Faculty Publications
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Item A novel CSI-fed induction motor drive(2006) Beig, A.R.; Ranganathan, V.T.Current source inverter (CSI) fed drives are employed in high power applications. The conventional CSI drives suffer from drawbacks such as harmonic resonance, unstable operation at low speed ranges, and torque pulsation. This paper presents a novel CSI drive which overcomes all these drawbacks and results in sinusoidal motor voltage and current even with CSI switching at fundamental frequency. The proposed CSI drive uses a three-level inverter as an active filter across motor terminals replacing the bulky ac capacitors used in the conventional drive. A sensorless vector controlled CSI drive based on proposed configuration is developed. The simulation and experimental results are presented. Experimental results show that the proposed drive has stable operation even at low speeds. Comparative results show that the proposed CSI drive has improved torque ripple compared to the conventional configuration. © 2006 IEEE.Item Modified SVPWM algorithm for three level VSI with synchronized and symmetrical waveforms(2007) Beig, A.R.; Narayanan, G.; Ranganathan, V.T.The objective of the present work is to improve the output waveform of three level inverters used in high-power applications, where the switching frequency is very low. This is achieved by maintaining the synchronization, half-wave symmetry, quarter-wave symmetry, and three-phase symmetry in the pulsewidth modulation (PWM) waveforms. The principles of achieving synchronization and symmetries in terms of space vectors for three level inverters are presented. A novel synchronized space vector pulsewidth modulation (SVPWM) algorithms is proposed and verified experimentally. The experimental waveforms of the inverter output voltage and motor no load current for different operating conditions of the drive are presented. The performance measure in terms of the weighted total harmonic distortion (THD) of the line voltage is computed for the linear modulation region of the drive for the proposed algorithm and compared with that of synchronized SVPWM and synchronized sine-triangle pulsewidth modulation (SPWM) technique. The comparative results show that consideration of synchronization and symmetry results in improved THD. Another significant feature of the proposed algorithm is that the symmetry and synchronization leads to self-balancing of the direct current (dc) bus capacitor voltages over every one third cycle of the fundamental. © 2007 IEEE.Item Dynamic performance of microturbine generation system connected to a grid(2008) Gaonkar, D.N.; Pillai, G.N.; Patel, R.N.The interconnection of distribution generation systems into distribution networks has great impact on real-time system operation, control, and planning. It is widely accepted that microturbine generation (MTG) systems are currently attracting a lot of attention to meet customers' needs in the distributed power generation market. In order to investigate the performance of MTG systems, their efficient modeling is required. This article presents the dynamic model of an MTG system, suitable for grid connection to study the performance of the MTG system. The presented model uses back-to-back power electronic converter topology for grid connection, which allows the bidirectional power flow between the grid and MTG system. Thus, the need of separate starting arrangements during launching of the microturbine is avoided. The components of the system are built from the dynamics of each part with their interconnections. The dynamics of the model have been studied under various grid disturbance conditions. The converter control strategies for MTG system operation in grid-connected mode are presented in this article. This article also compares the various grid connection topologies suitable for MTG system interconnection. The simulation results show that the developed model performance is not affected by the grid disturbances considered in the study, and that it has the ability to adjust the supply as per the power requirements of the load within the MTG system rating.Item Improved space vector PWM algorithm for three-level voltage source inverter in overmodulation region(Inderscience Publishers, 2013) Veeranna, S.B.; Yaragatti, U.In high power high performance AC drive industrial applications, multilevel inverters have established their importance, as they can synthesise output waveform with improved harmonic spectrum. In this paper, an improved synchronisation and symmetrical SVPWM algorithm is proposed for three-level inverter in overmodulation region for better utilisation of DC bus and to reduce harmonic distortion. The performance analysis of the proposed algorithm is compared with SHEPWM and STPWM for three-level voltage source inverter in terms of THD of line voltage and motor current along with fundamental component of the line voltage. It is shown that the proposed algorithm gives improved results compared to SHEPWM and STPWM algorithms. The algorithm is also verified experimentally on a constant v/f drive fed from IGBT-based voltage source inverter using Motorola power PC (MPC8240) based embedded controller. © 2013 Inderscience Enterprises Ltd.Item Modeling a grid connected photovoltaic system with perturb and observe based maximum power point tracking(2013) Naik, A.; Yaragatti, U.This article deals with the integration study of distributed generation (DG) in the form of a photovoltaic (PV) plant in a three-phase system. Here the active power generated by the photovoltaic (PV) plant is injected into the grid system through a current controlled dual inverter topology. The main contribution in this article is the dual inverter topology. In this topology, a three level inverter output is obtained which reduces the PV injected current harmonic distortion into the grid. The control algorithm used in this article is simple and easy to implement. The PV system is operated through a maximum power point tracking (MPPT) stage. Perturb & Observe (P&O) is the modeling approach of MPPT system operation. The system is simulated and analyzed for a different set of loads with renewable source at different atmospheric conditions using MATLAB/ Simulink tool. The grid current becomes sinusoidal with three levels inverter and compared to existing three levels