Chan-Woo Ahn

Unbalance Analysis of 15KW, 120krpm, Ultra High Speed Permanent Magnet Synchronous Motor

To accomplish the research of a PM synchronous motor driven by 15kW at a rated speed of 120krpm, this paper represents an approach to minimize the eddy current losses that occur frequently at high speeds. Various simulation and testing techniques are therefore applied to grasp the physical phenomena. Here, the proposed parameter for analysis is sleeve thickness. Finally, this paper studies the developed model which represents a tendency for minimizing eddy current loss, von-Mises stress, unbalance vibration response and for maximizing critical speed. It comes to the conclusion that sleeve thickness should be chosen when considering the function of mechanical stress, critical speed and unbalance vibration response of the rotor. The design efficiency is well suited to the efficiency test, having a maximum error of 2.7%.

A Study on the Shape Design of Micro Speaker Diaphragm

This study uses a characteristic function to explain correlations between the objective function and design variables. Analysis of means and table of orthogonal array were carried out. The change of shape of diaphragm, thickness of diaphragm and voice coil weight based on the table of orthogonal array Is made. Therefore this study carried to decide design variables for minimizing 1st natural frequency and maximizing 2nd natural frequency of diaphragm using design of experiments and characteristic function with constraints. we showed improved design variables.

Unbalance Response Analysis of Copper Die Casting High Speed Induction Motor

This paper deals with a copper die casting induction motor which has several advantages of motor performance. The developed motor is used as spindle motor in machining center. The dynamic characteristic analysis of rotor is dealt with for precision machining. The critical speed of rotor considering rotation and gyroscopic effect should be above operating speed, 18,000 rpm, and have a 201 % sufficient separation margin. Also, the 3-D unbalance vibration response analysis is performed and enabled the prediction of the expected vibration amplitude by unbalance in high speed. The unbalance vibration responses of each position on the rotor are satisfied with allowable vibration displacement of API 611 standard according to balancing G grade(G 0.4, G 2.5, G 6.3). Copper die casting high speed induction motor is successfully developed and verified by experiment.

Magnetic field and rotordynamic analysis of 30 krpm 220 kW rated high speed motor for blower supported magnetic bearing

This paper introduces the applied AMB(Active Magnetic Bearing) System supported by magnetic bearing which is controlled. The system needs component design technique for develop AMB System. Magnetic field analysis, PID control and 3D rotordynamic analysis of AMB is performed. The required performance of motor is a 220 kW, 30 krpm high speed motor. The 3D rotordynamic analysis considering magnetic bearings are simulated to find the critical speed of rotor by Cambpell diagram. The analysis shows that the critical speed of the rotor is higher than operating speed with sufficient separation margin. All the performances of the AMB high speed motor prototype are verified successfully

A Study on the Reduction of Over Head Crane′s Weight Considering Buckling, Vibration and Strength

In this study, structural optimum design was applied to the girder of magnet over head crane. The optimization was carried out using ANSYS Code for the deadweight of girder, especially focused on the thickness of its upper, lower, side and reinforced plates. The weight could be reduced up to around 15% with constraints of its deformation, stress, natural frequency and buckling strength. The structural safety was also verified by the buckling analysis of its panel structure. It might be thought to be very useful to design the conventional structures for the weight save through the structural optimization. Also this paper grasped the sensitivity influenced the design variables upon the objective function and the state variables.

Investigating Natural Frequency Analysis and Measurement of Railway Vehicle to Avoid Resonance

This paper deals with the natural frequency analysis and two experiments to evaluate first twisting and bending natural frequency of railway vehicle. The KS R 9228 testing method is generally performed as pseudo FRF(frequency response function) which is widely used by two accelerometers. The exciting method is utilized using the load weight(1 ton release). The modal testing is used to verify KS R 9228 testing result and the natural frequency analysis result. The first twisting and bending natural frequency should be above 10 Hz by resonance which is mostly generated between bogie and vehicle frame exciting low frequency. The first twisting and bending natural frequency of railway vehicle are successfully verified between analysis and test.

OPTIMUM DESIGN FOR IMPROVEMENT OF PM-TYPE LONGITUDINAL FLUX LINEAR MOTOR USING THE STATISTICAL METHODS

Permanent Magnet (PM) type Longitudinal Flux Linear Motors (LFLMs) are electromagnetic devices which can develop directly powerful linear motion. This paper presents statistical optimum design of PM type LFLM to reduce the weight of the machine with the constraints of avg. thrust force using the penalty method with characteristics function and Response Surface Methodology (RSM). The contribution and effect of the each design variable on the characteristic function is evaluated by the analysis of means (ANOM) and optimum design set is determined. The reduced gradient algorithm is adopted in RSM. Therefore, it is expected that the proposed optimization procedure using penalty method and RSM can be easily utilized to solve the optimization problem with constraint of electric machine.

Sound Control of Structural-acoustic Coupling System Using Optimum Layout of Absorbing Material and Damping Material

The absorbing material is mostly used to changing the acoustic energy to the heat energy in the passive control, and that consists of the porous media. That controls an air borne noise while the stiffened plates, damping material and additional mass control a structure borne noise. The additional mass can decrease the sound by mass effect and shift of natural frequency, and damping material can decrease the sound by damping effect. The passive acoustic control using these kinds of control materials has an advantage that is possible to control the acoustic in the wide frequency band and the whole space at a price as compared with the active control using the various electronic circuit and actuator. But the space efficiency decreased and the control ability isn`t up to the active control. So it is necessary to maximize the control ability in the specific frequency to raise the capacity of passive control minimizing the diminution of space efficiency such an active control. Therefore, the characteristics of control materials and the optimum layout of control materials that attached to the boundary of structure-acoustic coupled cavity were studied using sequential optimization on this study.

The Effect of Impact Absorbing System with 2 DOF Deformation According to the Variation of Cylinder Wall on Damping Coefficient

Many malfunction take place in container crane spreader due to impact. So we designed a 2 DOF hydraulic impact absorbing equipment to absorb the impact and we studied the change of damping coefficient with respect to the variation of dimensions of oil-Cylinder wail. When we design the dimension of hydraulic cylinder wall considering the displacement on the wall, the value of it over 20m didn`t affect the damping coefficient.

Interior Noise and Low Frequency Noise Characteristics of Busan Metro Line 3 Noise

This paper deals with the analysis of interior noise and low frequency noise characteristic for the Busan citizens to use public transport, Busan Metro Line 3. The interior noise evaluation index, articulation index(AI) is evaluated the lower value about average 22 % in a whole range, this is difficult to have a conversation. Also, noise criteria(NC) curve is partially evaluated as NC-65 below 2000 Hz, space type is evaluated as factories. Another of interior noise evaluation index, preferred speech interference level(PSIL) is evaluated the upper value about average 66 dB(A) in a whole range, this is evaluated to be interrupted. In the case of low frequency noise(20~200 Hz), the measurement of low frequency noise is assessed largely beyond noise criteria of ISO 226. The low frequency noise should be reduced because low frequency noise affects on psychological stress and displeasure although low frequency noise is not recognized by auditory sense. The low frequency noise criteria and guideline will be enacted from now on in Korea.