• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.9
• /
• pp.1249-1254
• /
• 2013

A torque control algorithm suitable for detecting an open circuit failure in which one of the three phases is unable to supply power to a motor in the permanent magnet synchronous motor is presented in this paper. When the failure occurs in the inverter, the output torque of motor is restricted. A new method which is implemented by using only a processor algorithm internally without any hardware redundancy circuit is proposed. A simulation and experimental study is carried out with a three phase inverter system to show the validity of the proposed method.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2000.11a
• /
• pp.233-238
• /
• 2000

CNC machine tool is assembled by central processor, PLC(Programmable Logic Controller), and actuator. The sequential control of machine generally controlled by a PLC. The main fault occured at PLC in 3 control parts. In LC faults, operational fault is charged over 70%. This paper describes diagnosis model and data processing for remote monitoring and diagnosis system in machine tools with open architecture controller. Two diagnostic models based on the ladder diagram. Logical Diagnosis Model(LDM), Sequential Diagnosis Model(SDM), are proposed. Data processing structure is proposed ST(Structured Text) based on IEC1131-3. The faults from CNC are received message form open architecture controller and faults from PLC are gathered by sequential data.. To do this, CNC and PLC's logical and sequential data is constructed database.

• Proceedings of the KIPE Conference
• /
• 2010.07a
• /
• pp.452-453
• /
• 2010

This paper proposes a novel diagnosis scheme using Extend Kalman Filter (EKF), especially, in subject to the open-phase faults of the inverter switches. The stator resistances of PMSM are estimated by the EKF in real time. The proposed diagnosis scheme is implemented without any extra devices. Moreover, since it uses a simple algorithm by analyzing only estimated stator resistances of each phase, the detection speed becomes fast. The feasibility of the proposed fault diagnosis scheme is proved by several simulation and experimental results.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.9
• /
• pp.1583-1589
• /
• 2016

This paper proposes an improved spread spectrum time domain reflectometry (ISSTDR) using time-frequency correlation and reference signal elimination method in order to have more accurate fault determination and location detection than conventional (SSTDR) despite increased signal attenuation due to the long distance to cable fault location. The proposed method has a two-step process: the first step is to detect a peak location of the reference signal using time-frequency correlation analysis, and the second step is to detect a peak location of the correlation coefficient of the reflected signal by removing the reference signal. The proposed method was validated through comparison with existing SSTDR methods in open-and short-circuit fault detection experiments of low voltage power cables. The experimental results showed that the proposed method can detect correlation coefficients at fault locations accurately despite reflected signal attenuation so that cable faults can be detected more accurately and clearly in comparison to existing methods.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.32 no.3
• /
• pp.232-239
• /
• 2008

The position sensors used in a magnetic bearing system are desirable to provide some degree of fault-tolerance as the rotor position is necessary for the feedback control to overcome the open-loop instability. In this paper, we propose an inductive position sensor that can cope with a partial fault in the sensor. The sensor has multiple poles which can be combined to sense the in-plane motion of the rotor. When a high-frequency voltage signal drives each pole of the sensor, the resulting current in the sensor coil contains information regarding the rotor position. The signal processing circuit of the sensor extracts this position information. In this paper, we used the magnetic circuit model of the sensor that shows the analytical relationship between the sensor output and the rotor motion. The multi-polar structure of the sensor makes it possible to introduce redundancy which can be exploited for fault-tolerant operation. The proposed sensor is applied to a magnetically levitated turbo-molecular vacuum pump. Experimental results validate the fault-tolerance algorithm.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.3
• /
• pp.526-531
• /
• 2016

This paper presents an experimental study on the optimal settings for the selected DC fault relay (50F) to improve the operating performance for the high-speed circuit breaker on DC feeding system which ensure safety within rolling stock maintenance depot. In this study, current supplied to overhead contact wire was calculated on 1 ms interval to analyze the correction values of DC fault selective relay for the operation of current supply cutout. Particularly, standards for the accurate detection of accidents between an electric railway vehicle and the electric power facilities are shown by investigating the optimal correction values for detection of fault current, and the results indicated that it takes about 213 ms for the DC fault selective relay(50F) to fully open. In the future, the correction values of DC fault selective relay suggested in this paper will be used as the reference values of protective relay for the safe operation of DC electric railroad system such as urban railway.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2017.05a
• /
• pp.218-223
• /
• 2017

This paper deals with a fault diagnosis algorithm using the Kalman filter for a 75-ton Liquid Propellant Rocket Engine (LPRE). To design the Kalman filter, we linearized a non-linear simulation model of a 75-ton LPRE at an operating point, and checked the performance of the Kalman filter by comparing the measured values with estimated values of the states. Then, we artificially injected a fault of the turbopump efficiency into the simulation to confirm the performance of the fault diagnosis algorithm with the developed Kalman filter by comparing the variation of the residuals of the normal state with that of the fault cases.

• Proceedings of the KIEE Conference
• /
• 1987.07b
• /
• pp.1185-1187
• /
• 1987

Digital systems are increasingly being used in the ranges of many control engineering. The residue number system offers the possibility of high speed operation and error correction. The compact self-checking pulse-train residue arithmetic circuit is proposed. A fault tolerant digital filter is practically implemented using these proposed circuits.

• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.4
• /
• pp.168-178
• /
• 2002

The CNC machine toots has two kinds of fault. One is the fault due to degraded parts and the other is the fault due to operation disability. The phenomena of degradation is predictable but the operational fault is unpredictable because it occurred without any warning. The major faults of CNC machine tool are operational faults which are charged over 70%. This paper describes the model of remote service and the intelligent fault diagnosis system to diagnosis operational faults of CNC machine tools. To generalize fault diagnosis, two diagnosis models such as SF(Switching Function) and SSF(Step Switching Function) are proposed. The SF is static model and SSF is dynamic model for expression of fault. The SF and SSF model can be generated using SFG(Switching Function Generator) which is developed in this research. The three major operational faults such as emergency stop error, cycle start disability and machine ready disability are applied to experiment of fault modeling. To remote service of faults fur CNC machine tool, the web server and client system based internet are proposed as the suitable environment. The developed two technologies are implemented with the internal function of open architecture controller. The implemental results for two technologies are presented to validate the proposed scheme.

• KEPCO Journal on Electric Power and Energy
• /
• v.8 no.1
• /
• pp.43-48
• /
• 2022

Although the distribution system has been structured as complicated as a mesh in the past, the connection points for each line are always kept open, so that it is operated as a radial distribution system (RDS). For RDS, the line utilization rate is determined according to the maximum load on the line, and the utilization rate is usually kept low. In addition, when a fault occurs in the RDS, a power outage of about 3 to 5 minutes occurs until the fault section is separated, and the healthy section is transferred to another line. To improve the disadvantages of the RDS, research on the construction of a networked distribution system (NDS) that linking multiple lines is in progress. Compared to the RDS, the NDS has advantages such as increased facility utilization, load leveling, self-healing, increased capacity connected to distributed generator, and resolution of terminal voltage drop. However, when a fault occurs in the network distribution system, fault current can flow in from all connected lines, and the direction of fault current varies depending on the fault point, so a high-precision fault current direction determination method and high-speed communication are required. Therefore, in this paper, we propose an accurate fault current direction determination method by comparing the peak value polarity of the fault current in the event of a fault, and a communication-based protection coordination method using this method.