PID Tuning of Servo Motor Using Bat Algorithm

AbstractThe Proportional-Integral-Derivative (PID) controller uses three parameters to produce the desired output of a system. The desired system performances are in terms of overshoot, rise time, settling time and steady state error. This has brought about various methods to tune the controller to the desired response. Therefore, the presence of the bat algorithm as part of the system will reduce the time and cost of tuning these parameters and improve the overall system performance

COMPARATIVE ANALYSIS OF THERMAL STRESS OF Si AND SiC MOSFETs

The performance of power MOSFET is affected by high thermal stress exposure. A high level of thermal stress is induced when the MOSFET experiences a temperature change. This finding is about the bonding wire lift-off on the solder pad. The MOSFET model is designed with the heatsink to ensure accurate results are obtained in this research work. The key intention of this research is to investigate the condition of silicon and silicon carbide power MOSFETs during thermal stress. The thermal properties of silicon and silicon carbide MOSFET were investigated by developing a 3D modal and thermal stress simulation in the COMSOL Multiphysics software. Thermal resistance was calculated by randomly selecting a power loss value of 100 Watts. Junction temperature for silicon and silicon carbide MOSFET was taken from several articles mentioned in the results and discussion

Impact of gamma-ray irradiation on dynamic characteristics of Si and SiC power MOSFETs

Power electronic devices in spacecraft and military applications requires high radiation tolerant. The semiconductor devices face the issue of device degradation due to their sensitivity to radiation. Power MOSFET is one of the primary components of these power electronic devices because of its capabilities of fast switching speed and low power consumption. These abilities are challenged by ionizing radiation which damages the devices by inducing charge built-up in the sensitive oxide layer of power MOSFET. Radiations degrade the oxides in a power MOSFET through Total Ionization Dose effect mechanism that creates defects by generation of excessive electron–hole pairs causing electrical characteristics shifts. This study investigates the impact of gamma ray irradiation on dynamic characteristics of silicon and silicon carbide power MOSFET. The switching speed is limit at the higher doses due to the increase capacitance in power MOSFETs. Thus, the power circuit may operate improper due to the switching speed has changed by increasing or decreasing capacitances in power MOSFETs. These defects are obtained due to the penetration of Cobalt60 gamma ray dose level from 50krad to 600krad. The irradiated devices were evaluated through its shifts in the capacitance-voltage characteristics, results were analyzed and plotted for the both silicon and silicon carbide power MOSFET

A High Step-Up Switched Z-Source Converter (HS-SZC) with Minimal Components Count for Enhancing Voltage Gain

Some applications such as fuel cells or photovoltaic panels offer low output voltage, and it is essential to boost this voltage before connecting to the grid through an inverter. The Z-network converter can be used for the DC-DC conversion to enhance the output voltage of renewable energy sources. However, boosting capabilities of traditional Z-network boost converters are limited, and the utilization of higher parts count makes it bulky and expensive. In this paper, an efficient, high step-up, switched Z-source DC-DC boost converter (HS-SZC) is presented, which offers a higher boost factor at a smaller duty ratio and avoids the instability due to the saturation of inductors. In the proposed converter, the higher voltage gain is achieved by using one inductor and switch at the back end of the conventional Z-source DC-DC converter (ZSC). The idea is to utilize the output capacitor for filtering and charging and discharging loops. Moreover, the proposed converter offers a wider range of load capacity, thus minimizing the power losses and enhancing efficiency. This study simplifies the structure of conventional Z-source converters through the deployment of fewer components, and hence making it more cost-effective and highly efficient, compared to other DC-DC boost converters. Furthermore, a comparison based on the boosting capability and number of components is provided, and the performance of the proposed design is analyzed with non-ideal elements. Finally, simulation and experimental studies are carried out to evaluate and validate the performance of the proposed converter

An Improved DC Circuit Breaker Topology Capable of Efficient Current Breaking and Regeneration

The DC power system, due to its convenience of conversion, integration, and use, is getting immense attention in the field of power transmission and distribution. It is superior to traditional AC systems in terms of efficiency, reliability, and control simplicity as well. A DC circuit breaker is one of the important elements of any DC power system. It is a sophisticated technology designed to break DC current only. The breaking of a DC current is always challenging compared to the breaking of an AC current, as DC current does not have natural zero crossing points like AC current has. Moreover, DC current breaking becomes more critical when the current is inductive as energy stored in the network inductance opposes instantaneous current breaking. Hence, this energy needs to be absorbed and dissipated as heat during the current breaking operation, which is exactly what is done in the traditional DC circuit breaker topologies. This paper introduces a new topology for DC circuit breakers with a mechanism to reuse this stored energy instead of dissipating it. The mechanism is analogous to regenerative braking in electric drive systems and can enhance the overall system efficiency. The proposed scheme was analyzed through rigorous computer simulation and was experimentally validated

