Browsing by Author "Sandeep, N."

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A comparison of seven-level inverter topologies for multilevel DC-AC power conversion
(Institute of Electrical and Electronics Engineers Inc., 2014) Salodkar, P.; Sandeep, N.; Kulkarni, P.S.; Yaragatti, R.Y.
Multilevel inverter (MLI) performance is high compared to the conventional two level inverters since they offer high power capability, associated with lower output harmonics and lower commutation losses. However the main drawback of MLI is their increased number of power devices, passive components, complex pulse width modulation control and balancing of capacitor voltages. In this paper the most popular topologies like diode-clamped inverter (neutral-point clamped), cascaded multicell with separate dc sources, and transistor clamped H-Bridge inverter are discussed. A simplified multilevel inverter (Switched Transistor MLI) is proposed and its performance is compared with the above said topologies. Component count and the % total harmonic distortion (THD) of the output voltage are considered as the indexes of the comparative performance. The operating principle of each topology, the most relevant modulation method of all the topologies and the detailed analysis of the proposed Switched Transistor MLI is included. The selection of topology and control techniques depends and varies according to power demands of inverter. Simulation study of all the topologies considered is carried out on MATLAB/SIMULINK platform and the performance of the proposed topology is verified experimentally by the tests performed on a scaled laboratory prototype. Â© 2014 IEEE.
A New Generalized Multilevel Converter Topology Based on Cascaded Connection of Basic Units
(Institute of Electrical and Electronics Engineers Inc., 2019) Jagabar Sathik, J.; Shalchi Alishah, R.; Sandeep, N.; Hosseini, S.H.; Babaei, E.; Krishnasamy, K.; Yaragatti, U.R.
In this paper, a new single-phase multilevel converter (MLC) topology based on the cascade connection of novel basic units is presented. The proposed basic unit generates 17-level output voltage waveform and can be extended for higher voltage levels by using a simple cascade connection. Both the proposed basic unit and cascaded topologies are compared with other state-of-the-art MLC topologies. From the comparison results, it will be shown that the proposed topology has several advantages such as the reduced number of power electronic components, lesser number of dc sources, and blocking voltage. Moreover, the proposed MLC has reduced power losses and improved efficiency. The operability and feasibility of the proposed converter are validated through extensive simulation and experiments. Finally, the corresponding results affirming the predominance of the proposed topologies are presented. © 2013 IEEE.
A new nine-level single-DC source-based inverter topology for distributed generation
(Institute of Electrical and Electronics Engineers Inc., 2017) Sandeep, N.; Yaragatti, U.R.
Multilevel inverter enables to completely remove the passive filtering requirement at the grid interfacing end, resulting in improved efficiency and reduced cost. These features have led to increasing attention towards their application to medium and high-power arena. In this paper, investigation of a hybrid 9-level inverter topology for grid integration of renewable energy sources is presented. The structural details, operating principle, capacitor voltage balancing control and the main features of the proposed inverter are presented. The proposed topology is compared with other similar 9-level converters to emphasize its superior characteristics and performance. Simulation results demonstrating the grid connected operation of the converter for two test cases are presented. The results affirm the effectiveness of the capacitor voltage balancing control in maintaining capacitor voltages at set values, under steady state and transient operation of the converter. Â© 2016 IEEE.
A Self-Balancing Five-Level Boosting Inverter with Reduced Components
(Institute of Electrical and Electronics Engineers Inc., 2019) Sandeep, N.; Jagabar Sathik, J.S.; Yaragatti, U.R.; Krishnasamy, K.
Two-Stage boosting multilevel inverters (MLIs), which are highly suitable for photovoltaic power plants, are known to suffer because of the high voltage stress on the switches of second stage. One of the ways to confront this issue is through eliminating the front-end booster. However, this leads to increased structural and control complexity of the resulting integrated boosting MLI. This letter presents a single-stage boosting MLI requiring lesser number of switches, diodes, and capacitors for renewable power generation applications. It requires nine switches and only one capacitor for five-level voltage generation. The topology has inherent self-balancing capability, thereby does not need additional balancing circuitry. The proposed topology has a uniform peak inverse voltage stress on the switches of value equal to the input dc voltage. A less complicated logic-form-equations-based gating pulse generation scheme is designed for enabling the proposed MLI to maintain its capacitor voltage. Further, a comparative study with state-of-the-art topologies is carried out to demonstrate the superior performance of the proposed topology. Finally, the feasibility of the proposed topology is validated through experimental tests and the corresponding results are elucidated. © 1986-2012 IEEE.
