• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.36 no.3
• /
• pp.171-178
• /
• 1987

A study of two phase chopper system with four separate groups of DC motors in powering. A novel two phase chopper system with four separate groups of DC motors which applies the principles of two phase chopper with two separate groups of DC motors is dealt with this article. The main circuit consists of eight sets of chopping parts, four diodes and four separate groups of DC motors. Four groups of DC motors are driven through the series and parallel connections to each other in accordance with the operating conditions of the choppers. Although the proposed chopper circuit requires more circuit elements than the conventional two phase chopper system with combined output or two phase chopper system with two separate groups of DC motors, it has the following advantages` (1). It is possible to drive twice as much motors as conventional system does, using esisting receiving-and equipments and motors. (2). It is possible to control load voltage continuously from 0 to source voltage by changing time-ratio from 0 to 1. (3). Load current division becomes equalized. Therefore it is possible to drive not only series motors but also shunt and separately exited motors. (4). When smoothing reactor L is small, harmonic components of the proposed circuit is not so large. Therefore, the value of L can be determined from viewpoints of allowable value of ripple-ratio and current unbalance factor.

• Journal of international Conference on Electrical Machines and Systems
• /
• v.2 no.4
• /
• pp.380-389
• /
• 2013

Application of linear electric motors to automation of manufacturing processes, gantry robots, machining processes, machining centers, additive manufacturing and laser scribing has been discussed. The paper focuses on replacement of ball lead screw mechanisms with linear electric motors, linear motor driven positioning stages, linear motor driven gantries, machining centers, machining of large objects and industrial lasers. The best linear electric motors for application to machining processes are permanent magnet (PM) linear synchronous motors (LSMs), especially those without PMs in the reaction tail, e.g., high thrust density linear (HDL) LSMs and PM flux switching (FS) LSMs.

• International Journal of Automotive Technology
• /
• v.6 no.4
• /
• pp.341-350
• /
• 2005

In this study, fault diagnosis and monitoring of serial wound pre-engaged starter motors have been carried out. Starter motors are DC motors that enable internal combustion engine (ICE) to run. In case of breakdown of a starter motor, internal combustion engine can not be worked. Starter motors have vital importance on internal combustion engines. Kohonen network based fault diagnosis system is proposed for fault diagnosis and monitoring of starter motors. A graphical user interface (GUI) software has been developed by using Visual Basic 6.0 for fault diagnosis. Six faults, seen in starter motors, have been diagnosed successfully by using the developed fault diagnosis system. GUI software makes it possible to diagnose the faults in starter motors before they occur by keeping fault records of past occurrences.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.60 no.4
• /
• pp.172-174
• /
• 2011

This paper is presented for robot vacuum cleaners using BLDC motors. Recently, BLDC motors which require smaller size, lower sound noise and higher efficiency have been placed in high value-added products including robot vacuum cleaners, vehicle cars and other industry applications. The DC motors have higher sound noise, higher height of the size and lower efficiency due to electro-magnetic structure using the brushes and the commutators. The proposed BLDC motors are appropriate for the motors adequate in regards to higher efficiency, longer life cycle time, and smaller height of the size when robot vacuum cleaners go to some lower height of the space like under sleeping beds and because it's power source is batteries. The paper shows the performance of the BLDC motors designed by the Finite Element Analysis(FEA) of the electro-magnetic field. This paper shows the mechanical structure and the prototype of the motor with the impeller. The performance characteristics of the BLDC motors with the hall sensor controller are verified by the experimental results.

• Proceedings of the KIEE Conference
• /
• 2001.07a
• /
• pp.187-189
• /
• 2001

In this paper, we have simulated the transient stability of power system with dynamic loads. Dynamic load characteristics have an important influence on power system stability. In study of power system stability, motors form a major portion of the system loads. Induction motors and synchronous motors in particular form the workhorse of the electric power industry. Therefore modelling of motors is important in system stability. We investigate the effect of motors loads of Kwang Yang network with three phase fault.

