• Tribology and Lubricants
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• 제35권3호
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• pp.158-168
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• 2019

This paper presents the investigation of two types of rotordynamic modeling issues for 2.2 kW-class, rated speed of 1,800 rpm, squirrel-cage type induction motors. These issues include the lamination structure of rotor cores, and the radial clearance of ball bearings that support the shaft of the motor. Firstly, we focus on identifying the effects of rotor core lamination on the rotordynamic analysis via a 2D prediction model. The influence of lamination is considered as the change in the elastic modulus of the rotor core, which is determined by a modification factor ranging from 0 to 1.0. The analysis results show that the unbalanced response of the rotor-bearing system significantly varies depending on the value of the modification factor. Through modal testing of the system, the modification factor of 0.079 is proven to be appropriate to consider the effects of lamination. Next, we investigate the influence of ball bearing clearance on the rotordynamic analysis by establishing a bearing analysis model based on Hertz's contact theory. The analysis results indicate that negative clearance greatly changes the bearing static behavior. Rotordynamic analysis using predicted bearing stiffness with various clearances from -0.005 mm to 0.010 mm reveals that variations in clearance result in a slight difference in the displacement of the system up to 18.18. Thus, considering lamination in rotordynamic analysis is necessary as it can cause serious analysis errors in unbalanced response. However, considering the effect of the bearing clearance is optional because of its relatively weak impact.

• Journal of Electrical Engineering and Technology
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• 제10권4호
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• pp.1558-1565
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• 2015

In this paper, we propose a new method for detecting bearing faults using vibration signals. The proposed method is based on support vector machines (SVMs), which treat the harmonics of fault-related frequencies from vibration signals as fault indices. Using SVMs, the cross-validations are used for a training process, and a two-stage classification process is used for detecting bearing faults and their status. The proposed approach is applied to outer-race bearing fault detection in three-phase squirrel-cage induction motors. The experimental results show that the proposed method can effectively identify the bearing faults and their status, hence improving the accuracy of fault diagnosis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 A
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• pp.51-53
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• 1997

Even though, many types of induction motors are known, most of the single phase induction motors being used are of squirrel cage type. However, basic structure of the machine has not been changed a lot during the past century. Author had been experienced many experiments with modified rotor. The modification was completed by doing two procedures: an elimination of lamination in central pan of the rotor and filling of melted aluminium in it instead. This paper demonstrates the reason for higher efficiency.

• 조명전기설비학회논문지
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• 제26권1호
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• pp.66-74
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• 2012

This paper propose a improved direct torque control(DTC) system for improving operation of five-phase squirrel-cage induction motor(IM). A five-phase IM drives present unique characteristics due to the additional degrees of freedom and also drives possess many others advantage compared with the traditional three-phase motor drive system, such as reducing a amplitude of torque pulsation and increasing the reliability. In order to maximize the torque per ampere, the proposed motor has concentrated windings and the produced back-electromotive force(EMF) is almost trapezoidal, and the motor is supplied with the combined sinusoidal plus third harmonic of currents, there is necessary to controlled 3rd harmonic current. Also a DTC method is advantageous when it is applied to the five-phase IM, because the five-phase inverter provides 32 space vectors in comparison to 8 space voltage vectors into the three-phase inverter drive system. For presenting the superior performance of the proposed DTC, experimental results of speed control are presented using a 32-bit fixed point TMS320F2812 DSP with 1.5[hp] IM.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1482-1484
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• 1996

To apply Magnetic wedges to the motor, comparing with not applying, showes its performance change of efficiency increse, reduction of temperature rise, harmonics, and magnetic noise. The motor specification and test condition are 37kW-4P-380V-60Hz,squirrel-cage, three phase induction motor with semiclosed type slots. The result of load test to compare with nonmagnetic wedges showed 1.5% increment of efficiency at 100% load and $8.0^{\circ}C$ decrement of temperature rise at stator coil. And for developing the magnetic wedge matrial, its manufacturing process was setting and TG-DTA, optical microscope, SEM, bending strength and permeability were investigated into the material made of through the process.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 1989년도 추계학술발표회논문집
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• pp.51-58
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• 1989

In this paper, the technique of particular harmonics elimination in three-phase PWM Inver-ter output waveform and the method for speed control of a squirrel cage I.M. are introduces. The required switching patterns are determind on personal computer and the results are stored in look-up table in EPROM for controlling the switching of the Inverter devices. In this system, the microprocessor(Intel 8086)computes the actual Motor speed from the pulses generated in a Incremental Encoder, compares the actual speed with the reference speed. And the PI(Proportional-Integral) controller is used to adjust the frequency of the Inverter that feeds the Motor.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.268-270
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• 1995

In crane drives, DC motor has been most widely used due to simple control characteristic and favorable transient behavior. Nowadays, however, the squirrel cage induction motor is known as an attractive candidate due to elimination of all sliding electrical contacts, resulting in an exceedingly simple and rugged construction. Especially, in hoist application, the smooth torque control and four quadrant operation are essential. In this paper, an operation of dual inverters with common DC bus fed by vector controlled induction motor is described. Single DSP is employed as a main processor to control dual inverters and communicates each input/output signal with PLC. As well as giving a detailed expression, full simulation and experimental results are presented.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.739-740
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• 2006

According to the rapid growth of high speed and precise industry, the application of synchronous motor has been increased. In the application fields, the large synchronous motor is not a self-starting motor. The rotor is heavy and, from a dead stop, it is impossible to bring the rotor into magnetic lock with the rotating magnetic field for this reason, all synchronous motor have some kinds of starting device. A simple starter is another motor which brings the rotor up to approximately 96 percent of it synchronous speed. The starting motor is disconnected and the rotor locks in step with the rotating field. The more commony used starting method is to have the rotor to include a squirrel cage indution winding. This indution winding brings the rotor almost to synchronous speed as an induction motor. So, this paper describes excessive condition interpretation of a exciter circuit to prevent starting failure of large synchronous motor. the large synchronous motor needs safety of it in accordance with operating frequent start and stop. the operating Problem point of synchronous motor appears potential element damage of Exciter circuit because synchronous motor is caused synchronous separation. hence we eliminate it and improve starting toque.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.891-895
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• 2004

This paper suggests the techniques in determining the values of the steady-state equivalent circuit parameters of a three-phase squirrel-cage induction machine using immune algorithm. The parameter estimation procedure is based on the steady state phase current versus slip and input power versus slip characteristics. The proposed estimation algorithm is of a nonlinear kind based on clonal selection in immune algorithm. The machine parameters are obtained as the solution of a minimization of least-squares cost function by immune algorithm. Simulation shows better results than the conventional approaches.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.2237_2238
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• 2009

This paper describes the design process of three-phase squirrel cage induction moter. stator and rotor were modelled with the result obtained from loading distribution on the provided specification. For proving validity of the result obtained from loading distribution, through Maxwell simulator the first test target values, output and efficency, synchronous speed and etc, were compared with the design result.