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

Gallium nitride (GaN) is a compound semiconductor that has tremendous potential to facilitate economic growth in a semiconductor industry that is silicon-based and currently faced with diminishing returns of performance versus cost of investment. At a material level, its high electric field strength and electron mobility have already shown tremendous potential for high frequency communications and photonic applications. Advances in growth on commercially viable large area substrates are now at the point where power conversion applications of GaN are at the cusp of commercialisation. The future for building on the work described here in ways driven by specific challenges emerging from entirely new markets and applications is very exciting. This collection of GaN technology developments is therefore not itself a road map but a valuable collection of global state-of-the-art GaN research that will inform the next phase of the technology as market driven requirements evolve. First generation production devices are igniting large new markets and applications that can only be achieved using the advantages of higher speed, low specific resistivity and low saturation switching transistors. Major investments are being made by industrial companies in a wide variety of markets exploring the use of the technology in new circuit topologies, packaging solutions and system architectures that are required to achieve and optimise the system advantages offered by GaN transistors. It is this momentum that will drive priorities for the next stages of device research gathered here.

/pdf/the-2018-gan-power-electronics-roadmap-2iunv619fh.pdf

The 2018 GaN power electronics roadmap

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

This timely second edition has been substantially expanded to keep students and practicing power conversion engineers ahead of the learning curve in GaN technology advancements. Acknowledging that GaN transistors are not one-to-one replacements for the current MOSFET technology, this book serves as a practical guide for understanding basic GaN transistor construction, characteristics, and applications. Included are discussions on the fundamental physics of these power semiconductors, layout and other circuit design considerations, as well as specific application examples demonstrating design techniques when employing GaN devices.

/pdf/gan-transistors-for-efficient-power-conversion-1vxm76211t.pdf

GaN Transistors for Efficient Power Conversion

This paper proposes a synthesis of different electrical methods used to estimate the temperature of power semiconductor devices. The following measurement methods are introduced: the voltage under low current levels, the threshold voltage, the voltage under high current levels, the gate-emitter voltage, the saturation current, and the switching times. All these methods are then compared in terms of sensitivity, linearity, accuracy, genericity, calibration needs, and possibility of characterizing the thermal impedance or the temperature during the operation of the converter. The measurement of thermo-sensitive parameters of wide bandgap semiconductors is also discussed.

/pdf/temperature-measurement-of-power-semiconductor-devices-by-1nz3bww95c.pdf

Temperature Measurement of Power Semiconductor Devices by Thermo-Sensitive Electrical Parameters—A Review

In this paper, a high-temperature, high-frequency, wire-bond-based multichip phase-leg module was designed, fabricated, and fully tested. Using paralleled Silicon Carbide (SiC) MOSFETs, the module was rated at 1200 V and 60 A, and was designed for a 25-kW three-phase inverter operating at a switching frequency of 70 kHz, and in a harsh environment up to 200 °C, for aircraft applications. To this end, the temperature-dependent characteristics of the SiC MOSFET were first evaluated. The results demonstrated the superiority of the SiC MOSFET in both static and switching performances compared to Si devices, but meanwhile did reveal the design tradeoff in terms of the device's gate oxide stability. Various high-temperature packaging materials were then extensively surveyed and carefully selected for the module to sustain the harsh environment. The electrical layout of the module was also optimized using a modeling and simulation approach, in order to minimize the device parasitic ringing during high-speed switching. Finally, the static and switching performances of the fabricated module were tested, and the 200 °C continuous operation of the SiC MOSFETs was verified.

A 1200-V, 60-A SiC MOSFET Multichip Phase-Leg Module for High-Temperature, High-Frequency Applications

This paper presents an experimental parametric study of the parasitic indu waveform ringing, switching loss, device stress, and electromagnetic interference. Based on the results obtained, a guideline has been established for the layout and design of high-speed switching circuits.

Experimental parametric study of the parasitic inductance influence on MOSFET switching characteristics

Characterization and Modeling of High-Switching-Speed Behavior of SiC Active Devices

This paper presents a generic and complete process to characterize and model the newly developed silicon carbide (SiC) MOSFET. The static characteristics, including MOSFET I-V curves, body diode, nonlinear junction capacitances, as well as package stray inductances, have been fully characterized on a prototype 1.2 kV, 20 A SiC MOSFET under varying temperature from 25 °C to 200 °C. Characteristics particular to the SiC MOSFET and its advantages over the silicon counterparts are analyzed and explained. The switching performance of the device, on the other hand, has also been tested under room temperature using a specially designed double-pulse tester with minimized circuit parasitics. The characterization results are then used to build a SiC MOSFET model using the MOSFET modeling tool in Synopsys Saber. Finally, discussions are presented on how to improve the model accuracy in its switching behavior by obtaining static characteristics from switching waveforms.

Characterization and modeling of 1.2 kv, 20 A SiC MOSFETs

Gallium-nitride (GaN) technology for power conversion is maturing, with a growing need to evaluate the capabilities of GaN devices in high switching frequency and elevated ambient temperature operation. These capabilities may particularly benefit systems constrained by strict EMI standards, due to the possibility of significant size and weight reduction. An inductive load tester circuit has been developed for switching characterization of a GaN transistor (EPC1010) and a paired silicon diode (SBR10U200P5). Maximum measured switching speeds for hard switching turn-on and turn-off transitions were dv/dt (on) = 4 V/ns, di/dt (on) = 4.5 A/ns, and dv/dt (off) = 18 V/ns, di/dt (off) = 5 A/ns respectively. Total measured switching energy loss was Etot = 40 µJ under 100 V supply voltage and 15 A load current conditions, with little change with increase of transistor junction temperature from 25 °C to 100 °C. Zero-voltage switching reduced loss to only E tot = 6 µJ, thus enabling high switching frequency operation. As the switching pair of a silicon diode and an EPC1010 is not suitable in hard switching mode and high switching frequency operation due to high switching loss of the turn-on process, another tester was built. Here, two EPC1010 devices were used in a phase-leg configuration. The fastest switching speeds were dv/dt (on) = 21 V/ns, di/dt (on) = 9 A/ns, and dv/dt (off) = 20 V/ns, di/dt (off) = 2 A/ns respectively. Total measured switching energy loss was E tot = 11 µJ, under 100 V supply voltage and 15 A load current conditions.

Zheng Chen

Papers

A 1200-V, 60-A SiC MOSFET Multichip Phase-Leg Module for High-Temperature, High-Frequency Applications

Experimental parametric study of the parasitic inductance influence on MOSFET switching characteristics

Characterization and Modeling of High-Switching-Speed Behavior of SiC Active Devices

Characterization and modeling of 1.2 kv, 20 A SiC MOSFETs

Evaluation of the switching characteristics of a gallium-nitride transistor