The transition to electric road transport technologies requires electric traction drive systems to offer improved performances and capabilities, such as fuel efficiency (in terms of MPGe, i.e., miles per gallon of gasoline-equivalent), extended range, and fast-charging options. The enhanced electrification and transformed mobility are translating to a demand for higher power and more efficient electric traction drive systems that lead to better fuel economy for a given battery charge. To accelerate the mass-market adoption of electrified transportation, the U.S. Department of Energy (DOE), in collaboration with the automotive industry, has announced the technical targets for light-duty electric vehicles (EVs) for 2025. This article discusses the electric drive technology trends for passenger electric and hybrid EVs with commercially available solutions in terms of materials, electric machine and inverter designs, maximum speed, component cooling, power density, and performance. The emerging materials and technologies for power electronics and electric motors are presented, identifying the challenges and opportunities for even more aggressive designs to meet the need for next-generation EVs. Some innovative drive and motor designs with the potential to meet the DOE 2025 targets are also discussed.

Electric Drive Technology Trends, Challenges, and Opportunities for Future Electric Vehicles

Wide-bandgap (WBG) power semiconductor devices have become increasingly popular due to their superior characteristics compared to their Si counterparts. However, their fast switching speed and the ability to operate at high frequencies brought new challenges, among which the electromagnetic interference (EMI) is one of the major concerns. Many works investigated the structures of WBG power devices and their switching performance. In some cases, the conductive or radiated EMI was measured. However, the EMI-related topics, including their influence on noise sources, noise propagation paths, EMI reduction techniques, and EMC reliability issues, have not yet been systematically summarized for WBG devices. In this article, the literature on EMI research in power electronics systems with WBG devices is reviewed. Characteristics of WBG devices as EMI noise sources are reviewed. EMI propagation paths, near-field coupling, and radiated EMI are surveyed. EMI reduction techniques are categorized and reviewed. Specifically, the EMI-related reliability issues are discussed, and solutions and guidelines are presented.

A Survey of EMI Research in Power Electronics Systems With Wide-Bandgap Semiconductor Devices

A large number of factors such as the increasingly stringent pollutant emission policies, fossil fuel scarcity and their price volatility have increased the interest towards the partial or total electrification of current vehicular technologies. These transition of the vehicle fleet into electric is being carried out progressively. In the last decades, several technological milestones have been achieved, which range from the development of basic components to the current integrated electric drives made of silicon (Si) based power modules. In this context, the automotive industry and political and social agents are forcing the current technology of electric drives to its limits. For example, the U.S Department of Energy’s goals for 2020 include the development of power converter technologies with power densities higher than 14.1 kW/kg and efficiencies greater than 98%. Additionally, target price of power converters has been set below $3.3/kW. Thus, these goals could be only achieved by using advanced semiconductor technologies. Wide-bandgap (WBG) semiconductors, and, most notably, silicon carbide (SiC) based power electronic devices, have been proposed as the most promising alternative to Si devices due to their superior material properties. As the power module is one of the most significant component of the traction power converter, this work focuses on an in-deep review of the state of the art concerning such element, identifying the electrical requirements for the modules and the power conversion topologies that will best suit future drives. Additionally, current WBG technology is reviewed and, after a market analysis, the most suitable power semiconductor devices are highlighted. Finally, this work focuses on practical design aspects of the module, such as the layout of the module and optimum WBG based die parallelization, placement and Direct Bonded Copper (DBC) routing.

Power module electronics in HEV/EV applications: New trends in wide-bandgap semiconductor technologies and design aspects

With growing interests in low-inductance silicon carbide (SiC)-based power module packaging, it is vital to focus on system-level design aspects to facilitate easy integration of the modules and reap system-level benefits. To effectively utilize the low-inductance modules, busbar and interconnects should also be designed with low stray inductances. A holistic investigation of the flux path and flux cancellations in the module-busbar assembly, which can be treated as differentially coupled series inductors, is thus mandatory for a system-level design. This article presents a busbar design, which can be adopted to effectively integrate the CREE’s low-inductance 1.2-/1.7-kV SiC power modules. This article also proposes a novel measurement technique to measure the inductance of the module-busbar assembly as a whole rather than deducing it from individual components. The inductance of the overall commutation loop of the inverter that encompasses the SiC power module, interconnects, and printed circuit board (PCB) busbar has been estimated using finite-element analysis (FEA). Insights gained from FEA provided the guidelines to decide the placement of the decoupling capacitors in the busbar to minimize the overall commutation loop inductance from 12.8 to 7.4 nH, which resulted in a significant reduction in the device voltage overshoot. The simulation results have been validated through measurements using an impedance analyzer (ZA) with less than 5% difference between the extracted loop inductance from FEA and measurements. The busbar design study and the measurement technique discussed in this article can be easily extended to other power module packages. Finally, the 135-kW inverter has been compared to a similar high-power inverter utilizing a laminated busbar to highlight the performance of the former.

