Faculty Publications
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Publications by NITK Faculty
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Item Real and reactive power control of solar grid-tie inverter under distorted grid conditions(Institute of Electrical and Electronics Engineers Inc., 2018) Damodaran, R.; Ramana, V.V.; Balasubramanian, B.; Mishra, S.Due to increasing density of integration of distributed generation systems (DGS) to the utility grid, continuous power supply from DGS is being considered desirable during temporary grid faults, to provide support to the grid under conditions like voltage sags. Researchers have been focusing on improved topologies and control strategies in order to enhance the performance of solar grid-tied inverters, especially during grid faults. This paper presents a simple yet accurate control strategy for three-level four-wire grid-tie inverters for real and reactive power injection which operates satisfactorily under distorted grid conditions. Independent control of the input and output side is obtained by using two-stages, with boost converter obtaining maximum power from the solar panels, and inverter injecting this power into the grid with grid standards being met. A DC link balancing technique using proportional controller is also presented. A three-level neutral point clamped grid-tie inverter with the proposed control is modeled in MATLAB-Simulink platform and its effectiveness, in terms of accuracy of operation under non-ideal grid conditions and reduction in total harmonic distortion, is validated using the simulation results. © 2018 IEEE.Item Efficient global peak tracking of PV system under mismatching conditions using searching technique and bisection method(Institute of Electrical and Electronics Engineers Inc., 2018) Ramana, V.V.; Mudlapur, A.; Damodaran, R.; Balasubramanian, B.; Mishra, S.Rapidly increasing energy demand is leading to increase in installation of photovoltaic (PV) plants across the globe. The PV modules are subjected to various conditions like shading, soiling and degradation because of which the performance of PV panels deteriorates. This will affect the characteristics of PV module which may lead to several stairs in I-V curves and several peaks in P-V curve. In this paper the various causes of occurrences of mismatching conditions are analyzed. An efficient two stage algorithm that tracks global maximum power point (GMPP) accurately under such mismatching conditions is proposed in the paper. In the first stage, a simple searching technique and bisection method are used to bring the operating point to the proximity of global maximum. In the second stage, hill climbing method maintains the operating point at global peak. MATLAB Simulations and experimental verifications are performed for validating the proposed approach. © 2018 IEEE.Item Experimental investigation of the effectiveness of the LC filter in PV fed induction motor water pumping systems with different type of inductors(Institute of Electrical and Electronics Engineers Inc., 2018) Mudlapur, A.; Subrahmanya Adiga, P.; Anusha, R.; Balasubramanian, B.This paper presents the experimental study of the effectiveness of the LC filter in PV fed water pumping systems. This study is very important in water pumping applications where prolonged running conditions is a major concern. LC filters are connected at the terminals of the inverter to avoid transient over voltages across the induction machine. The conventional LC filter with lumped gap inductor is studied initially. The temperature of the filter inductor is monitored to study its behaviour. It is inferred that the inductor temperature increases drastically due to the high winding losses and therefore may lead to system failure when run for longer duration. The inductor is replaced with uniformly distributed(powdered) core and low cost discretely distributed gap core so as to minimize the losses. Comparative study between the conventional and proposed inductors is carried out. It is inferred that discretely distributed gap inductors are a better choice over powdered core inductors. The experimentation is carried out on a 3-HP induction motor and results with lumped gap and discretely distributed gap inductors are presented along with their thermal profiles. Results show that, the discrete distributed gap inductor is the cost effective solution for the LC filter failures in water pumping applications. © 2018 IEEE.Item Modified Hysteresis Current Control for Single Phase Solar Grid-tie Z-Source Inverter(Institute of Electrical and Electronics Engineers Inc., 2018) Damodaran, R.; Balasubramanian, B.; Mudlapur, A.; Ramana, V.V.; Mishra, S.This paper proposes a simple novel technique to determine the shoot-through states in a hysteresis controlled solar grid