Rapid analysis & design methodologies of High-Frequency LCLC Resonant Inverter as Electrodeless Fluorescent Lamp Ballast

The papers presents methodologies for the analysis of 4th-order LCLC resonant power converters operating at 2.63 MHz as fluorescent lamp ballasts, where high frequency operation facilitates capacitive discharge into the tube, with near resonance operation at high load quality factor enabling high efficiency. State-variable dynamic descriptions of the converter are employed to rapidly determine the steady-state cyclic behaviour of the ballast during nominal operation. Simulation and experimental measurements from a prototype ballast circuit driving a 60 cm, 8W T5 fluorescent lamp are also included

A describing function for resonantly commutated H-bridge inverters

Abstract—The paper presents the derivation of a describing function to model the dynamic behavior of a metal oxide semiconductor field effect transistor-based, capacitively commutated H-bridge, including a comprehensive explanation of the various stages in the switching cycle. Expressions to model the resulting input current, are also given. The derived model allows the inverter to be accurately modeled within a control system simulation over a number of utility input voltage cycles, without resorting to computationally intensive switching-cycle level, time-domain SPICE simulations. Experimental measurements from a prototype H-bridge inverter employed in an induction heating application, are used to demonstrate a high degree of prediction accuracy over a large variation of load conditions is possible using the simplified model

Passive devices for UWB systems

Postprint (published version

Analysis, design and control of LCC resonant power converters

Through the judicious and efficient use of energy in both domestic and commercial products, the rate at which the world's fossil fuels and mineral resources are depleted, can be minimised, thereby securing energy reserves for the future. This thesis considers a number energy saving roles the power systems engineer can contribute, with specific emphasis on the impact of improving DC-DC power converters for providing significant energy savings. It is shown that by increasing the efficiency of such converters, through the greater use of switched-mode supplies, huge reductions in the production of green house gases can be obtained. Moreover, resonant converters, a specific subset of switched-mode supply, are identified as a candidate technology for future widespread use. Since the behavioural dynamics of resonant converters are inherently non-linear, the analysis and design of such systems is extremely complex when compared to other families of converter, and has been a critical factor in impeding their widespread adoption. This thesis therefore aims to provide new tools to aid the designer in overcoming such reservations. Novel analysis and design procedures are developed in Chapters 3 and 4, for the series-parallel inductively-smoothed and capacitively smoothed resonant converters, respectively, which, unlike previously reported techniques, allows a designer with little knowledge of resonant converter systems to readily select preferred components for the resonant tank based on design specifications. Specifically, the analysis in Chapter 3 develops a new methodology that extends 'Fundamental Mode Analysis' (FMA) techniques, and provides a first-order estimate of component values to meet a given specification. Chapter 4 then considers the steady state behaviour of the converter, from a state-plane perspective, and provides exact component values and electrical stress analyses based on ideal converter characteristics. The presented methodology normalises the converter behaviour, such that the gain of the resonant tank (at the resonant frequency and minimum load resistance), and the ratio between the two tank capacitances, fully characterises the behaviour of the converter as the load is varied and the output voltage regulated. To further aid the designer, various new design curves are presented that makes the use of traditional, and complicated, iterative calculation procedures, redundant. Chapter 5 further develops a high speed 1 transient analysis technique for resonant converters that is shown to provide a IOOx reduction in simulation times compared to integration-based methods, by considering only signal envelopes. The technique is shown to significantly aid in the design of variable frequency controllers. Chapters 6 and 7 further consider the control of resonant converters. Specifically, Chapter 6 derives a novel self-oscillating control methodology, which, unlike previously published techniques, approximately linearises the large-signal dynamics of the converter, and thereby readily enables the robust design of an outer loop controller for output-voltage/-current regulation purposes. Additionally, in contrast to other methods for the robust control of resonant converters, little knowledge of the converter state-variables is required, thereby minimising the number of high-bandwidth sensors necessary. The technique simply requires the real-time polarity of current-flow through the series-inductor, and output-voltage/-current, to be known. Through additional (optional) measurement of supply-voltage and a feed-forward control component, the effects of supply-voltage disturbance are shown to be greatly attenuated, thereby requiring reduced outer-loop control action and improving overall regulation performance. Finally, Chapter 7 considers the control of resonant converters when the cost of isolated feedback sensors is prohibitive. Unlike traditional techniques, where the output-voltage is estimated under fixed load conditions, through use of an Extended Kalman Filter observer scheme, non-isolated measurements are used to estimate both the output-voltage and the load-resistance. The load resistance estimation is then used to aid in fault-detection and for improving transient dynamic behaviour via the provision of feed-forward action, resulting in safer converter operation and enhanced regulation performance, and, ultimately, reduced cost