• 연구논문집
• /
• s.33
• /
• pp.53-65
• /
• 2003

Electrostatic micro-motors can be divided into three classes: (i) salient type side drive motor, (ii) radial gap type wobble motor, (iii) axial gap type wobble motor. The working mechanism, torque evaluation, fabrication, and operational characteristics of each micro motors are compared. It is proved that axial gap type wobble motor has the bigger generating torque than that of the other type. The gear ratio of wobble motors increases the driving torque at the cost of a decreasing angular speed and decreases the friction because of the rolling motion instead of sliding at the bearing. Techniques for characterizing micro-motors performance are presented.

• Proceedings of the KSR Conference
• /
• 2005.11a
• /
• pp.44-48
• /
• 2005

In general, the parallel-connected linear induction motors(LIM) are fed by one VVVF inverter in the magnetically levitated vehicle(MAGLEV) or linear motor subway drives. The air gap length of the parallel-connected linear induction motors operating at a grade or curved sections can be different each other. The air gap difference of the two motors attached to the same module causes unequal phase currents, asymmetic thrust and attraction force generation. In this paper, parellel-connected linear induction motors are operated by one IGBT inverter under the different air gap condition so that the phase current characteristics are examined experimentally.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.05a
• /
• pp.603-608
• /
• 2001

In order to distinguish fault electric motors automatically in real time. an intelligent diagnosis technique may be required. This paper presents an automatic fault detection system for electric motors by using their acoustic noises. Time signals of each candidate motor were measured in an anechoic chamber for further analysis. Spectral analysis was first carried out and they showed that two typical types of fault motors could be successfully distinguished in the frequency domain; bearing faults and scratches. Unlike the trend of normal motors that shows only a single dominant peak at around 2000 ㎐, several peaks are bunched together in bearing fault motors. On the other hand, large frequency noises at around 6500 ㎐ are newly arisen in scratchy fault motors. However, the processing time for spectral analysis was rather long for a real time application in production lines. Thus, a number of band-pass filters were used in the time domain instead for a real time application. Before applying filters, the bands of filters were set from the information of spectral analysis. By applying a set of band-pass filters, the RMS values of each filtered signal were calculated, and thus the normal and damaged motors could be successfully distinguished.

• 제어로봇시스템학회:학술대회논문집
• /
• 2004.08a
• /
• pp.1131-1135
• /
• 2004

In the virtual environment, force feedback to the human operator makes virtual experiences more realistic. However, the force feedback using active actuators such as motors can make the system active and sometimes unstable. To ensure the safe operation and enhance the haptic feeling, stability should be guaranteed. Both motors and brakes are commonly used for haptic device. A brake can generate a torque only against its rotation, but it is intrinsically stable. Consequently, motors and brakes are complementing each other. In this research, a two degree-of-freedom (DOF) haptic device equipped with both motors and brakes has been developed to provide better haptic effects. Each DOF is actuated by a pair of motor and brake. Modeling of the environment and the control method are needed to utilize both actuators. For various haptic effects, contact with the virtual wall and representation of friction effect are extensively investigated in this paper. It is shown that the hybrid haptic system is more suited to some applications than the motor-based active haptic system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.124-124
• /
• 2010

Diagnostic tests were performed on six high voltage motors. These tests included ac current, dissipation factor(tan6) and partial discharge(PD) magnitude. The rewind of motor stator insulation at rated voltage is assessed by the results of these tests. After completing the diagnostic tests, the stator windings of motors were subjected to gradually increasing ac voltage, until the insulation punctured. No. 1 and No.2 motors(4.16 kV) failed near rated voltage of 12.3 kV and 14.2 kV, respectively. The breakdown voltage of No.3 and No.4 motors(6.6 kV) was 17.6 kV and 17.8 kV, respectively. These motors are higher that expected for good quality coils in 6.6 kV class motors.