Department of Electrical Engineering

Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

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IIT Palakkad

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Maximum likelihood estimation of LPV-SS models: a sequential Monte-Carlo approach

In this paper, active power decoupling using six switch rectifier with a built-in ripple port (inductive or capacitive or combination of both) to reduce the size of the E-cap is studied. The six switch rectifier is analyzed as a three-port converter: (i) AC source at the input port, (ii) a load at the DC output port, and (iii) an inductor or capacitor connected to the third port called ripple port. With appropriate modulation technique, second harmonic ripple power is circulated between the input port and the ripple port without disturbing the active power flow between the input port and the output port. A suitable closed-loop controller is designed to regulate the DC bus voltage and minimize the second harmonic ripple simultaneously. The step response results presented in the paper confirm the stability of the closed loop design. The relation between modulation indices of ripple port and active port is derived to maximize the utilization of DC bus in these converters. Simulation results are presented to validate the analysis and effectiveness of the circuit. The analysis made for the ripple port can be extended to micro-inverters as well. © 2016 IEEE.

2016 IEEE 2nd Annual Southern Power Electronics Conference, SPEC 2016

Analysis of active power decoupling in single-phase rectifier using six-switch topology

For cascaded multilevel inverter topologies with a single dc supply, closed-loop capacitor voltage control is necessary for proper operation. This paper presents zero and reduced common-mode voltage (CMV) operation of a hybrid cascaded multilevel inverter with predictive capacitor voltage control. Each phase of the inverter is realized by cascading two-three-level flying capacitor inverters with a half-bridge module in between. For the presented inverter topology, there are redundant switching states for each inverter voltage levels. By using these switching state redundancies, for every sampling instant, a cost function is evaluated based on the predicted capacitor voltages for each phase. The switching state that minimizes cost function is treated as the best and is switched for that sampling instant. The inverter operates with zero CMV for a modulation index upto 86%. For modulation indices from 86% to 96%, the inverter can operate with reduced CMV magnitude (Vdc/18) and reduced CMV switching frequency using the new space-vector pulsewidth modulation (SVPWM) presented herein. As a result, the linear modulation range is increased to 96% as compared to 86% for zero CMV operation. Simulation and experimental results are presented for the inverter topology for various steady state and transient operating conditions by running an induction motor drive with open loop V/f control scheme.

Fulltext

IEEE Transactions on Industrial Electronics

A Predictive Capacitor Voltage Control of a Hybrid Cascaded Multilevel Inverter with a Single DC-Link and Reduced Common-Mode Voltage Operation

This paper proposes a new 9-level stacked inverter for a symmetric six phase induction motor with low voltage devices using a single DC link. The six phase inverter is developed using 2 three phase 9-level stacked inverters. Each of these three phase stacked inverter is developed by stacking two 5-level inverters. The three phase 9-level inverter needs two DC sources for its operation. All the capacitors in this topology can be balanced using the switching state redundancies within a sampling interval irrespective of load power factor and modulation index. Using proper switching state redundancies, the developed six phase inverter can be operated with a single DC link. A laboratory prototype is developed and a six phase IM is run using V/f control scheme. Both steady state and transient results are presented. © 2016 IEEE.

IEEE International Symposium on Industrial Electronics

A new nine level stacked inverter topology for a symmetric six phase induction motor with low voltage devices and using a single DC link

This paper presents a novel Asymmetrical-Pulse-Width-Modulated (APWM) half-bridge resonant converter with one additional active switching device at the secondary side of the transformer. The proposed converter features load-independent Zero-Voltage-Switching (ZVS) of both of the primary side switches with minimal magnetizing current. Empirical formulae are derived to design the resonant network and the high-frequency transformer systematically. The circulating current is minimized not only by operating the converter exactly at the resonant frequency, but also by reducing the magnetizing current. Moreover, the additional secondary-side switching device (which is a low-voltage and high-current rated MOSFET) achieves zero current turn-off at all load conditions. Thus the efficiency of the overall converter is significantly improved for wide load range. Simulation and experimental results are presented to validate the analysis and to prove the significance of the additional switching device at the secondary side of the transformer. © 2016 IEEE.

Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC

Design of a novel APWM half-bridge DC-DC resonant converter with load-independent soft-switching and reduced circulating current

In this paper, we present noise-robust photoplethysmographic (PPG) based biometric authentication method for wireless body area networks and m-health applications. The method consists of four steps: (i) preprocessing of PPG signals, (ii) systolic peak detection, (iii) ensemble averaged pulsatile waveform extraction and (iv) pulsatile waveform similarity matching using a normalized cross correlation (NCC) measure. The performance of the proposed method is tested and validated using different types of PPG signals taken from the standard PPG databases. For predefined threshold of 0.997, the NCC-based PPG biometric method achieves an average false rejection rate (FRR) of 0.32 and false acceptance rate (FAR) of 0.32. Performance evaluation results show that the proposed method achieves consistent authentication results as compared to the other methods under different kinds of artifacts and noise. © 2016 IEEE.

