Photovoltaic (PV) panels rely on environmental conditions such as irradiation or temperature, and thus they require an interface boost converter. Non-isolated DC-DC boost converters have a lower volume, lower costs and lower power dissipation compared with isolated converters. In this study, a novel high efficiency non-isolated DC-DC boost converter is proposed to be used in PV systems. The converter includes only one semiconductor switch which causes lower switching losses. The main advantages of the proposed converter include low input current ripples, low Voltage Stress on semiconductor switches, high efficiency and low conduction losses. Moreover, maximum power is achieved from PV panels. A prototype of the proposed converter has been built, and experimental results are presented which explicitly validate theoretical results, suggesting that this boost converter is desirable for PV applications.

A new output structure for class E power amplifier (PA) is proposed in this paper. A series LC resonator circuit, tuned near the second harmonic of the operating frequency is added to the output circuit. This resonator causes low impedance at the second harmonic. The output circuit is designed to shape the switch Voltage of the class E amplifier and lower the Voltage Stress of the transistor. The maximum switch Voltage of the conventional class E PA is 3.56Vdc. However, higher switch Voltage of about 4.5VDC may be occurred, by considering nonlinear drain-to-source capacitance in class E PA. The obtained peak switch Voltage of the designed class E PA is approximately 75% of the conventional one with the same conditions, which shows a significant reduction in peak switch Voltage. MOSFET parasitic nonlinear gate-to-drain and nonlinear drain-to-source capacitances of the MOSFET body junction diode also affect the switch Voltage in class E PA, which are considered in this paper. The actual MOSFETs have these parasitic capacitances; therefore, it is necessary to consider these elements in the design procedure. Reduced switch Voltage in class E PA relaxes the breakdown Voltage constraints of the active device. In the switch Voltage of the designed circuit, the zero Voltage and zero derivative switching (ZVS and ZVDS) conditions are satisfied. Simulation of the presented circuit is performed using PSpice and LTspice softwares. For verification of the designed circuit, the presented PA is fabricated and measured.

The Z-source converter was first introduced as a buck-boost dc-ac single-stage inverter in 2003. Different structures of impedance source inverters have been introduced for improving the performance of power inverters. Due to their specific structure, these inverters use shoot-through state in order to increase the output Voltage. Therefore, in addition to improving the reliability of systems, they create a single-stage dc-ac inverter capable of reducing and increasing Voltage at the same time. Recently, a three-winding network called the A-source network has been introduced. A new Pulse Width Modulation method has been proposed to improve the Voltage gain and reduce switching losses. In this new method, duty cycle of the switch is controlled using the third harmonic injection and the new reference Voltages in the three-phase A-source inverter. The proposed modulation method reduces the switching losses and increases Voltage gain without adding any additional hardware to the inverter structure. In this method, the buck-boost single-stage structure of the inverter is maintained. In this paper, the proposed method is partially analyzed and compared to the conventional Pulse Width Modulation methods. In this method, the third harmonic injection is used to increase the modulation index to 1. 15 and thereby reduce the switching losses. The simulation of the proposed and conventional methods and analyzes, demonstrated the ability of the proposed system.

High step-up DC-DC converters are considered the main components of some lowVoltage and low-power fuel cell power system applications. A new DC-DC converter topology based on a two-stage switched capacitor-switched inductor multiplier is proposed in this paper. In comparison with other conventional and high step-up DCDC converters, the proposed converter topology provides higher Voltage gain and lower switch Voltage Stresses for duty cycles in the range of 0. 6 or higher, the typical duty cycle of high step-up DC-DC converters. The proposed converter consists of a novel combination of switched capacitors and switched inductors methods that reduce the number of required switches and their duty cycles. The theoretical analysis was confirmed by simulation results in MATLAB/Simulink software environment results. A 100 W laboratory prototype of the proposed converter was implemented to investigate and validate the analytical and simulation results. The prototype DC-DC converter was designed and implemented for use in a commercial 100 W PEM fuel cell stack power system.

In this paper, a series Z-source inverter based on a switched inductor cell is proposed for the first time. This inverter is able not only to increase the Voltage gain, in comparison with the conventional Z–, source inverters, but also to solve the ST (shoot-through) state’, s problems. In this inverter, the value of the Voltage gain is increased by an increase in the number of used diodes and inductors in the switched inductor cells. The low value of the capacitors’,Voltage Stress is another advantage of the proposed inverter. The Voltage of the capacitors is increased from zero to the desired value by increasing the duty cycle of ST state from zero to the desired value. This leads to a soft start in the proposed inverter, which is impossible in conventional Zsource inverters. In this paper, in addition to investigating the operation of the proposed inverter in different operating modes, the value of Voltage Stress of the capacitors, current inductors, and the value of Voltage gain are also calculated. Moreover, the proposed inverter is compared with the conventional Z-source inverters to investigate the advantages and disadvantages of it. Finally, the accuracy performance of the proposed inverter is verified through the simulation results in PSCAD/EMTDC software programs.

