Browsing by Author "Karthikeyan, A."

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A Comparative Study of PI and PDF Controllers for DVR under Distorted Grid Conditions
(Institute of Electrical and Electronics Engineers Inc., 2018) Karthikeyan, A.; Krishna, D.G.A.; Tejaswini, A.; Panda, A.S.; Prasanna, R.L.
In this paper the enhancement of power quality related issue is dealt by using Dynamic Voltage Restorer (DVR). There are mainly two aspects with DVR injection voltages one is reference generation and the other is control of DVR. Under unbalanced grid conditions negative sequence components will appear in the grid voltage and causes continuous oscillations in the estimated dq - voltages, which makes sag detection difficult with conventional SRF-PLL. In this paper Double Second Order Generalized Integrator (DSOGI) prefilter based PLL is used for extracting the symmetrical components of grid voltage and further mitigate the harmonic ripple in estimated dq quantities. Further a Pseudo Derivative Feedback (PDF) controller is proposed for single loop voltage feedback control for DVR. The robustness of the proposed controller is verified through comparative studies with PI controller using time response analysis. It is observed that the proposed PDF controller improves the system dynamics i.e., eliminates oscillations and overshoot compared to PI controller. MATLAB/SIMULINK platform is used to perform simulation studies for the 10 kV system subjected to different disturbances viz balanced and unbalanced voltage sags for both PI and PDF based controller. Finally, the experimental studies are carried out for low voltage DVR of 0.5 kVA, 100 V laboratory prototype. Â© 2018 IEEE.
A novel reduced-cross-tied configuration for extracting maximum power output from a symmetrical PV array under partial shading conditions
(Springer Science and Business Media Deutschland GmbH, 2024) Ramesh, D.; Karthikeyan, A.; Gaonkar, D.N.
The primary reason for the decrease in power output from the PV array is partial shading. During partial shading conditions (PSCs) PV modules experience a mismatch in current and voltage generated. Also, the power voltage (P–V) characteristics of the PV array possess multiple peaks under PSCs. To mitigate the effects caused by PSCs, the configuration of the PV array is the finest solution. This paper proposes a novel Reduced Cross Tied (RCT) configuration to enhance maximum power output from a symmetrical PV array under PSCs. The RCT configuration has fewer cross-ties compared to the TCT configuration and is applicable to a square array of any size. The proposed RCT configuration along with conventional configurations such as Total Cross Tied (TCT), Series–Parallel, Bridge-Link, and Honey-Comb are validated in simulation and hardware for 7×7 and 8×8 symmetrical PV arrays under Short and Narrow (SN), Short and Wide (SW), Long and Narrow (LN) and Long and Wide (LW) shading patterns. A comparative analysis is done between the proposed configuration and conventional configurations in terms of mismatch loss (ML), fill factor, efficiency (η), Wiring Loss, and Global Maximum PowerPoint (GMPP). The proposed RCT configuration is able to achieve GMPP equal to the TCT configuration under the LN shading pattern and on par with the TCT configuration under SN, SW, and LW shading patterns. RCT-configured PV array possesses a minimum reduction of 25% in wiring loss for any array size. RCT configuration applies to a square array of any size.The results replicate the efficacy of the proposed RCT configuration compared to existing configurations. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2023.
A Simple Primary Key Algorithm Based Shade Dispersion Method for Maximizing PV Power Generation under Partial Shading Conditions
(Institute of Electrical and Electronics Engineers Inc., 2024) Koothu Kesavan, P.K.; Karthikeyan, A.; Kumar, M.; Mandal, S.
The output power generation of a photovoltaic (PV) array reduces under partial shading, resulting in multiple local maxima in the PV characteristics and inaccurate tracking of the global maximum power point (GMPP). Various interconnection schemes are available to reduce power losses under partial shading. In this study, a primary key algorithm is proposed for distributing shading across an array. This method is suitable for any n×n PV array configuration and involves fewer calculations and variables, leading to reduced computational complexity. The power generations of a 9×9 PV array under four different shading conditions were compared with the configurations of: total cross-tied (TCT) and Su Du Ku, physical relocation and fixed column position of modules with fixed electrical connection (PRFCPM-FEC), and magic square (MS) and improved-odd-even-prime (IOEP). The advantage of the proposed method is that once the primary key elements are obtained, the remaining array elements are numbered in a simpler manner. The results obtained using the proposed arrangement show that the power is enhanced with reference to the TCT and is comparable to the Su Do Ku, PRFCPM-FEC, MS, and IOEP reconfigurations. © 2024 China Machinery Industry Information Institute.