Analysis of Steady-State Characteristics for a Newly Designed High Voltage Gain Switched Inductor Z-Source Inverter

This paper aims to develop a new switched inductor assisted strong boost Z-source inverter (SL-SBZSI) topology with high voltage gain and analyze the steady-state characteristics of the proposed topology. In the proposed topology, two switched inductors are used within the series impedance structure of the Z-source inverter (ZSI) in order to achieve the high voltage gain. The steady-state characteristics of the proposed topology are analyzed to disseminate its several advantages as compared to traditional ZSIs. The key advantages include the higher boost factor with lower shoot-through duty ratio and lower voltage stresses on capacitors as well as on switches of the inverter bridge. Furthermore, the proposed topology has the soft-start ability which significantly reduces the inrush start-up current while comparing with the traditional ZSI. In the proposed topology, a common ground is shared between the output AC voltage and the input DC voltage source which categorizes this topology to the doubly grounded inverter. The characteristics of the proposed SL-SBZSI are analyzed by considering two operating condition where the simple boost pulse width modulation (PWM) scheme is used to extract the shoot-through pulses. The characteristics of the proposed topology are also compared with different existing topologies along with the conventional modified capacitor assisted Z-source inverter (MCA-ZSI), whose boost factor is much closer to the proposed topology. Rigorous mathematical analyses are presented to clearly demonstrate the benefits of the proposed topology while simulation studies are carried out to demonstrate its distinct features as compared to the existing topology. Finally, experimental studies are conducted to further validate the theoretical and simulation results

iWorksafe: Towards Healthy Workplaces During COVID-19 With an Intelligent Phealth App for Industrial Settings

The recent outbreak of the novel Coronavirus Disease (COVID-19) has given rise to diverse health issues due to its high transmission rate and limited treatment options. Almost the whole world, at some point of time, was placed in lock-down in an attempt to stop the spread of the virus, with resulting psychological and economic sequela. As countries start to ease lock-down measures and reopen industries, ensuring a healthy workplace for employees has become imperative. Thus, this paper presents a mobile app-based intelligent portable healthcare (pHealth) tool, called i WorkSafe, to assist industries in detecting possible suspects for COVID-19 infection among their employees who may need primary care. Developed mainly for low-end Android devices, the i WorkSafe app hosts a fuzzy neural network model that integrates data of employees’ health status from the industry’s database, proximity and contact tracing data from the mobile devices, and user-reported COVID-19 self-test data. Using the built-in Bluetooth low energy sensing technology and K Nearest Neighbor and K-means techniques, the app is capable of tracking users’ proximity and trace contact with other employees. Additionally, it uses a logistic regression model to calculate the COVID-19 self-test score and a Bayesian Decision Tree model for checking real-time health condition from an intelligent e-health platform for further clinical attention of the employees. Rolled out in an apparel factory on 12 employees as a test case, the pHealth tool generates an alert to maintain social distancing among employees inside the industry. In addition, the app helps employees to estimate risk with possible COVID-19 infection based on the collected data and found that the score is effective in estimating personal health condition of the app user

Micronutrient needs of tropical food crops

The trace element requirements of tropical crops are reviewed with special reference to their role, the differences between crop species, the differences between cultivars, paths of trace element uptake, effects of climate, the importance of crop management and yield levels

An Investigation on the Potential of Cellulose for Soil Stabilization

The construction industry remains a significant contributor to global carbon emissions. Several sustainable alternatives have emerged to overcome this issue in geotechnical engineering. In this study, cellulose, an abundant biopolymer, is investigated for its potential to modify geotechnical properties favourably. Sodium carboxymethyl cellulose (NaCMC) is an anionic ether derivative of natural cellulose with good binding and moisture-retaining capacity. Experimental investigations were conducted on organic silt stabilized with 0.25% to 1.00% NaCMC, and the results indicate that unconfined compression strength (UCS) increased by 76.7% with 0.5% NaCMC treated soil after 28 days. Hydraulic conductivity (HC) of the 0.5% NaCMC treated soil decreased by 91.7% after 28 days, and the additives suppressed the compression index of the soil by 50%. The California bearing ratio (CBR) test indicated that the additive improved the subgrade strength by 33.2%, improving it from very poor to a fair sub-grade material. Microstructural analysis using a scanning electron microscope (SEM) and chemical investigation using x-ray diffraction (XRD) indicates that NaCMC’s interaction with soil did not form any new chemical compounds. However, the viscous nature of the material formed fibrous threads that bind the soil to enhance the geotechnical properties, establishing itself as a prominent stabilizer for ground improvement applications