Induction Of Transformation Research Articles

Piezoelectric Transducers: Complete Electromechanical Model with Parameter Extraction.

This paper presents a complete electromechanical (EM) model of piezoelectric transducers (PTs) independent of high or low coupling assumptions, vibration conditions, and geometry. The PT's spring stiffness is modeled as part of the domain coupling transformer, and the piezoelectric EM coupling coefficient is modeled explicitly as a split inductor transformer. This separates the coupling coefficient from the coefficient used for conversion between mechanical and electrical domains, providing a more insightful understanding of the energy transfers occurring within a PT and allowing for analysis not previously possible. This also illustrates the role the PT's spring plays in EM energy conversion. The model is analyzed and discussed from a circuits and energy harvesting perspective. Coupling between domains and how loading affects coupled energy are examined. Moreover, simple methods for experimentally extracting model parameters, including the coupling coefficient, are provided to empower engineers to quickly and easily integrate PTs in SPICE simulations for the rapid and improved development of PT interface circuits. The model and parameter extractions are validated by comparing them to the measured response of a physical cantilever-style PT excited by regular and irregular vibrations. In most cases, less than a 5-10% error between measured and simulated responses is observed.

Efficient Integrated Transformer–Inductor With High PCB Utilization and Optimized Core

Efficient Integrated Transformer–Inductor With High PCB Utilization and Optimized Core

Hybrid Converter with Multiple Sources for Lithium Battery Charger Applications

This paper proposes a hybrid converter with multiple sources for lithium battery charger applications. Since the output voltage of a lithium battery charger is very low, its charger needs a higher step-down voltage for a utility line source or a step-down voltage for PV arrays. In order to implement the battery charger with utility line and PV arrays sources to simultaneously supply power to battery, a flyback converter is selected for utility line sources, and a buck converter is adopted for PV arrays source. Due to leakage inductor of transformer in flyback converter, an active clamp circuit is introduced into flyback converter to recover the energy stored in leakage inductor. In addition, flyback and buck converters can adopt switch integration techniques to simplify circuit structure. With this approach, the proposed hybrid converter has less components, is lighter weight and has smaller size and higher conversion efficiency. Finally, a prototype of the proposed hybrid converter with output voltage of 5 V~8.4 V and output maximum current of 12 A has been implement to verify its feasibility. It is suitable for the lithium battery charger applications.

CLL Resonant Converter With Secondary Side Resonant Inductor and Integrated Magnetics

A <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLL</i> resonant converter with transformer–inductor-integrated magnetics is proposed. The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLL</i> resonant converter is derived by placing the resonant inductor of an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converter on the secondary side of the transformer. In comparison with an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converter, the circulating current associated with the magnetizing current of the transformer is removed from the resonant inductor. More importantly, the phase difference between the flux in the magnetic cores of the transformer and the resonant inductor becomes larger. Therefore, the flux of the transformer and inductor can be cancelled with each other, resulting in a reduced loss and volume of the magnetic core. A novel structure is proposed to integrate the transformer and inductor with integrated winding structures. Detailed analysis and optimized design of the integrated transformer–inductor are presented. The effectiveness and feasibility of the proposed solutions are verified with simulation and experimental results.

Flicker-Free Resonant LED Driver With High Power Factor and Passive Current Balancing

A flicker-free resonant LED driver with high power factor (PF) and passive current balancing is proposed and analysed in this paper. The proposed LED driver are composed a buck power factor correction (PFC) unit and a resonant dc-dc unit by sharing an active switch. Based on this topology, the low output current ripple can be achieved via small voltage ripple on bulk capacitor and fast voltage-mode control loop. By the charge balance for resonant capacitor, the output current of each LED string can be balanced. In a half line cycle, owing to the small voltage ripple on bulk capacitor of pre-stage output, the duty cycle of active switch is almost constant. Therefore, when the inductor current of buck PFC unit operates in discontinuous conduction mode, high PF can be realized. Moreover, as the resonance is existed between resonant capacitor and leakage inductor of transformer, the diodes in resonant dc-dc unit can achieve zero-current turn-off. Thus, the efficiency can be improved. Finally, an 82W LED driver prototype with three-output is built to verify the studied results.