A Single DC Source Nine-Level Switched-Capacitor Boost Inverter Topology with Reduced Switch Count
(Institute of Electrical and Electronics Engineers Inc., 2020) Siddique, M.D.; Alamri, B.; Salem, F.A.; Orabi, M.; Mekhilef, S.; Shah, N.M.; Sandeep, N.; Jagabar Sathik, J.S.; Iqbal, A.; Ahmed, M.; Ghoneim, S.S.M.; Al-Harthi, M.M.
This paper presents a new boost inverter topology with nine level output voltage waveform using a single dc source and two switched capacitors. The capacitor voltages are self-balancing and thus is devoid of any sensors and auxiliary circuitry. The output voltage is twice higher than the input voltage, which eliminates the need for an input dc boost converter especially when the inverter is powered from a renewable source. The merits of the proposed topology in terms of the number of devices and cost are highlighted by comparing the recent and conventional inverter topologies. In addition to this, the total voltage stress of the proposed topology is lower and have a maximum efficiency of 98.25%. The operation and dynamic performance of the proposed topology have been simulated using PLECS software and are validated using an experimental setup considering a different dynamic operation. © 2013 IEEE.
A single-stage active damped LCL-filter-based grid-connected photovoltaic inverter with maximum power point tracking
(Institute of Electrical and Electronics Engineers Inc., 2015) Sandeep, N.; Kulkarni, P.S.; Yaragatti, R.Y.
In this paper, a simple single-phase grid-connected photovoltaic (PV) inverter topology consisting of a three-level inverter, an LCL filter, and a new current feedback method for active damping is considered. A dynamically rapid method is used for tracking the maximum power point (MPP) of photovoltaic arrays, known as ripple correlation control. The algorithm uses the current and voltage low-frequency oscillations as the perturbation signals, which are introduced in the output of PV array due to the sinusoidal power being injected into the single-phase utility grid, to enable operation at MPP. The capacitor of the conventional LCL filter is split into two parts and the current flowing between these two parts is used as the feedback for regulation of grid current being injected. By doing so the V - I transfer function of the grid connected inverter system degrades to first-order one from third order function. Due to which, wide control-loop bandwidth can be achieved with a large proportional control-loop gain ensuring good stability. Proportional-resonant (PR) current controller is suggested to provide power to the line with unity power factor and the PV inverter offers much less total harmonic distortion. The entire system has been numerically simulated in MATLAB/SIMULINK platform and the performance results are presented for variation in insolation levels and grid voltage profile showing the effectiveness of the proposed system. Â© 2014 IEEE.
A Switched-Capacitor-Based Multilevel Inverter Topology with Reduced Components
(Institute of Electrical and Electronics Engineers Inc., 2018) Sandeep, N.; Yaragatti, U.R.
This letter presents an improved sensorless nine-level inverter topology with reduced number of components. It is formed by cascading a three-level T-Type neutral clamped point inverter with a floating capacitor (FC) fed two-level converter unit. Additionally, two line-frequency switches are appended across the dc-link. A simple logic-form equations-based pulse width modulator is designed which is in-charge of maintaining the FC voltage at its reference value without any aid of voltage and current sensor. Thus, the complexity in control of the proposed topology is very minimal. The working principle of the proposed inverter and formulation of logic-form equations is deliberated in detail. Furthermore, experimental results obtained from the developed prototype are presented to validate feasibility and operability of the proposed topology. Finally, a comprehensive comparison with some of the recently reported inverter topologies proving the merits of the proposed topology is included. © 1986-2012 IEEE.
Architectural framework of on-board integrator: An interface for grid connected EV
(2017) Kumar, S.; Likassa, K.; Ayenew, E.; Sandeep, N.; Udaykumar, R.Y.
Vehicle to Grid (V2G) is the concept of connecting a group of electric vehicles (EV) to the grid for power transaction. EVs can be connected to the grid through the home interface or through the chargers available at charging stations. In this paper, a single phase on-board charger with low complexity control scheme is proposed for EV power transaction. The power flow from and to the grid is processed using two stage cascaded converters consisting of a bidirectional DC-DC and DC-AC converters. The LCL filter is used as an interface between DC-AC converter and the grid to attenuate the grid current harmonics. A proportional resonant (PR) controller is employed for the control of grid current and to enable the unity power factor operation of the DC-AC converter. The setbacks associated with the conventional proportional-integral (PI) controller for single phase system is elevated by employing PR controller. Filter design guidelines and the control strategy developed for the proposed system is numerically simulated and verified with extensive simulation carried using MATLAB/SIMULINK. The results demonstrating the feasibility and viability of the proposed system are presented. � 2017 IEEE.
