• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.515-518
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• 2002

In this study, the ellipsoidal cap type magnetic pole structure was proposed for the electro-magnet in B-H curve tracer. From the simulation for the electro-magnet without specimen, the area of effective uniform field(99% range for the central field value) was considerably increased in case of the newly proposed ellipsoidal cap type magnetic pole than that of the conventional simple-inclined cap type magnetic pole. Also, through the simulation for the electro-magnet with permanent magnet specimen(NaFe30), the optimal Positions of the magnetic field measurement sensor(Hall sensor) were found out in each case and the errors were decreased in case of the newly proposed ellipsoidal cap type magnetic pole.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.207-211
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• 2004

The performance of an inductive position sensor has approved by previous research papers. In this paper, magnetic circuit model of a ring-type multi-pole insuctive position sensor is described. The magnetic circuit model is required to design in ductive position sensor as well as draw a fault tolerance algorithm. Using the magnetic circuit theory, we derived the relationship between voltage applied and flux density in the normal air-gap. By idealizing the modulation/demodulation processes of signal processing circuit, sensor gain with respect to change of displacement is theoretically calculation using the magnetic circuit model, which validate the theoretical derivation.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.2
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• pp.124-129
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• 2005

This paper presents an advanced method for an initial pole position estimation of a Permanent Magnet Linear Synchronous Motor(PMLSM) that has an accurate incremental encoder for servo applications but does not have Hall sensors as a magnetic pole sensor. By appropriately using the secant method as a numerical method the proposed algorithm finds either of two zero force positions and then the correct d-axis by applying a q-axis test current. It only requires the tuned current controller and the relative position information md so it can be simply applicable to a rotary PMSM. The experimental results show the validity of the proposed method, which has an excellent performance with respect to an accurate pole position estimation under the minimal moving distance(average of about 85㎛) during the estimation process.

• Journal of Sensor Science and Technology
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• v.18 no.3
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• pp.197-201
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• 2009

This paper studies on the noncontact displacement sensor system to detect the displacement of the cylinder rod. For an inexpensive and a simple process, magnetic scales are printed on the cylinder rod, and magnetized by the specially designed magnetizer that has an yoke through the alternation of N and S pole. Noncontact displacement sensor system consists of cylinder with magnetic scales, Hall sensor, linear guide, controller and display. The system can detect the displacement of moving cylinder with 5 cm/sec in the case of 1 mm magnetic scale. It shows a possibility of position detection of hydraulic cylinder and air cylinder.

• Proceedings of the KIPE Conference
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• 2003.11a
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• pp.104-108
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• 2003

This paper explained algorithm for a initial pole position estimation of a permanent magnet linear synchronous motor(PMLSM). Generally this motor is considered initial pole position with a position sensor such as incremental encoder for the precise initial pole position estimation and high performance. But this is based on the principle that the initial pole position is accomplished by the PI controller using the maximum values of a position error generated by the new proposed two reference frames and also by using a rated force for input. the proposed algorithm does not utilize the general methods such as impedance ratio, EMF and using the magnetic saturation. In other words, this can be applied without respect to variety of the motor structure because of insensitivity to the motor parameters. In conclusion, simulation results are presented to confirm performance of initial pole position estimation method.

• Journal of Sensor Science and Technology
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• v.21 no.3
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• pp.172-179
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• 2012

This paper presents the design and analysis of a vibration-driven electromagnetic energy harvester that uses a multi-pole magnet. The physical backgrounds of the vibration electromagnetic energy harvester are reported, and an ANSYS finite element analysis simulation has been used to determine the different alignments of the magnetic pole array with their flux lines and density. The basic working principles for a single and multi-pole magnet are illustrated and the proposed harvester has been presented in a schematic diagram. Mechanical parameters such as input frequency, maximum displacement, number of coil turns, and load resistance have been analyzed to obtain an optimized output power for the harvester through theoretical study. The paper reports a maximum of 1.005 mW of power with a load resistance of $1.9k{\Omega}$ for 5 magnets with 450 coil turns.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.316-320
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• 2004

This paper presents an advanced method for an initial pole position estimation of a PMLSM (Permanent Magnet Linear Synchronous Motor) that has an incremental encoder for servo applications but does not have Hall sensors as a magnetic pole sensor. The proposed algorithm finds either of two zero force positions and then the correct d-axis by appropriately using the secant method as a numerical method. It only requires the tuned current controller and the relative position information and so it can be simply applicable to a rotary PMSM. The experimental results show the validity of the proposed method with respect to accurate pole position estimation under the minimal moving distance during estimation process.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.3
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• pp.232-239
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• 2008

The position sensors used in a magnetic bearing system are desirable to provide some degree of fault-tolerance as the rotor position is necessary for the feedback control to overcome the open-loop instability. In this paper, we propose an inductive position sensor that can cope with a partial fault in the sensor. The sensor has multiple poles which can be combined to sense the in-plane motion of the rotor. When a high-frequency voltage signal drives each pole of the sensor, the resulting current in the sensor coil contains information regarding the rotor position. The signal processing circuit of the sensor extracts this position information. In this paper, we used the magnetic circuit model of the sensor that shows the analytical relationship between the sensor output and the rotor motion. The multi-polar structure of the sensor makes it possible to introduce redundancy which can be exploited for fault-tolerant operation. The proposed sensor is applied to a magnetically levitated turbo-molecular vacuum pump. Experimental results validate the fault-tolerance algorithm.

• Journal of Sensor Science and Technology
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• v.14 no.6
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• pp.409-414
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• 2005

For an intelligent vehicle driving which uses magnetic markers and magnetic sensors, we can get every kind of road information while moving the vehicle if we use the code that is encoded with N, S pole direction of markers. If we make it an only aim to move the vehicle, it becomes easy to control the vehicle the more we put markers close. By the way, to recognize the direction of a marker pole it is much better that the markers have no effect each other. To get road informations and move the vehicle autonomously we propose the methods of arranging magnetic sensors and algorithm of recognizing the position of the vehicle with those sensors. We verified the effectiveness of the methods with computer simulation.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1029-1031
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• 2005

A magnetic position sensor is a apparatus that detect the rotating position by measuring the value of the flux density of the rotating position. In this paper, the magnetization system of the permanent magnet in the magnetic position sensor which detects the rotating position was designed. The permanent magnet was magnetized for the flux density into the hole element to be sinusoidal distribution according to the rotating position. To make the sinusoidal distribution of flux density, the magnetization values according to the position in permanent magnet were varied by adjusting the air gap between the pole of the magnetization fixture and the surface of the permanent magnet.