Design and Fabrication of Three-Dimensional Printed Air-Core Transformers for High-Frequency Power Applications

This article presents various designs of toroidal air-core transformers utilizing a 3-D printing and electroplating fabrication methodology. For certain applications and switching frequency regimes, limitations in core-based magnetics force circuit designers to use air-core components, which are conventionally wire-wound, and thus, constrained to simple structures with poor copper coverage. 3-D printing offers a solution to this constraint and provides more flexibility for transformer designs. This article includes design calculations, finite-element method (FEM) simulations, and loss analysis for three different toroidal transformer designs: one which features nested toroids, coupling their N2 flux, the second which uses stacked toroids, coupling the one-turn flux, and the third which interleaves two windings. Furthermore, the manufacturing procedure presented in this article allows for accurate modeling of the transformer's inductance matrix, which is advantageous over hand-wound air-core components. Additionally, we provide experimental demonstrations, including the implementation of these transformers in 100-W, 30-MHz resonant converters. Lastly, COMSOL FEM design automation MATLAB scripts for the various inductors and transformers discussed in this article are publicly available in the paper by Z. Tong (2019), allowing for fast parametric modeling of magnetic designs.

An Active-Clamp Forward Inverter Featuring Soft Switching and Electrical Isolation

Traditional photovoltaic (PV) grid-connection inverters with sinusoidal pulse-width modulation (SPWM) control suffer the problem of buck-typed conversion. Additional line-frequency transformers or boost converters are required to step-up output voltage, leading to low system efficiency and high circuit complexity. Therefore, many flyback inverters with electrical isolation have been proposed by adopting a flyback converter to generate a rectified sine wave, and then connecting with a bridge unfolder to control polarity. However, all energy of a flyback inverter must be temporarily stored in the magnetizing inductor of transformer so that the efficiency and the out power are limited. This paper presents a high-efficiency active-clamp forward inverter with the features of zero-voltage switching (ZVS) and electrical isolation. The proposed inverter circuit is formed by adopting a forward converter to generate a rectified sine wave, and combining with the active-clamp circuit to reset the residual magnetic flux of the transformer. Due to the boost capability of the transformer, this inverter is suitable for the PV grid-connection power systems with wide input-voltage variation. The operation principles at steady-state are analyzed, and the mathematical equations for circuit design are conducted. Finally, a laboratory prototype is built as an illustration example according to proper analysis and design. Based on the experimental results, the feasibility and satisfactory performance of the proposed inverter circuit are verified.

An LLC-Type Resonant Forward Converter With Adjustable Turning-Off Time Control

This paper proposes a LLC type resonant forward converter using adjustable turning-off time control for low power and voltage applications. The new circuit is derived from the conventional LLC converter, and it has simple structure while maintaining decent soft-switching characteristics. The switching losses are reduced by ZVS (zero voltage switching) and ZCS (zero current switching). Also, regulation of the output voltage does not require a small ratio between magnetizing inductor and resonant inductor, so the leakage inductor of transformer can be utilized instead of an external inductor to realize resonance, which makes it possible to use only one magnetic component in the resonant topology. Besides, the adjustable turning-off time control strategy is adopted in the scheme, which optimizes the switching condition while ensuring the wide range operation. In comparison to the traditional PWM (pulse width modulation) control, the proposed control strategy can further reduce the switching loss and improve power efficiency. This is also suitable for the utilization of GaN (gallium nitride) devices due to the requirement of higher switching frequencies at wide input applications. In addition to the detailed theoretical analysis, the validity of the proposed concept is confirmed by the experimental results of a prototype.