Architectural framework of on-board integrator: An interface for grid connected EV
(Institute of Electrical and Electronics Engineers Inc., 2017) Hampannavar, S.; Likassa, K.; Ayenew, E.; Sandeep, N.; Yaragatti, U.R.
Vehicle to Grid (V2G) is the concept of connecting a group of electric vehicles (EV) to the grid for power transaction. EVs can be connected to the grid through the home interface or through the chargers available at charging stations. In this paper, a single phase on-board charger with low complexity control scheme is proposed for EV power transaction. The power flow from and to the grid is processed using two stage cascaded converters consisting of a bidirectional DC-DC and DC-AC converters. The LCL filter is used as an interface between DC-AC converter and the grid to attenuate the grid current harmonics. A proportional resonant (PR) controller is employed for the control of grid current and to enable the unity power factor operation of the DC-AC converter. The setbacks associated with the conventional proportional-integral (PI) controller for single phase system is elevated by employing PR controller. Filter design guidelines and the control strategy developed for the proposed system is numerically simulated and verified with extensive simulation carried using MATLAB/SIMULINK. The results demonstrating the feasibility and viability of the proposed system are presented. Â© 2017 IEEE.
Asymmetric H-Bridge Single-Phase Seven-Level Inverter Topology with Proportional Resonant Controller
(Taylor and Francis Ltd, 2019) Salodkar, P.A.; Kulkarni, P.S.; Waghmare, M.A.; Chaturvedi, P.C.; Sandeep, N.
This paper presents an asymmetrical H-bridge single-phase seven-level inverter topology with modified gating scheme for reducing the number of high-frequency switches. Due to shortcomings like steady-state error and problems in removing low-order harmonics associated with proportional integral controller, proportional resonant controller is used for grid-connected converter current control. A practical application of proportional resonant current controller is developed using a low-cost dsPIC33EP256MC202 microcontroller to keep the current injected in to the grid. The validity of proposed inverter and control scheme is verified through simulation and implemented for low-voltage laboratory prototype. © 2017, © 2017 IETE.
A comparison of seven-level inverter topologies for multilevel DC-AC power conversion
(2014) Salodkar, P.; Sandeep, N.; Kulkarni, P.S.; Udaykumar, R.Y.
Multilevel inverter (MLI) performance is high compared to the conventional two level inverters since they offer high power capability, associated with lower output harmonics and lower commutation losses. However the main drawback of MLI is their increased number of power devices, passive components, complex pulse width modulation control and balancing of capacitor voltages. In this paper the most popular topologies like diode-clamped inverter (neutral-point clamped), cascaded multicell with separate dc sources, and transistor clamped H-Bridge inverter are discussed. A simplified multilevel inverter (Switched Transistor MLI) is proposed and its performance is compared with the above said topologies. Component count and the % total harmonic distortion (THD) of the output voltage are considered as the indexes of the comparative performance. The operating principle of each topology, the most relevant modulation method of all the topologies and the detailed analysis of the proposed Switched Transistor MLI is included. The selection of topology and control techniques depends and varies according to power demands of inverter. Simulation study of all the topologies considered is carried out on MATLAB/SIMULINK platform and the performance of the proposed topology is verified experimentally by the tests performed on a scaled laboratory prototype. � 2014 IEEE.
Design and Implementation of a Sensorless Multilevel Inverter with Reduced Part Count
(Institute of Electrical and Electronics Engineers Inc., 2017) Sandeep, N.; Yaragatti, R.Y.
This letter proposes a single-phase nine-level (9L) inverter topology suitable for grid-connected renewable energy systems. The proposed inverter is realized using a T-Type neutral-point-clamped inverter connected in cascade to a floating capacitor (FC) H-bridge. Additionally, two low-frequency switches are added across the dc-link enabling the inverter to generate a 9L waveform. A sensorless voltage control based on redundant switching state is developed and embedded with PWM controller, which is responsible for regulating the FC voltage at one-quarter of the dc source voltage. The proposed PWM technique employs the generation of 9L waveform without using any voltage sensor, thereby reducing the complexity of the overall control scheme. This, in turn, will make the overall system appealing for various industrial applications. In comparison to conventional and recent topologies, generation of the 9L waveform using a lower number of components is the notable contribution. Another important feature of the proposed inverter is that if FC H-bridge fails, it can be bypassed, and the inverter can still operate as a 5L inverter at its nominal power rating. Furthermore, a comprehensive comparison study is included which confirms the merits of the proposed inverter against those of other state-of-The-Art topologies. Finally, simulation and experimental results are included for validating the feasibility of the proposed system. © 1986-2012 IEEE.
