switches and diodes, voltage gain, and input current ripple are calculated. Finally, to demonstrate the accuracy performance of the proposed converter, a 450-W prototype is implemented practically.     

A new single‐phase multilevel converter topology with reduced power electronic devices,voltage rating on switches,and power losses

In this paper, a new extended single‐phase structure for multilevel converter is presented which consists of several bidirectional and unidirectional switches along with dc voltage sources. To generate all possible levels at output voltage waveform, 2 methods are presented for determination of the amplitudes of dc voltage sources. The proposed structure is compared with traditional cascade H‐bridge multilevel converter and other recently proposed structures in terms of the number of power electronic components, voltage rating on switches, and power losses. Based on the comparison results, it is demonstrated that the proposed structure needs minimum number of IGBTs, gate drivers, and anti‐parallel diodes. Moreover, the voltage rating on bidirectional and unidirectional switches in the proposed structure is less than other similar topologies. Also, power losses analysis on the proposed topology is investigated. It is shown that the power loss of proposed topology is less than H‐bridge multilevel converter topology. The number of on‐state switches in the current path of proposed topology is much lower than other topologies which lead to the reduction of voltage drop on the switches and power losses. Both experimental and simulation works are provided to verify the performance of the presented structure.     

A new topology for nonisolated multiport zero voltage switching dc‐dc converter

In this paper, a new multiport zero voltage switching dc‐dc converter is proposed. Multiport dc‐dc converters are widely applicable in hybrid energy generating systems to provide substantial power to sensitive loads. The proposed topology can operate in 3 operational modes of boost, buck, and buck‐boost. Moreover, it has zero voltage switching operation for all switches and has the ability to eliminate the input current ripple; also, at low voltage side, the input sources can be extended. In addition, it has the ability of interfacing 3 different voltages only by using 3 switches. In this paper, the proposed topology is analyzed theoretically for all operating modes; besides, the voltage and current equations of all components are calculated. Furthermore, the required soft switching and zero input currents ripple conditions are analyzed. Finally, to demonstrate the accurate performance of the proposed converter, the Power System Computer Aided Design(PSCAD)/Electro Magnetic Transient Design and Control(EMTDC) simulation and experimental results are extracted and presented.     

Design and fabrication of high performance condenser microphone using C-slotted diaphragm

Microsystem Technologies - In this paper, we present a new design of MEMS condenser microphone using SOI wafer. To improve the performance of the microphone, a perforated diaphragm with C-shape...     

High voltage gain dual-input dual-output DC-DC converter with reduced voltage stress on semiconductors

This paper proposes a new nonisolated multiport DC-DC converter with two inputs and two outputs with different voltage levels. Different energy sources with distinct voltage-current characteristics can be utilized as the input sources. Regarding multiple outputs, the proposed converter can be utilized in electric vehicles (EVs) to supply the DC traction motor and the auxiliary loads. The main advantages of the proposed converter include the high voltage gain with small values of the duty cycles, low normalized peak voltage stress (NPVS) across the semiconductors, and the continuous input currents. The voltage stress across the semiconductors is lower than the maximum output voltage. This feature makes it possible to use the switches with low turn-on resistance and the diodes with reduced rating voltage. Performance principals of the proposed converter along with the steady-state analysis, such as the derivation of the voltage gains, voltage and current stresses of the semiconductors, etc, are carried out. Experimental measurements made for the laboratory prototype of the proposed converter confirm the theoretical analysis.