Faculty Publications

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Subject: search.filters.subject.Hysteresis current control

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    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.
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    Implementation of Single-Phase Two-Switch Midpoint Unidirectional Multilevel Converter System
    (Walter de Gruyter GmbH, 2018) Roy, P.R.; Parthiban, P.; Babu, B.
    This paper deals with implementation of a single-phase three level converter system under low voltage condition. The frequency of the switches is made constant and involves change in $-t-on}}$ton and $-t-off}}$toff duration. For this condition the pulse width modulation control scheme for a single phase three level rectifier is developed to improve the power quality. The hysteresis current control technique is adopted to bring forth three-level PWM on the dc side of the bridge rectifier and to achieve high power factor and low harmonic distortion. Based on the proposed control scheme, the line current is driven to follow the sinusoidal current command which is in phase with the supply voltage. By using three-level voltage pattern the blocking voltage of each power device is clamped to half of the dc link voltage. The simulation and experimental results of 20W converter under low input voltage condition are shown to verify the circuit performance. Open loop simulation and hardware tests are implemented by applying a low voltage of 15 V(rms) on the input side. © 2018 Walter de Gruyter GmbH, Berlin/Boston 2018.
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    Fuzzy PI controller for bidirectional power flow applications with harmonic current mitigation under unbalanced scenario
    (AIMS Press, 2018) Nagaraj, C.; Manjunatha Sharma, K.
    The depletion of fossil fuels and environmental concern forces the extraction of power from low carbon fuels causes generation problem due to intermittent solar-wind renewable energy sources and power electronic applications. Furthermore, the significant amount of non-linear loads in the system causes power quality problems. Nowadays, the more and more DC loads like LED lights to save energy consumption are connected to the AC distribution system. These DC loads are connected at DC grid side in order to avoid the extra AC/DC power conversion loss. In this paper, the proposed d-q reference current method applied for shunt active power filter based 3-phase 4-leg bidirectional interfacing converter with fuzzy PI controller to achieve the real power transfer between DC grid side and AC grid side with current harmonics compensation at common connecting point simultaneously under balanced and unbalanced distorted grid and non-linear load conditions. The hysteresis current control comparator without PLL is used to compare actual grid current with reference filter current and generate the switching pulses for driving the bidirectional interfacing converter. The DC grid shunt connected intermittent hybrid solar-wind energy sources are integrating with AC grid utility through bidirectional interfacing converter has been into consideration for simulation studies. The MATLAB/SIMULINK tool is used to yield the improved grid current THD with fuzzy logic controller over PI controller. © 2018 the Author(s), licensee AIMS Press.
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    A Novel AC Current Sensorless Hysteresis Control for Grid-Tie Inverters
    (Institute of Electrical and Electronics Engineers Inc., 2020) Damodaran, R.; Mudlapur, A.; Ramana, V.V.; Balasubramanian, B.; Mishra, S.
    Amongst the modulation techniques used for grid-Tie inverters (GTIs), hysteresis current control (HCC) facilitates simple, stable and rugged control with improved dynamic response. However the variable switching frequency of HCC demands high precision AC current sensors (CS) which introduce noise in the power circuit in addition to measurement noise and delay. Therefore, this brief presents a hysteresis current control without AC current sensor based on switching instant computation for a two-level GTI. The proposed control strategy uses the DC link and instantaneous grid voltages to calculate the switching instants. The conventional methods of calculating switching instant of HCC can result in tracking errors. Hence the computations are modified in the proposed algorithm considering the effects of non-linearity in error current and dynamic variations due to supply and load changes. A single-phase GTI is simulated with the proposed control and the results are verified experimentally. The proposed method is observed to considerably reduce the computational time, DC shift and total harmonic distortion compared to the commonly used sensorless current control. © 2004-2012 IEEE.
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    A Precise Switching Frequency Formulation of Hysteresis-Controlled Grid-Connected Inverters Considering Nonlinear Ripple Current
    (Institute of Electrical and Electronics Engineers Inc., 2022) Damodaran, R.; Venkatesa Perumal, B.V.
    Hysteresis current control (HCC) is one of the most simple and rapid modulation techniques for multilevel grid-connected inverters (MGCIs). It controls the output current by limiting its ripple within fixed hysteresis limits. This results in a varying switching frequency, which is not known implicitly. The knowledge of switching frequency is essential for filter design, device selection, and loss calculations of the MGCI. The existing frequency estimations for HCC assume linear ripple current considering high-frequency operation. This assumption is invalid for the range of low frequencies. This leads to inaccurate estimation of switching frequency, which can have a considerable effect on system design. In this article, a more precise and generalized expression to estimate the switching frequency of the MGCI is obtained. The improvement in accuracy is demonstrated with an example of second-order filter design. The effect of change in hysteresis limits and input voltage on the switching frequency is analyzed to determine the operating point for accurate system design. Simulation and experimental results are found to be in good agreement with the theoretical claims. © 1982-2012 IEEE.
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    Analyzing the Performance of Fault-Tolerant Switched Reluctance Motor Control Strategies With Novel Commutation Angle Variation
    (Institute of Electrical and Electronics Engineers Inc., 2024) Santhosh Reddy, J.; Parthiban, P.
    This paper analyzes control techniques using a novel commutation angle variation for fault-tolerant operation in Switched Reluctance Motor (SRM) drives. It explores the use of hard chopping hysteresis current control (HCC) and pulse width modulation (PWM), and proposes a cascaded current and PWM technique for fault-tolerant SRM drive operation. The HCC method is most effective for low-speed operations with higher external loads, while the PWM method is suitable for medium to high-speed operations but it can't control current effectively at high external loads. The proposed control technique approach is developed to address the limitations of HCC and PWM methods, by combining current and PWM methods with optimized commutation angle control. This approach effectively controls current and variable speed operations even under fault conditions. This paper evaluates control strategies by varying commutation angles to determine the optimized angles that ensure balanced performance and better operation under fault conditions. This paper assesses the mechanical performance under light and high external loading conditions at optimized commutation angles during open circuit fault conditions. Simulation studies are conducted using a 4 kW, 4-phase, 8/6 SRM configuration on the MATLAB/Simulink platform. Additionally, real-time FPGA-based modelling experiments are performed using a Controller Hardware-in-Loop (CHIL) setup on the OPAL-RT 4510 platform. The performance analysis highlights the importance of identifying the best control techniques to ensure high fault tolerance and reliable mechanical performance, making this approach promising for variable-speed drive systems. The findings of this study significantly advance fault-tolerant SRM control techniques, enhancing their suitability for various industrial applications. © 2013 IEEE.