Modelling of a Buck converter with adaptive modulation and design of related driver stage

This thesis concerns the modelling of a buck converter with peak current mode control, and adaptive PWM/PFM (constant Ton) and provides a small signal model, derived from steady-state averaging, for all the operative regions of the converter, and used for stability analysis and parametric optimization. Eventually the design of a driver stage is proposed, with segmentation, dead time control and zero cross detection as main functionalities to improve efficienc

Electromagnetic Interference and Compatibility

Recent progress in the fields of Electrical and Electronic Engineering has created new application scenarios and new Electromagnetic Compatibility (EMC) challenges, along with novel tools and methodologies to address them. This volume, which collects the contributions published in the “Electromagnetic Interference and Compatibility” Special Issue of MDPI Electronics, provides a vivid picture of current research trends and new developments in the rapidly evolving, broad area of EMC, including contributions on EMC issues in digital communications, power electronics, and analog integrated circuits and sensors, along with signal and power integrity and electromagnetic interference (EMI) suppression properties of materials

On-line health monitoring of passive electronic components using digitally controlled power converter

This thesis presents System Identification based On-Line Health Monitoring to analyse the dynamic behaviour of the Switch-Mode Power Converter (SMPC), detect, and diagnose anomalies in passive electronic components. The anomaly detection in this research is determined by examining the change in passive component values due to degradation. Degradation, which is a long-term process, however, is characterised by inserting different component values in the power converter. The novel health-monitoring capability enables accurate detection of passive electronic components despite component variations and uncertainties and is valid for different topologies of the switch-mode power converter. The need for a novel on-line health-monitoring capability is driven by the need to improve unscheduled in-service, logistics, and engineering costs, including the requirement of Integrated Vehicle Health Management (IVHM) for electronic systems and components. The detection and diagnosis of degradations and failures within power converters is of great importance for aircraft electronic manufacturers, such as Thales, where component failures result in equipment downtime and large maintenance costs. The fact that existing techniques, including built-in-self test, use of dedicated sensors, physics-of-failure, and data-driven based health-monitoring, have yet to deliver extensive application in IVHM, provides the motivation for this research ... [cont.]

The behaviour and analysis of a three-phase AC-DC step-down unity power factor converter

Abstract unavailable please refer to PD

Maternal Engineered Nanomaterial Inhalation Exposure: Cardiac Molecular Reprogramming in Progeny through Epigenetic and Epitranscriptomic Mechanisms

Introduction: Nano-titanium dioxide (TiO2), a prominently utilized engineered nanomaterial (ENM), is being employed for its physiochemical properties in several fields including the food industry, manufacturing, and biomedicine. As the prevalence of this ENM, and other particulate matter grows, so does the concern for antagonistic consequences on long-term heart function in vulnerable populations, which until now have not been investigated. Due to the reliance of the heart on the ATP generating capacity of mitochondria for contraction, understanding the role of mitochondrial bioenergetics and structure is pivotal in understanding the repercussions of particulate matter exposure during gestation. As the mass population in cities, where particulate matter exposure is highest, do not have many options for mitigating their exposure, it is of utmost importance that strategies are developed that limit the detriments associated with xenobiotic exposure. Understanding the mechanisms, both epigenetic and epitranscriptomic, that regulate mitochondrial and cardiac function under these circumstances will allow for a better understanding of potential therapeutic or preventative strategies and mitigate the disease burden related to particulate matter exposure each year. The purpose of this compilation of work is to identify the mechanisms contributing to the acute and chronic pathological effects of ENM inhalation exposure during gestation as a prerequisite to developing strategies to reduce risks to public health. Methods and Results: Using an inhalation exposure paradigm that mimics the lung burden seen in an occupational setting, we first examined the effects of maternal nano-TiO2 inhalation exposure during gestation on the cardiac function of wild type offspring at the fetal (acute) and adult (chronic) stage using both conventional and speckle tracking stress-strain echocardiographic assessments. Cardiac contractile function was decreased in both the fetal (gestational day 15 (GD 15)) and the adult (11 weeks) offspring. Assessment of mitochondrial bioenergetic and electron transport chain (ETC) complex activities revealed a decreased oxygen consumption rate in offspring and decreased ETC Complex IV at both the fetal and adult stage following maternal ENM inhalation exposure during gestation. Furthermore ELISA-based assessment of 5-methylcytosine (5mC methylation) and Dnmt expression pointed to the involvement of epigenetic mechanisms in altered mitochondrial and cardiac function. Implementation of a novel breeding strategy, using a transgenic mouse model that overexpresses mitochondrial phospholipid hydroperoxide glutathione peroxidase (mPHGPx), an antioxidant enzyme, determined that enhanced antioxidant expression in the maternal environment can mitigate the effects of gestational nano-TiO2 inhalation exposure on fetal and adult offspring cardiac and mitochondrial function. N6-methyladenosine (m6A) was implicated as a modulator of altered mPHGPx activity following maternal ENM exposure in adult offspring, suggesting that epitranscriptomics also has a regulatory role in the adverse effects of particulate matter exposure. Conclusions: The work presented in this presentation demonstrates the ability for ENM inhalation exposure during gestation to alter cardiac function through a mechanism that involves altering mitochondrial function and elevating ROS levels. These studies also provide evidence that there is likely overlap and interplay between epitranscriptomic and epigenetic mechanisms that contribute to changes in the mitochondrial proteome that reduces the ability of the mitochondrion to regulate stress in the form of ROS and leads to dysfunction. Limiting ROS levels through mitochondrially-targeted antioxidant defense enhancement provides a potential preventative route that may allow for the evasion of the adverse cardiac outcomes in offspring that are gestationally exposed to xenobiotics

Evaluation of the off-state base-emitter voltage requirement of the SiC BJT with a regenerative proportional base driver circuit and their application in an inverter

A strong candidate device for use in high-efficiency and high-density power converters is the SiC bipolar junction transistor, which requires a continuous gate (base) current to maintain its on-state. A base driver circuit with regenerative collector current feedback using a current transformer, and a negative off-state base-emitter voltage is presented in this article. The off-state base-emitter voltage required to prevent simultaneous conduction of a commercially available device when subjected to dv/dt's is assessed. The device is then utilized in a three-phase dc-To-Ac power converter where the efficacy of using the proposed base driver is evaluated. The off-state base-emitter voltage used is informed by the dv/dt tests. The converter is supplied from a 600-V dc rail, switches at 50 kHz and supplies a 4.1-kW load at a modulation index of 0.9. An efficiency of 97.4% was measured