connected single phase Z-source inverter (ZSI). The ZSI along with the proposed controller exhibits high efficiency due to the single stage conversion. Fast and robust dynamic response can be obtained by using hysteresis control. Hence the proposed control for ZSI is ideal for grid integration of photovoltaic sources. The error current is used to determine shoot-through states based on calculation of current limits as a function of the boost ratio and modulation index. The maximum boost ratio, that can be obtained by the proposed control without causing low frequency ripples in Z-source network, is expressed as a function of modulation index. To verify the analysis, simulations are performed for input and grid voltage variations using MATLAB-Simulink platform. © 2018 IEEE.Item A Novel Back to Back Inverter Configuration for Solar Water Pumping and Grid-Tie Application(Institute of Electrical and Electronics Engineers Inc., 2018) Parmar, J.V.; Reddy, S.K.; Swaminathan, B.; Mudlapur, A.; Balasubramanian, B.The use of photovoltaic (PV) as an energy source for pumping water is one of the most promising areas of photovoltaic applications. Solar water pumps are eco-friendly substitutes for diesel and grid powered water pumps. They provide better energy efficiency compared to diesel and grid powered pumps and also gives zero-carbon foot print during their use, promoting a healthy and a more sustainable environment. But PV being an unreliable source, prediction of water output is not possible. Further if photovoltaic array generates more power than the load requirement, the excess power is not harvested and when the demand is not met sufficient water is not pumped out. To mitigate this problem this paper presents a back to back voltage source converter (VSC) configuration increasing reliability, robustness and efficiency of the entire system. A new control strategy for back to back VSC for switching between grid-tie and active power factor correction (APFC) mode based on the natural power balance is presented to optimize energy utilisation and ensure maximum water output at all times. Detailed simulation studies are carried out using MATLAB/Simulink to verify the effectiveness of proposed scheme. © 2018 IEEE.Item A Transformerless Photovoltaic Microinverter using High-gain Z-Source Boost Converter for Single-phase Grid connected Applications(Institute of Electrical and Electronics Engineers Inc., 2020) Prabhu, N.S.; Damodaran, R.; Balasubramanian, B.; Mishra, S.Microinverters are the latest advancements in the area of photovoltaic (PV) technology due to their compact design. They improve energy efficiency of PV systems due to the reduced effect of non-uniform operating conditions caused primarily by shading. However due to the low output voltage rating of PV modules, high output to input voltage gain ratio is required for microinverters integrated to the utility grid. Several of the existing techniques use transformers or coupled inductors to achieve high gain ratios. These often require precise design and increase the size and cost of the PV system. The Z-source network based high-gain converters can offer superior performance with reduced components, size and cost. However their operation in a microinverter for grid connected applications have not yet been studied. Therefore this paper presents a novel microinverter utilizing a high-gain Z-source boost converter followed by an H-bridge inverter. The principle of operation of the microinverter is detailed and the overall gain ratio is obtained. The operating region in the I-V characteristics of PV module is determined and the control strategies implemented are discussed in detail. Simulations are performed in MATLAB/Simulink platform to validate the performance of the proposed microinverter under possible operating condition. © 2020 IEEE.Item A Novel Bi-Directional Converter for Electric Vehicle to Grid Applications(Institute of Electrical and Electronics Engineers Inc., 2020) Deepak, P.; Damodaran, R.; Balasubramanian, B.; Mudlapur, M.This paper presents a power converter system that implements bidirectional energy flow between electric vehicle and single phase grid. The proposed topology and control ensures that all major grid requirements such as unity power factor, power quality and total harmonic distortion at grid side are achieved. It also features constant charging current for battery, constant DC link voltage, fast transition in power flow from one direction to another and independent control for power supplied to grid, battery charging current and DC link voltage. The control loop and configuration are such that the system can provide boosting at multiple points and thereby the DC link voltage remains constant irrespective of the power flow direction and turns ratio of the high frequency