Low-Power, High-Speed Transceivers for Network-on-Chip Communication

Networks on chips (NoCs) are becoming popular as they provide a solution for the interconnection problems on large integrated circuits (ICs). But even in a NoC, link-power can become unacceptably high and data rates are limited when conventional data transceivers are used. In this paper, we present a low-power, high-speed source-synchronous link transceiver which enables a factor 3.3 reduction in link power together with an 80% increase in data-rate. A low-swing capacitive pre-emphasis transmitter in combination with a double-tail sense-amplifier enable speeds in excess of 9 Gb/s over a 2 mm twisted differential interconnect, while consuming only 130 fJ/transition without the need for an additional supply. Multiple transceivers can be connected back-to-back to create a source-synchronous transceiver-chain with a wave-pipelined clock, operating with 6sigma offset reliability at 5 Gb/s

HIGH VOLTAGE RESONANT SELF-TRACKING CURRENT-FED CONVERTER

High voltage power supply design presents unique requirements, combining safety, controllability, high performance, and high efficiencies. A new Resonant Self-Tracking Current-Fed Converter (RST-CFC) is investigated as a proof-of-concept of a high voltage power supply particularly for an X-ray system. These systems require fast voltage rise times and low ripple to yield a clear image. The proposed converter implements high-frequency resonance among discrete components and transformer parasitics to achieve high voltage gain, and the self-tracking nature ensures operation at maximum gain while power switches achieve zero-voltage switching across the full load range. This converter exhibits an inherent indefinite short-circuit capability. Theoretical results were obtained through simulations and verified by experimental results through a complete test configuration. Converter topology viability was confirmed through hardware testing and characterization

Modelling and analysis of radial mode piezoelectric transformers and inductor-less resonant power converters.

Within the electronics industry there is a continual demand for DC-DC power converters that achieve high power density at low cost. Since a piezoelectric transformer (PT) has an electrical equivalent circuit that is similar to several resonant converter topologies, a PT can be used to replace many of the reactive components in these topologies with a single ceramic component, thereby offering potential savings in cost, size, and mass. The first part of this thesis presents a new equivalent circuit model for one of the most promising types of PT, the radial mode Transoner. This model relates the electrical characteristics of the PT to the physical dimensions and material properties. Considerable insight is then gained about how to design these devices to meet a particular set of converter specifications whilst simultaneously maximising PT power density. The second part of this thesis concerns the effect of the rectifier topology on PT power density. Using concepts from material science, together with equivalent circuit models of both the PT and the rectifier topologies, it is shown that a given PT will always achieve a higher thermally limited maximum output power when used in an AC-output topology compared to a DC-output topology. The half-bridge inductor-less PT-based converter topology is particularly attractive because it requires no additional components between the half-bridge and the rectifier. However, it is difficult to achieve zero-voltage-switching (ZVS) without significantly compromising PT power density when using this topology. The third part of this thesis details the development and experimental verification of a new model for the ZVS condition. Using a normalisation scheme and numerical optimisation techniques, the requirements for achieving inductor-less ZVS are accurately quantified for the first time. The impact of these requirements on PT power density is assessed, and design guidelines for maximising PT power density are given

Design, Fabrication and Characterization of Capacitively Coupled Silicon-Organic Hybrid Modulators

Silicon-organic hybrid (SOH) modulators [1] offer fast and efficient electro-optic modulation with very small footprints. Traditional SOH modulators suffer from bandwidth limitation due to the higher RC time constant that originates from the resistive coupling of the RF signal. In the current thesis, we propose a new modulator concept establishing a capacitive coupling of the RF signal as opposed to the resistive one in the conventional SOH modulators and hence the name capacitively coupled SOH (CC-SOH) modulator. A high-κ dielectric, BaT iO3 is characterized in optical and in RF regime and later used to design capacitively coupled SOH modulator. The fabicated CCSOH is characterized to have a flat frequency response up to 65 GHz indicating that the 3-dB bandwidth is at least 3 times higher than the SOH modulators

Plasmonic-Organic and Silicon-Organic Hybrid Modulators for High-Speed Signal Processing

High-speed electro-optic (EO) modulators are key devices for optical communications, microwave photonics, and for broadband signal processing. Among the different material platforms for high-density photonic integrated circuits (PIC), silicon photonics sticks out because of CMOS foundries specialized in PIC fabrication. However, the absence of the Pockels effect in silicon renders EO modulators with high-efficiency and large modulation bandwidth difficult. In this dissertation, plasmonic and photonic slot waveguide modulators are investigated. The devices are built on the silicon platform and are combined with highly-efficient organic EO materials. Using such a hybrid platform, we realize compact and fast plasmonic-organic hybrid (POH) and silicon-organic hybrid (SOH) modulators. As an application example, we demonstrate for the first time an advanced terahertz communication link by directly converting data on a 360 GHz carrier to a data stream on an optical carrier. For optical transmitter applications, we overcome the bandwidth limitation of conventional SOH modulators by introducing a high-k dielectric microwave slotline for guiding the modulating radio-frequency signal which is capacitively-coupled to the EO modulating region. We confirm the viability of such capacitively-coupled SOH modulators by generating four-state pulse amplitude modulated signals with data rates up to 200 Gbit/s