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

Wireless power transfer (WPT) using magnetic resonance is the technology which could set human free from the annoying wires. In fact, the WPT adopts the same basic theory which has already been developed for at least 30 years with the term inductive power transfer. WPT technology is developing rapidly in recent years. At kilowatts power level, the transfer distance increases from several millimeters to several hundred millimeters with a grid to load efficiency above 90%. The advances make the WPT very attractive to the electric vehicle (EV) charging applications in both stationary and dynamic charging scenarios. This paper reviewed the technologies in the WPT area applicable to EV wireless charging. By introducing WPT in EVs, the obstacles of charging time, range, and cost can be easily mitigated. Battery technology is no longer relevant in the mass market penetration of EVs. It is hoped that researchers could be encouraged by the state-of-the-art achievements, and push forward the further development of WPT as well as the expansion of EV.

Wireless Power Transfer for Electric Vehicle Applications

DC-link capacitors are an important part in the majority of power electronic converters which contribute to cost, size and failure rate on a considerable scale. From capacitor users' viewpoint, this paper presents a review on the improvement of reliability of dc link in power electronic converters from two aspects: 1) reliability-oriented dc-link design solutions; 2) conditioning monitoring of dc-link capacitors during operation. Failure mechanisms, failure modes and lifetime models of capacitors suitable for the applications are also discussed as a basis to understand the physics-of-failure. This review serves to provide a clear picture of the state-of-the-art research in this area and to identify the corresponding challenges and future research directions for capacitors and their dc-link applications.

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Reliability of Capacitors for DC-Link Applications in Power Electronic Converters—An Overview

Silicon carbide (SiC) power devices have been investigated extensively in the past two decades, and there are many devices commercially available now. Owing to the intrinsic material advantages of SiC over silicon (Si), SiC power devices can operate at higher voltage, higher switching frequency, and higher temperature. This paper reviews the technology progress of SiC power devices and their emerging applications. The design challenges and future trends are summarized at the end of the paper.

https://ieeexplore.ieee.org/ielaam/41/8031005/7815312-aam.pdf

Review of Silicon Carbide Power Devices and Their Applications

Gallium nitride (GaN) power devices are an emerging technology that have only recently become available commercially. This new technology enables the design of converters at higher frequencies and efficiencies than those achievable with conventional Si devices. This paper reviews the characteristics and commercial status of both vertical and lateral GaN power devices, providing the background necessary to understand the significance of these recent developments. In addition, the challenges encountered in GaN-based converter design are considered, such as the consequences of faster switching on gate driver design and board layout. Other issues include the unique reverse conduction behavior, dynamic $R_{\mathrm {{ds}},\mathrm {{on}}}$ , breakdown mechanisms, thermal design, device availability, and reliability qualification. This review will help prepare the reader to effectively design GaN-based converters, as these devices become increasingly available on a commercial scale.

Review of Commercial GaN Power Devices and GaN-Based Converter Design Challenges

A novel packaging structure for medium power modules featuring power semiconductor switches sandwiched between two symmetric substrates that fulfill electrical conduction and insulation functions is presented. The power switches in a popular phase leg electrical topology are orientated in a face up/face down configuration. Large bonding areas between dies and substrates combined with a compact busbar interface allow this packaging technology to offer dramatic improvements in electrical conversion efficiency and electromagnetic interference containment.

Reducing Parasitic Electrical Parameters with a Planar Interconnection Packaging Structure

Turn-off delay time is temperature sensitive and can be used to estimate the junction temperature of insulated-gate bipolar transistors (IGBTs). In this paper, a high-resolution measurement circuit is designed to detect the turn-off delay time and estimate the corresponding junction temperature. Details of the circuit are demonstrated. Turn-off delay time at different junction temperature, different switching current and different switching voltage is investigated using the measurement circuit. Based on the experimental results, the junction temperature estimation method is tested on IGBT device IKW40N120T2. Compared with the on-state collector-emitter voltage-based method and short current-based method, turn-off delay time-based method shows the feature of high accuracy and feasible online estimation.

A turn-off delay time measurement and junction temperature estimation method for IGBT

A high temperature wirebond-packaged phase-leg power module was designed, developed, and tested. Details of the layout, gate drive, and cooling system designs are described. Continuous power tests confirmed that the designed high-density power module can be successfully operated with 250 °C junction temperature. The power module was further utilized in an all-SiC rectifier system that achieves a 2.78 kW/lb power density.

A High Density 250 $^{\circ}{\rm C}$ Junction Temperature SiC Power Module Development

The hybrid switch (HyS), which is a parallel combination of the silicon (Si) insulated gate bipolar transistors (IGBTs) and the silicon carbide (SiC) metal-oxide semiconductor field-effect transistors (MOSFETs), can realize high switching frequency at a reasonable cost. In this paper, a compact HyS half-bridge power module, rated at 1200 V/200 A, was fabricated in house and fully tested for the first time. An electrothermal model of the HyS was set up in LTspice to determine the optimal gate sequence for the HyS. To minimize the HyS power loss, the turn-on gate signals are applied to the Si IGBTs and the SiC MOSFETs simultaneously while a prior turn-off period exists between the turn-off gate signals of the Si IGBTs and the SiC MOSFETs. By considering the power loss of the HyS and the junction temperature of the SiC MOSFETs, a novel index is proposed to select the optimal prior turn-off period. Based on the HyS power modules, a 5 kW aircooling voltage source inverter and a 30 kW water-cooling voltage source inverter were developed and tested to verify the analysis.

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A 1200 V/200 A Half-Bridge Power Module Based on Si IGBT/SiC MOSFET Hybrid Switch

This work presents the design, development and testing of a phase-leg power module packaged by a novel planar packaging technique for high temperature (250 °C) operation. Nano-silver paste is chosen as the die-attach material as well as playing the key functions of electrically connecting the devices' pads. The electrical characteristics of the SiC-based power semiconductors, SiC JFETs and SiC diodes, have been measured and compared before and after packaging. No significant changes are found in the characteristics of all the devices. Prototype module is fabricated and operated up to 400 V, 1.4 kW at junction temperature of 250 °C in the continuous power test. Thermo-mechanical reliability has also been investigated by passive cycling the module from -55 °C to 250 °C. Electrical and mechanical performances of the packaged module are characterized and considered to be reliable for at least 200 cycles.

Puqi Ning

Papers

Reducing Parasitic Electrical Parameters with a Planar Interconnection Packaging Structure

A turn-off delay time measurement and junction temperature estimation method for IGBT

A High Density 250 $^{\circ}{\rm C}$ Junction Temperature SiC Power Module Development

A 1200 V/200 A Half-Bridge Power Module Based on Si IGBT/SiC MOSFET Hybrid Switch

A Novel High-Temperature Planar Package for SiC Multi-Chip Phase-Leg Power Module