A Ku-band dual control path frequency synthesizer using varactorless Q-enhanced LC-type VCO

This study focused on the design principle and implementation of a high-frequency, wide-range frequency synthesizer by using a dual control path phase-lock loop (PLL) and a varactorless oscillator controlled by inductive–capacitive (LC-type) voltage (i.e., a voltage-controlled oscillator, VCO). Without a varactor in the LC tank, the tuned-transducer oscillator with Q-enhanced functionality can easily arrive at the requirements of high-frequency wide-range low-noise operations. We utilized a difference tuned varactorless VCO to create two different KVCOs and applied it to a dual control path PLL architecture to obtain wide tuning range and more favorable phase noise. In addition, a high-speed current-mode logic divider was employed given its high speed (because of the use of a transformer inductor), extremely high operation frequency, and wide-range. The proposed PLL was assembled using the standard 0.13-μm CMOS technology on a 0.95 × 1.05 mm2 chip. The PLL dissipated 40 mW at a 1.2 V supply. The measurement of phase noise at 17.64 GHz was − 98.12 dBc/Hz at a 1 MHz offset.

Development of a 1.5 kV, 1.2 kA Pulsed-Power Supply for Light Sintering

This paper presents the design and experimental results of the 36-kW pulsed-power supply for the xenon flash lamp. The continuous conduction mode series-parallel resonant converter is modified. This means that not only the few hundred kilohertz of high switching frequency is introduced to replace the resonant inductor with the leakage inductor of transformer but also the high output current is accomplished by using three-phase delta-connected transformers. In addition, the snubber capacitor of the inverter switches and the power factor correction module is both omitted in the compact structure. Although these main components have changed, the efficiency and power factor of the rated dummy load reach 96% and 0.96%, respectively. Within 36-kW average power, the proposed pulsed-power supply can generate as versatile combination of output pulse. For example, it can generate 20-ms pulse with 1-Hz repetition rate or generate 1-ms pulse with 20-Hz repetition rate. The used insulated gate bipolar transistor is protected from the turn-OFF peak voltage by the snubber circuit, and the effect of the snubber circuit is shown at the actual load condition.

A New Photovoltaic System Architecture of Module-Integrated Converter with a Single-sourced Asymmetric Multilevel Inverter Using a Cost-effective Single-ended Pre-regulator

In this paper, a new architecture for a cost-effective power conditioning systems (PCS) using a single-sourced asymmetric cascaded H-bridge multilevel inverter (MLI) for photovoltaic (PV) applications is proposed. The asymmetric MLI topology has a reduced number of parts compared to the symmetrical type for the same number of voltage level. However, the modulation index threshold related to the drop in the number of levels of the inverter output is higher than that of the symmetrical MLI. This problem results in a modulation index limitation which is relatively higher than that of the symmetrical MLI. Hence, an extra voltage pre-regulator becomes a necessary component in the PCS under a wide operating bias variation. In addition to pre-stage voltage regulation for the constant MLI dc-links, another auxiliary pre-regulator should provide isolation and voltage balance among the multiple H-bridge cells in the asymmetrical MLI as well as the symmetrical ones. The proposed PCS uses a single-ended DC-DC converter topology with a coupled inductor and charge-pump circuit to satisfy all of the aforementioned requirements. Since the proposed integrated-type voltage pre-regulator circuit uses only a single MOSFET switch and a single magnetic component, the size and cost of the PCS is an optimal trade-off. In addition, the voltage balance between the separate H-bridge cells is automatically maintained by the number of turns in the coupled inductor transformer regardless of the duty cycle, which eliminates the need for an extra voltage regulator for the auxiliary H-bridge in MLIs. The voltage balance is also maintained under the discontinuous conduction mode (DCM). Thus, the PCS is also operational during light load conditions. The proposed architecture can apply the module-integrated converter (MIC) concept to perform distributed MPPT. The proposed architecture is analyzed and verified for a 7-level asymmetric MLI, using simulation results and a hardware implementation.

The Non-Isolated Type Flyback-Boost Combination Converter for Solar Light LED

This paper, proposes a non-insulated type flyback-boost combination converter that has the step-up and down function as a converter for an independent solar light LED pole light system. The proposed combination converter is composed with the use of one switch, and the step-up function works with discontinuous current mode. The proposed electric power circuit allows for improving the efficiency of converting energy by removing the RCD(Residual-current device) snubber of the existing flyback converter, connecting the terminal to output and transferring the stored energy in the leakage inductor of transformer to output. Simulations and experiments were conducted to validate the proposed circuit and the results were discussed.

