• 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.

• Journal of Advanced Marine Engineering and Technology
• /
• v.6 no.1
• /
• pp.25-33
• /
• 1982

The characteristics of the stator current and torque of a small three- phase squirrel cage induction motor and studied experimentally under the situation of a single-phase operation due to various causes. Through the experiments, the torque-slip and current-slip curve of single-phase circuit as well as three-phase circuit are obtained and the needed constants are determined. The stator current and torque are calculated by the current and torque equations derived by the unbalanced circuit theory. The numerical values obtained from the above methods are compared with the experimental values under the same conditions. The results of the study are summerized as follow; 1) The values computed by the unbalanced circuit theory generally come to approach the values recorded through experiments. 2) Near the rated load, speed drop is less than 1.2 per cent of the speed of three-phase induction motor and torque reduces less than 3 per cent of it of three-phase induction motor when three-phase induction motor is run under a single-phase. On the other hand, the stator current in a single-phase circuit is more than 1.9 times of it in three-phase circuit. 3) The stalling torque in a single-phase circuit is reduced to about 41 per cent of it in three-phase circuit while the corresponding slip is moved toward the synchroneous speed and the corresponding stator current is increased.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.2
• /
• pp.304-310
• /
• 2016

This paper proposes a fault diagnosis method for an open-fault in inverter driving five-phase induction motor. The five-phase induction motor has a high output torque and small torque ripple in comparison to three-phase. The best advantage of the five-phase induction motor is fault diagnosis and tolerant control using redundancy of phases. This paper uses an inverter as a power converter for driving a five-phase induction motor. If a switch of inverter occurs to the open-fault, this problem is the influence on the output current and output torque. To solve this problem, there is need of an accurate diagnosis and fault switch distinction. Therefore, this paper propose a fault detection method of the open-fault switches for the fault diagnosis. First, analyzing the pattern for the open-circuit fault of one phase. next, analyzing the pattern for the open-circuit fault of each inverter switches. Through the pattern analysis, It defines the scope of each of the failure switch. Thereafter, By using an algorithm that proposes to perform a fault diagnosis method. The proposed algorithm is verified from the experiment with the 1.5 kW five-phase induction motor.

• 전기의세계
• /
• v.16 no.2
• /
• pp.1-8
• /
• 1967

From the discovery of Alago's disk, a number of trials and efforts have been concentrated on a small-sized and light-weighted induction motor. They have devoted themseleves, however, mainly to a improvement of cooling effect, a proper weight-distribution of copper and iron and desirable number of slots. In consequence, such an effort restricted only to the field of design, has resulted in unsatisfactory developments in the insulating materials consisting of the main parts of an induction motor. The quality of fibre and paper which are used as class-A insulation materials with their "compound" and "varnish" has been increased to some extent. Similarly Class-B insulation materials like asbest mica has been almost a combination of inorganic and binding materials. But nowadays synthesic chemistry is making a remarkable progress. So it comes possible for us to have silicon resin and other good ones of similar charateristics. And even a thin silicon resin insures us to get excellent heat-pro f and insulation, so a better space factor and cost-down in motor design have come possible in most advanced nations of the world, but not in our country. Furthermore, a consideration of productivity and economy in manufacturing process has been neglected by a majority of engineers. This is more unpleasant und more undesirable. I think this rational method of induction motor design using new synthesic resin will devote in making your productivity and economy better. And the nation-wide standard value of electric motor size is sited here. size is sited here.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.22 no.9
• /
• pp.25-31
• /
• 2008

The field of induction motor is magnetized and demagnetized for each reversal of the current. This field component of the motor accounts for most of the reactive component of inductive load. Reactive power needs to sustain the electromagnetic field required for the induction motor to operate. Power factor of induction motor is usually low and power factor correction needs. Power factor becomes low by the effect of the reduction operation of load capacity. In most cases, Capacitor capacity for the power factor correction should be complied with the recommendation by the motor capacity. But Capacitor value for power factor correction can't change during the normal operation. In this paper, we analyzed characteristics of power and power factor changing by load fluctuation of low-voltage small size induction motor and show that lower power factor correction's parameter of existing recommendation should be revised by new value.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.48 no.3
• /
• pp.124-130
• /
• 1999

Speed and position sensors require the additional mounting space, reduce the reliability in harsh environments and increase the cost of motor. Various control algorithms have been proposed for the elimination of speed senor. This paper investigates a novel speed sensorless control of induction motor. The proposed control strategy is based on MRAS(Model Reference Adaptive System) using state observer as a reference model for flux estimation. This algorithm may overcome several shortages of conventional MRAS: integrator problems, small EMF at low speed and relatively large sensitivity to resistance variation. The proposed algorithm is verified through simulation and experiment.

• Proceedings of the KSR Conference
• /
• 2005.11a
• /
• pp.49-54
• /
• 2005

Linear metro with single sided linear induction motor is applied to the urban transit system because of non adhesion drive. But linear induction motor is required to reduce the energy consumption to maximize efficiency of LIM. In this paper, design requirements such as pole pitch, motor length, air gap, overhang length and the material of secondary sheet are investigated as major parameter of SLIM. It is effective for increasing the efficiency to adopt the copper reaction plate and decrease the mechanical air gap as small as possible.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.29 no.5
• /
• pp.80-85
• /
• 2015

Recently, not only in the Middle East and Southeast Asia but in African area, too, industrial plant construction is being actually done. But unlike in Korea, a lot of them are small-scale isolated industrial plants. And because of the characteristics of industrial plants, induction motors' load forms a large part. The influence of stability resulted from the maneuver and operation of induction motors' load may lead to serious result in the isolated system. This study analyzed it through mathematical modeling on induction motors' maneuver phenomena in the isolated system, realized a case system with the E-TAP program, and simulated load follow performances according to the control variables of a generator inside the isolated system.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.50 no.5
• /
• pp.238-245
• /
• 2001

During an AC motor's start-up accelerating period, a large amount of current is required to reach to the rating speed. This is called in-rush current. This peak in-rush current can be more than about several times the operating or steady-state current in the full load rating of the motor. In-rush current is present in both and electronic ballasts. The main area of concern is the tripping of circuit breaker and fuses which can affect electrical system components From this, we can see that the electrical power controllers will be rather concerned, since they have to supply the actual current necessary to start the motor. This paper presents a new method to reducing in-rush current and energy saving of the single-phase induction motor used in air-conditioner. It can be obtained that proposed system is low cost and small size as compared with other controller. Experiments are focused on a capacitor starting single-phase induction motor. The optimal power saving and in-rush current limiting by phase angle control are verified by experimental results. Also, auxiliary winding was controlled by electronic starting switch.

• Proceedings of the KIEE Conference
• /
• 2002.07b
• /
• pp.1165-1168
• /
• 2002

This paper presents a neural network based self-tuning fuzzy PID control scheme with variable learning rate for sensorless vector controlled induction motor drives. MRAS(Model Reference Adaptive System) is used for rotor speed estimation. When induction motor is continuously used long time. its electrical and mechanical parameters will change, which degrade the performance of PID controller considerably. This paper re-analyzes the fuzzy controller as conventional PID controller structure, introduces a single neuron with a back-propagation learning algorithm to tune the control parameters, and proposes a variable learning rate to improve the control performance. The proposed scheme is simple in structure and computational burden is small. The simulation using Matlab/Simulink and the experiment using DS1102 board show the robustness of the proposed controller to parameter variations.