Research Projects


Investigation of DC-DC Converter Topologies Impact on Magnetic Components Miniaturization for Multi-mega Hz Applications

Participants: Youssef Kandeel (PhD Student), Dr Maeve Duffy (Supervisor)

Project collaborators: Tyndall National Institute, Ireland

Funding source: SFI, ADEPT Project

Project Abstract: 

Power electronic circuits are a key player in many essential electrical systems and applications; e.g. power converters. For computational and battery-powered consumer products, the desire for higher power densities and longer battery life increases the requirement for smaller and more power-efficient devices. Therefore, these requirements drive the research towards exploring different areas to improve the power converters like circuit topologies, integration, and technologies of the semiconductor devices and passive components. One of the main challenges in the power converter is the significant contribution of the passive components particularly inductors to the overall solution losses and size. Understanding the different topologies requirement of the passive components for a specific load requirement can lead to better utilization of the passive components, hence, to optimize the passive components particularly inductors from the circuit perspective which can optimize the manufacturing materials consumption.

This project aims to contribute to the optimization of DC-DC power converters. It presents a detailed analysis of passive components in multiphase buck and multiphase 3-Level converter topologies, and single-phase buck with 4th order resonance output filter. This study emphasises particularly the passive components’ performance in terms of size and efficiency. Besides, consideration of coupled inductors utilization in these circuits and coupling factor selection. Air-core PCB integrated inductors are considered in this study for easy implementation and testing; however, this study is suitable for inductors with the magnetic core as well.

Project Duration: February 2017 to present

Power Electronics for DC Distribution of Renewable Energy in Buildings.

 Participants: Meshari Alshammari (PhD Student) and Maeve Duffy (Supervisor)

 Funding Source: Saudi Cultural Bureau (SCB)

 Project Abstract:  

Recent developments in micro-grids have led to increased interest in DC distribution systems due to its high efficiency in distributing energy from renewable energy sources to DC loads. The project is aiming at improving the efficiency of renewable energy systems based on a DC distribution system. System level analysis of an existing installation on a school building on Inis Oirr, an island off the west coast of Ireland has shown that there is potential to improve the system performance through the development of DC/AC inverter needed to connect to the grid to ensure that there is a continuous supply of energy when renewable sources are unavailable. In particular, there is potential to improve the efficiency of the bidirectional inverter at light-loads, because the performance of most converters is optimised for the mid-high-power range, while typical load profiles show lower levels for much of the operating times.

 Project Duration: 2018 – Present

Enhancing the situational awareness and security of the active distribution networks of power system while maintaining its economic operation

Participants: Maman Ahmad Khan (PhD Student), Dr Barry Hayes (Supervisor), Dr Maeve Duffy (Co-Supervisor)

Project collaborators: University College Cork (UCC)

Funding Source: College of Engineering and Informatics postgraduate scholarship (COEI)

Project Abstract:

The main aim of this project is to study the situational awareness at the power distribution network. The distribution network is divided into Low Voltage (LV) network and Medium Voltage (MV) network. In most research cases to date, a deep investigation of the low voltage network has been left disregarded, even if it represents the asset bridging the medium voltage level down to final customers. This low voltage network segment is probably the most affected by regulatory actions promoting intermittent renewable generations, distributed storage, heat pumps and the growing diffusion of electric vehicles utilization. Due to lack of accurate measurement device at low voltage distribution network, in smart grids studies and implementations, one of the least explored field is represented by the Low Voltage (LV) network, the infrastructure spanning from Secondary Substations (SSs) down to final customers. Therefore, by developing a precise low--cost monitoring device for low voltage network, the distribution network can become more visible for monitoring and control purpose.