methods the dual inverter method is simple and easy to implement.Item Direct torque controlled induction motor drive based on cascaded three two-level inverters(Acta Press, 2014) Thippiripati, T.V.; Surapaneni, S.S.In this paper, a new and an effective voltage switching-state algorithm to Direct Torque Control (DTC) of induction motor drive is proposed, which makes less torque and flux ripple at various operating frequency conditions. In conventional DTC, the torque and flux ripples are difficult to reduce as the applied voltage vector is independent of rotor speed especially at low speeds. To overcome this problem, the proposed technique introduces a voltage switching-state algorithm for four-level inversion using cascading three two-level inverters, in which choice of inverter voltage states is the function of rotor speed. From simulation results, the torque and flux ripple are decreased with proposed DTC when compared with the conventional DTC technique at various operating frequencies.Item An integrated Control Approach and Power Management of Stand-alone Hybrid Wind/PV/Battery Power Generation System with Maximum Power Extraction Capability(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2015) Sabhahit, N.S.; Gaonkar, D.N.The production of electricity from renewable energy sources like wind and photovoltaic energy has increased in recent years, due to environmental problems and the shortage of traditional energy sources. In this article we present a detailed mathematical model and a control scheme for hybrid wind and PV based DG system with battery and maximum power extraction capability for isolated mode of operation. The wind power generation system uses wind turbine (WT), a permanent magnet synchronous generator (PMSG), a three-phase diode rectifier bridge, DC/DC boost converter with maximum power point tracking (MPPT) controller. The PV generation system uses PV array, a boost converter with maximum power point tracking controller. Both sources and battery are connected to common dc bus with a dc link capacitor and supply power to load through PWM voltage source inverter. The overall control system consists of MPPT controller for both Wind and PV power system, a bi-directional DC-DC converter controller for battery energy storage management and load side inverter controller for voltage and frequency regulation. Control strategies for individual system components of the proposed system are designed with a view to achieve an acceptable level of voltage and frequency regulation while extracting the maximum power from wind and PV system. The performance of the developed hybrid system is investigated in terms of voltage and frequency regulation capability under changing wind, solar irradiation and variable load conditions.Item Power control of PV/fuel cell/supercapacitor hybrid system for stand-alone applications(International Journal of Renewable Energy Research, 2016) Sabhahit, N.S.; Gaonkar, D.N.; Nempu, P.B.This paper presents modeling and control of photovoltaic/fuel cell/supercapacitor hybrid power system for stand-alone applications. The hybrid power system uses solar photovoltaic array and fuel cell as the main sources. These sources share their power effectively to meet the load demand. The supercapacitor bank is used to supply or absorb the power during load transients. The main control system comprises of controller for maximum power tracking from photovoltaic system, a DC-DC boost converter with controller for fuel cell system for power management and inverter controller to regulate voltage and frequency. The stand-alone hybrid system aims to provide quality power supply to the consumers with a constant voltage and frequency along with proper power management using simple control techniques. The modeling and control strategies of the hybrid system are realized in MATLAB/Simulink.Item Single-phase seven-level grid-connected photovoltaic system with ripple correlation control maximum power point tracking(International Journal of Renewable Energy Research, 2016) Sandeep, N.; Yaragatti, R.Y.This paper puts forward a control scheme for single-phase photovoltaic (PV) fed grid connected with cascade Hbridge (CHB) inverter. A unique control strategy based on the voltage ratio is proposed and is embedded with ripple correlation control (RCC) based maximum power point tracking (MPPT) to ensure the efficient energy conversion. The control scheme employed enables the independent operation and control of individual DC link voltage, ensuring the extraction of maximum power available from each PV panel. In addition, low harmonic grid currents are generated with an arbitrary power factor. Independent control of active and reactive power is exercised by decoupled component method. Numerical simulation was performed using the MATLAB/SIMULINK platform and results for three H-bridge cells connected in series are presented to support the theoretical concepts and control scheme proposed.Item Performance analysis of a variable-speed wind and fuel cell-based hybrid distributed generation system in grid-connected mode of operation(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2016) Ayyappa, S.K.; Gaonkar, D.N.This article presents the performance study of a variable-speed wind and solid oxide fuel cell-based hybrid distributed generation system, along with the energy storage devices in the grid connected mode of operation. The developed model has a salient feature of utilizing fluctuating output power of wind systems to produce hydrogen and also to charge the ultra capacitor. The presented model in the article also uses the stored energy in the ultra capacitor to compensate for the slow response time of the fuel cell. The distributed generation systems and energy storage devices considered in this study are integrated at common distributed generation links to form the hybrid system. The hybrid system is interfaced to the grid through the three-phase voltage source inverter in this article. The detailed modeling of the individual components of the hybrid distributed generation system, along with the necessary power electronic converter control schemes, are presented. The simulation results reported in this article show the effective performance of the hybrid model to produce reliable, low-cost electricity and hydrogen from the variable wind generation system. © 2016 Taylor & Francis Group, LLC.