The interleaved boost converters are the power circuits that provide high-Voltage, high-power with regulated output Voltage for renewable energy systems which are generally suffer from low-Voltage and unregulated output Voltages. The soft switching methods reduce electromagnetic noises and switching losses in these converters. In this paper, a ZVT interleaved boost converter with a simple auxiliary circuit is proposed. The proposed converter has a simple structure with low size and cost. In the proposed converter, soft switching condition is provided without any extra Voltage and current Stress on the main switches. The auxiliary circuit comprises two diodes and one auxiliary switch. The leakage inductance of the utilized coupled inductors is used as resonant inductor. The auxiliary switches benefit from significantly reduced Voltage Stress without requiring floating gate driver. The proposed converter can achieve zero Voltage switching operation for the main switches and zero current switching for diodes and auxiliary switches, which causes to alleviate the reverse recovery problems of all diodes.

Severe Voltage fluctuations at different points of the network are the main concerns of the widespread low-Voltage electrical energy distribution networks. In particular, small industrial loads and rural consumers in remote geographical areas, which are fed by long lines, always experience great Voltage drops. The use of common distribution transformers equipped with off-load tap changers has not been effective in solving this problem due to issues such as lack of access to all network points for operators, the need to de-energize the line during tap change, and the successive and unpredictable load changes. Therefore, the use of transformers with automatic Voltage adjustment at different points of distribution networks has attracted much attention. The present research aimed to implement a simple solid-state Voltage regulator (SSVR) in the low power range to automatically eliminate severe Voltage fluctuations. In this research, a solid-state Voltage regulator with a rated power of 5 KVA was designed and built to automatically compensate for the Voltage of a small group of home customers (who have a severe Voltage drop due to the distance from the distribution post). The results of the measurements showed that this equipment can limit the Voltage changes to 220±3%, while it does not affect the power quality. In addition, various hardware and software protections were designed for the device built against network disturbances and abnormal consumer functions.

Voltage stability may be improved by various control functions. In this paper, it is shown that how High Side Voltage Control (HIVC) may be employed for this purpose. Two test systems, namely a 22- bus and IEEE U8-bus systems are used to demonstrate the proposed tuning strategy for HSVC control parameters.

Purpose: Application of heavy forces to maxillary dentition during treatment with headgear, induces high concentration of Stresses in periodontal tissue. Quantification of this Stress is of great concern in orthodontics. This study was designed to investigate the quantity and quality of Stress response in the PDL of maxillary first molar which was subjected to high pull headgear traction using Finite Element method.Methods and Material: In an experimental study, a three-dimensional finite element model of maxillary dentition, consisting of 17096 elements and 23013 nodes, was developed based on a young human skull. The forces were applied to the maxillary first molar in the stabilized Arch by means of a rectangular full size arch wire in (022) slot bracket. Mechanical properties of this model were based on previous studies. A 350 gram force was used for high pull headgear to affect the dentition (+30 degree) and Stress distribution was investigated in buccal, palatal, mesial and distal side and in cervical, middle, apical sections of the PDL. The quantity of Stresses were expressed as principal Stresses (1,2,3), while the negative and positive signs indicated compressive and tensile Stresses.Results: The buccal surface of PDL of mesiobuccal root and the buccal, palatal and distal surface in cervical region of PDL of distobuccal root and the distal surface of the PDL of palatal root had received a great deal of Stresses, in addition, the over all Stress distribution in roots of molar had intrusive nature.Conclusion: The extension of high Stress concentration areas observed after using high pull headgear is limited to some root surfaces specially the distobuccal root.

Background: The most frequently used test for evaluation of fetal health is the Non Stress Test (NST). Unfortunately it has a high incidence of false positive results. The combination of vibroacoustic stimulation with the NTS has been shown to reduce non reactive results.Methods: A tests assessment method was chosen with a simple randomized sampling. 40 pregnant women with non reactive NST in the first 20 minutes who received VAS in one of Tehran University's Hospitals were compared with BPP scores. A vibroacoustic stimulation was applied for a 3 seconds on the maternal abdomen and fallowed within 10 minutes. Data collection tools were NST, sonography instruments, NST result paper, tooth brusher, watch, demographic questioner and check list. Data analysis was made by descriptive static and by using the Fisher's Exact Test (with level of significant at p<0/05). All statistical analysis were performed using an spss/win.Results: After VAS, 70% of non reactive tracing became reactive. All cases with fetal reactivity response after a VAS had a subsequent BPP score of 8 (negative predictive value of 100%). False positivity of VAS was lower than NST.Conclusion: VAS offers benefits, by decreasing the incidence of non reactive test and reducing test time. VAS lowers the rate of false positive NST. VAS is safe and allows more efficient of prenatal services. This test could be used as a rapid antepartum test to predict fetal well-being.