GaN technology is not only gaining traction in power and RF electronics but is also rapidly expanding into other application areas including digital and quantum computing electronics. This paper provides a glimpse of future GaN device technologies and advanced modeling approaches that can push the boundaries of these applications in terms of performance and reliability. While GaN power devices have recently been commercialized in the 15–900 V classes, new GaN devices are greatly desirable to explore both higher-voltage and ultra-low-voltage power applications. Moving into the RF domain, ultra-high frequency GaN devices are being used to implement digitized power amplifier circuits, and further advances using the hardware–software co-design approach can be expected. On the horizon is the GaN CMOS technology, a key missing piece to realize the full-GaN platform with integrated digital, power, and RF electronics technologies. Although currently a challenge, high-performance p-type GaN technology will be crucial to realize high-performance GaN CMOS circuits. Due to its excellent transport characteristics and ability to generate free carriers via polarization doping, GaN is expected to be an important technology for ultra-low temperature and quantum computing electronics. Finally, given the increasing cost of hardware prototyping of new devices and circuits, the use of high-fidelity device models and data-driven modeling approaches for technology-circuit co-design are projected to be the trends of the future. In this regard, physically inspired, mathematically robust, less computationally taxing, and predictive modeling approaches are indispensable. With all these and future efforts, we envision GaN to become the next Si for electronics.

Emerging GaN technologies for power, RF, digital, and quantum computing applications: Recent advances and prospects

Traction inverter has been the subject of many studies due to its essential role in the proper performance of the drive system. With the recent trend in increasing the input voltage in battery-powered electric vehicles, multilevel inverters have been proposed in the literature as a promising substitute for conventional two-level traction inverters. A critical aspect of utilizing multilevel structures is employing proper control and modulation techniques. The control system structure must be capable of handling a number of key issues, like capacitor voltage balancing and equal power loss sharing, which arise in multilevel topologies. This paper presents a review of the present-day traction drive systems in the industry, control and modulation techniques for multilevel structures in the inverters, as well as the principal challenges that need to be addressed in the control stage of the multilevel traction inverter. A comparison has been made between different methods based on the most important criteria and requirements of the traction drive system. Finally, future trends in this application are presented and some suggestions have been made for the next generation of traction drives.

A Review of Modulation and Control Techniques for Multilevel Inverters in Traction Applications

The main purpose of this article is to provide an instructive review of the technological challenges hindering the road toward more electric powertrains in aircraft. Hybrid, all-electric, and turboelectric powertrain architectures are discussed as possible fuel consumption and weight reduction solutions. Among these architectures, the short-term implementation of hybrid and all-electric architectures is limited, particularly for large-capacity aircraft due to the low energy/power density levels achievable by state-of-the-art electrical energy storage systems. Conversely, turboelectric architectures with advanced distributed propulsion and boundary layer ingestion are set to lead the efforts toward more electric powertrains. At the center of this transition, power converters and high-power density electric machines, i.e., electric motors and generators, and their corresponding thermal management systems are analyzed as the key devices enabling the more electric powertrain. Moreover, to further increase the fuel efficiency and power density of the aircraft, the benefits and challenges of implementing higher voltage powertrains are described. Lastly, based on the findings collected in this article, the projected roadmap toward more electric aircraft powertrains is presented. Herein, the individual targets for each technology, i.e., batteries, electric machines, and power converters, and how they translate to future aircraft prototypes are illustrated.

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Toward more electric powertrains in aircraft: Technical challenges and advancements

At present, the energy transition is leading to the replacement of large thermal power plants by distributed renewable generation and the introduction of different assets. Consequently, a massive deployment of power electronics is expected. A particular case will be the devices destined for urban environments and smart grids. Indeed, such applications have some features that make wide bandgap (WBG) materials particularly relevant. This paper analyzes the most important features expected by future smart applications from which the characteristics that their power semiconductors must perform can be deduced. Following, not only the characteristics and theoretical limits of wide bandgap materials already available on the market (SiC and GaN) have been analyzed, but also those currently being researched as promising future alternatives (Ga2O3, AlN, etc.). Finally, wide bandgap materials are compared under the needs determined by the smart applications, determining the best suited to them. We conclude that, although SiC and GaN are currently the only WBG materials available on the semiconductor portfolio, they may be displaced by others such as Ga2O3 in the near future.

https://www.mdpi.com/2079-9292/10/6/677/pdf

Role of Wide Bandgap Materials in Power Electronics for Smart Grids Applications

Review—Radiation Damage in Wide and Ultra-Wide Bandgap Semiconductors

Gallium Nitride High Electron Mobility Transistors (GaN HEMTs) enable higher efficiency, higher power density, and smaller passive components resulting in lighter, smaller and more efficient electrical systems as opposed to conventional Silicon (Si) based devices. This paper investigates the detailed benefits of using GaN devices in transportation electrification applications. The material properties of GaN including the applications of GaN HEMTs at different switch ratings are presented. The challenges currently facing the transportation industry are introduced and possible solutions are presented. A detailed review of the use of GaN in the Electric Vehicle (EV) powertrain is discussed. The implementation of GaN devices in aircraft, ships, rail vehicles and heavy-duty vehicles is briefly covered. Future trends of GaN devices in terms of cost, voltage level, gate driver design, thermal management and packaging are investigated.

