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

Electronic packaging is traditionally defined as the back-end process that transforms bare integrated circuits (IC) into functional products. As the IC feature size decreases and the size of silicon wafer increases, the cost per IC is reduced and the performance is enhanced. The future IC chips will be larger in size, have more input/output terminals (I/Os), and require higher power. In addition to the advancements in IC technology, electronic packaging is also driven by the market requirements for low cost, small size, and multi-functional electronic products. In response to these requirements, packaging related areas such as design, packaging architectures, materials, processes, and manufacturing equipment are all changing rapidly. Wafer-level packaging (WLP) offers the benefits of low cost and smallest size for single chip packages, since the package is done at wafer level other than individual die. After packages reach the horizontal limit of dimensions, 3D stacking solution provides more efficient packages through expanding packages in the vertical dimension. Functional integration is achieved with 3D stacking architectures. System in package (SiP), one of the solutions to system integration, incorporates electronics, non-electronic devices such as optical devices, biological devices, micro-electro-mechanical systems (MEMS), etc, and interconnection in a single package, to form smart structures or microsystems. MEMS devices require specialized packaging to serve new market applications. This paper and presentation describe the technology requirements and challenges of these advancing packaging areas. The potential solutions and future trends are presented.

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/6172/61720Z/Future-trends-in-electronic-packaging/10.1117/12.668750.pdf

Future trends in electronic packaging

A fully integrated Silicon Carbide (SiC) JFET/SBD based six-pack power module is designed and developed. The stability of the module assembly processes are confirmed with thermal shock test of −40 to +200 °C temperature cycling. A three phase inverter with the SiC power module is designed and developed for the EV/HEV applications. The liquid cooled inverter is 22.9 × 22.4 × 7.1 cubic centimeters in volume (∼8.35kW/L) and 3.53 kilograms in weight (∼8.5kW/kg). A conversion efficiency of 98.5% is achieved at 10 kHz switching frequency and 10 kW. The inverter is evaluated with coolant temperature up to 95 °C successfully.

Implementation of a fully integrated 50 kW inverter using a SiC JFET based six-pack power module

A key issue associated with the wider adoption of hybrid-electric vehicles (HEV) and plug in hybrid-electric vehicles (PHEV) is the implementation of the power electronic systems that are required in these products [1]. To date, many consumers find the adoption of these technologies problematic based on a financial analysis of the initial cost versus the savings available from reduced fuel consumption. Therefore, one of the primary industry goals is the reduction in the price of these vehicles relative to the cost of traditional gasoline powered vehicles. Part of this cost reduction must come through optimization of the power electronics required by these vehicles. In addition, the efficiency of the systems must be optimized in order to provide the greatest range possible. For some drivers, any reduction in the range associated with a potential HEV or PHEV solution in comparison to a gasoline powered vehicle represents a significant barrier to adoption and the efficiency of the power electronics plays an important role in this range. Likewise, high efficiencies are also important since lost power further complicates the thermal management of these systems. Reliability is also an important concern since most drivers have a high level of comfort with gasoline powered vehiclesmore » and are somewhat reluctant to switch to a less proven technology. Reliability problems in the power electronics or associated components could not only cause a high warranty cost to the manufacturer, but may also taint these technologies in the consumer's eyes. A larger vehicle offering in HEVs is another important consideration from a power electronics point of view. A larger vehicle will need more horsepower, or a larger rated drive. In some ways this will be more difficult to implement from a cost and size point of view. Both the packaging of these modules and the thermal management of these systems at competitive price points create significant challenges. One way in which significant cost reduction of these systems could be achieved is through the use of a single coolant loop for both the power electronics as well as the internal combustion engine (ICE) [2]. This change would reduce the complexity of the cooling system which currently relies on two loops to a single loop [3]. However, the current nominal coolant temperature entering these inverters is 65 C [3], whereas a normal ICE coolant temperature would be much higher at approximately 100 C. This change in coolant temperature significantly increases the junction temperatures of the devices and creates a number of challenges for both device fabrication and the assembly of these devices into inverters and converters for HEV and PHEV applications. With this change in mind, significant progress has been made on the use of SiC devices for inverters that can withstand much higher junction temperatures than traditional Si based inverters [4,5,6]. However, a key problem which the single coolant loop and high temperature devices is the effective packaging of these devices and related components into a high temperature inverter. The elevated junction temperatures that exist in these modules are not compatible with reliable inverters based on existing packaging technology. This report seeks to provide a literature survey of high temperature packaging and to highlight the issues related to the implementation of high temperature power electronic modules for HEV and PHEV applications. For purposes of discussion, it will be assumed in this report that 200 C is the targeted maximum junction temperature.« less

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High-Temperature High-Power Packaging Techniques for HEV Traction Applications

Comprehensive evaluation of ITO thick films produced under optimum annealing conditions

The current trend in commercial and industrial drives, such as electric vehicles and electronic motor drives, is toward the elimination of traditional mechanical or electromechanical systems in favor of power electronics systems (1kW and larger). Market pressures are forcing the design and packaging of power electronics to be compact in size, more reliable, thermally superior, and integrated with intelligence and control systems. As a result, new strategies in the topology design and materials selection are needed in order to fulfill these highly demanding requirements. Toward that end, the researchers have developed a low cost Power Packaging Strategy which extends the concept of Multichip Modules to high power electronic assemblies. This paper will discuss a novel power packaging design which allows for two high conductivity metal layers for power routing and up to ten layers of signal routing in a single compact module. Low power control and interface circuits have been integrated into the power module in bare die and packaged form using chip and wire as well as surface mount attachment. Proper thermal management is achieved through the use of an integrated Metal Matrix Composite heat spreader and substrate. In addition, a 3kW inverter has been fabricated using both the conventional approach and the new packaging concept. A thermal analysis and electrical characterization, as well as a comparison of these power module designs have been performed in this work and will be discussed in the paper.

Fred Barlow

Papers

Future trends in electronic packaging

Implementation of a fully integrated 50 kW inverter using a SiC JFET based six-pack power module

High-Temperature High-Power Packaging Techniques for HEV Traction Applications

Comprehensive evaluation of ITO thick films produced under optimum annealing conditions

High Density Power Modules: A Packaging Strategy