Dr Akhilesh Sharma
@nerist.ac.in
Assistant Professor Electrical Engineering Department
North Eastern Regional Institute of Science and Technology
RESEARCH, TEACHING, or OTHER INTERESTS
Electrical and Electronic Engineering, Energy Engineering and Power Technology, Renewable Energy, Sustainability and the Environment
Scopus Publications
Scopus Publications
Rupendra Kumar Pachauri, Mohit Kumar, Sudhakar Babu Thanikanti, Neeraj Kumar Shukla, Piyush Kuchhal, Ahmad Faiz Minai, and Akhilesh Sharma
Elsevier BV
Akhilesh Sharma and Sarsing Gao
IEEE
With the increased conversion of solar energy into electricity, the role of design engineers has increased to develop sophisticated, and efficient inverters for converting DC energy from the solar cell. In the field of inverter technology, numerous topologies have been developed in recent times, starting from conventional topologies like cascaded multilevel inverters to advanced hybrid inverters. Each topology has its limitation in terms of the number of voltage sources, switching devices, and other electrical passive components. One of the latest topologies that require a minimum number of power electronic switching components and voltage sources is a single-phase S3 inverter. The topology eliminates the need for filters. A single-phase S3 inverter has been extended to a three-phase S3 inverter to which a three-phase induction motor is connected. The switching pulses of the inverter have been obtained through the direct torque control method. The simulated results of the direct torque control method of the induction motor are presented, thus describing the fruitfulness of this inverter topology.
Akhilesh Sharma, Vikas Pandey, Shashikant, Ramendra Singh, and Meenakshi Sharma
Springer International Publishing
Akhilesh Sharma and Sarsing Gao
Springer International Publishing
Rupendra Kumar Pachauri, Mohit Kumar, Ankur Kumar Gupta, Ahmad Faiz Minai, and Akhilesh Sharma
Springer Nature Singapore
Akhil Deo Gangwar, Akhilesh Sharma, Th. Vimal Prakash Singh, and S. Gao
IEEE
The speed of separately excited DC Motor speed may be controlled above and below the rated value using DC-DC Converter. The desired speed can be achieved by applying proper DC voltage to the armature of the DC motor. The beauty of chopper is that it may provide variable DC voltage to the motor. The variable DC source is possible by properly firing the controlled power semi-conductor after receiving signal from the controller. The output of the controller is used to generate triggering pulses for the DC-DC converter circuit. The controller could be a PI, fuzzy logic or any other controller. The fuzzy logic provides faster control with no delay. In this research paper, the mathematical modelling of separately excited DC Motor is done. The speed of the motor is measured. The PI controller and fuzzy logic controller have been designed to minimize the error. After the simulation is carried out it is observed that fuzzy controller performed better than PI controller. The simulated results are presented.
Rupendra Kumar Pachauri, Vandana Jha, Akhilesh Sharma, Vikas Pandey, and Shashikant
IEEE
Photovoltaic (PV) array performance is reduced by shading causes, which can be avoided using a variety of methods for changing the connections between PV modules. This paper suggests a method to reduce the impacts of partial shading conditions (PSCs) on solar PV arrays, through the traditional configurations like SP, TCT, and through game puzzle arrangements like Su-Do-Ku and Sky - scraper setups, to make a 9×9 size array. In this paper, an exploration into conventional electrical strategies, namely series-parallel (SP) and total-cross-tied (TCT), is compared. Furthermore, the suggested algorithm can be used to set up Photovoltaic panels to maximize power throughout non-uniform irradiation rates. The findings of study are evaluated on the basis of power loss (PL) and fill factor (FF). The responsibility of demonstrating the productive results of the envisaged PV array setup falls on careful monitoring. This paper is helpful for educationists and scholars who are looking for new ways to lessen the partial shading consequence on PV arrays in order to achieve higher global maximum power point (GMPP).
Stephen Oko Gyan Torto, Rupendra Kumar Pachauri, Ahmad Faiz Minai, Ambreen Siddiqui, and Akhilesh Sharma
IEEE
The resultant curve of the solar photovoltaic (PV) array relies on the arrangement of the Photovoltaic array, distribution of shading, and level of illumination. Detrimental shadowing cases and its contrary effects on the productivity of the PV system have inspired people doing research in the field of solar energy to do research and present suitable techniques to reduce the resultant power loss (PL) due to considered situation. In this paper, series-parallel (SP), total-cross-tied (TCT) PV array models are investigated under non-uniform irradiation/shadow test cases. For extensive comparative study, the Symmetric Matrix (SM) puzzle is introduced to rearrange the traditional TCT arrangement. All the SPV array configurations are tested during detrimental shadowing cases depending on the investigation of the circuit. Different performance parameters such as, short-circuit current (ISC), Open-circuit voltage (VOC), power and voltage locations at global maximum power point (GMPP), PL, fill factor (FF), power gain (PG) and analysis of shading factor (SF) are estimated with the help of the MATLAB/Simulink study.
