• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2006.05a
• /
• pp.263-264
• /
• 2006

A new method for the electrostatic suspension of disk-shaped objects is proposed which is based on a time-optimal control scheme and deploys only high-voltage power supplies that can deliver do voltages of positive and/or negative polarity. This method possesses the unique feature that no high-voltage amplifiers are needed which leads to a remarkable system simplification and objects can be suspended stably even in vacuum environment. Using this scheme, an Aluminium disk employed in a 3.5-inch HDD was suspended stably at an airgap of 0.3mm.

• Journal of Power Electronics
• /
• v.13 no.2
• /
• pp.197-205
• /
• 2013

In energy injection resonant AC-AC converters, due to the low frequency effect of the AC input envelope and the low energy injection losses requirement, the constant and steady control of the high frequency AC output envelope is still a problem that has not been solved very well. With the aid of system modeling, this paper analyzes the mechanism of the envelope pit on the resonant AC current. The computing methods for the critical damping point, the falling time and the bottom value of the envelope pit are presented as well. Furthermore, this paper concludes the stability precondition of the system AC output. Accordingly, an optimal control method for the AC output envelope is put forward based on the envelope prediction model. This control method can predict system responses dynamically under different series of control decisions. In addition, this control method can select best series of control decisions to make the AC output envelope stable and constant. Simulation and experimental results for a contactless power transfer system verify the control method.

• Journal of Institute of Control, Robotics and Systems
• /
• v.4 no.4
• /
• pp.525-533
• /
• 1998

A conventional contact type brake system which uses a hydraulic system has mny Problems such as time delay response due to pressure build-up, brake pad wear due to contact movement, bulky size, and low braking performance in high speed region. As vehicle speed increases, a more powerful brake system is required to ensure vehicle safety and reliability. In this work, a contactless brake system of an eddy current type is proposed to overcome problems. Optimal torque control which minimizes a braking distance is investigated with a scaled-down model of an eddy current type brake. It is possible to realize optimal torque control when a maximum friction coefficient (or desired slip ratio) corresponding to road condition is maintained. Braking force analysis for a scaled-down model is done theoretically and experimentally compensated. To accomplish optimal torque control of an eddy current type brake system, a sliding mode control technique which is, one of the robust nonlinear control technique is developed. Robustness of the sliding mode controller is verified by investigating the braking performance when friction coefficient is varied. Simulation and experimental results will be presented to show that it has superior performance compared to the conventional method.

• Journal of the Korean Society for Precision Engineering
• /
• v.23 no.6 s.183
• /
• pp.104-110
• /
• 2006

A design and control of electrostatic suspension system for flexible objects is presented. A number of electrode pairs of which the number depends on the object flexibility are positioned above the object and the voltages applied to each electrode pair are controlled, independently on the others, on the basis of the gap length. To implement the system with low cost and compactness, switched-voltage control scheme that is based on the relay feedback control is utilized. Relay feedback control method deploys only a single high-voltage power supply that can deliver a DC voltage of positive and/or negative polarity and thus high voltage amplifiers that are costly and bulky are not needed any more. It is shown that despite the inherent limit cycle property of the relay feedback based control, an excellent performance in vibration suppression is attained due to the presence of a relatively large squeeze film damping originating from the electrodes and levitated object. Employing fourteen electrode pairs, a thin aluminum plate with a thickness of 0.1 mm has been suspended at a gap length of 0.75mm.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10a
• /
• pp.311-314
• /
• 1996

In contactless disk handling systems based on electrostatic suspension in which the stator is to be transferred, the limited stiffness in lateral direction severely restricts the achievable translational acceleration. In existing stator electrode pattern designs, the magnitude of the lateral force is determined by the magnitude of the control voltages which are applied to the individual electrodes to levitate the disk stably. As a result, the lateral force cannot be set arbitrarily. A new stator electrode pattern is presented for the electrostatic levitation of disk-shaped objects, in particular silicon wafers and aluminum hard disks, which allows the lateral forces to be controlled independently from the levitation voltages. Therefore, greater lateral forces can be obtained, compared with the existing stator designs. Experimental results will be presented for a 4-inch silicon wafer that clearly reveal the increased lateral stiffness by using the proposed stator electrode compared to the conventional electrode pattern.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.49 no.4
• /
• pp.265-271
• /
• 2000

A non-contact battery charger for cellular phone is designed using half-bridge series resonant converter. This converter utilizes series resonance to reduce the undesirable effect of large leakage inductance of the detachable transformer and ZVS operation can reduce switching loss and switching noise. In this paper, analysis and design procedure of half-bridge series resonant converter with detachable transformer is presented. The input voltage is 85VAC∼270VAC, and the output voltage and current is 4.1V and 800mA, respectively. Furthermore, a method of calculating the secondary current of the transformer to control the battery charging current in the constant current charging mode is proposed. The performance of the charger is verified through experiments.

