• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.635-637
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• 2001

The faults of the squirrel cage induction motor is grew increasingly complex as the faults resulting in the shorting of a stator winding and the broken rotor bar or cracked rotor end ring, bearing faults, and so on. The users of electrical machines initially relied on simple protections such as over-current, over-voltage, earth-fault, etc. to ensure safe and reliable operation. but this method cause heavy financial losses and the threat of safety therefore it has now become very important to diagnose faults at there very inception. in this paper, we are going to discuss the detection method of broken rotor bar of squirrel cage induction motor by the motor current signal analysis(MCSA) and the opening terminal voltage signal analysis.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.130-132
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• 1997

In this paper, we propose a new type of tubular linear induction motor(TLIM) with two-dimensional motion. The proposed motor consists of four short primary LIMs arranged on a same circumference and a common secondary. By adopting independently energized ring-windings to the primary, we can expect the reduction of coil-end region and the freedom of alternating current supply. The secondary conductor is capable of producing anyone of rotary, linear, and helical motions by controlling the phase of supply currents in each primary winding. From the 3-D finite element analysis and the experiment, we derive the feeding conditions to increase the subsidiary rotary-force and an optimal arrangement of primary currents to reduce the number of slot.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.1
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• pp.25-32
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• 2019

Recent high-end treadmills are demanding stable performance at lower speeds. In this study, a slip control-based induction motor sensorless algorithm for treadmills, which have heavy load variations, is proposed. A modified Gopinath flux estimator is used to evaluate the rotor flux. Results indicate that a good speed regulation performance is achieved even at a low speed of approximately 3 Hz with a nominal exercise load of 90 kg body weight. The slip calculation method in the stationary coordinate system is adopted to improve the control stability. The proposed algorithm is verified throughout the simulation study using PSIM, and the experimental test consists of a commercial treadmill system.

• 전기의세계
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• v.27 no.3
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• pp.47-52
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• 1978

This paper deals with the phase converter. The single-phase inverter with 120.deg.C phase-lagging is used for the phase conversion. As the waveform of the inverter is rectangular, the output waveforms of the three-phase lines include the harmonics. Single-phase operation by using phase converter and three-phase balanced operation of the three-phase induction motor are compared, and the effects of the harmonics are analyzed and discussed.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.2658-2660
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• 2005

This paper presents a stator winding fault diagnosis technique of induction motor on the PC - based virtual instrumentation system designed using the graphical programming language LabVIEW. This method collects the 3-phase current signals using the current probe amplifier and PXI/DAQ system then the preprocessing removes the noise using LPF, after then this method transforms the stator current to Park's vector and obtains the each Park's Vector pattern and detects stator winding fault by comparing the obtained faulted pattern with the healthy pattern. This proposed LabVIEW based diagnosis system is applied to the 3 phase 1 hp induction motor and obtained the reasonable results under no load condition. The test results give us the possibility a simple and realistic on-line winding fault diagnosis system.

• Journal of the Korean Society of Safety
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• v.9 no.4
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• pp.58-68
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• 1994

A miniature size electrostatic induction motor has been fabricated and studied parameters Influencing dominantly to the motor speed, such as a voltage and frequency of the 3 phase ac power source supplied to the stator of fabricated motor, the surface resistivity and relative dielectric constant of the rotor surface materials and the concurrently calculated relaxation time constants. It is found that the higher resitivity and/or the higher relative dielectric constant, concurrently the longer relaxation time constant of the rotor surface materials make the motor speed get higher speed. In case of discrete coated rotor surface it is found that the motor speed was increased logarithmically as narrow as width of the discrete coated Ti. And the degree of width of discrete coated Ti to the axial direction of the rotor was 60$^{\circ}$ and 150$^{\circ}$, the motor has got a 125% higher than that at the degree of 0$^{\circ}$.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.974-976
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• 1993

A design method of three phase induction motors that have characteristics of low starting current and high starting torque is proposed. This design method is based on the traditional theory related to the skin effect and the gap saturation effect. The starting performances and the analysis method are explained in short. Finally, comparison of example design data on electric hoist motor with standard motor is shown.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.7
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• pp.862-867
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• 1999

In general, the realization of high performance brushless permanent magnet motors which are widely used in servo drive is focused on the linear control for ripple-free torque. This is also the main problem that should be solved in all AC motors including induction motor to achieve high performance control, and recent papers deal with this problem. In this paper, the novel optimal excitation scheme of brushless permanent magnet motor producing loss-minimized ripple-free torque based on the d-q-0 reference frame is presented including 3 phase unbalanced condition. The optimized phase current waveforms that are obtained by the proposed method can be a reference values and the motor winding currents are forced to track it by delta modulation technique. As a results, it can be shown that the proposed work can minimize the torque ripple by the optimal excitation current for brushless permanent magnet motor with any arbitrary phase back EMF waveform. Simulation and experimental results prove the validity and practical applications of the proposed control scheme.

• Journal of Convergence for Information Technology
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• v.8 no.6
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• pp.187-192
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• 2018

This thesis is about the study of inverter terminal boxes in a explosion proof type exhaust fan that can control wind volume and operating time. In Korea, there is no ventilator to adjust the amount of wind and operating time when working in poor conditions. The purpose of the project is to create a explosion terminal box that can control the operating time and wind speed of a suitable explosion ventilator in hazardous environments. The two explosion-proof switches allow the operation time to be driven 1 hour, 3 hours and continuous time, and the speed of the induction motor rotation was set in 3 stages at 2000 rpm, 2600 rpm and 3000 rpm to control the volume. The tested motor used a half-horsepower barrier three-phase induction motor and a full-bridge inverter to set the desired flow rate and operating time.

• Journal of Electrical Engineering and Technology
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• v.3 no.2
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• pp.224-234
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• 2008

Multi-phase machines can be used in variable speed drives. Their applications include electric ship propulsion, 'more-electric aircraft' and traction applications, electric vehicles, and hybrid electric vehicles. Multi-phase machines enable independent control of a few numbers of machines that are connected in series in a particular manner with their supply being fed from a single voltage source inverter(VSI). The idea was first implemented for a five-phase series-connected two-motor drive system, but is now applicable to any number of phases more than or equal to five-phase. The number of series-connected machines is a function of the phase number of VSI. Theoretical and simulation studies have already been reported for number of multi-phase multi-motor drive configurations of series-connection type. Variable speed induction motor drives without mechanical speed sensors at the motor shaft have the attractions of low cost and high reliability. To replace the sensor, information concerning the rotor speed is extracted from measured stator currents and voltages at motor terminals. Open-loop estimators or closed-loop observers are used for this purpose. They differ with respect to accuracy, robustness, and sensitivity against model parameter variations. This paper analyses operation of an MRAS estimator based sensorless control of a vector controlled series-connected two-motor five-phase drive system with current control in the stationary reference frame. Results, obtained with fixed-voltage, fixed-frequency supply, and hysteresis current control are presented for various operating conditions on the basis of simulation results. The purpose of this paper is to report the first ever simulation results on a sensorless control of a five-phase two-motor series-connected drive system. The operating principle is given followed by a description of the sensorless technique.