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Theses

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2016 - 20197
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Subject: Electrical Engineering × End date: 2019 × Start date: 2016 × Type: Thesis × Thesis Type: Ph.D ×
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Now showing 1 - 7 of 7
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    ThesisItemOpen Access
    Design and performance investigation of line start permanent magnet synchronous motor
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-08) Arvind Kumar; Srivastava, Ajay
    Electric motors are the workhorse of the modern industries and consume about 70 % of the industrial electrical demand. Constructing motors with better efficiency can result in a reduction in energy consumption and cost savings to the consumer. The solution of increasing a motor’s efficiency is to use permanent magnets motors which eliminate the excitation losses experienced by induction machines, thereby increasing the motor’s efficiency. The past 25 years have been a significant period with advances in the development of line start permanent magnet motors. Over this period, these motors have expanded their presence in the industrial and domestic marketplace. LSPMSMs can offer higher efficiency than standard induction motors used in the industry. Due to nonlinear characteristics of magnetic materials, finite element method is considered to be a better approach for design and analysis of line start permanent magnet motors. In order to find the optimized structure, different rotor structures of line start permanent magnet motors are comparatively studied in terms of dynamics and steady state performance. The placement and volume of magnet plays a critical role in motor performance. Three types of rotors with different layers of permanent magnets are proposed and analyzed using finite element method. The performances of three motors are compared to get the best configuration of line start permanent magnet motor.
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    ThesisItemOpen Access
    Investigation of power quality impact on the performance of three phase induction motor
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-08) Singh, Sunil; Srivastava, Ajay
    Voltages are well balanced and sinusoidal at the generation and the transmission levels but it gets unbalanced and non-sinusoidal at the utilization or distribution levels due to unequal system impedances, unequal distribution of single-phase loads, and non-linear loading. Voltage unbalance, under/over voltage, and distorted waveform conditions generally occur simultaneously. An excessive level of voltage unbalance, undervoltage, overvoltage, and harmonics can result excess power loss, torque reduction, and torque pulsation in the induction motors. A comprehensive investigation of impacts of voltage unbalance, undervoltage, overvoltage, and harmonics has been done on the performance (loss, efficiency, currents, current unbalance, power factor, torque, speed, speed pulsation, and torque pulsation) of three phase induction motor using MATLAB/Simulink software. Investigation is done by taking the power quality disturbances separately and simultaneously. Some of the results obtained by simulation is also verified by conducting lab experiment on the similar machine and found good agreement with results. A relation is establish to estimate torque ripple factor (TRF) in terms of voltage unbalance factor and total harmonic distortion (THD). It has been concluded that terminal voltage unbalance (TVU) will not affect slightly, but undervoltage unbalance (UVU) affect the motor performance severely and immediate need to derate. It has been recommended that to derate the motor precisely, under/over voltage or positive sequence voltage should also be taken into consideration. The simulation models can be used for further study and research.
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    ThesisItemOpen Access
    Performance investigation of axially and transversally laminated synchronous reluctance motors
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2018-01) Rawat, Harendra Singh; Srivastava, Ajay
    Electric motors considered as workhorse of the modern industries, consume about 70% of the industrial electrical demand. Hence there is an increasing demand for motors which are highly efficient, economical and provides high power output per unit volume. A few newly adopted machines like permanent magnet and reluctance machines have replaced the conventional dc and induction motors in many applications. But the permanent magnets being made up of costly rare earth materials have now given way for more reliable and satisfactory reluctance machines. The rotor design of a Synchronous Reluctance Motor (SynRM) has a significant effect on its efficiency, torque ripple and maximum torque. In order to achieve a good compromise between these three goals, optimized rotor design is necessary. Due to nonlinear characteristics of magnetic materials, finite element method is considered to be a better approach for rotor optimization of the SynRM. The two most crucial design parameters of a SynRM are position and width of flux-barriers for the torque output and torque ripple. This paper proposes an approach to obtain the optimized values of the above mentioned parameters. So in order to achieve design with a low torque ripples and enhanced torque output for a SynRM with full pitch distributed windings in 24 slots on stator. This method is valid for a wide range of SynRMs. It also provides insight into the behaviour of the machine as a function of position and width of flux barriers. Furthermore, the torque and torque ripple of SynRMs having an axially and transversally laminated rotor are compared.
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    ThesisItemOpen Access
    Design, development and analysis of a new multilevel inverter topology using GSA based selective harmonic elimination technique
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2017-08) Kala, Peeyush; Arora, Sudha
    Power electronics finds its major role in the control and conversion of large amount of electric power. In many applications, conversion of dc power to ac power is often required which is achieved with the help of power inverters. Multilevel inverters are the class of inverters which are extensively being used in medium voltage and high power applications owing to their numerous advantages over conventional two-level power inverters. In the current global energy scenario, more emphasis is being given to harness energy from the renewable energy resources such as solar, wind, small hydro, geothermal, bio fuels, ocean energy etc. owing to rapid depletion of conventional energy resources, sharp rise in global energy demand and fuel prices, and growing environmental concerns. Hence, there is a lot of thrust to perform exhaustive research in MLIs for standalone or grid interfaced renewable energy applications. In this thesis work, topological and modulation scheme based solution have been proposed for distributed renewable energy systems such as PV systems, wind energy conversion systems, fuel cells etc., and for battery storage energy systems. As a topological solution, three new MLI topologies have been proposed. The first novel symmetric MLI topology consists of reduced number of switching devices and drivers as compared to various competent MLI topologies. This proposed topology has been implemented in experimental set-up for nine-level configuration. The second MLI topology is an asymmetric reduced switch count topology which is proposed for 31 level configuration. The third proposed MLI topology is 31-level asymmetric inverter topology which is intended for applications where purely resistive load is available. These proposed topologies have been compared with other popular MLI topologies in terms of number of switches, number of sources and number of components. The simulations of all of these proposed MLI topologies have been performed in MATLAB/Simulink environment. Experimental results of proposed symmetric nine-level inverter topology are also presented for the validation of the simulation results. As a modulation scheme based solution, GSA based SHE technique has been implemented in proposed symmetric nine-level inverter which showed the effectiveness of this switching scheme in achieving the objectives of SHE problem.
