There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Wide bandgap semiconductors show superior material properties enabling potential power device operation at higher temperatures, voltages, and switching speeds than current Si technology. As a result, a new generation of power devices is being developed for power converter applications in which traditional Si power devices show limited operation. The use of these new power semiconductor devices will allow both an important improvement in the performance of existing power converters and the development of new power converters, accounting for an increase in the efficiency of the electric energy transformations and a more rational use of the electric energy. At present, SiC and GaN are the more promising semiconductor materials for these new power devices as a consequence of their outstanding properties, commercial availability of starting material, and maturity of their technological processes. This paper presents a review of recent progresses in the development of SiC- and GaN-based power semiconductor devices together with an overall view of the state of the art of this new device generation.

A Survey of Wide Bandgap Power Semiconductor Devices

High-frequency-link (HFL) power conversion systems (PCSs) are attracting more and more attentions in academia and industry for high power density, reduced weight, and low noise without compromising efficiency, cost, and reliability. In HFL PCSs, dual-active-bridge (DAB) isolated bidirectional dc-dc converter (IBDC) serves as the core circuit. This paper gives an overview of DAB-IBDC for HFL PCSs. First, the research necessity and development history are introduced. Second, the research subjects about basic characterization, control strategy, soft-switching solution and variant, as well as hardware design and optimization are reviewed and analyzed. On this basis, several typical application schemes of DAB-IBDC for HPL PCSs are presented in a worldwide scope. Finally, design recommendations and future trends are presented. As the core circuit of HFL PCSs, DAB-IBDC has wide prospects. The large-scale practical application of DAB-IBDC for HFL PCSs is expected with the recent advances in solid-state semiconductors, magnetic and capacitive materials, and microelectronic technologies.

Overview of Dual-Active-Bridge Isolated Bidirectional DC–DC Converter for High-Frequency-Link Power-Conversion System

This paper proposes a novel dual-phase-shift (DPS) control strategy for a dual-active-bridge isolated bidirectional DC-DC converter. The proposed DPS control consists of a phase shift between the primary and secondary voltages of the isolation transformer, and a phase shift between the gate signals of the diagonal switches of each H-bridge. Simulation on a 600-V/5-kW prototype shows that the DPS control has excellent dynamic and static performance compared to the traditional phase-shift control (single phase shift). In this paper, the concept of ldquoreactive powerrdquo is defined, and the corresponding equations are derived for isolated bidirectional DC-DC converters. It is shown that the reactive power in traditional phase-shift control is inherent, and is the main factor contributing to large peak current and large system loss. The DPS control can eliminate reactive power in isolated bidirectional DC-DC converters. In addition, the DPS control can decrease the peak inrush current and steady-state current, improve system efficiency, increase system power capability (by 33%), and minimize the output capacitance as compared to the traditional phase-shift control. The soft-switching range and the influence of short-time-scale factors, such as deadband and system-level safe operation area, are also discussed in detail. Under certain operation conditions, deadband compensation can be implemented easily in the DPS control without a current sensor.

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Eliminate Reactive Power and Increase System Efficiency of Isolated Bidirectional Dual-Active-Bridge DC–DC Converters Using Novel Dual-Phase-Shift Control

This article reviews recent advances and developments in the field of wearable sensors with emphasis on a subclass of these devices that are able to perform highly-sensitive electrochemical analysis Recent insights into novel fabrication methodologies and electrochemical techniques have resulted in the demonstration of chemical sensors able to augment conventional physical measurements (ie heart rate, EEG, ECG, etc), thereby providing added dimensions of rich, analytical information to the wearer in a timely manner Wearable electrochemical sensors have been integrated onto both textile materials and directly on the epidermis for various monitoring applications owing to their unique ability to process chemical analytes in a non-invasive and non-obtrusive fashion In this manner, multi-analyte detection can easily be performed, in real time, in order to ascertain the overall physiological health of the wearer or to identify potential offenders in their environment Of profound importance is the development of an understanding of the impact of mechanical strain on textile- and epidermal (tattoo)-based sensors and their failure mechanisms as well as the compatibility of the substrate employed in the fabrication process We conclude this review with a retrospective outlook of the field and identify potential implications of this new sensing paradigm in the healthcare, fitness, security, and environmental monitoring domains With continued innovation and detailed attention to core challenges, it is expected that wearable electrochemical sensors will play a pivotal role in the emergent body sensor networks arena

