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Fault detection and protection is an important design aspect for any power converter, especially in high-power high-voltage applications, where cost of failure can be high. The three-level dc-dc converter and its varied derivatives are attractive topologies in high-voltage high-power converter applications. The protection method can not only prevent the system failure against unbalanced voltage stresses on the switches, but also provide a remedy for the system as faults occur and save the remaining components. The three-level converter is subject to voltage unbalance in certain abnormal conditions, which can result in switch overvoltage and system failure. The reasons for the unbalanced voltage stresses are fully investigated and categorized. The solutions to each abnormal condition are introduced. In addition to the voltage unbalance, the three-level converters can be protected against multiple faults by the proposed protection method through monitoring the flying capacitor voltage. Phenomena associated with each fault are thoroughly analyzed and summarized. The protection circuit is simple and can be easily implemented, while it can effectively protect the three-level converters and its derivatives, which has been verified by the experiment with a three-level parallel resonant converter. [ABSTRACT FROM AUTHOR]

This paper describes the design and implementation of a prototype 30-kW (or 30-kJ/s) pulsed-power supply for capacitor charging. The system operates at 200-kHz maximum switching frequency, which is considerably higher than the conventional practice at this power level, leading to smaller passive components. A high power density of 143 \W/in^3 is achieved with the converter operating at a high ambient temperature of 65 ^\circ\C with 90 ^\circ\C cooling oil, by utilizing various technologies on topology, control, devices, passives, and thermal management. The experimental results demonstrate that the converter meets the performance requirements while achieving a high power density. [ABSTRACT FROM AUTHOR]

A SiC avalanche breakdown diode (ABD) having a nominal 1-kV breakdown voltage was fabricated to provide improved suppression of voltage transients induced during hard-switched turn-off of solid-state devices. Three SiC ABDs were pulsed 1000 times in an inductive load circuit at peak currents of over 100 A. Superior performance in peak pulse current, clamping voltage, and peak pulse power was seen, compared to the results of two series-connected commercial TVS devices, collectively having a comparable breakdown voltage. The transient thermal response of the SiC ABDs was calculated using a model for energy dissipation in short pulses. SiC ABD design parameters and test data were used to show that the reported performance of these devices was not related to package thermal impedance. [ABSTRACT FROM AUTHOR]

To demonstrate higher efficiency and more compact high-voltage power conversion systems, a 15 kV full-bridge rectifier module has been developed by the U.S. Army Research Laboratory. The module utilizes 15 kV, 3 A silicon carbide junction-barrier Schottky diodes manufactured by CREE Inc. In this paper, we will present the analyses, design, and characterization of this module using conventional materials and processes and introduce a novel technique to reduce electric field stress and associated failure modes. [ABSTRACT FROM AUTHOR]