Stuck-at fault

About: Stuck-at fault is a research topic. Over the lifetime, 9707 publications have been published within this topic receiving 160254 citations.

Photovoltaic Systems Reliability Improvement by Real-Time FPGA-Based Switch Failure Diagnosis and Fault-Tolerant DC–DC Converter

Abstract: The increased penetration of photovoltaic (PV) systems in different applications with critical loads such as in medical applications, industrial control systems, and telecommunications has highlighted pressing needs to address reliability and service continuity. Recently, distributed maximum power point tracking architectures, based on dc–dc converters, are being used increasingly in PV systems. Nevertheless, dc–dc converters are one of the important failure sources in a PV system. Since the semiconductor switches are one of the most critical elements in these converters, a fast switch fault detection method (FDM) is a mandatory step to guarantee the service continuity of these systems. This paper proposes a very fast FDM based on the shape of the inductor current associated to fault-tolerant (FT) operation for boost converter used in PV systems. By implementing fault diagnosis and reconfiguration strategies on a single field-programmable gate array target, both types of switch failure (open- and short-circuit faults) can be detected, identified and handled in real time. The FDM uses the signal provided by the current sensor dedicated to the control of the system. Consequently, no additional sensor is required. The proposed FT topology is based on a redundant switch. The results of hardware-in-the-loop and experimental tests, which all confirm the excellent performances of the proposed approach, are presented and discussed. The obtained results show that a switch fault can be detected in less than one switching period, typically around 100 ms in medium power applications, by the proposed FDM.

PROOFS: a fast, memory efficient sequential circuit fault simulator

Abstract: A super-fast fault simulator for synchronous sequential circuits, called PROOFS, is described. PROOFS achieves high performance by combining all the advantages of differential fault simulation, single fault propagation, and parallel fault simulation, while minimizing their individual disadvantages. PROOFS minimizes the memory requirements, reduces the number of events that need to be evaluated, and simplifies the complexity of the software implementation. PROOFS requires an average of one fifth the memory required for concurrent fault simulation and runs 6 to 67 times faster on the ISCAS sequential benchmarks. >

System for locating faults and estimating fault resistance in distribution networks with tapped loads

Abstract: Both fault location and fault resistance of a fault are calculated by the present method and system. The method and system take into account the effects of fault resistance and load flow, thereby more accurately calculating fault resistance by taking into consideration the current flowing through the distribution network as well as the effect of fault impedance. A direct method calculates fault location and fault resistance directly while an iterative fashion method utilizes simpler calculations in an iterative fashion which first assumes that the phase angle of the current distribution factor Ds is zero, calculates an estimate of fault location utilizing this assumption, and then iteratively calculates a new value of the phase angle βs of the current distribution factor Ds and fault location m until a sufficiently accurate determination of fault location is ascertained. Fault resistance is then calculated based upon the calculated fault location. The techniques are equally applicable to a three-phase system once fault type is identified.

Further improvements on impedance-based fault location for power distribution systems

Abstract: In this study, further improvements regarding the fault location problem for power distribution systems are presented. The proposed improvements relate to the capacitive effect consideration on impedance-based fault location methods, by considering an exact line segment model for the distribution line. The proposed developments, which consist of a new formulation for the fault location problem and a new algorithm that considers the line shunt admittance matrix, are presented. The proposed equations are developed for any fault type and result in one single equation for all ground fault types, and another equation for line-to-line faults. Results obtained with the proposed improvements are presented. Also, in order to compare the improvements performance and demonstrate how the line shunt admittance affects the state-of-the-art impedance-based fault location methodologies for distribution systems, the results obtained with two other existing methods are presented. Comparative results show that, in overhead distribution systems with laterals and intermediate loads, the line shunt admittance can significantly affect the state-of-the-art methodologies response, whereas in this case the proposed developments present great improvements by considering this effect.

Integrated control and fault detection of HVAC equipment

Abstract: Fault detection is implemented on a finite state machine controller for an air handling system. The method employs data, regarding the system performance in the current state and upon a transition occurring, to determine whether a fault condition exists. The fault detection may be based on saturation of the system control or on a comparison of actual performance to a mathematical model of the air handling system. As a consequence, the control does not have to be in steady-state operation to perform fault detection.