Wearable Electrochemical Sensors and Biosensors: A Review

Low-temperature cofired ceramic (LTCC) was used for a novel band-pass filter design. The filter is based on metallic strips parallel to the E-plane and mounted in a substrate-integrated waveguide (SIW). A new iterative technique based on the variation principle was used to obtain the inductive reactance of equivalent T-network of the metallic strip. The design method of the filter was derived by applying the equivalent network of the metallic strip to the usual method of the filter design. A set of curves relating the various filter parameters is introduced. This filter was designed such that it is electromagnetically isolated inside the SIW and excited using grounded coplanar waveguide (GCPW) to SIW transitions; therefore, it can be easily integrated with MMICs. The design steps are explained and verified by examples and results. Three-dimensional electromagnetic field modeling and simulation was carried out using a high frequency structure simulator (HFSS). A comparison between different types of SIW is...

A Novel Design of Substrate Integrated Waveguide (SIW) E-Plane Inductive Strip Filter Implemented Using LTCC

Embedded passives in low-temperature co-fired ceramic for RF & microwave applications

Passivity enforcement techniques are widely used in DRAM package model development. The Hamiltonian method is one of the common methods used for checking/enforcing passivity of these multiport networks. Enforcing the passivity for non-passive models is not trivial because it is built on several approximation steps starting from building the macromodel, which captures the frequency domain response, and ending with a suitable spice model for the DRAM circuits. Several approximation steps take place to achieve that result, and multiple constraints are used to preserve the original design characteristics. In this paper, we compared residue perturbation with and without error control in order to calculate how passivity enforcement affects the original model accuracy.

Comparison of passive enforcement techniques for DRAM package models

This paper describes the design and processing of a zero meta-material phase shifter (ZMPS) embedded within a low temperature co-fired ceramics (LTCC) structure. The designed ZMPS is based on a composite right/left handed meta-material (CRLH MTM) transmission line approach. L-C networks were used to achieve zero phase shift at a specified frequency. The proposed design combines the advantages of an accurate zero phase shift using meta-material concepts and the advantages of passive components (capacitors and inductors) embedded inside LTCC to reduce device size, weight, and cost. The designed phase shifter provides an accurate 0o phase shift at 0.73 GHz with −16.7 dB return-loss and −0.31 dB insertion-loss at the center frequency. The paper also provides a comparison between BST and BZT as dielectric materials embedded inside LTCC with respect to the preparation process and shrinking effects.

Zero Meta-material Ferroelectric Phase Shifter Embedded inside LTCC

This paper presents the design and implementation of a digital communication interface between a Motor Drive Controller (MDC) and a digital network supervisor. This work is part of the DOE/CARAT project "Integrated Controllers for Automotive Auxiliary Electric Motors", being performed between the University of Arkansas and at GEA (Applied Electronics Group), National University of Rio Cuarto. The Controller Area Network (CAN) is the digital communication protocol of choice for automotive applications. The MDC was implemented using a Digital Signal Processor (DSP) and the network supervisor using a standard personal computer (PC) with a CAN communication board.

Fred Barlow

Papers

A Novel Design of Substrate Integrated Waveguide (SIW) E-Plane Inductive Strip Filter Implemented Using LTCC

Embedded passives in low-temperature co-fired ceramic for RF & microwave applications

Comparison of passive enforcement techniques for DRAM package models

Zero Meta-material Ferroelectric Phase Shifter Embedded inside LTCC

Digital communication interface for an automotive application