Project Duration: October 2017- Present

DC-DC Power Conversion using Piezoelectric Transformers

 Participants: Ajay Chole (PhD Student), Dr. Maeve Duffy (Supervisor)

 Funding Source: Hardiman Scholarship, NUI Galway

 Project Abstract: 

In this research project, the performance of Piezoelectric Transformers (PTs) in DC-DC converter applications will be investigated. The PETs are a special type of transformers which do not make use of electromagnetic energy transfer mechanisms. The principle is to use vibration as a coupling medium to transfer input electrical energy to mechanical energy and then again back to electrical energy at the output with different voltage amplitude. Lead zirconate titanate (PZT) or modified PZT-type ceramic materials are being used for PET applications with their unique properties like high quality-factor, response-speed and power-density, compared to other piezoelectric materials.

 The PT has very low Electromagnetic Interference (EMI) profile that makes it suitable for application in a high strength magnetic environment such as in Magnetic Resonance Imaging (MRI) and computed tomography applications where the presence of magnetic fields can affect the normal working of a conventional magnetic transformer. The power density of PT is higher than magnetic transformer and that makes it suitable for space applications where light-weight power converters are essential. A PT based DC-DC Converter will be developed, tested, and analysed.

 A DC-DC converter steps-up or steps-down the input DC voltage level as per the application requirement. The combined operation of PTs will be studied to extend the power transfer limits as currently PTs are available only up to the power rating of 40 watts.

 Project Duration: October 2019 to February 2024

Development of high-power density and ultra-wide output voltage DC power supplies

 Participants: Oisín Anderson (PhD Student), Dr. Maeve Duffy (Supervisor) Dr. Brendan Barry (Supervisor)

 Project Collaborators: Advanced Energy

 Funding Source: Irish Research Council, Advanced Energy

 Project Abstract:

The aim of this project is to develop power electronic solutions that will enable the development of power supply products with a wide output voltage range, where there are ongoing demands for lower operating voltages in the range of 200 – 300 W. Currently, different circuit solutions are required to address different output voltage levels, and this limits the scope for product optimisation in terms of functionality, size, power density and cost. By developing a single solution that can address a wide output voltage range, there is potential to combine the best aspects of designs focussed on high versus low voltage, resulting in an overall improved design that can be scaled for future applications. The proposed approach will combine state-of-art and emerging developments in power converter topologies, semiconductor switches, passive components and control techniques to achieve this.

 Project Duration: Sept 2020 – Sept 2024

High Quality eco-efficient Magnet Wire: Alternative Technology to produce insulated wire for motor applications (HI-ECOWIRE)

 Participants: Dr. Maeve Duffy (PI)

 Project collaborators: GREEN ISOLIGHT INTERNATIONAL, Université d’Artois, Schwering & Hasse Elektrodraht GmbH, Material Nova, JEUMONT Electric SAS, KDE ENERGY FRANCE, ESIX, NEWTECH, NextMove, Hochschule Esslingen, Institute für Nachhaltige Energietechnik und Mobilität

 Funding source: Interreg NWE

Project Abstract: 

Magnet wire (approx. annual production of 120 000 tons in NWE) is used for transformers and electric motors. Materials technologies are facing increasing environmental challenges, productivity and competitiveness requiring a review of their production methods. Therefore, HI-ECOWIRE aims at developing a more sustainable and competitive production process with two main technical objectives: 

  • Improve the energy performance and efficiency of electrical motors by 20% to 30% compared to the current situation by increasing the thermal class;
  • Considerably reduce the consumption of (partly toxic) solvents and VOC emissions.

One main overall target of this research activity is to develop a more environmentally friendly product and process and thus reducing the CO2 footprint.

 The project is based on an international consortium (SMEs, Industries, Research Centres and Universities) aiming at strengthening European competitiveness in the transport sector and energy production (wind turbine). 

Our role is to model the electrical and thermal performance of the new insulated wires to be produced, under conditions to be encountered when integrated within target end products (generators, motors). Issues to be considered include the effects of high frequency voltages and increased temperatures on the new wire windings' performance.  

Project Duration: April 2020 to September 2023

Energy Harvesting for Enhanced RFID Security

 Participants: Dr. Alireza Namadmalan (Postdoctoral Researcher), Dr. Maeve Duffy (Supervisor)

 Project collaborators: HID Global

 Funding Source: Enterprise Ireland, HID Global

 Project Abstract:

 The main aim of this project is to develop an enhanced security feature on an RFID tag that will be wirelessly powered when placed on a standard RFID reader. The main challenge will be to design a wireless power system that provides sufficient power without impacting on the normal RFID functionality.