An effective reference generation scheme for DFIG with unbalanced grid voltage
(Institute of Electrical and Electronics Engineers Inc., 2014) Asha Rani, M.A.; Nagamani, C.; Saravana Ilango, G.; Karthikeyan, A.
This paper presents a reference current generation scheme for improved dynamic performance of a doubly fed induction generator (DFIG) subjected to unbalanced grid voltage. The power and torque oscillations induced due to the unbalance in grid voltage are minimized using additional compensatory terms in the reference currents. The focus is on estimating the reference currents and control implementation without the need for dual vector control. Real and reactive power control is implemented in the positive mbi d - q reference frame using stator flux-oriented vector control. The rotor-side converter (RSC) is controlled to enable effective reduction of oscillations in torque and active and reactive power. The dc-link voltage oscillation is minimized and the grid-side power factor is maintained unity using the grid-side converter (GSC). Unlike the previously reported techniques, the proposed scheme enables effective reduction of oscillations in torque, active, and reactive power, and the dc-link voltage, all in a single target. The performance of DFIG is investigated in consideration with the Indian Electricity Grid Code (IEGC). Numerical simulations are carried out in power system computer aided design/ electromagnetic transients including direct current (PSCAD/EMTDC) for the laboratory 3-hp DFIG test setup. The results establish that the performance of DFIG is notably enhanced with the proposed scheme. © 2014 IEEE.
A Comparative Study of PI and PDF Controllers for DVR under Distorted Grid Conditions
(2018) Karthikeyan, A.; Krishna, D.G.A.; Tejaswini, A.; Panda, A.S.; Prasanna, R.L.
In this paper the enhancement of power quality related issue is dealt by using Dynamic Voltage Restorer (DVR). There are mainly two aspects with DVR injection voltages one is reference generation and the other is control of DVR. Under unbalanced grid conditions negative sequence components will appear in the grid voltage and causes continuous oscillations in the estimated dq - voltages, which makes sag detection difficult with conventional SRF-PLL. In this paper Double Second Order Generalized Integrator (DSOGI) prefilter based PLL is used for extracting the symmetrical components of grid voltage and further mitigate the harmonic ripple in estimated dq quantities. Further a Pseudo Derivative Feedback (PDF) controller is proposed for single loop voltage feedback control for DVR. The robustness of the proposed controller is verified through comparative studies with PI controller using time response analysis. It is observed that the proposed PDF controller improves the system dynamics i.e., eliminates oscillations and overshoot compared to PI controller. MATLAB/SIMULINK platform is used to perform simulation studies for the 10 kV system subjected to different disturbances viz balanced and unbalanced voltage sags for both PI and PDF based controller. Finally, the experimental studies are carried out for low voltage DVR of 0.5 kVA, 100 V laboratory prototype. � 2018 IEEE.
Design and analysis of frequency adaptive CDSC-PLL for Dynamic Voltage Restorer during adverse grid conditions
(Institute of Electrical and Electronics Engineers Inc., 2020) Abhilash Krishna, D.G.A.; Karthikeyan, A.
This paper presents frequency feedback loop based Cascaded Delayed Signal Cancellation PLL employed for dynamic voltage restorer (DVR) application to compensate grid voltage disturbances. The primary and key function of PLL is continuous tracking of grid voltage angle in a precise manner and feed it to DVR control. The conventional CDSC-PLL performance during frequency variation is poor which affects the estimation of grid voltage angle and thereby leads to maloperation of DVR control. Thus in this paper FFL is added to the CDSC-PLL to adapt for frequency variations for effective operation of DVR control. The performance analysis of FFL based CDSC-PLL is presented for various disturbances. Finally, FFL based CDSC-PLL is incorporated in the 10 kV, DVR system and the simulation results of the system for different voltage disturbances by using MATLAB/SIMULINK. Â© 2020 IEEE.