/pdf/current-status-and-future-trends-of-gan-hemts-in-electrified-13003y1cgy.pdf

Current Status and Future Trends of GaN HEMTs in Electrified Transportation

With the aim towards lighter and more efficient electrical systems in future aircraft, design of DC/DC converters with high efficiency, power density and improved thermal management becomes necessary. This paper investigates the detailed design of isolated bidirectional DC/DC converters for more electric aircraft (MEA). Use of wide bandgap (WBG) devices to enhance system efficiency is considered. A transformer optimization technique based on switching frequency for different converter topologies is investigated. The control strategy of the discussed configurations are verified in the PLECS simulation environment. Dual active bridge (DAB), input-series output-parallel (ISOP), neutral point clamped (NPC) and active neutral point clamped (ANPC) converters are considered to exploit benefits offered by WBG devices for MEA. A comparison is performed in terms of efficiency, thermal management, power density and electromagnetic interference (EMI). The results indicate that the ANPC converter is better for efficiency, thermal management and power density. The DAB converter showed similar results to the ISOP with the DAB yielding higher efficiency. The NPC and ANPC configurations resulted in the best EMI performance. The NPC converter proved to be the least effective solution with regard to efficiency, thermal management and power density.

/pdf/comparison-of-isolated-bidirectional-dc-dc-converters-using-4v35y4s7gc.pdf

Comparison of Isolated Bidirectional DC/DC Converters Using WBG Devices for More Electric Aircraft

In this article, we propose an optimization approach targeting rms current minimization in a dual active bridge (DAB) converter controlled by triple-phase-shift modulation. The proposed technique overcomes the drawbacks in the existing optimization solutions, namely, the high complexity of the time-domain optimization and the low accuracy of the fundamental harmonic minimization. A finite-component harmonic model is employed in the optimization approach to calculate the current harmonic values in the converter. The total rms current is approximated as the summation of dominant harmonics using the harmonic model. A numerical assessment technique is also proposed in this research that guarantees the accuracy of the adopted harmonic model. The proposed method ensures that the harmonic approximation error is less than a certain level over the operating range. The converter's optimal parameters are calculated through a standard nonlinear optimization procedure. The results are verified in the PLECS simulation environment and experimentally validated on a <inline-formula><tex-math notation="LaTeX">$5{\rm{\ kW}}$</tex-math></inline-formula> DAB converter. The prototype input and output voltage ranges are <inline-formula><tex-math notation="LaTeX">$600{\rm{\ V}} - 800{\rm{\ V}}$</tex-math></inline-formula> and <inline-formula><tex-math notation="LaTeX">$200{\rm{\ V}} - 450{\rm{\ V}}$</tex-math></inline-formula>, respectively.

RMS Current Minimization in a SiC-Based Dual Active Bridge Converter Using Triple-Phase-Shift Modulation

The powertrain voltages in battery electric vehicles (BEVs) have witnessed an upward trend due to advantages such as reduced runtime losses and extremely high DC fast charging power levels; aiding in reduced range anxiety and lower battery charging duration. This trend requires original equipment manufacturers (OEMs) to re-assess the design of electronic sub-assemblies (ESAs). Due to newly released DC fast charging standards, there are implications on the on-board charger (OBC), which is one of the ESAs in a BEV. This paper performs a comprehensive review of identifying system-level and use-case related challenges in transitioning on-board chargers to higher voltages compared to state-of-the-art, while considering the impact of newly introduced DC fast charging standards like Megawatt Charging Systems (MCS) and ChaoJi/ CHAdeMO 3.0. The existing research in academia and proof-of-concept designs compatible for high-voltage on-board charging sub-systems, such as the power factor correction (PFC) and isolated DC-DC conversion stages is consolidated. Due to the demand for integration driven by cost-optimization targets, single-stage, traction-integrated, and auxiliary power unit (APU) integrated on-board chargers are discussed. Finally, the disparity between state-of-the-art technology and future requirements is defined to establish challenges and the direction of future research areas.

https://ieeexplore.ieee.org/ielx7/8782709/8932554/10058538.pdf

On-Board Chargers for High-Voltage Electric Vehicle Powertrains: Future Trends and Challenges

In this paper, a new seven-level Voltage Source Converter (VSC) is proposed for medium-voltage (MV) applications. The new configuration is compared to other seven-level converter topologies. The proposed converter has fewer number of components compared to existing seven-level topologies. All switches have the same voltage rating. The operation of the proposed topology is investigated in detail. A Space Vector Modulation (SVM) technique is developed to control the voltages of the flying capacitors. Performance of the proposed converter is verified at both steady-state and transient operating conditions in MATLAB/Simulink environment.

Niloufar Keshmiri

Papers

Current Status and Future Trends of GaN HEMTs in Electrified Transportation

Comparison of Isolated Bidirectional DC/DC Converters Using WBG Devices for More Electric Aircraft

RMS Current Minimization in a SiC-Based Dual Active Bridge Converter Using Triple-Phase-Shift Modulation

On-Board Chargers for High-Voltage Electric Vehicle Powertrains: Future Trends and Challenges

A New 7-Level Voltage Source Converter for Medium-Voltage Application