transformer. Simulated results validate the feasibility of the system and effectiveness of its control. The nonlinearities of the system is taken into account in the simulations. © 2020 IEEE.Item Design and Analysis of Single SiC MOSFET Switch Flyback Converter based Control Power Supply for Renewable Applications(Institute of Electrical and Electronics Engineers Inc., 2020) Jagannath, S.; Agarwal, N.; Balasubramaniasarma, S.; Ma, K.W.; Balasubramanian, B.This paper presents the use of a 1700 V silicon carbide (SiC) MOSFET in a single switch configuration for a high input voltage control power supply (CPS) design in a flyback topology. Such a CPS is used to power the control and monitoring systems employed in renewable power generation, general purpose drives and uninterrupted power supply (UPS). Renewable applications often see DC bus voltages up to 1000 V. Hence, flyback topology is chosen as it provides an efficient DC voltage step-down for a wide input voltage range with low voltage ripple and desirable regulation. The performance of the flyback converter using a CoolSiCTM MOSFET is observed through appropriate simulations and verified through the hardware prototype. Further, the switching and conduction losses of the MOSFET along with system performance parameters are calculated and the results are presented in this paper. © 2020 IEEE.Item A novel AC module with high gain Z-Source converter and pseudo DC-link inverter(Institute of Electrical and Electronics Engineers Inc., 2020) Damodaran, R.; Dastagiri Reddy, B.D.; Balasubramanian, B.The effects of partial shading in low power PV systems can be considerably reduced by using a single PV module of appropriate rating. Such a system is termed as the AC module in the literature and consists of a PV module along with the required power electronic circuitry, known as module integrated converter (MIC). The AC module integrated with the grid is required to operate at high efficiency and provide an output voltage of the expected magnitude and frequency. In this paper an efficient MIC with pseudo DC-link (pDC-l) for grid integration of AC module is proposed. The proposed MIC is claimed to be high efficient due to the fundamental frequency operation of the inverter. To obtain a pDC-l of required magnitude from single photovoltaic (PV) module, a high gain Z-source buck-boost converter (ZBBC) is used. It is followed by an unfolding circuit which operates at fundamental frequency to convert the pDC-l to sinusoidal output. The fundamental frequency operation reduces the switching losses without affecting the total harmonic distortion (THD). The operation of the ZBBC, when used to obtain a pDC-l output is analysed and a simple closed loop control is developed. The control ensures a pseudo DC-link voltage at the input of the H-bridge that acts as an unfolding circuit. The control also ensures power balance by controlling the current injected to the grid. Simulations of the proposed AC module with ZBBC cascaded with pDC-l inverter have been carried out using MATLAB/Simulink platform and the results are presented to validate the proposed MIC and its closed loop control. © 2020 IEEE.Item A PFC Hysteresis Current Controller for Totem-pole Bridgeless Bi-directional EV charger(Institute of Electrical and Electronics Engineers Inc., 2022) Adiga, P.S.; Kumar, H.; Iyer, S.R.; Arjun, M.; Dsouza, R.C.; Balasubramanian, B.The sheer increase in greenhouse gas emissions coupled with depleting fossil fuel reserves has created widespread interest in the design and development of Electric Vehicles; however, the design of reliable charging infrastructures for Electric Vehicles is posing challenges to engineers. Additionally, to enhance the efficiency of these Electric Vehicles, it is desirable for the chargers to have bidirectional power processing capabilities. Therefore, the development of bidirectional Battery chargers is one of the main areas of interest when it comes to EVs. In this regard, this paper presents a Hysteresis Controller for a Bridgeless bidirectional On-Board Battery Charger for Electric Vehicle applications. The AC power is fed from a grid via a totem pole-based AC-DC converter. However, the problem with such a power supply unit is that the design of inner current loop PID compensators is challenging due to the increase in complexity of the mathematical model. Therefore, in this paper, the conventional PID controller of the inner current loop is replaced with a Hysteresis controller. The control strategies have been developed to ensure that the power drawn by the grid is harmonic-free. The simulation study is carried out on a 1.5kW setup using MATLAB/SIMULINK. The proposed system is tested for bi-directional power flow. The simulation results are found to be in total agreement with the studied theory. © 2022 IEEE