High step-up isolated efficient single switch DC-DC converter for renewable energy source

In this paper, an isolated high step-up single switch DC-DC converter for renewable energy source is proposed. In the proposed converter high step-up voltage is obtained by single power switching technique that operates low duty cycle with isolated transformer inductors and switched capacitors and power diodes. The disadvantage of conventional converters is that it has high duty ratio and high voltage stress on power devices with less efficiency. The proposed converter eliminates the switching losses and recycles the leakage energy which includes reverse recovery energy of the power diode by using passive clamp circuit. To achieve high output voltage gain, the isolated transformer primary terminal and secondary terminal are connected in series during switching operation. PSIM software has been used for simulation. Simulation circuit is analyzed at 40Vdc/400Vdc, 200W and this operation is validated by implementing in the hardware model at 12Vdc/120Vdc, 60W.

Isolated high boost DC-DC flyback converter

This paper presents isolated high boost dc-dc flyback converter with high voltage gain suitable for renewable energy source. The circuit consists of active clamp circuit and boost converter with isolated transformer. The circuit employs capacitors are charged in parallel and discharged in series by isolated transformer inductors. The active clamp circuit is used during the turn off-period to reduce the voltage spike on power switch. To achieve high output voltage gain the flyback converter output terminal and boost converter output terminal are connected in serially with the isolated inductors with less voltage stress on controlled power switch and power diodes. PSIM software has been used for simulation. Hardware model implemented and tested in the laboratory

Abstract 2964: Epigenetic mechanisms of transformation by WHSC1L1 in breast cancer cells with the 8p11-p12 amplicon.

Abstract An amplified region of chromosome 8, the 8p11-p12 amplicon, is observed in ∼15% of breast cancers. This region contains 55 genes, of which 22 have been identified as candidate oncogenes based on higher than normal copy number and associated elevated expression levels in breast tumor cells compared to normal breast epithelial cells. Our lab previously identified the short isoform of one amplicon gene, Wolf Hirschhorn Syndrome Candidate 1-Like 1 (WHSC1L1), to be a potent inducer of transformation when over expressed in MCF10A breast epithelial cells in vitro. WHSC1L1 is a member of the NSD family of methyltransferases, and has been shown to methylate lysines 4, 27, and 36 of the histone H3 subunit, however, the potently transforming short isoform (WHshort) lacks the catalytic SET domain. Our lab has shown that over expression of WHshort in the immortalized human breast epithelial cell line MCF10A causes a significant increase in proliferation in insulin-free culture conditions, and the ability to form colonies in soft agar. In SUM44 cells, an ER+ breast cancer cell line harboring the 8p11-p12 amplicon, shRNA knockdown of WHSC1L1 resulted in growth arrest. The WHSC1L1 family member NSD1 has been shown to act as an oncogene in acute myelogenous leukemia by blocking differentiation in developing lymphocytes through H3K36me3-mediated inhibition of the polycomb repressor complex, resulting in constitutive activation of the HOXA gene family. While WHSC1L1 may work by a similar mechanism, little is known about the specific substrates of WHSC1L1, or even whether its oncogenic activity is caused by histone methylation changes. Knockdown by shRNA of WHSC1L1 in SUM44 cells resulted in a significant reduction in transcript levels of several genes important in breast cancer cell proliferation, including ESR1, MYCN (amplified in SUM-44), ERBB3, and ERBB4. Interestingly, Carroll et al. recently reported that ER+ breast tumors can be stratified by gene expression signature into poor outcome and good outcome groups, and that ER-alpha binding site patterns on chromatin were altered in the two groups. In this study, WHSC1L1 was part of the ER-regulated gene signature of the poor outcome group. Therefore, we hypothesize that WHSC1L1 may influence histone H3K36me3 marks at specific gene loci, leading to altered ER-alpha binding that is associated with the expression signatures of poor-outcome ER+ breast cancers. To investigate chromatin changes as a result of changes in WHSC1L1 expression, we have accomplished shRNA knockdown of WHSC1L1 in SUM44 cells using GIPZ and TRIPZ lentiviral vectors. Using these cell lines, we are investigating changes in H3K36me3 marks and ER-alpha binding patterns by chromatin immunoprecipitation followed by sequencing (ChIP-seq). These experiments will help to elucidate the interaction of WHSC1L1 and ER in regulated gene expression in breast cancer cells with the 8p11 amplicon. Citation Format: Jonathan C. Irish, Gang Liu, Stephen P. Ethier. Epigenetic mechanisms of transformation by WHSC1L1 in breast cancer cells with the 8p11-p12 amplicon. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2964. doi:10.1158/1538-7445.AM2013-2964

