Mohd Tariq

Bio: Mohd Tariq is an academic researcher from Aligarh Muslim University. The author has contributed to research in topics: Inverter & Photovoltaic system. The author has an hindex of 15, co-authored 185 publications receiving 851 citations. Previous affiliations of Mohd Tariq include Maulana Azad National Institute of Technology & Nanyang Technological University.

Aircraft batteries: current trend towards more electric aircraft

Abstract: Competition in the aircraft industry market and global warming has driven the industry to think along economic and environmental lines. This has resulted in the emergence of more electric aircraft (MEA). The increase in the power demand of aircraft, especially in the last two decades, coupled with advancement in battery materials and technology has led to the development of many high energy density batteries. This study presents an overview of the battery systems for MEA. In this paper, a study on the battery technologies used in aircraft in the last five decades is being done. A general background of the battery system is presented and the performance of the batteries based on energy densities and low temperature capabilities are evaluated and discussed. Evolution of MEA with its power system architecture and load profile is presented to understand the requirements of the battery system. Weight saving and cost analysis is done for the Li-ion and Ni-Cd batteries with respect to the requirement of an MEA `Aircraft X'. Battery management system (BMS) for Li-ion batteries is also explored and discussed. Based on the analysis, Li-ion battery is selected and integrated with the power distribution DC network for future MEA.

Most Valuable Player Algorithm based Maximum Power Point Tracking for a Partially Shaded PV Generation System

Abstract: Inclusion of bypass diodes at the output terminal of the PV array mitigates the effect of partial shading (PS) but causes multiple peaks of power at the output. The conventional hill climbing and perturb and observe algorithms cannot track the optimal point during partial shading phenomena for multiple peaks corresponding to the different shading pattern on the Power-Voltage (P-V) curve. Fuzzy logic controller and artificial neural network-based methods for Maximum Power Point Tracking (MPPT) provide satisfactory results but at the cost of increased memory and computational burden. Recent work to incorporate exploration and exploitation phenomena of nature-inspired algorithms to track optimal power point have shown encouraging results by preventing convergence to local maxima and posing less burden on the processor. However, due to performance variation between different algorithms of this category newer algorithms with improved performances are still a requirement. In this paper, a novel most valuable player algorithm (MVPA) has been used to track the optimal operation point for extracting maximum power from a solar PV system. The algorithm's performance is compared with the commonly employed particle swarm optimization (PSO) and the recently proposed Jaya algorithm's modified form. It is observed that the proposed algorithm outperformed both the algorithms with a considerable improvement in terms of tracking speed, power tracking efficiency, robustness, faster decision for convergence after tracking the maximum power and lesser number of power fluctuations for different shading patterns.

Evaluation of level-shifted and phase-shifted PWM schemes for seven level single-phase packed U cell inverter

Abstract: An evaluation of level shifted and phase shifted triangular and sawtooth carrier modulation schemes for a seven level packed U cell (PUC) inverter is presented in this paper. The investigated PUC is the recently introduced topology for multilevel inverter having reduced switch count in comparison to the conventional topologies of multilevel inverters. The PUC inverter has six switches for 7 level inverter which is very less in comparison to the conventional topologies. In this paper, the level-shifted pulse width modulation (LS-PWM) and phase-shifted PWM (PS-PWM) for triangular and sawtooth carrier are presented and compared. A comparative harmonic analysis for all the cases is performed and results are presented in the paper. The difference in harmonics of the two modulation methods given by the theoretical approach for both the carrier is validated by the experimental results. DC voltage controller and load current controller of the PUC inverter are also designed and presented. The investigated PUC topology is tested in dynamic and steady state conditions and results obtained are presented. The analysis is done and validated using simulation in MATLAB Simulink environment and experimental approaches using FPGA platform.

