Wide bandgap (WBG) device-based power electronics converters are more efficient and lightweight than silicon-based converters. WBG devices are an enabling technology for many motor drive applications and new classes of compact and efficient motors. This paper reviews the potential applications and advances enabled by WBG devices in ac motor drives. Industrial motor drive products using WBG devices are reviewed, and the benefits are highlighted. This paper also discusses the technical challenges, converter design considerations, and design tradeoffs in realizing the full potential of WBG devices in motor drives. There is a tradeoff between high switching frequency and other issues such as high dv/dt and electromagnetic interference. The problems of high common mode currents and bearing and insulation damage, which are caused by high dv/dt , and the reliability of WBG devices are discussed.

Wide Bandgap Devices in AC Electric Drives: Opportunities and Challenges

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

In recent decades, several factors such as environmental protection, fossil fuel scarcity, climate change and pollution have driven the research and development of a more clean and sustainable transport. In this context, several agencies and associations, such as the European Union H2020, the United States Council for Automotive Research (USCAR) and the United Nations Economic and Social Commission for Asia (UN ESCAP) have defined a set of quantitative and qualitative goals in terms of efficiency, reliability, power losses, power density and economical costs to be met by next generation hybrid and full electric vehicle (HEV/EV) drive systems. As a consequence, the automotive electric drives (which consists of the electric machine, power converter and their cooling systems) of future vehicles have to overcome a number of technological challenges in order to comply with the aforementioned technical objectives. In this context, this paper presents, for each component of the electric drive, a comprehensive review of the state of the art, current technologies, future trends and enabling technologies that will make possible next generation HEV/EVs.

Next generation electric drives for HEV/EV propulsion systems: Technology, trends and challenges

Wireless power transfer is a state-of-the-art technology with the advantage of convenience and flexibility, as well as the capability of enabling fully automated charging. With power transfer levels increasing beyond 100 kW, many technical and risk management challenges emerge. Instead of focusing on the progress review of wireless power transfer technology, this paper discusses the future challenges and risks for high power wireless charging for light-duty electric vehicles. Aiming at 200 kW or higher wireless power transfer, we discuss technology and risk management challenges in the area of electromagnetic safety, resonant frequency determination, and cybersecurity risks in detail. As potential solutions to overcome these challenges, the latest technologies with an emphasis on advanced shielding solutions and recent progress on SiC converters from both industrial and academic institutions are reviewed, and some perspectives and propositions are provided.

Challenges of future high power wireless power transfer for light-duty electric vehicles----technology and risk management

This paper presents the technological advancements of the electric vehicles (EVs) all over the world. The first emphasis is on the various types of the EVs along with the energy management strategies (EMSs). The EVs are equipped with different energy storage elements such as lithium-ion batteries, super capacitors (SCs) and fuel cells (FCs). Hence, it is important to optimize the power split between the various energy storage systems (ESSs) under the complex driving conditions. The second imperative aspect is the utilization of the energy efficient wide bandgap (WBG) semiconductor technology. The WBG materials present the superior properties like wide bandgap, high saturated drift velocity and high critical breakdown field. This has led a path for the development of SiC and GaN based power semiconductor devices (PSDs). However, this paper mainly focuses on the utilization of the SiC devices for the EV applications. The substantial features of the various SiC devices are presented along with the performance aggrandization methods. Furthermore, this paper presents the updated survey and various performance measures of the SiC based power converter topologies. It also emphasizes the necessity of energy optimization for the EV charging systems. On the other hand, the burning issues associated with the SiC power modules other than the power converters are explored in detail. This extensive literature survey provides insightness for the design and research engineers in view of fulfilling the research gaps between the current and the desired targets. 

A review on energy efficient technologies for electric vehicle applications

A SiC-based high power density (34 kW/L) Electric vehicle (EV) traction inverter is developed for 105°C ambient temperature operation and 100 kW peak power output. The thermal properties of this high-temperature system are analyzed and the system is designed based on the thermal behavior of the switching devices. The liquid cooling system is designed and testing approach is proposed to estimate the maximum device die temperature. The key components, such as dc-link capacitors and dc busbar are designed and arranged to achieve high power density at high ambient temperature. The system prototype has been built and tested up to 60 kW continuous and 100 kW for 20 seconds, at 105°C ambient temperature and 65°C coolant temperature.

A SiC-Based 100 kW High-Power-Density (34 kW/L) Electric Vehicle Traction Inverter

Today, high power density, high efficiency, and wide-input-voltage operation are becoming increasingly important in power electronics for automotive applications. Active-clamp flyback (ACF) converters, showing a good tradeoff between simplicity and efficiency, are widely used in this industry. With benefits of small profile, low cost, and high reliability in mass production, the printed-circuit-board (PCB) embedding technique of magnetic components has attracted strong interest; however, magnetic cores can lose significant permeability due to the mechanical stress during this fabrication process; as a result, transformer properties, such as leakage inductance, coupling coefficient, and effective turns ratio change, affecting the input-voltage operating range as well as the working temperature. In this article, a detailed analysis of the design constraints of automotive ACF converters with a wide-input-voltage requirement is presented, focusing on the impact that the embedding process has on the transformer properties and the converter operation. Specifically, experiments are performed to investigate the permeability degradation effect, based on which correction factors are derived and added to the proposed design optimization process. A 10-W dual-output high power density (53.2 W/in3) integrated ACF converter prototype based on GaN devices operating at 1 MHz is built and demonstrated for this purpose.

Design of a Wide-Input-Voltage PCB-Embedded Transformer Based Active-Clamp Flyback Converter Considering Permeability Degradation

This paper presents the optimal design of a wide-input range, dual-output 10 W isolated active-clamp flyback (ACF) gate-drive power supply (GDPS) for high-temperature automotive applications Detailed analysis and comparison between Critical Conduction Mode (CRM) and Continuous Conduction Mode (CCM) are provided to select the operating mode A printed-circuit-board-embedded (PCB-embedded) transformer is carefully designed and it significantly improves the power density of the power supply A 10 W, GaN-based converter prototype switching at 1MHz has been developed to demonstrate the attained power density (532 W/in3), peak efficiency (897%), input voltage range (85 V to 28 V), maximum operating ambient temperature (105 °C at 85 V and 115°C at 28 V), and transformer input-output capacitance (97 pF)

The Optimal Design of A High-Temperature PCB-Embedded Transformer GaN-Based Gate-Drive Power Supply with A Wide-Input Range

This paper presents an overcurrent protection scheme based on parasitic inductance between the power source and the Kelvin source of the power module. A complete design process and comprehensive analysis of the overcurrent protection scheme, which can be applied generally, to any power module containing Kelvin source is shown. The protection circuit can be used to detect both very intense short-circuit fault (SC) and relatively slow overcurrent fault (OC), fault out of load for example. A 1.2 kV SiC MOSFET gate driver prototype with integrated overcurrent protection circuit is designed to verify the functionality of the protection method.

Yonghan Kang

Papers

A SiC-Based 100 kW High-Power-Density (34 kW/L) Electric Vehicle Traction Inverter

Design of a Wide-Input-Voltage PCB-Embedded Transformer Based Active-Clamp Flyback Converter Considering Permeability Degradation

The Optimal Design of A High-Temperature PCB-Embedded Transformer GaN-Based Gate-Drive Power Supply with A Wide-Input Range

Analysis and design of an overcurrent protection scheme based on parasitic inductance of SiC MOSFET power module