Conference Papers
Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/28506
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Item 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. © 2016 IEEE.Item Pseudo derivative feedback current controlled sensorless PMSM drive with flux-Torque based MRAS estimator for low speed operationestimator for low speed operation(Institute of Electrical and Electronics Engineers Inc., 2017) Karthikeyan, A.; Koothu Kesavan, K.K.; Venkatesa, P.B.; Nagamani, C.In this paper, a simple and robust speed estimator and Pseudo Derivative Feedback (PDF-PDF) controller are proposed for sensorless PMSM drive to improve its performance at standstill and low speed regions. The speed estimator is formed using stator flux and electromagnetic torque based model reference adaptive system, which performs better during transient conditions and reduces steady state error for wide rotor speed variations which includes low speed regions. The proposed PDF-PDF controller reduces the overshoot and improves settling time of the system. The stability of the proposed estimator is verified through small signal model and the machine parameter sensitivity is also analyzed. The performance of the proposed estimator and controller is validated by considering variation in the low speed regions which includes standstill condition. The simulations are carried out through MATLAB/Simulink and it is also experimentally verified through FPGA controller based 1.2hp laboratory prototype PMSM drive. It is found that the maximum estimated rotor speed and position error are ±2 rad/s and ±1° respectively during low speed operation at transient and steady state conditions. ©2017 IEEE.Item 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. © 2016 IEEE.Item Four quardrant operation of direct torque controlled PMSM drive using speed loop PDFF controller(Institute of Electrical and Electronics Engineers Inc., 2018) Karthikeyan, A.; Koothu Kesavan, K.K.; Nagamani, C.This paper presents a comprehensive evaluation of proposed speed loop pseudo derivative feedforward (PDFF) controller based DTC, speed loop PI based direct torque controller (DTC) and speed loop PI based hysteresis current controller (HCC) for permanent magnet synchronous motor (PMSM) drive. The proposed controller reduces the torque and stator current ripples and significantly reduces overshoot and oscillation in the actual rotor speed. The proposed controller is verified for different cases viz., forward and reverse motoring, forward and reverse braking operation. The simulations are carried out through MATLAB/Simulink for 1.2 hp PMSM drive and results demonstrates the efficacy of the proposed controller. © 2018 IEEE.Item Standalone single stage PV fed reduced switch inverter based independent control of two PMSM drive(Institute of Electrical and Electronics Engineers Inc., 2018) Karthikeyan, A.; Koothu Kesavan, K.K.; Abhilash Krishna, D.G.; Nagamani, C.This paper proposes a standalone singe stage PV fed air cooler which consists of two motors (fan blower and water pump). The proposed system comprises of PV source, reduced switch inverter and two PMSM drive. The proposed system aims at reducing the switching losses and overall cost by using reduced switch inverter. The reduced switch inverter uses only eight switches whereas the conventional VSI utilizes twelve switches. In the proposed scheme, blower and pump are independently controlled using field oriented control scheme where speed reference is obtained using Perturb and Observe (PO) technique. Simulation studies for the proposed PV fed two 400 W PMSM driven blower and pump is performed using MATLAB platform and respective results are presented to show the efficacy of the system. © 2018 IEEE.Item Virtual Impedance based DFCL for DVR during Downstream Faults(Institute of Electrical and Electronics Engineers Inc., 2018) Karthikeyan, A.; Abhilash Krishna, D.G.; Nagamani, C.This paper proposes a Downstream Fault Current Limiter (DFCL) for DVR during downstream faults. It Is based on the concept of Virtual Impedance (VI) which introduces the impedance in series to the system to suppress the large fault currents in the line. In the present work no additional equipment is involved for limiting the fault current and DVR itself is controlled such that FCL operation is ensured. The proposed VI based FCL features flexible implementation and can effectively suppress the fault current during the downstream faults and thereby the DVR is protected along with restoration of PCC voltages. Simulation studies are performed for 10 kV system using PSCAD/EMTDC platform and respective results are presented which proves the feasibility and efficacy of the proposed FCL. © 2018 IEEE.Item Stator flux based MRAS speed and stator resistance estimator for sensorless PMSM drive(Institute of Electrical and Electronics Engineers Inc., 2018) Karthikeyan, A.; Koothu Kesavan, K.K.; Nagamani, C.In this paper, a simple and robust speed and stator resistance estimator is proposed for sensorless permanent magnet synchronous motor drive to improve its performance at standstill and low speed regions. The speed and stator resistance estimator is formed using stator flux based model reference adaptive system, which yields fast transient response, reduces steady state error for low rotor speed variation and load disturbances. The proposed method improves the performance of the drive at low speed regions. The simulations are carried out through MATLAB/Simulink environment and results show the effectiveness of the sensorless PMSM drive. The maximum estimated rotor speed and position error are found to be are ±3 rad/s, ±1 °respectively, during low speed operation at transient and steady state conditions. © 2017 IEEE.Item Design and Analysis of Multi-Loop Feed Forward Control Schemes for DVR under Distorted Grid Conditions(Institute of Electrical and Electronics Engineers Inc., 2018) Karthikeyan, A.; Abhilash Krishna, D.G.A.; Kumar, S.; Nagamani, C.Voltage sags are considered as important power quality problems and the Dynamic Voltage Restorer(DVR) is an effective solution to mitigate the sags and other power quality problems related to voltage. The DVR involves two major aspects: (i) reference generation and (ii) control algorithm. Under unbalanced grid conditions the presence of negative sequence components in the grid voltage causes sustained oscillations in the estimated dq- voltages, which makes sag detection difficult with conventional SRF-PLL and there by chances of controller malfunctioning. In this paper, a Delayed Signal Cancellation (DSC) pre-filter based Positive and Negative Sequence Extractor (PNSE) is employed to extract the Instantaneous Symmetrical Components (ISC) of the grid voltage and filter out the harmonic voltages from the estimated dq-voltages. As the response of the DVR mainly depends on the controller action this paper presents an multiloop PI feed forward controller for enhancing the operation of DVR under distorted grid conditions. The efficacy of the proposed controller is illustrated by comparative study with multiloop feed forward P controller using time response and relative stability analysis. Simulation studies are performed in PSCAD/EMTDC for a 10kV medium voltage DVR under various voltage disturbances such as symmetric and asymmetric voltage sags. © 2017 IEEE.