Modeling and Integration of a Lithium-Ion Battery Energy Storage System With the More Electric Aircraft 270 V DC Power Distribution Architecture

Abstract: With an aim to decrease pollution level due to aviation transportation sector, aircraft industries are focusing on more electric aircraft (MEA). The design of MEA is made with an aim to reduce the CO2 emission, noise pollution, increased comfort level for the passengers, and so on. In this paper, a detailed study of the evolution of the MEA along with the load profile for electrical load is presented. Based on the requirements of the electrical load, a high-energy-density lithium-ion “Li iron phosphate” battery is selected, designed, and modeled. The modeling is based on the modified Shepherd curve-fitting model with the addition of the voltage polarization term to have a lower complexity and more proximity with the real battery profile. The phase shifted high power bidirectional dc–dc (PSHPBD) converter is used in the battery energy storage system (BESS) as a battery charger. The modeled Li-ion battery is integrated to the 270- $\text{V}_{dc}$ MEA power distribution bus using the optimal harmonic number-based harmonic model of the PSHPBD converter. Since BESS has to provide the transient loads, the fast dynamic response is required for the PSHPBD converter working as the charger in the BESS. A predicted peak current-based fast response control technique is proposed in this paper for the integration of the BESS with an MEA power system architecture. The proposed control structure provides a maximum limit on the coupled inductor current to the predicted peak current value as well as it gives fast transient response desired in the MEA system.

Online Condition Monitoring System for DC-Link Capacitor in Industrial Power Converters

Abstract: This paper proposes an online condition monitoring system for aluminum electrolytic capacitors used as dc-link capacitors in industrial power converters. Electrolytic capacitors are one of the most fragile components of a power converter system because of their wear-out failures and short lifespan. Therefore, the use of condition monitoring systems for aluminum electrolytic capacitors allow preventive maintenance to be performed, thereby avoiding unexpected shutdown and downtime. The dominant wear-out mechanisms in aluminum electrolytic capacitors are characterized by the increase in equivalent series resistance. Hence, the condition monitoring system proposed in this paper is based on the online estimation of the capacitor's equivalent series resistance using the switching frequency components of the dc-link capacitor voltage and current. The equivalent series resistance estimation method is tested using the PSpice circuit simulator and is validated experimentally using a custom-made inverter. Finally, the equivalent series resistance estimation method is adapted for the condition monitoring of capacitors in industrial power converters and the proposed condition monitoring system is implemented in a commercial ac drive system to prove the applicability of the proposed method to industrial power converters.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Multi-level conversion : high voltage choppers and voltage-source inverters

Abstract: The authors discuss high-voltage power conversion. Conventional series connection and three-level voltage source inverter techniques are reviewed and compared. A novel versatile multilevel commutation cell is introduced: it is shown that this topology is safer and more simple to control, and delivers purer output waveforms. The authors show how this technique can be applied to either choppers or voltage-source inverters and generalized to any number of switches.<>

Electric power converter

Abstract: Provided is an electric power converter. A First and second series circuits of switching devices and a series circuit of capacitors are connected in parallel. Between the connection point in the first series circuit of switching devices and the connection point in the series circuit of capacitors, a first bidirectional switch is connected and, between the connection point in the second series circuit of switching devices and the connection point in the series circuit of capacitors, a second bidirectional switch is connected. The connection point in the first series circuit of switching devices is connected through a reactor to an input-output common connection line connected to one end of an AC power supply and the other end of the AC power supply is connected to the connection point in the series circuit of capacitors.

Ultimate tensile strength of tooth structures

Abstract: Objective . This study determined the ultimate tensile strength (UTS) of enamel (E), dentin (D) and dentin–enamel junction (DEJ) using the microtensile technique. It was hypothesized that the UTS of dental structures varies according to location and nature. Methods . Intact occlusal enamel surfaces from extracted human third molars were etched with 37% phosphoric acid and bonded with a one-bottle adhesive system. The bonded occlusal surfaces received a resin composite build-up and teeth were serially, vertically sectioned into several 0.7 mm thick slabs. Each slab was then trimmed to a dumbbell-shaped specimen with irrigated diamond burs to reduce the cross-sectional area to approximately 0.5 mm 2 at E, D or DEJ. E was tested according to its prismatic orientation (parallel, EP; and transversally, ET) and D as function of depth (superficial, DS; middle, DM and deep, DD). Specimens were tested in tension in an Instron testing machine at 0.5 mm/min. Results were analyzed by one-way ANOVA and Duncan's Multiple Range test. Results. UTS mean values ( N =20) were, MPa (SD): DEJ, 46.9 (13.7) b ; EP, 42.1 (11.9) b ; ET, 11.5 (4.7) d ; DS, 61.6 (16.2) a ; DM, 48.7 (16.6) b and DD, 33.9 (7.9) c . Enamel stressed transversally to its prismatic orientation was significantly weaker ( p p p >0.05). Significance . The UTS of dental structures varies according to its nature and location.