It is with great pleasure that we announce the publication of a research paper titled “Self-Learning Controller Design for DC-DC Power Converters with Enhanced Dynamic Performance,” jointly authored by Dr Tousif Khan N, Associate Professor, Department of Electrical and Electronics Engineering, and Dr Ramanjaneya Reddy & Dr Arghya Chakravarty, Assistant Professors, Department of Electrical and Electronics Engineering. The research paper introduces a novel self-learning control for precise output voltage tracking in DC-DC buck power converters.

Abstract:

This article introduces a self-learning robust control approach for accurate output voltage tracking in DC-DC buck power converters, focusing on scenarios with high precision requirements and significant load uncertainties. The method employs a simple online neural network to swiftly estimate unexpected load changes and disturbances across a wide range. Operating within a backstepping framework, the controller utilises neural network-learned uncertainties to enhance stability and improve dynamic and steady-state performance of both output voltage and inductor current. Extensive numerical simulations and practical experiments on a laboratory prototype demonstrate substantial enhancements in dynamic performance with a 94% reduction in settling time and precise steady-state tracking. The reliability of the proposed controller is further supported by the consistency between computational and experimental outcomes, showcasing its potential for real-world applications.

Practical implementations:

The proposed controller can be implemented/used for robotics applications, industrial processes, and medical equipment where precise control is needed.

Future research plans:

The following are the potential future directions of the proposed work;

(i) Design and development of the proposed self-learning neural network-based control for DC-DC buck converter systems with real-time DC sources, such as solar PV and fuel cells, experiencing highly intermittent input voltage changes.

(ii) Incorporating inductor current constraints and output voltage limitations into the proposed controller would also be an avenue worth exploring.

We congratulate the professors for their valuable contribution and look forward to future breakthroughs in this area.

In a significant academic accomplishment, Dr Ramanjaneya Reddy, Assistant Professor in the Department of Electrical and Electronics Engineering, along with UG students Ms Mehataj Syed and Mr Busam Gopichand, have recently published a groundbreaking paper titled “A Three Leg Asymmetrical Voltage Resonant Converter with Independent Dimming Control for Multiple Load LED Lighting Applications” in the esteemed Q1 journal IEEE Transactions on Industry Applications. The journal boasts an impressive impact factor of 4.4, further underscoring the importance of this research contribution.

The paper delves into the development of a novel Three Leg Asymmetrical Voltage Resonant Converter that offers independent dimming control for multiple load LED lighting applications. This innovation holds great promise for enhancing the efficiency and versatility of LED lighting systems, paving the way for more sustainable and adaptable lighting solutions in various industrial applications.

Dr Ramanjaneya Reddy’s leadership and the collaborative efforts of Ms Mehataj Syed and Mr Busam Gopichand have culminated in this significant publication, which not only adds to the body of knowledge in the field but also showcases the talent and dedication of the researchers at the department.

This achievement highlights the commitment to excellence and innovation within the Department of Electrical and Electronics Engineering, positioning it as a hub for cutting-edge research and academic prowess. The impact of this research is expected to reverberate across the industry, contributing to advancements in LED lighting technology and its applications.

The publication of this paper underscores the quality and rigour of the research solidifying their reputation as leaders in the field. This accomplishment is a testament to the department’s commitment to pushing boundaries and making meaningful contributions to the field of electrical engineering.

Congratulations to Dr Ramanjaneya Reddy, Ms Mehataj Syed, and Mr Busam Gopichand on this remarkable achievement, and we look forward to seeing the continued impact of their research in the field.

Abstract

This work proposes a three-leg asymmetrical voltage resonant converter for multiple load Light Emitting Diode (LED) lighting applications. The proposed converter is developed with a common leg-1 for both load-1 and load-2. The load-1 is powered from asymmetrical voltage between leg-1 and leg-2. Similarly, load-2 is powered from asymmetrical voltage between leg-1 and leg-3. The proposed circuit provides the following major contributions: (1) Independent dimming control of LED loads; (2) Zero Voltage Switching (ZVS) of all power switches; (3) High efficiency; and (4) Asymmetrical voltage regulation. To achieve independent dimming control, the voltages between legs are made zero by dimming leg-2 and leg-3 independently. Two resonant circuits are connected in the proposed circuit. Owing to this all the power switches operate with ZVS, which reduces the switching losses. Further, two LED lamps are connected in series with battery sources to supply the threshold voltage to lamps which in turn results in a lower power processing of the converter.

