• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.11
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• pp.541-547
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• 2003

Speed and torque controls of permanent magnet synchronous motors are usually attained by the application of position and speed sensors. However, speed and position sensors require the additional mounting space, reduce the reliability in harsh environments and increase the cost of a motor. Therefore, many studies have been peformed for the elimination of speed and position sensors. This paper investigates a novel speed sensorless control of a permanent magnet synchronous motor. The proposed control strategy is based on the MRAS(Model Reference Adaptive System) using the state observer model with the current error feedback and the magnet flux model as two models for the back-emf estimation. The proposed algorithm is verified through the simulation and experiment.

• Progress in Superconductivity and Cryogenics
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• v.7 no.3
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• pp.21-28
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• 2005

Superconducting synchronous motors and generators have the field coil composed of superconductor with almost zero resistance at superconducting state. Therefore, copper loss at the conventional field coil is eliminated and the superconducting machine gets higher efficiency. The armature coil of the superconducting machine is composed of copper wire and supported by non-magnetic material such as FRP (Fiber Reinforced Plastic) This paper contains the design Procedure of a 1MW superconducting synchronous motor using high-temperature superconductor only for the field coil. Especially, the armature coil is designed by water-cooling in order to dissipate Joule heat easily. Moreover, 3-dimensional electromagnetic design is conducted to get a proper design result and reduce design errors from 2-dimensional approach.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.6
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• pp.543-546
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• 2017

This paper presents a simple approach for improving the performance of back-electromotive force (back-EMF)-estimation-based sensorless drives for surface-mounted permanent magnet synchronous motors (SPMSM). Similar to conventional approaches, a hypothetical d-q synchronous reference frame model of SPMSM is employed in the proposed approach to estimate the back-EMFs. This approach also employs a dual phase locked loop structure to compensate for the effect of the dead time and parameter uncertainty of the inverter on the estimated back-EMFs. The proposed algorithm is validated by conducting experiments.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.9
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• pp.62-73
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• 2013

In this paper, a new linear synchronous motor - permanent magnet double-sided synchronous motor with perpendicular arrangement (PMDLSM), was proposed. It was designed to account for the drawbacks of conventional linear motors, such as the normal force and end effects. The detent force and the thrust were analyzed for different combinations of primary core modules and magnet poles of the machine, and the optimum combination was made. The characteristics of the perpendicular PMDLSM were analyzed by finite element method, and the experiments agreed well with the analysis.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.86-88
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• 2005

The line-start permanent magnet synchronous motor has a high efficiency and an advantage in constant speed operation regardless of the effect of load variation. However it is difficult to predict the performance of characteristics accurately, because of the unbalanced starting torque with the initial starting position of the rotor and the generation of a break torque. In this paper the dynamic characteristics of the line-start permanent magnet synchronous motor arc described and compared with those of the squirrel-cage induction motor through the simulation to find the characteristics of the permanent magnets and the rotor bars in the line-start permanent magnet synchronous motor.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.7
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• pp.115-121
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• 1996

Multi-axes driving system is more suitable for FMS(Flexible Manufacturing System) compared with a conventional single-azis driving system. It has some merits such as flexibility in operation, improvement of net working rate, maintenance free because of no gear train, etc. However, studies on position synchronous control for high precision in the multi-axes driving system are not enough. In this paper, a new method of position synchronous control is suggested in order to apply to the multi- axes driving system. The proposed method is structured very simply using speed and position controller based on PID control law. Especially, the position controller is designed to keep position error to minimize by controlling either speed of two motors. The effectiveness of the proposed method is successfully confirmed through several experiments.

• Journal of Power System Engineering
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• v.5 no.3
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• pp.104-113
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• 2001

This paper describes a precise position synchronous control of two axes rotating system using BLDC motors and a cooperative control based on decoupling technique and PI control law. The system is required performances both good speed following and minimum position synchronous errors simultaneously. To accomplish these goals, the three kinds of controllers are designed. At first, the current and speed controller are designed very simply to compensate the influences of disturbances and to follow up speed references quickly. Especially, the two degree of freedom PI controller is used considering both good tracking for speed reference input and quick rejection of disturbances in speed controller. Finally, a position synchronous controller is designed as a simple proportional controller to minimize position synchronous errors. The validity of the proposed method is confirmed through some numerical simulations. Moreover, the results are compared to the conventional master-slave control ones to show the effectiveness of the proposed system.

• Progress in Superconductivity and Cryogenics
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• v.6 no.3
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• pp.38-43
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• 2004

1MW class superconducting synchronous motor is designed considering several conditions such as superconducting wire length, machine efficiency and size. As the machine is larger and larger, the superconducting machine shows the advantages more and more over the conventional machines. Although the advantages at 1MW rating are not so great, the design approach to get an appropriate result would be very helpful for larger superconducting synchronous machine design. Major design concerns are focused on reducing expensive Bi-2223 HTS(High Temperature Superconducting) wire which is used for superconducting field coil carrying the rating current around 30K(-243$^{\circ}C$) while the machine efficiency is higher than conventional motors or generators with the same rating. Furthermore, some iron cored structure is considered to reduce the HTS wire requirement without bad effect on machine performances such as sinusoidal armature voltage waveform, synchronous reactance and so on.

• Journal of Power Electronics
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• v.18 no.1
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• pp.195-203
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• 2018

In the variable speed Wind Turbine based on ElectroMagnetic Coupler (WT-EMC), a synchronous generator is coupled directly to the grid. Therefore, like conventional power plants, WT-EMC is able to inherently support grid frequency. However, due to the reduced inertia of the synchronous generator, WT-EMC is expected to be controlled to increase its output power in response to a grid frequency drop to support grid frequency. Similar to the grid frequency support control of Type 3 or Type 4 wind turbine, inertial control and droop control can be used to calculate the WT-EMC additional output power reference according to the synchronous generator speed. In this paper, an experimental platform is built to study the grid frequency support from WT-EMC with inertial control and droop control. Two synchronous generators, driven by two induction motors controlled by two converters, are used to emulate the synchronous generators in conventional power plants and in WT-EMCs respectively. The effectiveness of the grid frequency support from WT-EMC with inertial control and droop control responding to a grid frequency drop is validated by experimental results. The selection of the grid frequency support controller and its gain for WT-EMC is analyzed briefly.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.4146-4151
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• 2012

In this paper, we have simulated the transient stability of power system with dynamic loads. Dynamic load characteristics have an important influence on power system stability. In study of power system stability, motors form a major portion of the system loads. Induction motors and synchronous motors in particular form the workhorse of the electric power industry. Therefore modelling of motors is important in system stability. We investigate the effect of motors loads of Kwang Yang network with three phase fault.