• Proceedings of the KIPE Conference
• /
• 2001.07a
• /
• pp.638-641
• /
• 2001

Connectorless power transmission and supply are the power transfer device revealed by resonant inverter or transformer using inductant device. Recently, on power supply have been going on frequently, so several power supply circuit forms are announced. But Compared with the circuit of previous paper, instead of the circuit composed of a simple sylinder Ferrit, I was manufacture in a sylinder that It was a double overlab to a sylinder and I was followed a double flux in inner flux path. Above all, for practicalization, supply circuit operation character analysis and development of controller should be preceded. According to this paper, power transmission and supply analyze characters and design control circuit like the analysis of general resonant inverter for power transmission. They compose the circuit to get sinusoid wave output voltage using pulse width modulation control mode. For Supply, output wave form through power track and power pick-up of magnetic inductance includes ripper component. So I intend to design the controller including filter and regulator, compare analyze theoretical result with real measurement value and then show you their practicality

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.21 no.6
• /
• pp.55-64
• /
• 2007

This paper represents characteristics and design example of series loaded LCC type high frequency resonant DC-DC converter with variable parallel capacitor in the secondary side of inductive power transformer. In this converter, ZVS(zero voltage switching) technique is applied to reduce turn-off switching losses, and the applied converter used the PFM switching pattern to control output voltage. The operating characteristics of the proposed converter is analyzed using nomalized parameter such as switching frequency and load factor with varing the secondary parallel resonant capacitor. The results of analysis show the operating characteristics and design method of the proposed converter using characteristic values. And the proposed converter can be applied for the contactless power supply with linear transfer system such as dean room facilities of semiconductor and Flat Panel Display.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.1838-1844
• /
• 2011

In this paper, the propulsion control of a high-speed maglev train is studied. Electromagnetic suspension is used to levitate the vehicle, and linear synchronous motors (LSM) are used for propulsion. In general, a low-speed maglev train uses a linear induction motor (LIM) for propulsion that is operated under 300[km/h] due to the power-collecting and end-effect problem of LIM. In case of the high-speed maglev train over 500[km/h], a linear synchronous motor (LSM) is more suitable than LIM because of a high-efficiency and high-output properties. An optical barcode positioning system is used to obtain the absolute position of the vehicle due to its wide working distance and ease of installation. However, because the vehicle is working completely contactless, the position measured on the vehicle has to be transmitted to the ground for propulsion control via wireless communication. For this purpose, Bluetooth is used and communication hardware is designed. A propulsion controller using a digital signal processor (DSP) in the ground receives the delayed position information, calculates the required currents, and controls the stator currents through inverters. The performance of the implemented propulsion control is analyzed with a small maglev train which was manufactured for experiments, and the applicability of the high-speed maglev train will be explored.

• Transactions on Electrical and Electronic Materials
• /
• v.16 no.1
• /
• pp.42-45
• /
• 2015

The ability to take electrocardiographic measurements while performing our daily activities has become the people-choice for modern age vital sign sensing. Currently, wet and dry ECG electrodes are known to pose threats like inflammations, allergic reactions, and metal poisoning due to their direct skin interaction. Therefore, the main goal in this work is to implement a very small ECG sensor system with a capacitive coupling, which is able to detect electrical signals of heart at a distance without the conductive gel. The aim of this paper is to design, implement, and characterize the contactless ECG electrodes. Under a careful consideration of factors that affect a capacitive electrode functional integrity, several different sizes of ECG electrodes were designed and tested with a pilot ECG device. A very small cotton-insulated copper tape electrode ($2.324cm^2$) was finally attained that could detect and measure bioelectric signal at about 500 um of distance from the subject's chest.