Explanation of Research in Layperson’s Terms

This work proposes a three-leg asymmetrical voltage resonant converter with independent dimming control for multiple load LED lighting applications. The proposed converter drives multiple loads independently with a dimming feature. The converter is developed with leg-1 is common for both LED loads. The major contributions of the proposed LED driver are independent dimming control, asymmetrical voltage regulation, zero voltage switching of all the power switches, and high efficiency. The threshold voltage of LED loads is supplied by batteries connected in series with LED loads, which will help in lower power processing of the proposed converter. Further, due to soft switching technology implemented in this converter, it reduces the losses in the system considerably increasing efficiency.

Title of Research Paper in the Citation Format

A Three Leg Asymmetrical Voltage Resonant Converter with Independent Dimming Control for Multiple Load LED Lighting Applications.

Citation: Ramanjaneya Reddy Udumula, et. al, “A Three Leg Asymmetrical Voltage Resonant Converter with Independent Dimming Control for Multiple Load LED Lighting Applications,” IEEE Transactions on Industry Applications, Feb 2024. doi: 10.1109/TIA.2024.3363676

Practical and Social Implementation of Research

To achieve effective and efficient use of energy resources under the sustainable development goals, Light Emitting Diodes (LEDs) have emerged as a global lighting industry solution. Over the conventional lighting sources such as incandescent lamps, fluorescent lamps, and high intensity discharge lamps, LEDs are i) more efficient, ii) eco-friendly due to absence of toxic gases, iii) have longer life span up to one lakh year, iv) high luminous intensity and v) good colour rendering index. LED’s requires low voltage direct current supply and the V-I characteristics of LEDs which is like Shockley diode represents the exponential growth of current over a small voltage variation which may damage the LED or effects the illumination. Hence, an LED driver is necessary in an LED system to supply LEDs with constant current. DC fed LED drivers are more reliable due to absence of AC-DC conversion stage and power factor correction stage which are crucial in AC fed LED drivers. Therefore, DC fed LED drivers are paid more attention in recent times in the majority of battery-powered/solar-powered applications. Given its features of high power, exceptional efficiency, cost-effectiveness, and flicker-free operation, this innovation is well-suited for streetlight/stadium lighting applications.

Collaborations

Dr. Kasi Ramakrishna Reddy, Assistant Professor
Department of Electrical and Electronics Engineering, Vasavi College of Engineering, Hyderabad

Future Research Plans

The future work is on PV/battery fed LED driver topologies suitable for streetlighting/stadium lighting applications with low component count, high efficiency, reduced device stress, and flicker free lighting system

Electric Vehicles are in vogue today, thanks to the heightened environmental concerns, greater availability of models, increased cost competitiveness and improved vehicle ranges. To contribute to the growing field of electric vehicle technology, Assistant Professors, Dr Tarkeshwar Mahto, Dr Somesh Vinayak Tewari and Dr Ramanjaneya Reddy from the Department of Electrical and Electronics Engineering at SRM University-AP along with the research scholar, Ms K Mounika Nagabushanam, conducted a study and published a research paper titled “Development of High-Gain Switched-Capacitor Based Bi-Directional Converter for Electric Vehicle Applications.” The team’s research focuses on creating a bi-directional DC-DC converter that enables power flow from the battery to the motor and vice versa while maintaining necessary voltage gains and ensuring improved efficiency and low cost.

