Investigation of Fault-Tolerant Capabilities in an Advanced Three-Level Active T-Type Converter

A novel fault-tolerant three-level power converter topology, named advanced three-level active T-Type (A3L-ATT) converter, is introduced to increase the reliability of multilevel power converters used in safety-critical applications. This new fault-tolerant multilevel power converter is derived from the conventional T-Type converter topology. The topology has significantly improved the fault-tolerant capability under any open circuit or certain short-circuit faults in the semiconductor devices. In addition, under healthy condition, the redundant phase leg can be utilized to share overload current with other main legs, which enhances the overload capability of the converter. The conduction losses in the original outer devices can be reduced by sharing the load current with the redundant leg. Moreover, unlike other existing fault-tolerant power converters in the literature, full output voltages can be always obtained in this proposed A3L-ATT converter during fault-tolerant operation. A 13.5-kW ATT-A3L converter prototype was developed and constructed using silicon carbide MOSFETs. Simulation and experimental results were obtained to substantiate the theoretical claims of this new fault-tolerant power converter

Efficiency Improvement of Fault-Tolerant Three-Level Power Converters

Fault-tolerant power converters play a critical role in the transportation electrification. However, fault-tolerant operation, high efficiency, and low cost usually result in design criteria that have conflicting constraints and goals. The majority of the fault-tolerant power converter topologies presented in the literature confirm these conflicts. In this paper, three types of fault-tolerant neutral-point clamped (NPC) converters are investigated. Various modulation strategies are explored to reduce the losses of the redundant phase leg. The simulation and experimental results show that the Switching Frequency Optimal Phase opposition Disposition modulation strategy is the most effective approach in minimizing the losses in the redundant phase leg

Tolerance of Muslim beliefs and practices: Age related differences and context effects

Tolerant judgments of Muslims’ political rights and dissenting beliefs and practices by ethnic Dutch adolescents (12–18 years) were examined. Participants (N = 632) made judgments of different types of behaviors and different contexts in an experimental questionnaire study. As in other studies, tolerance was found to not be a global construct. Adolescents took into account various aspects of what they were asked to tolerate and the sense in which they should be tolerant. The type of actor, the nature of the social implication of the behavior, the underlying belief type, and the dimension of tolerance, all made a difference to the tolerant judgments. Additionally, the findings strongly suggest that tolerance judgments do not develop through an age-related stage-like sequence where an intolerant attitude is followed by tolerance. For females, there were no age differences, and older males were less tolerant than younger males. There were also gender differences with males being less tolerant for some types of behavior and females being less tolerant for behaviors that negatively affected Muslim females. Level of education had a positive effect on tolerance. The findings are discussed with reference to social-cognitive domain theory.