Browsing by Author "Venkatesa Perumal, B.V."

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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.
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 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.
Speed loop pseudo derivative feedback controller based direct torque controlled permanent magnet synchronous motor drive
(Institute of Electrical and Electronics Engineers Inc., 2017) Koothu Kesavan, K.K.; Venkatesa Perumal, B.V.; Karthikeyan, A.; Nagamani, C.
This paper presents a comprehensive evaluation of PI controller and proposed pseudo derivative feedback (PDF) controller based direct torque controlled (DTC) permanent magnet synchronous motor (PMSM) drive. The proposed controller eliminates oscillation and overshoot in the actual rotor speed and significantly reduces the flux, torque and stator current ripples. The performance of the proposed controller is tested for different cases viz., no load starting response, load variations at rated speed, wide speed reversal and low speed regions including standstill condition at rated torque. The simulations are carried out through MATLAB/Simulink environment for 1.2hp PMSM drive and results demonstrates the efficacy of the proposed controller. Â© 2016 IEEE.
Standalone Single Stage PV-Fed Reduced Switch Inverter Based PMSM for Water Pumping Application
(Institute of Electrical and Electronics Engineers Inc., 2020) Koothu Kesavan, K.K.; Karthikeyan, A.; Varsha, S.; Venkatesa Perumal, B.V.; Mishra, S.
This article proposes a standalone single stage photovoltaic (PV) fed reduced switch inverter (RSI) based permanent magnet synchronous motor (PMSM) drive for water pumping application. The proposed system aims at reducing the switching losses and overall cost by using reduced switch inverter. The proposed system comprises a PMSM drive, fed by PV source through an inverter employing reduced number of switches. The inverter uses only four switches whereas the conventional voltage source inverter utilizes six switches. Field oriented control scheme is employed to control the PMSM drive. Perturb and observe maximum power point tracking technique is used to generate a speed reference to PMSM drive. The proposed system is simulated using MATLAB/Simulink platform, and it is also experimentally verified with field programmable gate array (FPGA) controller based 400 W laboratory prototype PMSM drive. The simulation and experimental results demonstrate the efficacy of the proposed system. © 1972-2012 IEEE.