Sharif Digital Repository

This paper presents an experimental evaluation of the effectiveness of the Master/Checker (M/C) architecture in a 32-bit Pentium® processor system using both power-supply disturbance (PSD) fault injection and software-implemented fault injection (SWIFI) methods. A total of 6000 faults were injected in the Master processor to measure the error detection coverage of the Checker processor. The results of the experiments with PSD fault injection show that the error detection coverage of the M/C architecture is about 66.13%, which is not quite effective. This low coverage depends on the high rate of Master processor hangs because of voltage fluctuation. The coverage increased to about 99.73% when... 

A novel high-voltage direct current (HVdc) power supply which has no transformer or voltage multiplier circuit is presented and analyzed in this paper. This is made possible upon the diodes storage delay phenomenon. This proposed power supply is compact, lightweight, and low cost. Its basic structure includes a diode with a proper reverse recovery specification that plays the role of a step-up transformer in the conventional HVdc supplies and a high-voltage capacitor which stabilizes the output voltage. This structure has remarkable advantages over the conventional transformer-based HVdc supplies, such as compactness, a low ripple output, and a low-cost power supply. Performance of the... 

High-voltage power supplies (HVPSs) are widely used to supply vacuum tubes. The amount of delivered energy from the HVPS to the tube is an important issue during the vacuum arc in the tube. The conventional protection mechanism consists of a shunt crowbar which diverts the fault current from the tube to itself as a parallel path. The crowbar circuit is usually built of the devices without the turn-off capability. It is a drawback since the output of the power supply is shortened for a long time. Thus, the restoration time of these power supplies is excessive. This demerit can have detrimental effects on mission-critical applications. In this paper, the insulated-gate bipolar transistor... 

Short-circuit fault (SCF) detection is mandatory in a high voltage DC power supply (HVPS) to prevent fatal damage. The majority of converters employ a single sensor to detect the SCF. This attribute increases the interference vulnerability of the fault detection (FD) system in the presence of noise. Therefore, miss detections and false alarms are possible to occur. Miss detections and false alarms are harmful catastrophes in most applications. A commonly used method to suppress the noise impacts is using a low-bandwidth low-pass filter. However, the use of the low-bandwidth low-pass filter reduces the speed of FD due to the filter delay. This paper proposes a fast FD algorithm based on... 

Vacuum tubes are widely used for various applications. These vacuum tubes are supplied by high voltage power supplies. The amount of delivered energy from the high voltage power supply to the vacuum tube is an important issue during the vacuum arc in the tube. The protection mechanism consists of a shunt crowbar which diverts the fault current from the tube to itself as a parallel path. Detection of the vacuum arc is crucial and only one sensor is usually employed to detect the vacuum arc. This characteristic intensifies the interference susceptibility of the vacuum arc diagnosis system in a noisy environment. As a result of the noise, the arc detection system can report false alarms. False... 

High-voltage power supplies (HVPSs) are widely used to drive vacuum tubes, inherently susceptible to vacuum arc faults. Owing to the considerable cost of vacuum tubes, the HVPS should enjoy a reliable, fast protection mechanism. A common protection mechanism against vacuum arc faults is the shunt crowbar. The crowbar diverts the energy stored in the elements of the HVPS through itself as a parallel path, thereby protecting vacuum tubes from irrecoverable damages. Among all types of the shunt crowbar, the thyristor-based crowbar along with the fault current limiter (FCL) resistors attracts more attention because of its more reliable operation. The absence of the comprehensive design procedure... 

The idea of power electronic transformer (PET), which work with solid-state switches, have been considered noticeably recently. Every power electronic transformer has several parts which each of them needs its own reliable supply voltage. So the appropriate performance of a PET depends on the existence of various proper supply voltages. The distributed power supply (DPS), which can produce several different supply voltages simultaneously with various powers and high reliability, may be the optimum choice available for the supply of different modules of a PET. Additionally, distributed energy generation sources may be used as the alternative source for the PET which in that case it's... 

This paper presents a new self-powered hybrid electromagnetic damper that can mitigate vibration of a structure. The damper is able to switch between a power-regenerative passive mode and a semi-active mode depending on the power demand and capacity. The energy harvested in the passive mode due to suppression of vibration is employed to power up the sensing and electronic components necessary for the semi-active control. This provides a hybrid control capability that is autonomous in terms of its power requirement. The device mechanism and the circuitry that can realize this self-powered electromagnetic damper are described in this paper. The parameters that determine the device feasible...