It is an exciting time for power systems as there are many ground-breaking changes happening simultaneously. There is a global concensus in increasing the share of renewable energy-based generation in the overall mix, transitioning to a more environmental-friendly transportation with electric vehicles as well as liberalizing the electricity markets, much to the distaste of traditional utility companies. All of these changes are against the status quo and introduce new paradigms in the way the power systems operate. The generation penetrates distribution networks, renewables introduce intermittency, and liberalized markets need more competitive operation with the existing assets. All of these challenges require using some sort of storage device to develop viable power system operation solutions. There are different types of storage systems with different costs, operation characteristics, and potential applications. Understanding these is vital for the future design of power systems whether it be for short-term transient operation or long-term generation planning. In this paper, the state-of-the-art storage systems and their characteristics are thoroughly reviewed along with the cutting edge research prototypes. Based on their architectures, capacities, and operation characteristics, the potential application fields are identified. Finally, the research fields that are related to energy storage systems are studied with their impacts on the future of power systems.

Comparative Review of Energy Storage Systems, Their Roles, and Impacts on Future Power Systems

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

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

The physical integration of power electronics and electric machines to form integrated motor drives (IMDs) eliminates the need for special enclosures and connecting cables in order to achieve mass, volume, and cost savings. The objective of this paper is to examine the future of integrated motor drive technology by first reviewing the history of IMD products from the 1960s to today, highlighting both the reasons for their success as well the significant technical obstacles that they had to overcome. Special attention is directed to the application of IMD technology to electric vehicle traction motor drives during the past 15 years. A long-term vision for IMDs is presented that calls for embedding the drive electronics directly inside the machine enclosure. In keeping with this vision, wide-bandgap (WBG) power semiconductor switches (SiC and GaN) offer exciting prospects for shrinking the size of power converters and simplifying their cooling requirements. New concepts for applying this WBG technology to IMDs are introduced, including revived interest in PWM current-source inverters. In the concluding section, a variety of other promising technologies are introduced that will be critical to realizing the full potential of integrated motor drives.

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The past, present, and future of power electronics integration technology in motor drives

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

Silicon carbide (SiC) MOSFETs and gallium nitride (GaN) high-electron mobility transistors are perceived as future replacements for Si IGBTs and MOSFETs in medium- and low-voltage drives due to their low conduction and switching losses. However, it is widely believed that the already significant conducted common-mode (CM) electromagnetic interference (EMI) emission of motor drives will be further exacerbated by the high-speed switching operation of these new devices. Hence, this paper investigates and quantifies the increase in the conducted CM EMI emission of a pulse width modulation inverter-based motor drive when SiC and GaN devices are adopted. Through an analytical approach, the results reveal that the influence of dv/dt on the conducted CM emission is generally limited. On the other hand, the influence of switching frequency is more significant. Lab tests are also conducted to verify the analysis.

Comparative Analysis on Conducted CM EMI Emission of Motor Drives: WBG Versus Si Devices

The purpose of this paper is to review three emerging technologies for grid-connected distributed energy resource in the power system: grid-connected inverters (GCIs), utility-scaled battery energy storage systems (BESSs), and vehicle-to-grid (V2G) application. The overview of GCIs focuses on topologies and functions. Different functions of utility-scaled BESS are introduced and a comprehensive review is provided for currently operating BESSs that are interconnected at the distribution level. Possible grid support functions of utility-scaled BESS are presented. This paper also presents the current electro-chemical based ESSs in the U.S. with different grid support functions. The V2G technology is introduced focusing on benefits for grid support. The state-of-the-art of GCI, BESS, and V2G technologies presents many opportunities and challenges that need to be addressed in the future.

Reviews on grid-connected inverter, utility-scaled battery energy storage system, and vehicle-to-grid application - challenges and opportunities

The purpose of this paper is to introduce a novel approach for modeling and studying an internal short circuit for interior permanent magnet machines. It is first necessary to develop an understanding of how the flux linkage in the machine behaves under an internal short circuit. This will enable the model of the machine to be developed into two parts. The first part corresponds to the expected model of a healthy machine, with disturbances coming from the second part. The second part involves all of the short-circuited turns fed by the currents of the machine. This form of the model opens the possibility to study the dynamics of the machine under short circuit conditions. The model also offers opportunities to develop failure detection techniques, being able to compensate the disturbances from the shorted turns in the windings.

Internal short-circuit modeling and analysis based on a dynamic model for interior permanent magnet synchronous machines

Wide bandgap devices are believed to replace Si devices in next generation drives, due to their superior characteristics such as low loss, high speed, and high temperature operating capabilities. However, the adoption of these devices also brings up new challenges on common mode voltage related issues, such as ground leakage current, common mode EMI emission, and bearing current. As a potential solution, this paper proposes a novel method for controlling the common mode voltage of motor drives during zero switching states by gating the two extra switches between DC bus and inverter in a regulated manner. The relationship between gating timing and common mode voltage amplitude during zero states are particularly investigated and quantified for the proposed approach.

Zero state common mode voltage control in motor drives through inverter topology

Battery energy storage systems (BESS) are considered to be an effective approach to mitigating the intermittency of renewable energy sources such as solar and wind The cost versus the benefit of the total energy stored and utilized needs to be evaluated for each BESS installation However, solely focusing on the cost of the energy saved is not sufficient to confirm the economic value The capital investment also needs to be considered for the BESS This paper provides a methodology for an economic analysis of a PV system both with and without a BESS These two systems are analyzed by the benchmark provided by the National Renewable Energy Laboratory (NREL) The study presented in this paper focuses on the procedure to determine the economic viability of a BESS system

Yujiang Wu

Papers

Comparative Analysis on Conducted CM EMI Emission of Motor Drives: WBG Versus Si Devices

Reviews on grid-connected inverter, utility-scaled battery energy storage system, and vehicle-to-grid application - challenges and opportunities

Internal short-circuit modeling and analysis based on a dynamic model for interior permanent magnet synchronous machines

Zero state common mode voltage control in motor drives through inverter topology

Methodology for Evaluating Potential Benefits and Economic Value of Residential Photovoltaic and Battery Energy Storage System