• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.29 no.3
• /
• pp.61-68
• /
• 2015

When medium and large induction motors are driven by 2-level inverters with low switching frequency, induction motors provoke deteriorated performances resulted from large torque ripples, flux ripples, and large current distortion. Model predictive torque control(MPTC) for a fast torque control of induction motors is also suffered from large torque ripples when the induction motors are fed by 2-level inverters that are based on 6 active voltage vectors with low switching frequency restricted. To solve this problem, this paper proposes a new MPTC method based on both a 12 active voltage vector and an optimized duty ratio calculation. The proposed control strategy illustrates its effectiveness under the various operating conditions through simulation works.

• Journal of the Korean Society for Heat Treatment
• /
• v.17 no.2
• /
• pp.73-77
• /
• 2004

The efforts which increase the strength of the auto-body structure and decrease its weight lead to develop a new concept of part production systems, such as Post-Form Strengthening by induction heat treatment. In this study, several cold and hot-rolled sheet steels were used to find out optimum induction heat treatment conditions. After induction heat treatment, strength of heat-treated sheet steels was increased significantly compared with that of as-rolled steels. From these results, auto-body structure which has more light and safe has been made by using this induction hardening method.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.40-44
• /
• 2007

Light rail vehicle is optimized vehicle system for complex urban circumstance. LRT systems have many merits such as improve accuracy, speediness and safety. There are many LRT systems such as monorail, tram, automated guideway transit, linear induction motor propulsion and so on. These systems have operated in Japan and other advanced countries. In Korea, local government has many projects to apply the advanced LRT system. But there are no standardized specification, performance test specification, construction specification for monorail system, linear induction motor propulsion system, tram in Korea up to now. So, we need to establish of standardized to economical construction and safety. The linear induction motor system has been usually applied in Japan subway and ART(Advanced Rapid Transit) of Canada. In Korea, the linear induction motor system has been adopted for Yongin LRT and currently under construction. This paper covers the contents and technical base for main items of rolling stock, performance standard, carbody structure, bogie, electronic unit and brake equipment in order to implement linear induction motor LRT system according to local conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.467-470
• /
• 2002

Internet provides the useful method to monitor the current states of the machine tool no matter where a personnel is monitoring them. In this paper, a monitoring method of the torque of the machine tool's spindle induction motor using internet is suggested. The torque of vector controlled induction motor is estimated without speed measuring sensor. Only stator currents are measured to estimate the magnetizing current which is used to calculate flux linkage, rotor velocity and motor torque. Graphical programming is used to implement the suggested algorithm, to monitor the torque of an induction motor in real time and to make the estimated torque monitored on client computers. To solve the fluctuation problem of estimated torque caused from instantly varying rotating speed of an induction motor, the rotating speed is reconstructed based on the measured current signals. Mechanical part of the machine tool is also reconstructed using the data obtained from preliminary experiments. Torque of the spindle induction motor is well monitored on the client computers with 3% error range under various cutting conditions.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.28 no.5
• /
• pp.23-30
• /
• 2014

This paper presents an on-line diagnosis system for identifying health and faulted conditions in squirrel-cage induction motors using stator current, temperature, and partial discharge signals. The proposed diagnosis system can diagnose induction motor faults such as broken rotor bars, air-gap eccentricities, stator winding insulations, and bearing faults. Experimental results obtained from induction motors show that the proposed system is capable of detecting induction motor faults.

• Journal of Power Electronics
• /
• v.6 no.4
• /
• pp.322-329
• /
• 2006

In the last decade, the increasing restrictions imposed on the exhaust emissions from internal combustion engines and traffic limitations have increased the development of electrical propulsion systems for automotive applications. The goal of electrical and hybrid vehicles is the reduction of global emissions, which in turn leads to a decrease in fuel resource exploitation. This paper presents a novel approach for control of Induction Motors (IM) using the Particle Swarm Optimization (PSO) algorithm to optimize the parameters of the Proportional Integral Controller (PI-Controller). The overall system is simulated under various operating conditions. The use of PSO as an optimization algorithm makes the drive robust and insensitive to load variation with faster dynamic response and higher accuracy. The system is tested under variable operating conditions. The simulation results show a positive dynamic response with fast recovery time.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2008.05a
• /
• pp.277-280
• /
• 2008

In this work, the development of the diagnosis algorithm is carried out for identifying health and faulted conditions in three-phase induction motors. The algorithm consists of feature calculation, feature extraction, and feature classification procedures in sequence. Signals for this algorithm are acquired by current and flux sensors simultaneously, the latter is to measure the change of magnetic flux at the air-gap, This work proposes the efficient diagnosis method for induction motors by developing the powerful algorithm. The calculated features show a good linearity according to faults severities. Moreover. the final results show a good classification rate on motor conditions.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.2
• /
• pp.139-147
• /
• 2005

The lubricant impregnated MC nylon has good frictional properties, but its mechanical strength is inferior to steel for the mechanical elements. For the tribological application Nylon as gears, sliding bearings, cam and etc, the steel shafts are fitted in pre-heated nylon cylinder by a process of interference expansion fit and bonded by induction heating method. The joint shear strength of the two materials was measured by a universal test machine. From the study, the adhesive shear strength between these two materials was affected by the factors of the interference between nylon and steel, the size of nylon cylinder, knurl of steel shaft and inducting heating conditions. The most effective jointing conditions were analyzed and decided for the practical application in the industry.

• Journal of international Conference on Electrical Machines and Systems
• /
• v.2 no.2
• /
• pp.154-158
• /
• 2013

Reduction of electromagnetic vibration and acoustic noise from three-phase squirrel-cage induction motors (IMs) is very important, particularly from the standpoint of environmental considerations. Although the electromagnetic vibration of IMs has been studied for several years, the relationships between the radial distribution of the electromagnetic vibration and noise and the electromagnetic forces responsible for them have not yet been analyzed in sufficient detail. In the present study, we investigated this relationship experimentally for a small IM under different load conditions. Our results clearly show that the radial distributions of the dominant electromagnetic vibration and noise components match the mode shape of the dominant electromagnetic force producing these components.

• 전기의세계
• /
• v.27 no.5
• /
• pp.69-75
• /
• 1978

3 phase induction motor applied in the method of connecting it directly across the line needs large current when it starts. At that time, leakage magnetic pathes of interior of the motor are severely saturated and leakage reactances are decreased because of saturation. Consequently, increased current and raised powerfactor yield increase of starting torque. The author, noticing those phenomena, derived experimentally the raion of decreasing leakage reactance from the fact that when voltage applied to motor is increased under locked condition the magnitude of current and phase angle are varied, and determined tha equations of starting current and starting torque, considering the decrease of leakage reactance by the large starting current. The author calculated the characteristics of Current-Time and Speed-Time with the determined equation at specific load conditions, and compared the values obtained from above calculations with those from circle diagram's method and the practically recorded values at same load conditions. Therefore, the authos got a confidience that the results of the derived theory coincide with the practically measured values more well than circle diagram's results and circle diagram's equation should be modified in order to analize the starting status of a induction motor.