Estimation, Minimization, and Validation of Commutation Loop Inductance for a 135-kW SiC EV Traction Inverter

The main objective of the article is to provide a thorough review of currently used AC-DC converters for alkaline and proton exchange membrane (PEM) electrolyzers in power grid or wind energy conversion systems. Based on the current literature, this article aims at emphasizing the advantages and drawbacks of AC-DC converters mainly based on thyristor rectifier bridges and chopper-rectifiers. The analysis is mainly focused on the current issues for these converters in terms of specific energy consumption, current ripple, reliability, efficiency, and power quality. From this analysis, it is shown that thyristors-based rectifiers are particularly fit for high-power applications but require the use of active and passive filters to enhance the power quality. By comparison, the association combination of the chopper-rectifier can avoid the use of bulky active and passive filters since it can improve power quality. However, the use of a basic chopper (i.e., buck converter) presents several disadvantages from the reliability, energy efficiency, voltage ratio, and current ripple point of view. For this reason, new emerging DC-DC converters must be employed to meet these important issues according to the availability of new power switching devices. Finally, based on the authors’ experience in power conversion for PEM electrolyzers, a discussion is provided regarding the future challenges that must face power electronics for green hydrogen production based on renewable energy sources.

https://hal.archives-ouvertes.fr/hal-02733976/document

AC-DC Converters for Electrolyzer Applications: State of the Art and Future Challenges

The near magnetic field emitted from magnetic components may generate electromagnetic interference (EMI) and degrade EMI filter's performance. This article discussed the near magnetic field emission from toroidal inductors. The emission mechanisms are analyzed for different inductor winding structures with either common-mode (CM) or differential-mode (DM) excitation. The winding structures with low near magnetic field emission are identified. A CM inductor structure is proposed to improve inductor's high-frequency CM performance and greatly reduce its near magnetic field emission due to DM currents. The improvements are achieved with a small extra toroid. The proposed structure can also increase CM inductor's DM inductance for DM noise reduction at the expense of a reduced DM saturation current. To avoid saturation, a design procedure is developed for the proposed CM inductor to achieve desired CM inductance, minimized near magnetic field emission, high DM inductance, and optimal magnetic flux density. Three-dimensional (3-D) finite-element analysis models were developed and experiments were conducted to validate the developed theory and techniques. EMI measurement results show that the proposed CM inductor has a better performance for both DM and CM noise reduction than a conventional CM inductor.

Analysis and Reduction of the Near Magnetic Field Emission From Toroidal Inductors

This article first developed an inductance model that includes the parasitic mutual inductance between parallel current path segments for SiC multichip power modules. Based on the developed model, the SiC multichip module's transient response was analyzed, important parasitic inductances were identified. The layout was improved based on the transient analysis. The improved package layout can reduce the parasitic inductance without increasing the fabrication difficulty. Experiments were conducted to validate the reduction of parasitic inductances. The parasitic ringing and the crosstalk effect were significantly reduced with the proposed technique. The thermal performance was also improved with the proposed layout.

Parasitic Inductance Modeling and Reduction for Wire-Bonded Half-Bridge SiC Multichip Power Modules

Wide band gap (WBG) power semiconductor devices have been increasingly desirable due to their superior characteristics compared to their Si counterparts. However, their faster switching speed and abilities to operate at higher frequency than Si devices have brought new challenges, among which Electromagnetic interference (EMI) issue is one of the major concerns. EMI issues in WBG device applications had been reported in many papers. However, package layout determined characteristics has not yet been connected to electromagnetic compliance (EMC) analysis. In this paper, characteristics of WBG power devices as EMI noise sources are investigated, package design considerations that could reduce EMI are reviewed.

An Overview of Wide Bandgap Power Semiconductor Device Packaging Techniques for EMI Reduction

The parasitic inductance in the current commutation loop (CCL) could cause current and voltage oscillations during switching transient, increase switching loss, EMI and voltage stress on power semiconductor devices. These undesirable features intensify with the use of Wide Bandgap (WBG) devices due to increased switching speed and lower on-resistance. In this paper, the parasitic inductance of the current commutation loop is modeled with Partial Element Equivalent Circuit (PEEC) method for SiC multichip module. Different from other studies, the mutual inductance between paralleled branches are thoroughly analyzed and included in the model. As shown in Finite Element Analysis (FEA) simulation and experiment measurement, the mutual inductance has significant influence on the accuracy of the model. A wire bonded package layout is then proposed for SiC multichip half bridge modules that could reduce parasitic inductance without increasing fabrication difficulty. The effectiveness of the developed structure is verified with 3D FEA simulation and experiment.

Boyi Zhang

Papers

A Survey of EMI Research in Power Electronics Systems With Wide-Bandgap Semiconductor Devices

Analysis and Reduction of the Near Magnetic Field Emission From Toroidal Inductors

Parasitic Inductance Modeling and Reduction for Wire-Bonded Half-Bridge SiC Multichip Power Modules

An Overview of Wide Bandgap Power Semiconductor Device Packaging Techniques for EMI Reduction

Parasitic Inductance Modeling and Reduction for a Wire Bonded Half Bridge SiC MOSFET Multichip Power Module