• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.6
• /
• pp.1039-1046
• /
• 2007

This paper presents the analysis for power consumption, mechanical vibration and acoustic noise characteristics of the Coreless and Slotless Brushless DC motor in Digital Lightening Processor(DLP) Motor with the Air-Dynamic Bearing. The Coreless BLDC motor has not the stator yoke as well as the stator slot to remove the unbalance force by the interaction between the stator yoke and Air-Dynamic Bearing clearance. The assembling tolerance and the processing error make the air-gap difference between the magnet and the stator yoke .which occurs the unbalanced electro-magnetic force in the Slotless BLDC motor. It imposes the air-dynamic bearing on the disturbance force and makes the Air-Dynamic Bearing vibrated and noised. Also, The attractive force between the magnet and the silicon steel stator yoke increases the power consumption. In this paper, the power consumption, mechanical vibration and acoustic noise of the Coreless BLDC motor and the Slotless BLDC motor with the silicon steel stator yoke are simulated, analyzed, and tested using the manufactured proto-type motors with Air-Dynamic bearing. The simulated and tested results present that the Coreless BLDC motor without the silicon steel stator yoke has the lower mechanical vibration and noise ,and lower power consumption than the Slotless BLDC motor with the silicon steel stator yoke in Digital Lightening Processor Motor with Air-Dynamic Bearing.

• Journal of Institute of Control, Robotics and Systems
• /
• v.18 no.7
• /
• pp.627-631
• /
• 2012

Observable mathematical model of DDM (Direct Dirve Motor) was suggested. The motor that operates the object system directly is called DDM. DDM has many strong points, however, it has a significant disadvantage, that it is more sensitive to the external force than the motor with reduction gear. In other word, if the force is applied, air gap of the motor can be perturbed. This causes not only difficulty in motor control but also even more serious problem, such as the breakdown of motor. However, if the air gap variation can be estimated, it can help prevent these problems. DDM should be modeled to estimate the air gap variation. The type of researched DDM is PMSM (Permanent Magnet Synchronous Motor) and precedent model of PMSM includes only characteristics of electro-magnetic system and rotational motion. However, suggested model should also include characteristics of translational motion of rotor to estimate the air gap variation. Also, this model should satisfy observability condition, because state observer is designed based on this model.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.1
• /
• pp.853-859
• /
• 2015

1-DOF shear building was designed, built and tested to investigate the interactions between the shear building and the shaking table excited harmonically by the electro-magnetic forces. In the experiments horizontal accelerations of the shaking table and the shear building were measured. To understand the experimental results experimental setting was modeled as an unconstrained 2-DOF system under the hormonic forces. The responses of the shear building and the shaking table of the unconstrained 2-DOF system were found with the equations of motions. The magnification factors of the table and the shear building with respect to the amplitude of the harmonic forces and the transmission of the shear building with respect to the table excitations were found and compared with the experimental results.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1999.06a
• /
• pp.15-32
• /
• 1999

A relationship between stress and stain is very important to design a die to avoid defects of products during semi-solid forming process. Since the liquid will be of eutectic composition in alloys liquid segregation will result in significant or undesirable situation. The materials used in this experiment are A 357. A390, Al2024 alloys that is fabricated by the electro-magnetic stirring process from Pechiney in France. The compression test was performed by induction heating equipment and MTS. In order to prevent the liquid segregation these measured temperature would be useful to control of strain rate during compression test. The liquid segregation is controlled as change of the strain rate and solid fraction during the compression process, The characteristics of flow between solid and liquid phase considering liquid segregation is examined through the above experiments. In the case of medium and high volume fractions of solid the distribution of strain rate is calculated by using compression test data of semi-solid materials (SSM). The thixoforming experiments with the designed die are carried out successfully. The die filling patterns of SSM for variation of die temperature and pressing force have been investigated. The hardness of the thixoformed scroll products is evaluated in terms of the microstructure for each position.

• Journal of the Korean Society for Precision Engineering
• /
• v.33 no.7
• /
• pp.601-606
• /
• 2016

In this paper, an energy harvester is developed that has advantages regarding piezoelectric noise minimization, mass production, and an easily available environmental energy source, electromagnetic induction, as well as low-frequency bandwidth and high amplitude. A process for fabricating a three-dimensional multilayered planar coil using micro-electro-mechanical systems (MEMS) on a flexible printed circuit board FPCB is introduced. Optimal shape and size were calculated via internal resistance and inductance, and a prototype was fabricated through the MEMS procedure while considering the possibility of mass production. Although the internal resistance matched the designed value, the electromotive force generated did not reach the intended amount. The main reason for the decrease in efficiency was the low area of coil outskirt exposed to the magnetic field while there was relative motion between the magnet and the coil.

• 전기의세계
• /
• v.18 no.4
• /
• pp.7-15
• /
• 1969

In this method the condenser excite winding has the phase angle of 90 electrical degree, with the load winding in stator. The condenser excite wing is connected with the condenser while the load winding is with the full rectifer. Direct and quardrature axis components of rotating field winding are composed, of balanced two phase winding, and each one of them is connected with half wave rectifiers. Initically, small amount of lead current can be induced at the condenser excite winding by residual magnetism of rotor. The induced lead current forces the rotating field winding to be excited by synchronous alternating magnetic field. The speed electromotive force, there for, induced in rotating field winding shall electro magnetize the rotating field pole by rotating half wave rectifiers. In the case of the charging generator directly coupled with engines at the operation of wide range speed, the generated region, such as vehicles, aircraft, ships etc, is occured. In conclusion, we can take the advantage of, omitting of voltage regurator and current limiter for charging load and reducing the consumption of fuel using the generated region which can be devided in to Impossible generated region, Generated region, and suspension generated region.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.3
• /
• pp.519-523
• /
• 2007

In this paper, we propose a precise parameter extraction of interior permanent magnet (IPM) motors based on finite element analysis. For the calculation of the two-axis inductances Ld and Lq, the slotting effect and cross magnetization due to torque angle are considered. It is examined that back electro-motive force (BEMF) constant is affected by the magnetic saturation in different ways dependent on motor types. Numerical analyses and some measurements are performed for a spoke type and a flux barrier type IPM motors

• Proceedings of the KIEE Conference
• /
• 2009.07a
• /
• pp.752_753
• /
• 2009

This paper deals with controller design and dynamic simulation of hybrid magnetic bearing. The flux density at air-gap is obtained from system modeling which considers permanent magnet and electro magnet. The vertical force is derived yb that flux density using maxwell's stress tensor.

• Proceedings of the KIEE Conference
• /
• 2001.07b
• /
• pp.846-848
• /
• 2001

In this paper, electromagnetic fields of a linear induction motor with cage-type secondary are analyzed by the finite element method. Contact resistances between end-bars and secondary conductors are considered in the finite element analysis. The field quantify is a magnetic vector potential transformed into a phasor form. As a result, the sensitivities of a phase current thrust and normal force are presented according to the variation of the contact resistance.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2001.04a
• /
• pp.381-384
• /
• 2001

The combined stirring method to uniform distribution of particle is consisted of two strring force both electro-magnetic stirring generated from induction heating and mechanical stirring with graphite stirrer. PMMC billets were fabricated with the volume fractions ranged from 0% to 20% and particle sizes ranged from 14$\mu\textrm{m}$ to 25$\mu\textrm{m}$. It is important to control the size of primary ${\alpha}$-AI solid particles because it could become the cause of the particle pushing or capture phenomena from the fact that secondary dendrite arm spacing size depends on the cooling rate during the solidification in hypoeutectic AI-Si alloy.