Design and Analysis of Multi-Loop Feed Forward Control Schemes for DVR under Distorted Grid Conditions
(2018) Karthikeyan, A.; Abhilash, Krishna, D.G.; Kumar, S.; Nagamani, C.
Voltage sags are considered as important power quality problems and the Dynamic Voltage Restorer(DVR) is an effective solution to mitigate the sags and other power quality problems related to voltage. The DVR involves two major aspects: (i) reference generation and (ii) control algorithm. Under unbalanced grid conditions the presence of negative sequence components in the grid voltage causes sustained oscillations in the estimated dq- voltages, which makes sag detection difficult with conventional SRF-PLL and there by chances of controller malfunctioning. In this paper, a Delayed Signal Cancellation (DSC) pre-filter based Positive and Negative Sequence Extractor (PNSE) is employed to extract the Instantaneous Symmetrical Components (ISC) of the grid voltage and filter out the harmonic voltages from the estimated dq-voltages. As the response of the DVR mainly depends on the controller action this paper presents an multiloop PI feed forward controller for enhancing the operation of DVR under distorted grid conditions. The efficacy of the proposed controller is illustrated by comparative study with multiloop feed forward P controller using time response and relative stability analysis. Simulation studies are performed in PSCAD/EMTDC for a 10kV medium voltage DVR under various voltage disturbances such as symmetric and asymmetric voltage sags. � 2017 IEEE.
Design and Analysis of Multi-Loop Feed Forward Control Schemes for DVR under Distorted Grid Conditions
(Institute of Electrical and Electronics Engineers Inc., 2018) Karthikeyan, A.; Abhilash Krishna, D.G.A.; Kumar, S.; Nagamani, C.
Voltage sags are considered as important power quality problems and the Dynamic Voltage Restorer(DVR) is an effective solution to mitigate the sags and other power quality problems related to voltage. The DVR involves two major aspects: (i) reference generation and (ii) control algorithm. Under unbalanced grid conditions the presence of negative sequence components in the grid voltage causes sustained oscillations in the estimated dq- voltages, which makes sag detection difficult with conventional SRF-PLL and there by chances of controller malfunctioning. In this paper, a Delayed Signal Cancellation (DSC) pre-filter based Positive and Negative Sequence Extractor (PNSE) is employed to extract the Instantaneous Symmetrical Components (ISC) of the grid voltage and filter out the harmonic voltages from the estimated dq-voltages. As the response of the DVR mainly depends on the controller action this paper presents an multiloop PI feed forward controller for enhancing the operation of DVR under distorted grid conditions. The efficacy of the proposed controller is illustrated by comparative study with multiloop feed forward P controller using time response and relative stability analysis. Simulation studies are performed in PSCAD/EMTDC for a 10kV medium voltage DVR under various voltage disturbances such as symmetric and asymmetric voltage sags. Â© 2017 IEEE.
DSC filter based unit vector estimator for reference generation and control of dynamic voltage restorer
(2017) Kasyap, M.S.; Karthikeyan, A.; Perumal, B.V.; Nagamani, C.
DVR control requires a robust algorithm for computing grid voltage magnitude and phase angle. Conventional SRF-PLL performs poorly as it cannot filter out negative sequence voltages and harmonics that could occur in the grid voltage. In this paper a Positive and Negative Sequence Extractor (PNSE) is formed by a Delayed Signal Cancellation (DSC) filter, which filters harmonics and extracts Instantaneous Symmetrical Components (ISC) of the source voltage in stationary reference frame. The phase angle information of the grid voltage is derived by computing the unit vectors of the ISC in stationary frame. This eliminates the need for a conventional PLL and thus simplifies the reference generation algorithm. A PI controller tracks the capacitor reference voltage in synchronous reference frame to restore the fundamental load voltage while resonant controllers are tuned to mitigate the lower order odd harmonics in the load voltage. Simulation studies carried out in PSCAD/EMTDC for a Medium Voltage DVR model shows that the presented control works effectively for all the test cases considered such as voltage sags and harmonics. � 2016 IEEE.
