Search

Considering the increasing use of intelligent DC-DC converters especially in Renewable Energy Sources (RESs) applications, designing a proper control system is important and can increase the efficiency and reliability. In normal operating conditions, each DC-DC power converter structure, often has a constant voltage control loop in the converter output and a duty cycle controller in the semiconductor power switch side of the converter. The classical methods have a proportional–integral–derivative (PID) controller in their feedback control loop. The problem with these controllers is that in non-linear systems such as DC-DC converters, their behavior is only optimal at the point of operation of the system. A fuzzy logic controller can be used to improve their behavior in large signal variation scenarios. In addition, the behavior of the system in normal conditions and in the event of an error in the converter, has a significant improvement. In this paper, the principles of fuzzy logic are used to control the Boost converter. Since the output voltage of the converter should be stable against system errors such as noise, load changings, and input voltage variations, the novelty of the designed fuzzy controller is based on the input-output information of the previous designed controllers as well as the experimental knowledge based on the time-dependent variables. By using the fuzzy logic controller, the system parameters will be stable against these volatilities. Performance conditions are simulated using MATLAB software., Akıllı DA-DA Dönüştürücülerinin özellikle yenilenebilir enerji kaynakları (RES) uygulamalarında artan kullanımı göz önünde bulundurulduğunda, uygun bir kontrol sistemi tasarımı, verim ve güvenilirlik açısından son derece önemlidir. Normal çalışma koşullarında, her DA-DA güç dönüştürücü yapısı, genellikle dönüştürücü çıkışında sabit bir gerilim kontrol bloğuna ve dönüştürücünün yarı iletken güç anahtarı tarafında bir görev döngüsü kontrolü bloğuna sahiptir. Klasik yöntemlerde, geri besleme kontrol döngülerinde orantılı-integral türev (PID) kontrolörü kullanılmaktadır. Bu kontrolör ile ilgili temel sorun, DA-DA dönüştürücüler gibi doğrusal olmayan sistemlerde, davranışlarının yalnızca sistemin çalışma noktasında en uygun olmasıdır. Bulanık mantık denetleyicisi, bu tür sistemlerin büyük sinyal değişimi senaryolarındaki davranışlarını iyileştirmek için kullanılabilir. Ek olarak, normal şartlarda ve dönüştürücüde bir hata olması durumunda, sistemin davranışında önemli bir iyileşme görülmektedir. Bu çalışmada, yükseltici dönüştürücüyü kontrol etmek için bulanık mantık ilkeleri kullanılmıştır. Dönüştürücünün çıkış gerilimi, gürültü, yük değişimleri ve giriş gerilimi değişimleri gibi sistem hatalarına karşı kararlı olmalıdır. Tasarlanan bulanık denetleyicideki yenilik, bu denetleyicinin daha önce tasarlanan kontrolörlerin giriş-çıkış bilgisine ve deneysel olarak zamana bağlı değişkenlere dayanmasıdır. Bulanık mantık denetleyicisini kullanarak, sistem parametreleri bu oynamalara karşı kararlı olması sağlanmaktadır. Performans koşulları MATLAB yazılımı kullanılarak benzetilmiştir.

WOS:000530832200116 This study presents the effects of the vibration and thermal cycling on the fatigue life of a power Metal Oxide Semiconductor Field Effect Transistor (MOSFET) in a power converter circuit. The fatigue mechanism in per loading mode was investigated separately and based on the overlap approach, the synchronous effects were analyzed. The solder creeps & x2019; attitudes are depended on the fatigue life for the thermal loops. The success of the deposited strain per thermal loop is in direct relation with the fatigue lifetime. The main source of the stress in the packaging process is the differences between the components & x2019; thermal coefficients. To evaluate the effects of the vibration on the fatigue life for the solder layers, the RMS value of the peeling stress was considered. According to the results, the maximum stress and main affected points realized at the corners of the layers. It has been identified that the assembling of the thermal effects and mechanical loads are quickened the failure rate at the solder joints for this device. The Finite Element Method (FEM) is used for the simulation and the results confirm the estimated crack formation places in the layers.

WOS:000473125300008 Renewable Energy Sources (RES) including full cells, wind turbines, and photovoltaic panels, widely are spreading. Among all the renewable energy sources, solar power generation system tops the list. The first choice is the boost converter when the voltage step-up is the issue. But the most important subject is applying an efficient structure with high gain, cheap and quick controller circuit. Our proposed cascaded boost converter is one of such converters which consists of several cheap components such as diode, inductor, capacitor and power switch, which has same switching frequency and phase shift in comparison with conventional boost converters. In comparison with the classic cascaded boost converter, the voltage gain for the proposed structure is very high and by forming a preamplifier layer, for a duty cycle of 80 % by adding only two diodes, one inductor, and one capacitor for the second block, voltage gain is increased by 5 times compared to the classic boost converter. The proposed method provides the increased output voltage along with the duty cycle. The projected strategy has been verified with the help of Matlab/Simulink. Also, a hardware implementation of the proposed converter has been done around 200 W by applying a Jiangyin HR-200W-24V type solar panel. Scientific Research Projects Units of Bursa Technical University, Bursa, Turkey [182N06] This research was funded by a grant (No. 182N06) from the Scientific Research Projects Units of Bursa Technical University, Bursa, Turkey.

