Silicon carbide (SiC) switching power devices (MOSFETs, JFETs) of 1200 V rating are now commercially available, and in conjunction with SiC diodes, they offer substantially reduced switching losses relative to silicon (Si) insulated gate bipolar transistors (IGBTs) paired with fast-recovery diodes. Low-voltage industrial variable-speed drives are a key application for 1200 V devices, and there is great interest in the replacement of the Si IGBTs and diodes that presently dominate in this application with SiC-based devices. However, much of the performance benefit of SiC-based devices is due to their increased switching speeds ( di/dt, dv/ dt), which raises the issues of increased electromagnetic interference (EMI) generation and detrimental effects on the reliability of inverter-fed electrical machines. In this paper, the tradeoff between switching losses and the high-frequency spectral amplitude of the device switching waveforms is quantified experimentally for all-Si, Si-SiC, and all-SiC device combinations. While exploiting the full switching-speed capability of SiC-based devices results in significantly increased EMI generation, the all-SiC combination provides a 70% reduction in switching losses relative to all-Si when operated at comparable dv/dt. It is also shown that the loss-EMI tradeoff obtained with the Si-SiC device combination can be significantly improved by driving the IGBT with a modified gate voltage profile.

An Experimental Investigation of the Tradeoff between Switching Losses and EMI Generation With Hard-Switched All-Si, Si-SiC, and All-SiC Device Combinations

Energy storage system (ESS) is an essential component of electric vehicles, which largely affects their driving performance and manufacturing cost. A hybrid energy storage system (HESS) composed of rechargeable batteries and ultracapacitors shows a significant potential for maximally exploiting their complementary characteristics. This study focuses on optimal HESS sizing of an example electric vehicle using a multi-objective optimization algorithm, with the overarching goal of reducing the ESS cost while prolonging battery life. To this end, a battery state-of-health model is incorporated to quantitatively investigate the impact of component sizing on battery life. The wavelet-transform-based power management algorithm is adopted to realize the power coordination between the batteries and ultracapacitors, in which the ultracapacitors are responsible for handling high-frequency power transients, whereas the batteries deal with average power leveling. The Urban Dynamometer Driving Schedule is used to represent real power demands.

Multiobjective Optimal Sizing of Hybrid Energy Storage System for Electric Vehicles

The higher voltage blocking capability and faster switching speed of silicon-carbide (SiC) mosfet s have the potential to replace Si insulated gate bipolar transistors (IGBTs) in medium-/low-voltage and high-power applications. In this paper, a state-of-the-art commercially available 325 A, 1700 V SiC mosfet module has been fully characterized under various load currents, bus voltages, and gate resistors to reveal their switching capability. Meanwhile, Si IGBT modules with similar power ratings are also tested under the same conditions. From the test results, several interesting points have been obtained: different to the Si IGBT module, the over-shoot current of the SiC mosfet module increases linearly with the increase of the load current and it has been explained by a model of the over-shoot current proposed in this paper; the induced negative gate voltage due to the complementary device turn- off (crosstalk effect) is more harmful to the SiC mosfet module than the induced positive gate voltage during turn- on when the gate off-voltage is –6 V; the maximum dv / dt and di / dt (electromagnetic interference) during switching transients of the SiC mosfet module are close to those of the Si IGBT module when the gate resistance is larger than 8 Ω but the switching loss of the SiC mosfet module is much smaller; the switching losses of the Si IGBT module are greater than those of the SiC mosfet module even when the gate resistance of the former is reduced to zero. An accurate power loss model, which is suitable for a three-phase two-level converter based on SiC mosfet modules considering the power loss of the parasitic capacitance, has been presented and verified in this paper. From the model, a 96.2% efficiency can be achieved at the switching frequency of 80 kHz and the power of 100 kW.

Performance Evaluation of High-Power SiC MOSFET Modules in Comparison to Si IGBT Modules

II. Eignungsprüfung § 5 Inhaltliche Anforderungen und Durchführung der Eignungsprüfung § 6 Prüfungsausschuss § 7 Prüfungskommission § 8 Bewertung der Prüfungsleistungen § 9 Anrechnung anderer Leistungen § 10 Wiederholung der Prüfung § 11 Zuteilung freier Studienplätze § 12 Rücktritt, Ausschluss von der Prüfung, Rücknahme von Zulassungsund Prüfungsbescheiden § 13 Zeitliche Begrenzung der Zulassung und Immatrikulation

근첨하 분절 골절단술을 병행한 iii급 양악 전돌증의 교정치료 증례

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 band-gap (WBG) field-effect devices are known to provide a system-level performance benefit compared to silicon devices when integrated into power electronics applications. However, the near-ideal features of these switching devices can also introduce unexpected behavior in practical systems due to the presence of parasitic elements. The occurrence of self-sustained oscillation is one such behavior that has not received adequate study in the literature. This paper provides an analytical treatment of this phenomenon by casting the switching circuit as an unintentional negative resistance oscillator. This treatment utilizes an established procedure from the oscillator design literature and applies it to the problem of power circuit oscillation. A simulation study is provided to identify the sensitivity of the model to various parameters, and the predictive value of the model is confirmed by experiment involving two exemplary WBG devices: a SiC vertical-channel JFET and a SiC lateral-channel MOSFET. The results of this study suggest that susceptibility to self-sustained oscillation is correlated to the available power density of the device relative to the parasitic elements in the circuit, for which wide band-gap devices, to include SiC and GaN transistors, are in a class approaching that of the radio frequency domain.