DSC filter based unit vector estimator for reference generation and control of dynamic voltage restorer
(Institute of Electrical and Electronics Engineers Inc., 2017) Kasyap, M.S.; Karthikeyan, A.; Venkatesa Perumal, B.V.; Nagamani, C.
DVR control requires a robust algorithm for computing grid voltage magnitude and phase angle. Conventional SRF-PLL performs poorly as it cannot filter out negative sequence voltages and harmonics that could occur in the grid voltage. In this paper a Positive and Negative Sequence Extractor (PNSE) is formed by a Delayed Signal Cancellation (DSC) filter, which filters harmonics and extracts Instantaneous Symmetrical Components (ISC) of the source voltage in stationary reference frame. The phase angle information of the grid voltage is derived by computing the unit vectors of the ISC in stationary frame. This eliminates the need for a conventional PLL and thus simplifies the reference generation algorithm. A PI controller tracks the capacitor reference voltage in synchronous reference frame to restore the fundamental load voltage while resonant controllers are tuned to mitigate the lower order odd harmonics in the load voltage. Simulation studies carried out in PSCAD/EMTDC for a Medium Voltage DVR model shows that the presented control works effectively for all the test cases considered such as voltage sags and harmonics. Â© 2016 IEEE.
Dual Converters Coupled to Thermal Grid for Simultaneous Control on Regulation and Compensation in a Hybrid AC-DC Network
(Taylor and Francis Ltd., 2024) Sowmmiya, U.; Keerthana, M.S.; Karthikeyan, A.; Padmanathan, K.
In conventional, radial, AC distribution system, the unbalances in load voltages & source currents at distributor junction (DJ) may affect the quality of power. Mostly, a single converter is employed to address any one unbalance at an instant and the power transfer during critical conditions is not met out effectively. To overcome this, an effective, coordinated operation of dual converters (C1&C2) in a hybrid AC-DC network coupled to thermal grid (Electro-thermal network) for meeting the heating demand of a community, is enunciated in this paper. The DC micro grid (DCM) is energized by renewable for serving the community’s heating and public electrical demands. Irrespective of source voltage & load conditions, the C1&C2 aim at voltage regulation & load compensation at DJ, respectively. Also, the control exhibits around 3% THD which is well within the standard levels. During any source outage/less power production, DCM supplies power to loads through inversion. An uninterrupted, quality power to loads at DJ by the dual converters, irrespective of source voltage & load variations along with a conservative approach through the thermal grid, claims the prime merit of the setup. Various unbalance cases including voltage sag & swell, no source & excess DCM power cases are examined through a supervisory control algorithm for analyzing the effectiveness of the control & system flexibility. The effective performance of the above is verified in real time using Hardware-in-Loop approach through DS1104 (dSPACE Controller) and OP4510 (Opal-Real Time) Controllers. © 2024 Taylor & Francis Group, LLC.
Dual Role CDSC-Based Dual Vector Control for Effective Operation of DVR with Harmonic Mitigation
(Institute of Electrical and Electronics Engineers Inc., 2019) Karthikeyan, A.; Abhilash Krishna, D.G.A.; Kumar, S.; Venkatesa Perumal, B.V.; Mishra, S.
For the effective operation of a dynamic voltage restorer (DVR), a control strategy plays a significant role. This paper presents an enhanced control strategy for DVR using dual role cascaded delay signal cancellation (CDSC)-based dual vector control (DVC) under unbalanced and distorted grid conditions. Based on the numerical analysis, it is found that the CDSC prefilter is a promising solution when grid voltage is distorted by symmetric, asymmetric harmonics, and unbalanced sag. Mainly, the CDSC prefilter extracts instantaneous symmetrical components of the grid voltage required for voltage sags detection and generation of fundamental component of reference voltage for the DVR. A CDSC-based DVC algorithm with inductor current and capacitor voltage feedback is implemented in a synchronous reference frame, which tracks the fundamental DVR reference voltages. An extractor based on the modified CDSC strategy is designed to extract harmonics from load voltage during distorted grid conditions. These extracted harmonic components (nonfundamental) are added in phase opposition with fundamental component and fed to pulse width modulation block to generate reference voltages. Experimental studies are conducted on scaled down (100 V, 0.5 kVA) laboratory prototype DVR to verify the effectiveness of the proposed control algorithm under unbalanced and distorted grid conditions. © 1982-2012 IEEE.