2016 22nd National Conference on Communication, NCC 2016

Robust photoplethysmographic (PPG) based biometric authentication for wireless body area networks and m-health applications

Early detection of life-threatening arrhythmias such as ventricular fibrillation (VF) and rapid ventricular tachycardia (VT) is most essential for an automatic external defibrillator and remote cardiac patient monitoring. In this paper, we present a low-complexity, robust detection method for automatically detecting VT and VF events in the ECG signal. The proposed detection method consists of four stages: (i) discrete Fourier transform (DFT) based noise removal, (ii) addition of random noise; (iii) zero-crossing rate (ZCR) estimator and (iv) detection rule. The proposed method is tested and validated using the MIT-BIH arrhythmia database (MITADB), Creighton university ventricular tachycardia database (CUDB) and the MIT-BIH malignant ventricular arrhythmia Database (MITMVFDB). The method achieves an overall sensitivity (Se) of 99.34%, and specificity (Sp) of 99.97% for 5 s signal. The robustness of the method is tested using different types of PQRST morphological patterns and various kinds of noises including the baseline wanders, powerline interference, muscle artifacts and white Gaussian noise. The results demonstrate the proposed method with additive random noise with single ZCR feature can achieve significantly better detection rates as compared with the existing detection methods based on the combination of morphological, spectral, time-frequency, and complexity features and the machine learning techniques such as neural networks, support vector machines (SVM), fuzzy neural networks (FNN). © 2016 IEEE.

2016 International Conference on Wireless Communications, Signal Processing …

Detection of life-threatening arrhythmias using random noise and zerocrossing information

Volts-per-hertz (V/f) controlled induction motor drives could exhibit small-signal instability in the low and medium speed ranges, and particularly under light-load conditions. This results in sustained sub-harmonic oscillations in motor current, torque and speed. This instability is accentuated on account of inverter dead-time. This paper examines improving the stability by connecting an external inductor in series with the stator winding. Further, to avoid an actual external three-phase inductor which could be expensive in the case of high-power drives, a simple control scheme which emulates this series inductor is proposed. The emulation scheme also has the advantage that the value of series inductor could be programmable. This inductive emulation scheme, along with V/f control, is implemented on a TMS320F2812 DSP processor platform to control a 100-kW induction motor drive. Simulation and experimental results show that the proposed control scheme is effective in mitigating the oscillations in the 100-kW induction motor drive. © 2015 IEEE.

2015 IEEE International Transportation Electrification Conference, ITEC-India 2015

Inductance-emulation-based active damping of dead-time-induced oscillations in a 100-kW induction motor drive

The objective of this paper is to study the influence of inverter dead-time on steady as well as dynamic operation of an open-loop induction motor drive fed from a voltage source inverter (VSI). Towards this goal, this paper presents a systematic derivation of a dynamic model for an inverter-fed induction motor, incorporating the effect of inverter dead-time, in the synchronously revolving dq reference frame. Simulation results based on this dynamic model bring out the impact of inverter dead-time on both the transient response and steady-state operation of the motor drive. For the purpose of steady-state analysis, the dynamic model of the motor drive is used to derive a steady-state model, which is found to be non-linear. The steady-state model shows that the impact of dead-time can be seen as an additional resistance in the stator circuit, whose value depends on the stator current. Towards precise evaluation of this dead-time equivalent resistance, an analytical expression is proposed for the same in terms of inverter dead-time, switching frequency, modulation index and load impedance. The notion of dead-time equivalent resistance is shown to simplify the solution of the non-linear steady-state model. The analytically evaluated steady-state solutions are validated through numerical simulations and experiments. © 2016, Indian Academy of Sciences.

Sadhana - Academy Proceedings in Engineering Sciences

Modelling and analysis of an open-loop induction motor drive incorporating the effect of inverter dead-time

In this paper, a new and high accuracy, dual-purpose Direct-Digital Converter (DDC) is presented. The proposed Switched-Capacitor (SC) DDC can be used to interface sensors whose electrical equivalent is (a) a capacitor Cx or (b) a resistor Rx or (c) Cx and Rx in parallel. Irrespective of (a)-(c), the DDC gives digital outputs proportional to Cx and Rx of the sensor. Capacitance-to-Digital Converters (CDC) and Resistance-to-Digital Converters (RDC) have been reported earlier, but no accurate dual-purpose DDC has been reported. In comparison with most of the CDCs/RDCs, the DDC presented uses no noticeable additional hardware. In the DDC, the conversion is obtained based on a SC dual-slope technique, which guarantees high immunity to interference. The DDC uses a dc reference voltage for excitation and helps to achieve high accuracy. A prototype of the proposed DDC has been developed. The prototype was tested for Rx from 50 kΩ to 1 MΩ and Cx from 50 pF to 250 pF. The results obtained from the DDC confirmed its usefulness. © 2016 IEEE.