Design and implementation of active neutralpoint-clamped nine-level reduced device count inverter: An application to grid integrated renewable energy sources
(Institution of Engineering and Technology journals@theiet.org, 2018) Sandeep, N.; Yaragatti, U.R.
Multilevel inverters are one of the preferred choices in medium-voltage and high-power applications in the recent past. Active neutral-point-clamped (ANPC) inverter is the most popular topology, especially in the class of five-level (5L) inverters. In this study, a nine-level topology with improved output waveform quality is proposed based on ameliorating the 5L ANPC inverter with least modifications. The addition of only two switches operating at line frequency to the conventional 5L ANPC inverter while maintaining an identical precursor part count is the proposed modification. A logic form equation-based active voltage balancing scheme that is independent of load current and power factor is developed to regulate the flying capacitor voltage at the reference value. The operating principle, salient features, and the developed control scheme are comprehensively detailed. The operation of the proposed inverter considering a grid integrated case is simulated in MATLAB/ Simulink, and the results corresponding to steady-state and dynamic conditions are presented. The benefits of the proposed topology are elucidated by comparing it with other classic topologies considering various prominent viewpoints. This comparison has illustrated the proposed topology's distinctive characteristics and profound advantages. The performance validation, feasibility, and practicability of the proposed inverter are established through the experimental results obtained from a laboratory-scale prototype. © The Institution of Engineering and Technology 2017.
Design and Implementation of Transformer-Based Multilevel Inverter Topology with Reduced Components
(Institute of Electrical and Electronics Engineers Inc., 2018) Behara, S.; Sandeep, N.; Yaragatti, U.R.
This paper presents a nine-level transformer-based inverter requiring only eight switches. The envisaged structure consists of two standard H-bridges fed from a single dc source. Besides, a single-phase transformer is employed to aid the process of intermediate voltage level generation. An ad-hoc pulsewidth modulation scheme based on boolean logic form equations is developed to derive the gating pulses. An effortless extension of the proposed inverter to a higher number of voltage levels is also achieved by generalizing the switching functions. Furthermore, the superior performance of the proposed topology is demonstrated through a comprehensive cost-based analysis. Finally, the validation of the proposed topology is accomplished through experiments on a down-scale prototype, and the measurement results are included. © 1972-2012 IEEE.
Development of a microcontroller based PV emulator with current controlled DC-DC buck converter
(International Journal of Renewable Energy Research icolak@gazi.edu.tr, 2014) Balakishan, C.H.; Sandeep, N.
Testing and validation of Photovoltaic based energy conversion systems requires Photovoltaic (PV) panels in laboratory environment. A flexible testing system, which eliminates these panels and emulating the dynamic characteristics of PV sources in real time are gaining importance. This paper presents a new algorithm for emulation of PV characteristics using a DC-DC buck converter in current control mode. The algorithm tracks the point on the V-I characteristics of the PV under varying loads by generating the corresponding current reference. This reference current is used for the generation of gate pulses for the DC-DC converter, which acts like a constant current source to emulate the PV panel. In the proposed system, real time variation of irradiance and temperature are incorporated as a time varying input parameters to the PV emulator. The proposed algorithm has been simulated numerically using MATLAB/SIMULINK platform and is experimentally verified on a laboratory test bench consisting of a DC-DC buck converter of 50 W rating with AT'mega328 as a core controller. Both simulation and hardware results are presented showing the effectiveness of the proposed system under dynamic loading and environmental conditions.
High gain active neutral point clamped seven-level self-voltage balancing inverter
(Institute of Electrical and Electronics Engineers Inc., 2020) Jagabar Sathik, M.J.; Sandeep, N.; Blaabjerg, F.
This brief presents a novel seven-level (7L) inverter topology for grid-connected renewable applications. It consists of ten active switches and one inner flying-capacitor unit forming a structure similar to conventional active neutral point clamped inverter. The proposed unique arrangement reduces the number of active, passive components and it does not require any sensor to balance the floating capacitor voltage, thereby reduces cost and complexity in the control system design. In addition, compared to major conventional 7L inverter topologies, the proposed topology is capable of boosting the input voltage by a factor of 1.5, thereby, eliminating the need for an intermediate boosting stage. In other words, it reduces the dc-link voltage requirement by 50%. To prove the advantage of the proposed topology over other recent topologies, a comparative study in terms of power components and cost is presented. The operation and performance of the proposed topology for various loading conditions are validated through experimental tests and measurements. © 2004-2012 IEEE.