Electromagnetic torque-based model reference adaptive system speed estimator for sensorless surface mount permanent magnet synchronous motor drive
(Institute of Electrical and Electronics Engineers Inc., 2020) Koothu Kesavan, K.K.; Karthikeyan, A.
This article proposes simple and robust electromagnetic torque-based model reference adaptive system speed estimator with cascaded pseudoderivative feedback controller for sensorless surface mount permanent magnet synchronous motor (SMPMSM) drive to improve its performance at standstill and low-speed regions. The proposed estimator is formed using instantaneous and estimated electromagnetic torque. Using small signal modeling, the stability and sensitivity analysis are performed. Results show that the estimator is stable over a wide speed region (including low-speed regions) and exhibits robustness against uncertainties in machine parameters. The proposed estimator is implemented for the 1.5-kW laboratory prototype SMPMSM drive using field programmable gate array (FPGA) ALTERA Cyclone II. Experimental results demonstrate the efficacy of the proposed scheme under different test conditions viz., over a wide adjustable speed range which includes different low-speed regions and standstill, i.e., 157 to -157 rad/s at different load conditions with uncertainty in machine parameters. © 1982-2012 IEEE.
Exploring the Potential of Kite-Based Wind Power Generation: An Emulation-Based Approach
(Multidisciplinary Digital Publishing Institute (MDPI), 2023) Castelino, R.V.; Kumar, P.; Kashyap, Y.; Karthikeyan, A.; Sharma K, M.; Karmakar, D.; Kosmopoulos, P.
A Kite-based Airborne Wind Energy Conversion System (KAWECS) works by harnessing the kinetic energy from the wind and converting it into electric power. The study of the dynamics of KAWECS is fundamental in researching and developing a commercial-scale KAWECS. Testing an actual KAWECS in a location with suitable wind conditions is only sometimes a trusted method for conducting research. A KAWECS emulator was developed based on a Permanent Magnet Synchronous Machine (PMSM) drive coupled with a generator to mimic the kite’s behaviour in wind conditions. Using MATLAB-SIMULINK, three different power ratings of 1 kW, 10 kW, and 100 kW systems were designed with a kite surface area of 2.5 m (Formula presented.), 14 m (Formula presented.), and 60 m (Formula presented.), respectively. The reel-out speed of the tether, tether force, traction power, drum speed, and drum torque were analysed for a wind speed range of 2 m/s to 12.25 m/s. The satellite wind speed data at 10 m and 50 m above ground with field data of the kite’s figure-of-eight trajectories were used to emulate the kite’s characteristics. The results of this study will promote the use of KAWECS, which can provide reliable and seamless energy flow, enriching wind energy exploitation under various installation environments. © 2023 by the authors.
Finite control set model predictive control of three-port converter for interfacing a PV-battery energy storage system to a three-phase stand-alone AC system
(Oxford University Press, 2024) Preeti, G.A.; Karthikeyan, A.
