National Institute of Technology, Meghalaya

About: National Institute of Technology, Meghalaya is a education organization based out in Shillong, India. It is known for research contribution in the topics: Control theory & Electric power system. The organization has 503 authors who have published 1062 publications receiving 6818 citations. The organization is also known as: NIT Meghalaya & NITM.

A Single-Source Switched-Capacitor-Based Step-Up Multilevel Inverter With Reduced Components

Abstract: Switched-capacitor-based multilevel inverters (SC MLIs) have received a great deal of interest that reduces the dc source requirement and improves the power quality. However, multiple dc sources and the requirement of a large number of switches to generate a high-quality boost output are the fundamental issues in the SC MLIs. This article presents a step-up 17-level SC MLI using reduced number of switches, three capacitors, and a single dc source. The steady-state voltage across the capacitors is maintained in the ratio 1:2:0.5 that contributes to quadruple boosting ability without using any auxiliary capacitor voltage balancing circuit. Besides, lower switch count in the conduction path and operation of 50% of the switches at fundamental frequency ensures total power loss reduction in the proposed circuit. A comparative assessment with recently developed 17-level MLIs in terms of the number of components, gain, stress, and cost factor elucidates the advantages of the proposed MLI. After a detailed circuit analysis and loss evaluation, simulations are performed to verify the step-up and inherent balancing features of the proposed MLI. Further, using both the fundamental frequency and high-frequency switching techniques, extensive experimental test results are presented under different transient conditions to validate the operational feasibility of the 17-level prototype.

Second Law Analysis of Flow in a Circular Pipe With Uniform Suction and Magnetic Field Effects

Abstract: The present paper investigates analytically the two-dimensional heat transfer and entropy generation characteristics of axi-symmetric, incompressible viscous fluid flow in a horizontal circular pipe.The flow is subjected to an externally applied uniform suction across the wall in normal direction and a constant radial magnetic field. Constant wall temperature is considered as the thermal boundary condition.The reduced Navier-Stokes equations in a cylindrical coordinate system are solved to obtain the velocity and temperature distributions. The velocity distributions are expressed in terms of stream function and thesolution is obtained using the Homotopy Analysis Method (HAM). Validation with earlier non-magnetic solutions in the literature is incorporated. The effects of various parameters on axial and radial velocities, temperature, axial and radial entropy generation numbers, and axial and radial Bejan numbers and are presented graphically and interpreted at length. Streamlines, isotherms, pressure, entropy generation number and Bejan number contours are also visualized. Increasing magnetic body force parameter shifts the peak of the velocity curve near to the axis where as it accelerates the radial flow. The study is relevant to thermodynamic optimization of magnetic blood flows and electromagnetic industrial flows featuring heat transfer.

FPGA-Based Real-Time Implementation of Quadral-Duty Digital-PWM-Controlled Permanent Magnet BLDC Drive

Abstract: Brushless dc (BLDC) motors are sparsely employed for domestic applications due to the mandatory cost inflation related to BLDC drive besides their numerous constructional advantages. Controllers involving lesser computational complexity, which ultimately leads to reduced-size application-specific integrated circuits (ASICs) for the drive, are highly advantageous in addressing the issue. Recent state-of-the-art dual-duty digital pulsewidth modulation (DDDPWM) techniques are among such. However, the DDDPWM-based controller restricts the motor speed within a narrow range, and the motor suffers from inevitable speed and torque ripples. In this article, an advanced quadral-duty digital pulsewidth modulation (QDDPWM) technique has been proposed to drive the BLDC motor. The QDDPWM-technique-based BLDC motor drive can be controlled in a wider range of speed with reduced steady-state speed ripples, audible noise, and vibrations. The controller has been implemented in real-time using field-programmable gate array, which can also be fabricated in a reduced-size ASIC. Various dynamic and steady-state speeds, vibration responses, time response, and speed tracking ability have been examined and reported in this article. The effectiveness of the proposed technique is justified by the comparison of the real-time responses with the DDDPWM-algorithm-based BLDC motor drive.