 This project will focus on the design of an RFID card that includes a wirelessly powered security feature and which will be developed for manufacturing and commercialisation within HID. It will also provide knowledge of the scope for application of wireless power transfer in other applications of interest to the company.

 Project Duration: November 2020 to August 2023

ENdoscopic outpAtient Cancer Treatment platform (ENACT)

 Participants: Dr. Maeve Duffy (PI)

 Project collaborators: Mirai Medical Ltd., Excelsys Technologies Ltd., Trinity College Dublin (TCD)

 Funding Source: Enterprise Ireland under DTIF

 Project Abstract:

The objective of ENACT is to disrupt the standard of care for the entire GI Cancer treatment pathway by offering a rapid outpatient solution without side effects or long recovery to the benefit of the patient, clinician, the health provider and helping Ireland achieve its climate objectives. Due to the particular unmet need for oesophageal cancer (>80% mortality rate) we will focus our efforts on validating our technology in this cancer first. It will address National Strategic Outcome (NSO) 5 and NSO-10, as well as 10 of the 17 United Nations sustainable development goals reflecting our commitment to the Project 2040 government climate action plan. It also sits firmly within the Governments Research Priority Areas 2018-2023 within the Health and Wellbeing Theme under "Medical Devices".

 Existing electroporation generators designed for use in the treatment of cancer are large, expensive and have limited configurability for electrode designs. This project aims to address a gap in the market for an electroporation generator which can deliver high frequency reversible (RE) and irreversible (IRE) electroporation pulses for a wide range of electrode designs to accommodate different cancer indications. Power technologies and delivery systems will be researched and developed to achieve the extremely challenging rise times, switching frequencies and high voltages into a resistive tumour tissue impedance. Further complexity will be added by the target specification of variable voltage, variable pulse rate, variable pulse width and pulse repeatability, which is desired in order to enable a broad range of applications and treatments from the same modular power solution.

 NUI Galway’s roles in the project are to (i) develop new power electronics solutions for a high-voltage, high frequency pulse generator and (ii) to investigate the design of novel electrodes suitable for the delivery of high-voltage electroporation therapy.

 Project Duration: November 2021 to November 2024

Miniaturization and Improving Efficiency of High-Performance Audio Amplifiers

Participants: Robert Bakker (PhD Student) & Maeve Duffy (Supervisor)

Funding Source: Irish Research Council

Project Abstract:

High-performance class-D audio amplifiers have seen application in many modern consumer electronic devices including smartphones, wireless speakers and headphones, laptops, TVs, etc. While the efficiency and size of modern class-D amplifiers are far superior to their analogue counterparts, the ever-increasing demands for smaller devices and lower power consumption motivates the drive to optimize the amplifier designs further. Furthermore, statistical analysis of real-world audio signals such as music shows that the actual time-averaged efficiency of a class-D amplifier is often many times lower than its advertised peak efficiency. As such, the work in this thesis aims to both miniaturize as well as improve the efficiency of high-performance class-D amplifiers.

Firstly, the class-D amplifier design itself is examined. The results of this analysis show that the output low-pass filter inductor is responsible for a significant proportion of the overall power loss, as well as often being the largest component of the amplifier. As such, a systematic approach to designing and optimising the inductor design is presented to both reduce the overall power loss, as well as minimize its footprint.

Secondly, it was identified during the previous analysis that the class-D amplifier can benefit significantly from the use of envelope tracking (ET) to reduce the overall power losses. As such, an investigation into the benefits of ET on the class-D amplifier, as well as its associated power supply is discussed. Two ET demonstrator systems are designed and analysed, including both a battery-operated step-up converter design, as well as a mains-operated step-down converter design. Measurement results from both indicate a significant increase in overall time-averaged efficiency, particularly when used with high crest factor signals such as music.

Project Duration: October 2016 to February 2022