A new nine-level single-DC source-based inverter topology for distributed generation
(2017) Sandeep, N.; Udaykumar, R.Y.
Multilevel inverter enables to completely remove the passive filtering requirement at the grid interfacing end, resulting in improved efficiency and reduced cost. These features have led to increasing attention towards their application to medium and high-power arena. In this paper, investigation of a hybrid 9-level inverter topology for grid integration of renewable energy sources is presented. The structural details, operating principle, capacitor voltage balancing control and the main features of the proposed inverter are presented. The proposed topology is compared with other similar 9-level converters to emphasize its superior characteristics and performance. Simulation results demonstrating the grid connected operation of the converter for two test cases are presented. The results affirm the effectiveness of the capacitor voltage balancing control in maintaining capacitor voltages at set values, under steady state and transient operation of the converter. � 2016 IEEE.
Novel asymmetrical multilevel inverter topology with reduced number of switches for photovoltaic applications
(2015) Mudadla, D.; Sandeep, N.; Rao, G.R.
The performance of multilevel inverter is high compared to the classical two level inverters owing to their reduced total harmonic distortion, and lower electromagnetic interference. However the setbacks of multilevel inverter are increased number of power devices, complex PWM and gating circuitry. In this paper, a new multilevel inverter topology, capable of generating large number of levels with fewer number of power switches, gating circuits and power diodes is proposed. In contrast to classical multilevel topologies, the presented topology consequences in reduction of the number of power devices and conduction losses. The proposed topology is asymmetrical, employing isolated dc sources of voltage ratio 421 (Binary fashion). Staircase control PWM at fundamental frequency is employed for the gating of power switches makes it suitable in applications like flexible alternative current transmission systems (FACTS), renewable energy sources, drives control and vehicle propulsion system. The structure of the proposed inverter is modular and thus best suited for PV applications. Detailed simulation is carried out using MATLAB/SIMULINK platform and simulation results are presented. � 2015 IEEE.
Novel asymmetrical multilevel inverter topology with reduced number of switches for photovoltaic applications
(Institute of Electrical and Electronics Engineers Inc., 2015) Dhananjaya, D.; Sandeep, N.; Rao, G.R.
The performance of multilevel inverter is high compared to the classical two level inverters owing to their reduced total harmonic distortion, and lower electromagnetic interference. However the setbacks of multilevel inverter are increased number of power devices, complex PWM and gating circuitry. In this paper, a new multilevel inverter topology, capable of generating large number of levels with fewer number of power switches, gating circuits and power diodes is proposed. In contrast to classical multilevel topologies, the presented topology consequences in reduction of the number of power devices and conduction losses. The proposed topology is asymmetrical, employing isolated dc sources of voltage ratio 421 (Binary fashion). Staircase control PWM at fundamental frequency is employed for the gating of power switches makes it suitable in applications like flexible alternative current transmission systems (FACTS), renewable energy sources, drives control and vehicle propulsion system. The structure of the proposed inverter is modular and thus best suited for PV applications. Detailed simulation is carried out using MATLAB/SIMULINK platform and simulation results are presented. Â© 2015 IEEE.
Operation and Control of a Nine-Level Modified ANPC Inverter Topology with Reduced Part Count for Grid-Connected Applications
(Institute of Electrical and Electronics Engineers Inc., 2018) Sandeep, N.; Yaragatti, U.R.
This paper presents a nine-level active-neutral-point-clamped (ANPC) based multilevel inverter (MLI) topology for grid-connected applications requiring only ten switches. The envisaged structure comprises two parts, namely five-level ANPC unit, and a two-level converter leg whose midpoint is used as another ac terminal. An ad hoc switching state redundancy based modulation strategy is used to ensure that the voltage across the flying capacitor is tightly balanced and is implemented using a look-up table further simplifies the control complexity. The performance and effectiveness of the proposed topology with its control scheme are validated through simulations and experimental tests. Comparison with other MLIs is included to highlight the merits of the proposed topology. From the results, it will be shown that the proposed inverter requires the least part count as compared to other topologies with the same performance and output quality. © 1982-2012 IEEE.