Akhilesh Sharma, Anandh N., and Sarsing Gao
Institute of Advanced Engineering and Science
Due to a substantial increase in the use of inverter for numerous electrical appliances starting from domestics to industrial drives, an inverter may be directly connected to the power grid system. The dependency on an inverter has been increased over the years. Hence, the proper and efficient design of the inverter will lead to higher efficiency. One of the major challenges is the generation of suitable gate pulses for power switching devices, which in turn depends on the modulation index. The selection of proper modulation index will help in the production of the rated voltage. If the modulation index is less, the duration of on-time pulses will be less and hence, the device's conduction time is also less, thereby the output voltage of the inverter is reduced. A reduced voltage, when applied to an induction motor will have lower speed and even its performance will be sluggish. The speed of the motor improves when it is operated in a closed-loop for the same modulation index. This research paper tries to bring out the effect of modulation index on speed control of an induction motor based on an inverter for both open as well as closed-loop operation. The simulated results indicate that the modulation index in the vicinity to unity will provide rated voltage for the smooth operation of the motor.
Anandh N, Akhilesh Sharma, Julius Fusic S, and Ramesh H
Institute of Advanced Engineering and Science
An improved zero-voltage zero-current transition boost converter (IZVZCTBC) is introduced. This converter is basically a fourth-order DC-DC converter wherein a L-C-S (Inductor–Capacitor–Switch) resonant circuit is embedded for soft-switching. L-C-S tank network is the modified version of conventional ZVZCT switch cell. The main feature of L-C-S tank circuit is to enhance the performance of zero-voltage zero-current transition boost converter in terms of eliminating the high current stress, decreasing the switching losses and increasing the efficiency of converter. This converter exhibits both zero-voltage turn on and zero-current turn off switching characteristics based on the gating signals applied to switches. The principle of operation and time domain expressions of IZVZCT boost converter with L-C-S cell are presented. For the closed loop operation, digital controller is designed and the performance of the controller has been validated through simulation for different line and load variations. The mathematical and theoretical analysis is verified accurately by a 12-24 V, 30 W converter through PSIM simulation software and the results ensures that overall efficiency of the converter has improved to 97% along with elimination of current stress.
Akhilesh Sharma, Deepak Singh, Vikas Pandey, and S Gao
IEEE
This paper proposes two different techniques to optimize the harmonic content in 15-level cascaded H-bridge multi-level inverter (MLI). The proposed techniques are used to determine the switching angle for cascaded H-bridge MLI by solving the non-linear equation using Genetic algorithm (GA) and Newton Raphson (NR) method. Operation for medium voltage and High power converter requires a high-quality waveform with low switching loss. The quality of waveform depends on the number of voltage levels. Higher the voltage level, less will be the harmonics content of different orders. Dominant orders of harmonics have more deteriorating effect in the output wave shape of the inverter. If they are reduced, it will improve the nature of the wave shape. This may be done by applying selective harmonics elimination (SHE) technique. Genetic Algorithm (GA) and Newton-Raphson (NR) techniques have been used in SHE for generating switching pulses for a cascaded multilevel inverter. The simulated results have been presented in this paper indicating the elimination of dominant order of harmonics.
, Akhilesh Sharma, Vikas Pandey, and
Blue Eyes Intelligence Engineering and Sciences Engineering and Sciences Publication - BEIESP
A two level VSI has output voltage either equal to positive or negative source voltage. This inverter has more ripple. In order to reduce the ripple content more number of switches are needed to produce many number of stepped voltage waveform. This improves the quality of power. This switching losses depends on the frequency of operation so when a two level inverter is operated at high frequency, the switching losses are predominant. This limits the use of such inverters. Hence, being replaced by Multilevel inverters. They have attracted academician and industry personal for medium and high-power power control. Such attractive features are available in hybrid multilevel inverter. Hence, these are preferred. They provide multi-level operation by using hybrid sources. Moreover, the number of power electronics components needed are less than conventional CMI for same voltage level. Thus, such inverters have more efficiency. In the proposed techniques, an asymmetrical hybrid multilevel inverter has been simulated using MATLAB Simulink. The results obtained have been presented for three different types of load.
