Search results for "tolerance"
showing 10 items of 956 documents
Compact instrumentation for radiation tolerance test of flash memories in space environment
2010
Aim of this work is the description of a test equipment, designed to be integrated on board of a microsatellite, able to investigate the radiation tolerance of non-volatile memory arrays in a real flight experiment. An FPGA-based design was adopted to preserve a high flexibility degree. Besides standard Program/Read/Erase functions, additional features such as failure data screening and latch-up protection have been implemented. The instrument development phase generated, as a by-product, a non-rad-hard version of the instrument that allowed performing in-situ experiments using 60Co and 10 MeV Boron irradiation facilities on Ground. Preliminary measurement results are reported to show the i…
A Comparative Analysis of the Reliability of Simple and Two-Level Checkpointing Techniques in two Different Distributed Industrial Control System Arc…
2003
In Distributed industrial control systems it is necessary to guarantee certain reliability level. In this sense, Checkpointing and Rollback techniques offer interesting possibilities to achieve fault tolerance without appreciable cost and complexity increment. Several Checkpointing techniques have been proposed. Most of them suppose the presence of stable storage in the system. But distributed industrial control systems usually do not dispose of this kind of storage. So, another storage strategy has to be employed. If Checkpoints were locally stored (Simple Checkpointing), the system tolerates only transient faults. If Checkpoints were locally, at the same node, and, additionally, at anothe…
DC link voltage swinging and load current unbalance in fault tolerant VSI. overview and compensation strategies
2015
The topic of this paper is the discussion on the performance of a three-phase fault tolerant inverter with particular attention to the underrated aspect of current unbalances occurring due to the DC link voltage fluctuates after the inverter reconfiguration. Capacitor voltage unbalance affects not only the average output voltage of the inverter, but also its performance. In fact, the inverter performance depends on the fluctuating DC-link voltage components rather than on the average DC-link voltage. After a brief analysis of the voltage fluctuation phenomena resulting from fault tolerant configuration and their effect on load current unbalance, the Authors consider different compensating p…
Reducing DC Link Voltage Unbalance in a Fault-Tolerant Inverter
2014
Today, continuous working of power inverter drives is mandatory for several applications. Damages to materials, machines or even risks to human life have to be absolutely avoided. In the literature, fault-tolerant algorithms and architectures to achieve a successful fault handling are investigated. Researchers aim at reducing the number and cost of additional components, improving at the same time the inverter performances under postfault conditions. Cost, post-fault power derating and increasing distortion are usually conflicting requirements. In this paper, a fault-tolerant three phase inverter is presented. A reconfigurable architecture and a novel fault-tolerant algorithm is designed to…
Development of Diagnostic Systems for the Fault Tolerant Operation of Micro-Grids
2010
The progressive penetration level of Distributed Generation (DG) is destined to cause deep changes in the existing distribution networks no longer considered as passive terminations of the whole electrical system. A possible solution is the realization of small networks, namely the Micro-Grids, reproducing in themselves the structure of the main production and distribution of the electrical energy system. In order to gain an adequate reliability level of the micro-grids the individuation and the management of the faults with the goal of maintaining the micro-grid operation (fault tolerant operation) is quite important. In the present paper after the introduction of the aims of several diagn…
A review of multiple faults diagnosis methods in Voltage Source Inverters
2015
This paper examines, as in short review, the methods of diagnosis of simple and multiple faults on Voltage Source Inverter (VSI). The methods examined here are essentially based on the inspection of the load currents. Some of these diagnosis methods are characterized by low computational effort, other for a better reliability avoiding faultless positive tests. Some solutions are characterized by a share of these benefits while others prefer an enforcement of trustworthiness, in spite of the lower calculation amount. The analysis of the technical literature, certainly, offers a glimpse about the creation of new algorithms and significant advances for the future.
A Geometrical Simple Approach for Power Silicon Devices Fault Detection and Fault-Tolerant Operation of a Voltage Source Inverter
2012
Fault-tolerant converters have been widely investigated for years and nowadays an extensive technical literature on this field exists. This paper presents a novel fault detection algorithm based on a simple geometrical approach. In the algorithm analysis both the case of faults in single device and the lose of an entire inverter leg have been considered. False positive detections are avoided by considering a proper number of current samples. The proposed fault detection algorithm is characterized by simplicity, low computational and implementation effort with a consequent enough fast execution, easy control integration with the possibility to use it both in hardware in the loop systems and …
A suitable control technique for fault-tolerant converters in Distributed Generation
2011
The penetration of Distributed Generation (DG) in power systems is deeply changing the existing distribution networks which is becoming a very sophisticated and complex systems incorporating both active (generators) and passive systems (distribution systems, converters and loads). The necessary simplification can be obtained dealing with small networks, namely Micro-Grids, reproducing, in a smaller scale, the structure and the problems of large networks including production, transmission and distribution of the electrical energy. In order to achieve an adequate level of reliability, fault-tolerant operations of micro-grids become very important. This result can be achieved only using power …
Improved Planning In-Service Inspections of Fatigued Aircraft Structures Under Parametric Uncertainty of Underlying Lifetime Models
2014
Certain fatigued structures must be inspected in order to detect fatigue damages that would otherwise not be apparent. A technique for obtaining optimal inspection strategies is proposed for situations where it is difficult to quantify the costs associated with inspections and undetected failure. For fatigued structures for which fatigue damages are only detected at the time of inspection, it is important to be able to determine the optimal times of inspection. Fewer inspections will lead to lower fatigue reliability of the structure upon demand, and frequent inspection will lead to higher cost. When there is a fatigue reliability requirement, the problem is usually to develop an inspection…
A General Mathematical Model for non-Redundant Fault-Tolerant Inverters
2011
Industrial systems able to release trusted services is an integrated concept that resumes the attributes of availability, reliability, safety, integrity, and maintainability. In power electronics this can be aimed via the introduction of fault tolerant architectures. While In the past technical literature the mathematical modeling problem for non-redundant converters was fronted studying separately the cases of fault leg by leg, in this paper a general model able to include the three possible cases of leg faults with a unique set of equation is introduced and discussed. The same model allows to evaluate the DC Link transient and steady state evolution and also allows to develop with much ea…