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Instability in Half-Bridge Circuits Switched With Wide Band-Gap Transistors

Owing to their very low intrinsic capacitance and on-resistance, silicon carbide FETs have been shown to produce poor dynamics in certain power electronics applications, particularly those based on the half-bridge configuration. This letter catalogs three separate phenomena that are observed in the context of such applications and provides a detailed treatment of the most troublesome of these behaviors: the occurrence of sustained oscillation at switch turn-off. This behavior is analyzed in the context of established oscillator design theory; both simulation and experimental results are shown to verify this analysis; and practical suggestions are made to application designers to manage this behavior.

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Stability Considerations for Silicon Carbide Field-Effect Transistors

Collision avoidance is a critical task in many applications, such as ADAS (advanced driver-assistance systems), industrial automation and robotics. In an industrial automation setting, certain areas should be off limits to an automated vehicle for protection of people and high-valued assets. These areas can be quarantined by mapping (e.g., GPS) or via beacons that delineate a no-entry area. We propose a delineation method where the industrial vehicle utilizes a LiDAR (Light Detection and Ranging) and a single color camera to detect passive beacons and model-predictive control to stop the vehicle from entering a restricted space. The beacons are standard orange traffic cones with a highly reflective vertical pole attached. The LiDAR can readily detect these beacons, but suffers from false positives due to other reflective surfaces such as worker safety vests. Herein, we put forth a method for reducing false positive detection from the LiDAR by projecting the beacons in the camera imagery via a deep learning method and validating the detection using a neural network-learned projection from the camera to the LiDAR space. Experimental data collected at Mississippi State University’s Center for Advanced Vehicular Systems (CAVS) shows the effectiveness of the proposed system in keeping the true detection while mitigating false positives.

LiDAR and Camera Detection Fusion in a Real-Time Industrial Multi-Sensor Collision Avoidance System

This paper describes the development of a dedicated electromagnetic interference (EMI) characterization platform for the evaluation of wide bandgap-based converters in ungrounded architectures of the type likely to be employed on the future shipboard systems. This platform is designed to support the characterization of wide-bandgap-based converters operating at switching frequencies of hundreds of kilohertz; with power levels up to 100 kVA and with expected emissions up to 100 MHz. To illustrate the capabilities of this platform, the conducted emissions of a SiC-based half-bridge converter are evaluated (with a focus on common-mode (CM) behavior), and a parametric study is conducted which considers variations in the impedance between the half-bridge module base plate and a representative grounding structure. The focus of this work is not only the half-bridge converter which serves as the preliminary test subject, but also rather the custom metrological setup used for characterization, which is designed to discover sensitivities to resonant paths so that the design guidelines for peripheral structures and EMI mitigating components can be developed in the future studies. One major contribution of this work is the discovery that the symmetry of the parasitic capacitances within the converter’s multichip power module is an important factor which significantly influences the CM conducted emissions of the half-bridge structure, which serves as a building block for more complex converter topologies.

Methodology for Characterization of Common-Mode Conducted Electromagnetic Emissions in Wide-Bandgap Converters for Ungrounded Shipboard Applications

This paper describes a new parameter estimation algorithm for a well-recognized electrical analogue battery model. The limited bandwidth characteristic of the electrical analogue battery model is introduced and discussed, on which the new parameter estimation algorithm is built. While a real battery system is non-linear and time variant, a truncated representation of the system is provided by a commonly studied non-physical "electrical analogue" battery model. However, the limited bandwidth characteristic of the electrical analogue battery model is often overlooked. The proposed algorithm starts by assessing a desired battery application, followed by modeling the battery according to the application bandwidth, and then estimating the model parameters using the sequential quadratic programming method. This approach recognizes and makes use of the limited bandwidth of the battery model by reconciling the approximation with the limited bandwidth required by the simulation. This approach has been experimentally verified on a 6.8 Ah Ultralife UBBL10 Lithium-ion battery module. Since this electrical analogue battery model is independent of the battery chemistry it is applicable to Lithium-ion, Nickel-Metal-Hydride (NiMH), and Lead-acid batteries, among others.

James Gafford

Papers

Instability in Half-Bridge Circuits Switched With Wide Band-Gap Transistors

Stability Considerations for Silicon Carbide Field-Effect Transistors

LiDAR and Camera Detection Fusion in a Real-Time Industrial Multi-Sensor Collision Avoidance System

Methodology for Characterization of Common-Mode Conducted Electromagnetic Emissions in Wide-Bandgap Converters for Ungrounded Shipboard Applications

A new parameter estimation algorithm for an electrical analogue battery model