Abstract

High efficiency, high voltage transfer ratio (VTR), and low input ripple current are required in any bidirectional DC-DC converter (BDC) that plays a major role in interfacing batteries in applications like DC microgrids and electric vehicles (EVs). To meet these requirements, a switched capacitor-based BDC is proposed to interface the battery with a propulsion system via a DC Link. It has a simple circuit with only a set of switching operations, High VTR, and lesser ripple current on the low voltage (LV) side, which are advantages of the proposed High Gain Switched-Capacitor Bi-directional DC-DC Converter (SC-BDC), making it appropriate for use in EVs. The steady-state analysis, design consideration of passive components, loss and efficiency analysis are presented. Finally, the proposed High Gain SC-BDC is compared with a few of the existing BDCs in the literature. The feasibility of the converter was demonstrated by simulating a 200 W converter and validating results produced in a MATLAB environment.

Practical implementation of your research or the social implications associated with it.

The developed converter can be used in Electric Vehicle for integration of battery to traction motor.

Collaborations.

1. Majed A. Alotaibi, Department of Electrical Engineering, College of Engineering, King Saud University, 11421, Saudi Arabia.

2. Hasmat Malik, Department of Electrical Power Engineering, Faculty of Electrical Engineering, University Technology Malaysia (UTM), Johor Bahru 81310, Malaysia.

3. Fausto Pedro García Márquez, Ingenium Research Group, Universidad Castilla-La Mancha, 13071 Ciudad Real, Spain.

As part of their future research plans the team plans of working on noise reduction methods that are brought on by regeneration action and to incorporate various control techniques to keep the DC link voltage of the propulsion system constant.

We wish the team all success in their future endevours!

Link to the article

Remarkable research of Dr. Tousif Khan N is honoured with APJ Abdul Kalam Memorial International Travel Award

SRM University AP, Andhra Pradesh faculty, Dr. Tousif Khan N, Assistant Professor and Head of the Department, Department of Electrical and Electronics Engineering, is to present a paper “Laguerre Neural Network Driven Adaptive Control of DC-DC Step Down Converter” in the renowned International Federation for Automatic Control (IFAC) World Congress to be held in Germany during July 12-17, 2020. Further this research article is also selected for the prestigious APJ Abdul Kalam Memorial International Travel Award by the Automatic Control and Dynamic Optimization Society (ACDOS) chaired by Professor Ravi Gudi of Indian Institute of Technology Bombay.

The research work of Dr. Tousif proposes a novel Laguerre neural network estimation technique for the approximation of unknown and uncertain load function, followed by its subsequent compensation in the adaptive backstepping controller. A detailed design of the proposed estimator and adaptive backstepping controller along with closed loop asymptotic stability have been presented. Further, the proposed control mechanism is evaluated through extensive numerical simulations while subjecting the converter to input voltage, reference voltage, and load resistance perturbations. Furthermore, the results are verified by testing the proposed controller on a laboratory prototype with DSP based TM320F240 controller board. The analysis of results reveals that the proposed control methodology for DC-DC step down converter offers a faster transient output voltage tracking with smooth and satisfactory inductor current response over a wide operating range. Dr. Tousif informs, “Under the class of DC-DC converters, the dynamics of DC-DC step down converter are nonlinear in nature and are largely influenced by both parametric and unanticipated external perturbations. In its closed loop operation, obtaining a precise output voltage tracking besides satisfactorily inductor current response is a challenging control objective. Hence, in this regard, this article proposes a solution.”

Electric power supply is the principal entity behind any electrical circuits and systems. Irrespective of their function in the digital domain, these circuits necessarily require a reliable and efficient energy source for their operations. Among the two existing forms of electrical energy, namely, the direct current (DC) and the alternating current (AC), the DC power finds wide use in numerous applications in the field of telecommunication, instrumentation, medical electronics, aerospace, defence and power transmission.

Ever since the fundamental innovations in DC systems by Thomas Alva Edison in 1880, DC rectification, and modulation method have remained central to various utilities. During the initial years, DC power conversion primarily resorted to the use of vacuum tube technology in delivering a desirable level of voltage from an AC source. The rectification stage was subsequently followed by filtering of the voltage at the output end. Nonetheless, the vacuum tube technology supported very low current density and featured a high ripple content in the DC voltage. Additionally, the output voltage was inconsistent or rather unregulated, making it inappropriate for DC power operated electrical and electronic systems. Much later in 1967, integrated series regulators were developed which eventually became popular as linear power supplies (LPS). Such a classical DC power generation method involved an AC transformer, AC-DC rectifier, and a voltage regulator in its assembly. The transistors in LPS operate under active region and dissipate large amounts of heat due to the voltage drop while high current flows through the collector-emitter junction, thereby causing substantial power loss and a very low energy efficiency. Even though they characterize the low level of noise and find better suitability in audio applications, yet their critical limitations of huge size, heavy weight and high cost make them infeasible for use in portable electronic devices.