Akhilesh Sharma, Deepak Singh, and Sarsing Gao
IEEE
Growth of a nation depends on the optimum utilization of energy, especially electrical energy, as all the industries, directly or indirectly, need electrical source which is mostly obtain through conventional sources of energy. These sources are limited which are likely to vanish in near future. This has forced harnessing of electrical energy from non-conventional energy resources. The electrical energy obtain through these sources are direct current but most of the electrical drives need alternating current for its operation hence an alternating current at fundamental frequency and magnitude could be achieve through inverter. It acts not only as back-up for drives systems but also as standby supply at domestic levels. An inverter contains controllable power electronic devices which could be switched on and off thereby leading to generation of harmonics, especially dominant orders of harmonics have their effect in form of generating heat within the inverter and also in other power system components. Hence, they need to eliminate. One among many techniques could be Selective harmonic elimination PWM (SHE-PWM). In this paper, a multi-level Cascaded H-bridge inverter has been proposed. The optimized switching angles have been generated through Genetic Algorithm optimization tool by solving nonlinear equations. The simulated result shows that harmonics order, up to 17th order, have been reduced in no load output voltage. This waveform could be smoothened using low pass filter and intern applied to different types of load.
Akhilesh Sharma, Deepak Singh, Pukhrambam Devachandra Singh, and S. Gao
IEEE
In today's world, when there is crisis of conventional energy resources, it has become essential to harness energy from non-conventional energy resources. However, the electrical energy obtained through renewable sources is mostly variable or in the form of direct current. The output voltage obtained from solar or wind needs to be converted through either ac-dc-ac or dc-ac converters. The utility grid compatible ac output from these sources can only be applied to home appliances and electrical drives. Thus, an inverter is an indispensable device in the present energy scenario. In the design of inverter, gate pulse generation plays a vital role. There are several techniques available to generate gate pulses. Some of the techniques are space vector modulation (SVM) and sinusoidal pulse width modulation (SPWM) which could be used not only for two-level inverters but multilevel inverters as well. Because of ease, a two-level inverter is used for low voltage and low power application whereas, for high voltage and high-power applications, multilevel inverters are best suited. In this paper, an attempt is made to bring out a comparison of the performances of two-level and three-level inverters based on SPWM and SVPWM techniques for linear and non-linear loads based on MATBAB R2016a simulation. The results obtained are presented. The results indicate that the inverter with SVPWM technique performs better than the one with SPWM technique as the former generates less total harmonic distortion (THD) compared to latter for the same load parameters. Also, it is seen that the non-linearity in the load has its effect on the harmonics.
Deepak Singh, Akhilesh Sharma, Pukhrambam Devachandra Singh, and S. Gao
IEEE
Frequent power failures, non-availability of electrical energy from conventional energy sources at the load center or insufficient generation of electrical energy are the major reasons of utilization of non-conventional resources to harness electrical energy. From these sources, usually direct current form of electrical energy is obtained which needs to be regulated for conversion into alternating form of voltages through inverter. Thus, the design of inverters which are widely used as standby power supply at domestic levels, ac drives control, distribution of power generation, play a vital role. The ease of utilization of inverter depends on the magnitude of ac output voltage and frequency which could be directly controlled by switching the controlled semi-conductor devices. However, this leads to injection of harmonics in the output waveform. The dominant order of harmonics needs to be eliminated which otherwise, causes power losses in the form of heat, damaging the inverter. Eliminating these harmonics is a big challenge. Therefore, selective harmonic elimination PWM (SHE-PWM) is one among many techniques which could be used for multi-level Cascaded H-bridge inverter. The optimized switching angles have been generated through Newton-Raphson by solving non-linear equations. This paper tries to bring comparative study of presence of harmonics for different types of load.
P. Devachandra Singh, Akhilesh Sharma, and S. Gao
IEEE
This paper presents performance analysis of a PWM based AC-DC-AC converter implemented for a three phase self-excited induction generator (SEIG)based micro hydro power generation. In this work, the feasibility study of generating and supplying reliable power from freely flowing water to a remote area is presented. The power generation with variable water flow to the turbine is found to be feasible with satisfactory power qualities at different loading conditions of the generator. Investigations on power quality issues are carried out for both linear and non-linear types of loads. The proposed system is modeled in MATLAB/Simulink environment. The simulation results are presented.
Krishanu Nath, Amlesh Kumar, Amarjit Roy, and Akhilesh Sharma
IEEE
DC motors have a very fine speed control characteristics and so are widely used in various industrial applications. Their performance can be optimised, if along with fine speed control a motor can be made energy efficient. In this paper an attempt is made to achieve the speed control at the condition of maximum efficiency for a separately excited DC motor using both field control and armature control methods. In recent trends, it is seen that artificial intelligence based controllers have superior performance compared to the power electronic based controllers PID controllers. The controller chosen for the desired task is an Artificial Neural Network, as any non-linear data can be fit in it. The network is trained and a model is generated in MATLAB. The neural network is then connected to a model of a separately excited DC motor and a few simulated results were obtained to verify the task. The whole simulation work is performed in Simulink and the output curves were obtained for various types of load torques and reference speeds.