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

Research on high voltage (HV) silicon carbide (SiC) power semiconductor devices has attracted much attention in recent years. This paper overviews the development and status of HV SiC devices. Meanwhile, benefits of HV SiC devices are presented. The technologies and challenges for HV SiC device application in converter design are discussed. The state-of-the-art applications of HV SiC devices are also reviewed.

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Overview of high voltage sic power semiconductor devices: development and application

This paper presents a novel compact circuit combining function of gate control and voltage balancing for series-connected silicon carbide (SiC) metal–oxide–semiconductor field-effect transistor (MOSFET) Two series-connected SiC MOSFETs with the proposed circuit only require a single standard gate driver to achieve the gate control and voltage balancing during both steady-state and switching transition Moreover, the proposed circuit is only composed of ten passive components Therefore, the proposed circuit provides a low-cost and highly reliable method to increase the blocking voltage of the SiC MOSFET The operation principles of the proposed circuit are theoretically analyzed In addition, the high-blocking-voltage device is not only required in switching-mode power supply (SMPS) but also in dc-breaker applications The proposed circuit is then modified to make it suitable to the dc-breaker applications The simulation and experimental results validate the effectiveness and superiority of the proposed circuit in both SMPS and dc-breaker applications

A Compact Gate Control and Voltage-Balancing Circuit for Series-Connected SiC MOSFETs and Its Application in a DC Breaker

While the use of power electronics based Smart Transformer (ST) is becoming a reality in traction applications, and it has been considered as an interesting option for interfacing different transmission systems, the possibility to use it in distribution systems is still considered futuristic. Replacing primary distribution transformers with ST can lead to more flexible handling of the distribution feeders, while replacing secondary distribution transformers can allow decoupling of distribution network. This paper reviews different power converter solutions for the ST focusing on modularity, control and communication needs, to meet high reliability requirements. Five topologies for the ST are considered and compared.

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Review of modular power converters solutions for smart transformer in distribution system

This paper presents a thorough characterization of 10 kV SiC mosfet power modules, equipped with third-generation mosfet chips and without external free-wheeling diodes, using the inherent SiC mosfet body-diode instead. The static performance (e.g., I DS– V DS , I DS– V GS, C – V characteristics, leakage current, body-diode characteristics) is addressed by measurements at various temperatures. Moreover, the power module is tested in a simple chopper circuit with inductive load to assess the dynamic characteristics up to 7 kV and 120 A. The SiC mosfet power module exhibits an on-state resistance of 40 mΩ at room-temperature and leakage current in the range of 100 nA, approximately one order of magnitude lower than that of a 6.5 kV Si-IGBT. The power module shows fast switching characteristics with the turn-on (turn-on loss) and turn-off (turn-off loss) times of 130 ns (89 mJ) and 145 ns (33 mJ), respectively, at 6.0 kV supply voltage and 100 A current. Furthermore, a peak short-circuit current of 900 A and a short-circuit survivability time of 3.5 μ s were observed. The extracted characterization results could serve as input for power electronic converter design and may support topology evaluation with realistic system performance predictability, using SiC mosfet power modules in the energy transmission and distribution networks.

Assessment of 10 kV, 100 A Silicon Carbide mosfet Power Modules

The short-circuit behavior of power devices is highly relevant for converter design and fault protection. In this paper, the degradation during short circuit of a 10-kV 10-A 4H-SiC MOSFET is investigated at 6 kV dc-link voltage. The study aims to present the behavior of the device during short-circuit transients as it sustains increasing short-circuit pulses during its lifetime. As the short-circuit pulse length increases, degradation of the device can be observed in periodically performed characterizations. The initial degradation seems to be associated with the channel region, and continuous stressing leads to an overall increase in device on-state resistance at the end of the degradation study. Thermal simulation shows that the surface aluminum metalization reached its melting temperature and the top part of the device reaches temperatures above the rated junction temperature. Scanning electron microscope investigation shows aluminum reconstruction and cavities at the contact interface between the aluminum surface metalization and source contacts.

Short-Circuit Degradation of 10-kV 10-A SiC MOSFET

The recent developments in wide band-gap devices based GaN and SiC is showing a high impact on the PV-inverter technology, which is strongly influenced by efficiency, power density and cost. Besides the high efficiency of PV inverters, also the mechanical size, the compactness and simple structure have an important role in the cost reduction. To increase the efficiency of PV systems, most of solutions for PV inverters have moved to three-level (3L) structures reaching typical efficiencies of 98% due to low switching losses of 600V Si IGBT or MOSFET and reduced core losses in the filter. With the appearance of SiC 1200V MOSFETs, it becomes possible to return to more simple two-level (2L) structure with comparable efficiency but high potential to reduce the overall cost. This paper deals with a comparison study between a Si-based 3L-Diode Neutral Point Clamped (DNPC) and a SiC-based 2L-Full Bridge (FB) three-phase PV-inverter topologies in terms of efficiency, thermal loading distribution and costs. Moreover the above mentioned PV-inverters are built and tested in laboratory in order to validate the obtained results.

Wide-band gap devices in PV systems - opportunities and challenges

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Modular Multilevel Converter Control Strategy with Fault Tolerance

The short-circuit capability of a power device is highly relevant for converter design and fault protection. In this paper a 10kV 10A 4H-SiC MOSFET is characterized and its short circuit withstand capability is studied and analyzed at 6 kV DC-link voltage. The test setup for this study is also introduced as its design, especially the inductance in the switching loop, can affect the experimental results. The study aims to present insights specific to the device which are different from that of silicon (Si) based devices. During the short-circuit operation, MOSFET saturation current, ID,sat, increases for a few microseconds before decreasing gently. Degradation of the device can be observed at pulses longer than 5.9µs. The SiC MOSFET failed after-turn off, after a pulse of 8.6µs, due to an increase in the leakage current.

Short-circuit characterization of 10 kV 10A 4H-SiC MOSFET

Auxiliary source bond wires and connections are widely used to in the power module with paralleled MOSFETs or IGBTs. This paper investigates the working mechanism and the effects of the auxiliary source connections in multichip power modules. It reveals that the auxiliary source connections cannot totally decouple the power loop and the gate loop like how the Kelvin source connection does, because they are still in the loop of power source current. Three effects of the auxiliary source connection are investigated and analyzed: common source stray inductance reduction, transient drain-source current imbalance mitigation and influence on the steady state bond wire current distribution. Simulation and experimental results validate the working mechanism analysis and the effects of the auxiliary source connections.

Emanuel-Petre Eni

Papers

Short-Circuit Degradation of 10-kV 10-A SiC MOSFET

Wide-band gap devices in PV systems - opportunities and challenges

Modular Multilevel Converter Control Strategy with Fault Tolerance

Short-circuit characterization of 10 kV 10A 4H-SiC MOSFET

Effects of auxiliary source connections in multichip power module