In tandem to these aforementioned developments, the advancements in power semiconductor technology led to the invention of low cost reliable power switches exhibiting fast switching response. This proved to be instrumental in building an energy efficient switched mode power supply which gradually gained popularity. “Its impact on electrical technology was phenomenal, replacing conventional linear voltage supplies with switched mode power supplies giving rise to enhanced efficiency, light weight, compactness, and comparably lower cost. Such a modern DC conversion system primarily includes DC-DC converters, wherein the rectified input voltage is fed to the DC-DC converter circuits for obtaining specific voltage levels. The primary objective in DC-DC converters is to transfer the energy among different DC circuits functioning at a specific voltage and current levels. This process of energy transfer is performed by temporarily storing the energy from the input source in an operating mode, followed by releasing it in the other operational mode of the converter. Thus, one level of DC input voltage is converted to another level of average DC output voltage at the load end. Meanwhile, the converter being ideal is expected to consume no energy. Any consumption of energy in the converter interface amounts to direct power loss in the overall supply system. Typically, converters render high input-output conversion.”, enlightens Dr. Tousif Khan N. His notable research work offers to mitigate these issues, leading to the venerated APJ Abdul Kalam Memorial International Travel Award. Advancing his work in the future, Dr. Tousif will be closely working on the society’s activities with ACDOS as a member for mutual benefit.

Dr Tarkeshwar Mahto, Assistant Professor, in the Department of Electrical and Electronics Engineering has published a paper titled “Design and Implementation of Frequency Controller for Wind Energy-Based Hybrid Power System Using Quasi-Oppositional Harmonic Search Algorithm” in the reputed research journal, Energies.

An innovative union of fuzzy controller and proportional-integral-derivative (PID) controller under the environment of fractional order (FO) calculus is described in the present study for an isolated hybrid power system (IHPS) in the context of load frequency control. The proposed controller is designated as FO-fuzzy PID (FO-F-PID) controller. The undertaken model of IHPS presented here involves different independent power-producing units, a wind energy-based generator, a diesel engine-based generator and a device for energy storage (such as a superconducting magnetic energy storage system). The selection of the system and controller gains was achieved through a unique quasi-oppositional harmony search (QOHS) algorithm. The QOHS algorithm is based on the basic harmony search (HS) algorithm, in which the combined concept of quasi-opposition initialization and HS algorithm fastens the profile of convergence for the algorithm. The competency and potency of the intended FO-F-PID controller were verified by comparing its performance with three different controllers (integer-order (IO)-fuzzy-PID (IO-F-PID) controller, FO-PID and IO-PID controller) in terms of deviation in frequency and power under distinct perturbations in load demand conditions. The obtained simulation results validate the cutting-edge functioning of the projected FO-F-PID controller over the IO-F-PID, FO-PID and IO-PID controllers under non-linear and linear functioning conditions. In addition, the intended FO-F-PID controller, considered a hybrid model, proved to be more robust against the mismatches in loading and the non-linearity in the form of rate constraint under the deviation in frequency and power front.

The research group believes that the study will boost the use of renewable energy utilization for fulfilling energy requirements in a more reliable and stable manner. In future, they plan to use the knowledge gained from the isolated systems to develop a Multi-Migrigrid system.

Collaborations:

1. Department of Electrical and Electronics Engineering, M S Ramaiah Institute of Technology, Bengaluru 560054, India
2. The Berkeley Education Alliance for Research in Singapore, The National University of Singapore, Singapore 138602, Singapore
3. Clean and Resilient Energy Systems (CARES) Lab, Texas A&M University, Galveston, TX 77553, USA;
4. Department of Electrical Engineering, College of Engineering, Taif University, Taif 21944, Saudi Arabia