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    ThesisItemOpen Access
    Development and performance investigation of a novel meta-heuristic based MPPT for photovoltaic systems
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2017-07) Joshi, Puneet; Arora, Sudha
    Solar energy is transformed into Electrical energy through PV systems consisting of PV panels, power conditioners & controllers and a load. Generally, there is a shift in the maximum power point with the change in the environmental conditions, a load change or due to partial shading. Hence, Maximum Power Point Tracking (MPPT) controller is required that ensures the maximum power extraction under all conditions. Many MPPT techniques for PV systems have been developed that are broadly classified as conventional methods and the modern approaches. These techniques vary in many aspects such as PV array dependency, application domain, complexity, convergence speed, periodic tuning, efficiency, simplicity, digital or analog implementation, sensors required, and cost. This work presents a novel hybridization of the Particle Swarm Optimization and the Coral reef Optimization approaches for MPPT for PV systems. In order to study the performance of the proposed method, ten widely-adopted MPPT algorithms; viz., Perturb and Observe (P&O) method, Adaptive step-size P&O method, Drift-free P&O method, Incremental Conductance (INC) Method, Adaptive step-size INC method, Incremental Resistance (INR) Method, Adaptive step-size INR method and three meta-heuristics based approaches, viz., Particle Swarm Optimization (PSO) based method, Gravitational Search Algorithm (GSA) based method, hybrid PSO-GSA method are compared with it using the Matlab/Simulink software. Firstly, the behavior of the conventional techniques was studied in presence of solar irradiation variations, imitating the natural variations occurring in the irradiance throughout the year, under constant temperature (250C). Thereafter, the methods were ranked based on the power obtained under each test conditions. In addition, the superiority of the methods was highlighted by simulation results. It was concluded that both INC method and the conventional P&O method showed the best overall efficiency ( ≈ 97%) under all test patterns. However, the meta-heuristics based approaches displayed even better results for the MPPT application. These methods, in general, exhibited very high efficiency ( ≈ 98.8%) and convergence rate under various test conditions. Amongst the selected methods, the proposed PSO-CRO method displayed highest efficiency ( ≈ 99.6%) and fastest convergence rate. Additionally, statistical analysis and two-sampled T-test were performed to determine the ordering of the methods. In addition, the meta-heuristics based approaches were tested under four partial shading conditions as well. All the methods were able to converge to the global maximum power again very quickly with an excellent efficacy. Simulation results show that the proposed PSO-CRO method can rapidly track the true MPP under different conditions with reduced steady state oscillations (to practically zero) once it is located. Furthermore, the proposed method has the ability to track the MPP for the extreme environmental condition, e.g., large fluctuations of insolation and partial shading condition. The outcome indicates the proposed method has obvious advantages, especially the performance being superior to the conventional methods. Additionally, the algorithm is simple to program and can be computed very rapidly using state-of-the art hardware technologies.
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    ThesisItemOpen Access
    A new approach for voltage sag estimation and effect of voltage sag on performance of induction motor
    (G.B. Pant University of Agriculture and Technology, Pantnagar (Uttarakhand), 2017-01) Gupta, Shobhit; Srivastava, Ajay
    Power quality has become a major concern in the recent time. Most of the power quality disturbances are due to voltage sag. Voltage sag can be characterized on the basis of its magnitude and duration. Since voltage sag is defined on the basis of its magnitude, hence it is very important to find out a method which can quantify the sag magnitude accurately. In this thesis a new hybrid method is proposed for the calculation of sag magnitude and duration. It has been found that this method estimates the sag more accurately in comparison to RMS voltage method and Peak voltage method. Minimum sampling frequency and size of sliding window is also proposed for the precise assessment of voltage sag. About 80% of the motors used in industry are induction motor. Electromagnetic torque generated by induction motor is directly proportional to the square of applied voltage. Hence during voltage sag, performance of the induction motor could be affected severely. In this thesis effect of voltage sag on induction motor performance has been investigated for various initial points on wave. To find out the effect of voltage sag on the rating and loading of induction motor, two different motors of 10 hp and 50hp power rating have been simulated on MATLAB SIMULINK platform. Simulation results have compared on the basis of current, torque and speed loss peak.
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    ThesisItemOpen Access
    System identification and control using multiplicative neuron models
    (G.B. Pant University of Agriculture and Technology, Pantnagar (Uttarakhand), 2016-12) Yadav, Abhishek; Swami, Anurag Kumar
    The conventional control systems perform satisfactorily as long as the design of the controller is based on the accurately known fixed dynamics of the plant or the process. But, the model that is used to represent the dynamics of the plant or the process is generally not accurate and also it is subjected to the parameters and environmental variations with time. To overcome the above problem, various strategies of artificial neural networks based nonlinear adaptive control are used. Neuron models that are generally used in the neural networks of control systems are simple units with summation type of aggregation and sigmoid type of activation functions. However, various neuron models with multiplicative type of aggregation exhibit better learning capability. Control task could be improved significantly by improving the learning capability of the neural networks of control systems. In this thesis work, some novel methods of control have been developed using different multiplicative models of artificial neurons. Different multiplicative models of neurons have been compared in terms of their usefulness in solving control problems. It has been shown that the steady-state and transient response of neural network control systems are improved by using these multiplicative models.