• The Transactions of the Korean Institute of Electrical Engineers
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• v.44 no.4
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• pp.447-452
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• 1995

In this paper a simple method of a position control for brushless DC motor is presented. For precise position control, a high performance torque controller is needed and a novel current control method is proposed. The current controller detects the uncommutating mode current for every 60.deg. (elec. angle) and controls it with PI controller. The current control loop includes the feedforward of back EMF and the feedforward of the neutral voltage between the neutral point of the inverter and the neutral point of the machine. In the position control, the acceleration pattern is calculated from the position reference. Then the speed trajectory is calculated from the acceleration pattern. The experimental results are presented to verify the proposed methods.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.337-339
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• 2001

High speed brushless permanent magnet (PM) machines are a key technology for electric drives and motion control systems for many application, since they are conductive to high efficiency, high power density small size and low weight. Proposed slotless PM machine is constructed without stator winding slots. Its stator magnetic material is in the form of a ring and winding have a toroidal configuration and its rotor consists of a 4-pole Halbach array or radially magnetized PM rotor.

• Journal of the Korea Institute of Military Science and Technology
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• v.8 no.3 s.22
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• pp.18-23
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• 2005

Ships have been propelled and maneuvered by electrical drives since trle late seventies. Recently, rare earth PMs allow the design of brushless motors with very high efficiency over a wide speed range. This is the most important factor in ship propulsion technology. Several types PM motors have been developing for ship propulsion system. However these have disadvantage such as cogging torque. It causes an undesired effect that contributes to output ripple, vibration, and noise of machine. Therefore several techniques may be adopted in designing PM motor in order to reduce the cogging torque. This paper describes cogging torque receding methods such as adjusting arigap length, magnet arc, and magnet thickness. That are analysed by using the finite element method(FEM) and the maxwell stress tensor method.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.1
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• pp.60-66
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• 1996

Brushless DC(BLDC) motor have been increasingly used in machine tools and robotics applications due to the reliability and the efficiency. In control of BLDC motor, it is important to construct the controller which is robust to parameter variations and external disturbances. Variable structure controller(VSC) has been known as a powerful tool in robust control of time varying systems. In practical systems, however, VSC has a high frequency chattering which deteriorates system performances. In this paper, a binary controller(BC) which takes the form of VSC and MRAC combined is presented to solve this problem. BC consists of the primary loop controller and the external loop controller to change the gain of primary loop controller smoothly. So it can generate the continuous control input and is insensitive to parameter variations in the given domain. To confirm the validity, various investigations of control characteristics for various design parameters in a position control system of BLDC motor are carried out. (author). 11 refs., 18 figs., 1 tab.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.4B no.3
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• pp.108-113
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• 2004

This paper presents methods to improve performance of the power supply system in a NASA deep space explorer. In the Stirling engine driven reciprocating Brushless DC (BLDC) generator, the accurate position information of the prime mover is important to diagnose the performance of the engine and prevent distortion of the output power. Since sensors to detect the position are fragile and unreliable, and conventional sensorless techniques have drawbacks in the low speed region, a novel sensorless position detection technique for the prime mover has been proposed and verified. Another major issue of the generator for the spacecraft is power density maximization. The mass of the power system is important to the mass of the satellite. Therefore, the components of the spacecraft should be lightweight. Conventional rectification methods cannot achieve the maximum power possible due to non-optimal current waveforms. The optimal current waveform for maximizing power density and minimizing machine size and weight in a nonsinusoidal power supply system has been derived, incorporated in a control system, and verified by simulation work.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1142-1144
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• 2003

This Paper presents a speed controller based on the adaptive fuzzy tuning method for brushless DC(BLDC) motor drives under load variations. Generally, the speed tracking control systems use PI controller due to its simple structure and easy of design. PI controller, however, suffers from the electrical machine parameter variations and disturbances. In order to improve the tracking control performance under load variations, PI controller of which the parameters are modified during operation by adaptive fuzzy tuning method. This method based on optimal fuzzy logic system has simple structure and computational simplicity. It needs only sample data which is obtained by optimal controller off-line. As the sample data implemented in the adaptive fuzzy system can be modified or extended, a flexible control system can be obtained. Simulation results show the usefulness of the proposed controller.

• Journal of the Korean Magnetics Society
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• v.25 no.6
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• pp.189-197
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• 2015

As enforced the regulation of fuel efficiency, the electrification of automotive components in internal combustion vehicle has been applied instead of hydraulic pressure. A typical example of such parts is the EPS (electric power steering), and it is applied to most automotive at present. In electric power steering system, the core component is motor. The reduction of cogging torque and torque ripple is required to improve steering feeling and reduce NVH (Noise Vibration Harshness) in EPS. Generally the skewed design of stator or rotor is applied in order to reduce cogging torque and torque ripple. This paper propose the design and analysis methodology of Brusheless PMSM (Permanent Magnet Synchronous Motor) which is applied to skewed stator. The proposed methodology is as follows: First Intial Design PMSM with skewed stator for EPS, Second Optimal design using RSM (Response surface method), Third Performance Analysis such as Phase Back EMF, Inductance, Load torque using FEA (Finite Element Method). Finally, the reliability of proposed design methodology will be verified through the experiments of prototype sample.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.33-37
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• 2004

Slotless Permanent magnet Brushless DC Motor(PM BLDC) with the characteristics of high speed and high power density has been more widely used in industrial and automatic machine. Generally, PM BLDC meter is necessary that the three Hall-ICs evenly be distributed around the stator circumference in case of the 3 phase motor. The Hall-ICs are set up in this motor to detect the main flux from the rotor. therefore the output signal from Hall-ICs is used to drive a power transistor to control the stator winding current. However, instead of using three Hall-ICs, if only we used one Hall-IC, we estimate information of the others phase in sequence through a revolving rotor. This paper identified the characteristics and performance by using one Hall-IC for the 3 phase PM BLDC whose six stator and two rotor designed.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.3
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• pp.107-114
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• 2001

Electro-mechanical battery (EMB) consists of a high-speed fly wheel with an integral motor/ generator suspended on magnetic bearings and in an evacuated housing. Permanent magnet (PM) machines as the EMB motor/ generator are a popular choice, since there are no excitation losses which means substantial increase in the efficiency. In this paper we present the comparison of conventional slotted and slotless ring-wound types, aimed at EMB and other high-speed drives. We firstly discuss the topology of each machine for this particular application. these machines are primarily designed as 1kW two-pole PM generator with the rated speed of 40000 rpm. the motoring torque of 0.51 Nm has to be enough to accelerate the flywheel to the rated speed. We then present the comparison of the open-circuit field, the armature reaction field and winding inductance. next we analyze the induced voltage and the developed torque per unit stack length and unit weight of different machines. Finally, we estimate and compare the losses and the efficiency at motoring and generating modes.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.1
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• pp.13-19
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• 2001

This paper deals with decentralized control scheme and its application to multi-machine power systems. Decentralized control scheme has several practical advantages, because power system has geographically distributed characteristics. In this paper, decentralized observer-based optimal Power System Stabilizer(PSS) and Thyristor-Controlled Series Capacitor(TCST) controller are designed and tested in WSCC 9 bus system with one TCSC installed. Simulation results show that the proposed decentralized controller has satisfactory performances comparable to the centralized controller. In addition, using modal analysis, this paper shows that the proposed decentralized controller significantly affects only one pair of eigenvalues which have high participation with each generator, while slightly affects other eigenvalues. This result indicates that the application of the decentralized control scheme to enhance power system dynamic stability via excitation control have potential advantages because each low-damped mode occurs dominantly by each decentralized subsystem.