Abstract 2190: Epigenetic mechanisms of transformation for the NSD3 oncogene in human breast cancer cells with the 8p11-p12 amplicon

Abstract An amplified region of chromosome 8, the 8p11-p12 amplicon, is observed in 12-15% of breast cancers. This region contains 55 genes, of which 22 have been identified as candidate oncogenes based on the presence of higher than normal copy number and associated elevated expression levels in breast tumor cells compared to normal breast epithelial cells. Our lab previously identified the short isoform of one amplicon gene, nuclear SET domain-containing protein 3 (NSD3s), to be the most potent inducer of transformation to a neoplastic phenotype of all genes on the 8p11-p12 amplicon when over expressed in MCF10A breast epithelial cells in vitro. NSD3 is a member of the NSD family of methyltransferases, and has been shown to methylate lysine 4, 27, and 36 on the H3 subunit of histones, however the potently transforming short isoform lacks the catalytic SET domain. Our lab has shown that over expression of NSD3s in the immortalized human breast epithelial cell line MCF10A causes a significant increase in proliferation in insulin-free culture conditions, and the ability to form colonies in soft agar. In SUM44 cells, a breast cancer cell line with the 8p11-p12 amplicon, shRNA knockdown of NSD3s resulted in decreased proliferation. Immunoblotting with anti-H3K4me2 antibody shows MCF10A cells have higher global levels of H3K4me2 than SUM 44 cells, and over expression of NSD3s in MCF10A cells reduces global H3K4me2 levels. Other NSD family members have been shown to act as oncogenes in certain leukemias by blocking differentiation in developing lymphocytes through H3K36me3-mediated inhibition of the polycomb repressor complex, resulting in constitutive activation of the HOX gene family. This epigenetic dysregulation of HOX through the NSD1 oncogene results in acquisition of a stem-like phenotype in these cells that is essential for the development of these leukemias. We predict a similar mechanism in breast cancers that over express NSD3. Genome-wide expression analysis has shown that IRX3, a gene expressed in cells of the ectoderm lineage during differentiation, is upregulated in cells over expressing NSD3s. Based on previous findings with other NSD family genes we predict that genes involved in pluripotency or stemness will be targets of NSD3s activity in breast cancers with the 8p11-p12 amplicon. To investigate whether over expression of NSD3s induces a stem-like phenotype in MCF10A cells, we have measured the expression level of breast cancer stem cell surface markers CD44 and CD24 by flow cytometry, and found that NSD3s over expression results in a sub-population of cells that has higher CD44 expression than parental MCF10A, while maintaining low CD24 expression. These data suggest that NSD3s may act as a driving oncogene in breast cancer by altering histone methylation patterns in a way that promotes the expression of genes that result in the acquisition of stem-like phenotypes. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2190. doi:1538-7445.AM2012-2190

Investigating Agrobacterium-Mediated Transformation of Verticillium albo-atrum on Plant Surfaces