This paper proposes a multiport bidirectional non-isolated converter topology that provides advantages in terms of simultaneous multiple operations, single-stage conversion, high power density and reduced power losses due to the lower number of switches. The proposed multiport converter uses a centralized non-linear controller known as a finite control set model predictive controller to manage the flow of power between different ports. It deals with the parallel operation of photovoltaic and battery energy storage systems for stand-alone alternating current (AC) systems. The converter connects the lower voltage battery to the photovoltaic port using a bidirectional buck/boost converter and the photovoltaic port is linked to the stand-alone AC load through a three-phase full-bridge inverter. Each leg of the three-phase converter will act as a bidirectional direct current (DC)/DC converter as well as an inverter simultaneously. Only six switches manage the power transfer between all the connected ports of photovoltaic-battery energy storage system linked to the stand-alone AC load. The proposed multiport converter is mathematically modelled and controlled by a finite control set model predictive controller. The system is validated in simulation (1-kW rating) and experimental environment (200-W rating). The hardware prototype is developed in the laboratory and the controller is implemented on the field-programmable gate array board. Two independent case studies are carried out to validate the efficacy of the system. The first scenario is for a change in solar irradiance, while the second scenario is for a change in the output load. © The Author(s) 2024. Published by Oxford University Press on behalf of National Institute of Clean-and-Low-Carbon Energy.
Four quardrant operation of direct torque controlled PMSM drive using speed loop PDFF controller
(2018) Karthikeyan, A.; Prabhakaran, K.K.; Nagamani, C.
This paper presents a comprehensive evaluation of proposed speed loop pseudo derivative feedforward (PDFF) controller based DTC, speed loop PI based direct torque controller (DTC) and speed loop PI based hysteresis current controller (HCC) for permanent magnet synchronous motor (PMSM) drive. The proposed controller reduces the torque and stator current ripples and significantly reduces overshoot and oscillation in the actual rotor speed. The proposed controller is verified for different cases viz., forward and reverse motoring, forward and reverse braking operation. The simulations are carried out through MATLAB/Simulink for 1.2 hp PMSM drive and results demonstrates the efficacy of the proposed controller. � 2018 IEEE.
Four quardrant operation of direct torque controlled PMSM drive using speed loop PDFF controller
(Institute of Electrical and Electronics Engineers Inc., 2018) Karthikeyan, A.; Koothu Kesavan, K.K.; Nagamani, C.
This paper presents a comprehensive evaluation of proposed speed loop pseudo derivative feedforward (PDFF) controller based DTC, speed loop PI based direct torque controller (DTC) and speed loop PI based hysteresis current controller (HCC) for permanent magnet synchronous motor (PMSM) drive. The proposed controller reduces the torque and stator current ripples and significantly reduces overshoot and oscillation in the actual rotor speed. The proposed controller is verified for different cases viz., forward and reverse motoring, forward and reverse braking operation. The simulations are carried out through MATLAB/Simulink for 1.2 hp PMSM drive and results demonstrates the efficacy of the proposed controller. Â© 2018 IEEE.
FPGA based direct torque control with speed loop Pseudo derivative controller for PMSM drive
(Springer, 2019) Karthikeyan, A.; Koothu Kesavan, K.; Nagamani, C.
This paper presents a comprehensive evaluation of proposed speed loop pseudo derivative feedback (PDF) controller based DTC with speed loop PI based direct torque controller (DTC) for permanent magnet synchronous motor (PMSM) drive. The proposed PDF-DTC system significantly improves dynamic response i.e. completely eliminates overshoot in speed, reduces 50% overshoot in electromagnetic torque and has two times faster settling time compared to PI-DTC system during step changes in speed with load disturbance. The proposed controller is verified for different cases viz., speed variation at constant load and variation in the load torque at constant speed. The proposed controller is implemented for 1.5 kW laboratory prototype PMSM drive using FPGA ALTERA cyclone II. Experimental results demonstrates the efficacy of the proposed controller. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.
Hybrid Control of Single-Phase to Three-Phase Reduced Switch Converter for PMSM Drive
(Institute of Electrical and Electronics Engineers Inc., 2018) Karthikeyan, A.; Varsha, S.; Koothu Kesavan, K.K.
This paper proposes hybrid control for single phase to three phase reduced switch converter based PMSM drive that can be used in remote locations where only single phase grid is available. PI, hybrid (hysteresis+ PI) controllers are employed for controlling the input and output sides of the converter respectively. This configuration for PMSM drive has a shared leg between output and input sides. The input side PI controller synchronizes input grid current with the grid voltage to maintain unity power factor during load and speed variations. This configuration has unity input power factor and allows bidirectional power flow. The proposed system is modeled for 400W motor in MATLAB/SIMULINK environment and the simulation results are presented. Â© 2018 IEEE.