WOS:000576421400014 Solder joints are the critical components of the printed circuit boards (PCBs) in the moving electronic systems, such as satellites and automotive industries that are most vulnerable to accidental vibrations. Therefore, the reliability of these boards since they are designed to be used for long-time applications is important. Since the laboratory tests are time-consuming and require well-equipped and costly measurement devices, reliability tests are preferred to perform through the analytical methods. In this article, an analytical model based on the multilayer plate theory is presented for the random vibration analysis, and the results are obtained for the different vibration frequencies, including the natural vibration frequency. For the proposed model, the state of the PCB layer and the amount of the stress in the solder joints are investigated separately, and the normal and shear stresses are obtained through the combined sinusoidal-exponential equation. Results by the finite-element method (FEM) analysis show that the cracks form at the edge of the interconnection points of the board, and the solder and void formation and crack propagation appear in the corners of the PCB in frequencies closed to the natural vibration frequency. Reliability increases by the reduced solder height. VILLUM FONDEN [Center for Research on Microgrids (CROM)] under the VILLUM Investigator Grant [25920] This work was supported by VILLUM FONDEN [Center for Research on Microgrids (CROM)] under the VILLUM Investigator Grant 25920.

WOS:000563947300001 Many of the photovoltaic (PV) panels generate the low amounts of the voltages under the limited values of the powers. In order to increase these voltages to be applicable for grid utilization, DC-DC boost converters are used. A novel nonisolated transformer-less switched-capacitor-based DC-DC power boost structure is combined with the quadratic converter in this study. The proposed converter has many advantages such the low-voltage stresses on the power components, higher voltage-gain, and ability to supplying the load under the low amounts of the switching time intervals. These features lead to fewer amounts of the currents for the power components in the topology for the continuous conduction mode which means less dynamic losses and higher efficiency. Another advantage of the proposed converter is including only one power switch that simplifies the controller design for implementation purposes. A comprehensive mathematical analysis is presented and simulation with MATLAB/SIMULINK and implemented hardware test results confirm the theoretical investigations. National Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [61702238, 61862027, 61762043, 61661022]; Science and Technology Foundation of Educational Commission of Jiangxi Province of China [GJJ170316, GJJ180264] The National Natural Science Foundation of China under Grant No. 61702238, No. 61862027, NO.61762043, No. 61661022 and the Science and Technology Foundation of Educational Commission of Jiangxi Province of China under Grant NO. GJJ170316, NO. GJJ180264.

WOS:000510557100001 PV-based and wired type of the electrical bicycles (e-bike) battery charging stations widely is spreading because of the resonant network limitations and low efficiency of the wireless mode for these stations. The generated voltage of many of the PV panels such as JIYANGYIN HR-200 W-24 V at the maximum power point is around 36VDC. So, a step-down converter with a PID controller for Maximum Power Point Tracking (MPPT) of the PV panels is considered between PV panels and boost converter in order to decrease this voltage and enhance the current values for the load side. A sliding mode controller (SMC) equipped with a non-isolated DC-DC boost converter with reduced voltage stresses on the power switch is presented. The step-up converter increases the voltage to the utility level of the e-bike with around 360 Wh amount of energy. The main concerns about the converters are the efficiency, voltage, and current stresses, number of active or passive components in the converter topology and simplicity. In comparison with a conventional step-up converter, the selected converter has a lower dynamic loss in the input inductor that can give a proper efficiency by considering its higher voltage gain. The average state-space model for the SMC is used and the main advantage of the controller is its independency to the inductor current or the amount of the load. The proposed SMC is compared with PID and Fuzzy Logic Controller (FLC) methods and based on the results, the robustness, overshoot, and damping factor of the controller are at an acceptable and better level. All mathematical, simulation and comparison results are presented. A 720 Wh circuit has been implemented for charging all types of the Li-Ion or Li-Polymer batteries with 36VDC and 10 Ah specifications.

WOS:000489225700006 This study presents a unique comprehensive mathematical model for both transient and steady states of the step-up power converter in order to structure physical aspects evaluations. The main disadvantage of different existence mathematical models such as impedance, small signal analysis and steady space average models is that they use numerical analysis methods or simplification solutions that lead to approximate analysis. Therefore, the physical behaviours of the system such as inductor current, output voltage and physical effects of components will not be accurately predictable. This study presents very accurate equations and all aspects of the structure are predictable. In our research, this issue is investigated in Laplace and Z domains using the output-to-input transfer function calculations, and the effect of converter circuit elements is assessed using equations obtained. For extracting the transfer function, initial values are calculated in the Z domain and based on the final value theorem, converter output voltage and input current have been calculated. Effects of converter components on capacitor voltage and input current ripples have been analysed and reported. In the final step, results of the theoretical analysis were confirmed by simulation results obtained in MATLAB/SIMULINK environment and implementation on a prototype in laboratory scales.

MINAZ, Mehmet Recep/0000-0001-8046-6465; toren, murat/0000-0002-7012-7088; Ghaderi, davood/0000-0003-2234-3453 WOS: 000436583500003 So as to keep the converter in small size, high switching frequencies are normally used. As a result, in higher frequencies, switching losses seriously affect the efficiency. Current and voltage stresses on power switch can be serious problems particularly in high amount of powers where MOSFET switches are generally applied. A snubber circuit can reduce or eliminate spike voltage and currents, decrease the di/dt or dv/dt values on power switch and transfer the power losses on switch to load and increases the lifelong of the switch. This study presents a method for improving the power transmission efficiency for DC-DC Cascaded Boost Converter and uses a passive snubber sub-circuit, which consists of an inductor, a capacitor, and two diodes for reducing the switching loss. the role of resonant capacitor of this structure is discharging directly through the load and is parallel with the power switch. Thus, it is effective in lossless switching and increasing the DC voltage gain of the boost converter. Soft switching is achieved through the use of a LC resonant tank circuit. the tank circuit is responsible for zero voltage switching (ZVS) and zero current switching (ZCS), eliminating the power loss in the switches appreciably. the proposed structure, done by MATLAB SIMULINK based on simulations, has shown more efficiency toward the same structure without snubber circuit. Besides, an application has been conducted in laboratory scales, and results confirm theoretical findings.