Background Agrobacterium tumefaciens has long been known to transform plant tissue in nature as part of its infection process. This natural mechanism has been utilised over the last few decades in laboratories world wide to genetically manipulate many species of plants. More recently this technology has been successfully applied to non-plant organisms in the laboratory, including fungi, where the plant wound hormone acetosyringone, an inducer of transformation, is supplied exogenously. In the natural environment it is possible that Agrobacterium and fungi may encounter each other at plant wound sites, where acetosyringone would be present, raising the possibility of natural gene transfer from bacterium to fungus.Methodology/Principal FindingsWe investigate this hypothesis through the development of experiments designed to replicate such a situation at a plant wound site. A. tumefaciens harbouring the plasmid pCAMDsRed was co-cultivated with the common plant pathogenic fungus Verticillium albo-atrum on a range of wounded plant tissues. Fungal transformants were obtained from co-cultivation on a range of plant tissue types, demonstrating that plant tissue provides sufficient vir gene inducers to allow A. tumefaciens to transform fungi in planta.Conclusions/SignificanceThis work raises interesting questions about whether A. tumefaciens may be able to transform organisms other than plants in nature, or indeed should be considered during GM risk assessments, with further investigations required to determine whether this phenomenon has already occurred in nature.

Soft switching active-clamped dual-series resonant converter

A soft switching active-clamp dual-series resonant converter is proposed here. Two small transformers are used in the proposed topology to provide more load power. An active-clamp circuit is used to absorb the energy stored in the leakage inductor of transformer, to clamp voltage stresses across switches and to realise the zero-voltage switching turn-on of switches in order to alleviate the switching losses. In order to remove the reverse-recovery problem on output diodes, the zero-current switching turn-off is realised by choosing the proper angle frequency on the secondary side. Analysis of mode operation, design considerations and experimental results of the proposed zero-voltage zero-current switching (ZVZCS) converter are described in detail. Finally, a 200 W ZVZCS prototype treated under Vin=48 V, Vo=200 V is implemented to verify the practicability of the proposed converter.

An Atmospheric-Pressure Glow-Discharge Plasma Jet and Its Application

An atmospheric-pressure glow-discharge plasma jet driven by a transformer of 1 : 500 and an alternating current of 50 Hz is presented. Discharge characteristics are investigated by oscillograph observations, and it is verified no risk of arcing. The stable glow discharge is deemed to benefit from the transformer's inductance. The electric characteristics and the plasma parameters are studied. The jet is employed in CO2 reforming of CH4 to syngas (H2, CO). It brings out higher conversion ability than other plasmas such as dielectric barrier discharge and corona discharge, which is due to its special design and special plasma characteristic.

Analysis, Design, and Control of a Transcutaneous Power Regulator for Artificial Hearts

Based on a generic transcutaneous transformer model, a remote power supply using a resonant topology for use in artificial hearts is analyzed and designed for easy controllability and high efficiency. The primary and secondary windings of the transcutaneous transformer are positioned outside and inside the human body, respectively. In such a transformer, the alignment and gap may change with external positioning. As a result, the coupling coefficient of the transcutaneous transformer is also varying, and so are the two large leakage inductances and the mutual inductance. Resonant-tank circuits with varying resonant-frequency are formed from the transformer inductors and external capacitors. For a given range of coupling coefficients, an operating frequency corresponding to a particular coupling coefficient can be found, for which the voltage transfer function is insensitive to load. Prior works have used frequency modulation to regulate the output voltage under varying load and transformer coupling. The use of frequency modulation may require a wide control frequency range which may extend well above the load insensitive frequency. In this paper, study of the input-to-output voltage transfer function is carried out, and a control method is proposed to lock the switching frequency at just above the load insensitive frequency for optimized efficiency at heavy loads. Specifically, operation at above resonant of the resonant circuits is maintained under varying coupling-coefficient. Using a digital-phase-lock-loop (PLL), zero-voltage switching is achieved in a full-bridge converter which is also programmed to provide output voltage regulation via pulsewidth modulation (PWM). A prototype transcutaneous power regulator is built and found to to perform excellently with high efficiency and tight regulation under variations of the alignment or gap of the transcutaneous transformer, load and input voltage.