Investigations on Sensor/Sensorless control of PMSM drive for grid connected and standalone applications
(National Institute of Technology Karnataka, Surathkal, 2019) Prabhakaran, K. K.; Karthikeyan, A.
The goal of present work is to study, develop and analyze the sensor/sensorless control of Permanent Magnet Synchronous Motor (PMSM) drive for grid connected and standalone applications. The research work carried out in this thesis is mainly divided into three parts. Firstly, to find simple and effective algorithm to estimate the rotor speed and position of the PMSM drive. The second part mainly focus on developing a controller for sensor based PMSM drive. The main moto of presenting the proposed estimation scheme and controller separately is to show the efficacy of the PMSM drive by validating their performance individually. Finally, the third part is to develop a standalone PV fed PMSM drive for rural areas. This thesis proposes two speed/position estimation algorithms based on MRAS method for sensorless PMSM drive. In literature, initially proposed MRAS technique is based on stator current to compute the speed and position information of PMSM drive. Following this, many other functional candidates such as stator flux, reactive power are reported with varying system performance. So far, all these functional parameters have a physical understanding (stator flux) or a practical existence (such as current, power etc.). Stator flux based MRAS has unsatisfactory performance in the low speed regions. Thereby, going beyond such selection, a new Flux-Torque based MRAS is proposed and satisfactory performance is reported with stability in low speed operation. FluxTorque is combination of physical and practical existence. The proposed speed estimator is formulated using stator flux and electromagnetic torque based MRAS. It performs better during transient conditions and reduces steady state error for wide rotor speed variations including low speed regions. The stability of the proposed estimator is verified through small signal model and the machine parameter sensitivity is also analyzed. The performance of the proposed estimator is validated for variation in the low speed regions including standstill condition. Flux-Torque based MRAS is stable in the low speed region but this scheme requires information of actual and estimated stator flux and electromagnetic torque to estimate speed and position. In order to reduce mathematical complexity and to avoid computation of stator flux, the simple and robust electromagnetic torque based MRAS speed/position estimator is proposed. The proposed estimator is formed usinginstantaneous and estimated electromagnetic torque. Using small signal modelling, the stability and sensitivity analysis are performed. Results show that, the estimator is stable over a wide speed region (including low speed regions) and exhibits robustness against uncertainties in machine parameters. Simulation and experimental results demonstrate the efficacy of the proposed scheme under different test conditions viz. over a wide adjustable speed range which include different low speed regions and standstill at different load conditions with uncertainty in machine parameters. Further this thesis proposes a simple cascaded Pseudo Derivative Feedback and Feed Forward (PDF plus PDFF) controller for permanent magnet synchronous motor drive. The PI plus PI controller and proposed PDF plus PDFF controller are designed and their stability is analyzed using extended root locus technique, and further influence of damping coefficient is discussed in detail. The proposed control scheme significantly improves dynamic response viz. reduces 50 % of overshoot in stator current, eliminates overshoot in speed and has two times faster settling time of the overall system compared to cascaded PI plus PI controller during wide variation in speed with load disturbance. Simulation and experimental results demonstrate the efficacy of the proposed scheme under different test conditions viz. over the wide adjustable speed range which includes different low speed regions and standstill i.e. 0 to 157 rad/s at different load conditions. Finally, this thesis proposes a standalone PV fed PMSM drive for water pumping. The proposed system aims at reducing the switching losses and overall cost by using reduced switch inverter. The proposed system comprises of a PMSM drive, fed by PV source through an inverter employing reduced number of switches. The inverter uses only four switches whereas the conventional VSI utilizes six switches. Field oriented control scheme is employed to control the PMSM drive. Perturb and Observe (P&O) MPPT technique is used to generate a speed reference to PMSM drive. Simulation and experimental results demonstrate the efficacy of the proposed scheme. All aforementioned simulation studies are carried out through MATLAB/ Simulink and it is also experimentally verified through laboratory prototype consists of FPGA controller based PMSM drive.