• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.4
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• pp.273-278
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• 2019

This study proposes a method for improving the overmodulation performance of a three-phase inverter to obtain an enhanced output torque for the AC motors. In the inverter-fed AC motor drives, the output torque of the motor can be enhanced by utilizing the overmodulation region as well as the linear modulation regions of the inverter. The overmodulation method is used for this overmodulation operation of the inverter. However, the voltage gain, the ratio of the output voltage of the inverter to the reference voltage achieved by the conventional overmodulation methods becomes nonlinearly smaller than unity. Therefore, the effect of improving the output torque of the AC motors is insignificant even when the overmodulation region is utilized. In this study, we propose a method that improves the overmodulation performance of the inverter by compensating the limited amount of the reference voltage in the overmodulation operation to enhance the output torque of the AC motors. The effectiveness of the proposed method is verified through the simulations and experiments with an 800 W permanent magnet synchronous motor.

• Progress in Superconductivity and Cryogenics
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• v.2 no.2
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• pp.44-48
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• 2000

The high temperature superconducting bulk can be used as the rotor of an ac motor. This paper presents the fabrication and test results of a ac motor with HTS bulk rotor. The rotor of a conventional squirrel cage induction motor was replaced with cylinder type YBCO bulk. Height and outer diameter of the HTS bulk was 15mm and 46mm, respectively. Eddy current brake using aluminium disk was used to measure the torque of the HTS motor. No load test, locked rotor test and load test were performed to examine the characteristics of the HTS motor. Test results show the motor can rotate at synchronous speed without any special starting circuit. Maximum output power of the constructed HTS motor was 408W.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.596-599
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• 1989

Vector control has been widely used in AC machines for precise control. The application of Vector control for the permanent magnet synchronous motor drive and complete modeling,simulation and analysis of the drive are discussed in this paper. The nonlinear model of the permanent magnet synchronous motor is linearized. Then the theory of vector control is applied to the linearized model in designing controllers. The operation and relevant mathematics model of s pseudo derivative feedback controller are then presented. Two different speed controller design are then considered. A comparative evalation of the two speed controller is also presented.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.232-234
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• 1994

In this paper. to estimate starting torque of synchronous motor by simple test, we propose a new method which is the combination of commercial tests and single phase AC applied test of synchronous motor. A driving characteristic was examined when field winding is supplied a de and chopper current. The starting characteristics are assumed and agreed with actual data.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.241-243
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• 1999

This paper describes a series of experiments investigating the operational characteristics of high-Tc superconducting synchronous motor of five to six hundred watts capacity. In this experiment, ac 220V stator phase voltage and DC 4A excitation current are used, and the synchronous speed runs at 1800rpm. Hall Sensors are installed on the pole face and at the side of the Ag/Bi-2223 high-Tc superconducting tape in order to analyze the effect of the time-varying magnetic field on the motor performance when the load changes its value. The experimental observations are compared with the theoretical predictions.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.25-27
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• 2007

Brushless DC Motor (BLDCM) is DC motor and Interior PM Synchronous Motor (IPMSM) is AC motor. Besides their way of control is different. But it is similar that both motors rotate synchronous velocity and use the permanent magnet. So, it is an objective to grasp a tendency of motor design and efficiency of motor through a characteristic comparison of BLDCM and IPMSM with the same power, rotation velocity, torque and input voltage.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.6
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• pp.223-232
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• 2001

Aiming at a small axial pump with a levitated rotor, an axial-type self-bearing motor is presented, which has a rotor wish four permanent magnets and two stators with two-pole three-phase windings. In this system, only the axial motion of rotor is actively controlled by two opposite self-bearing motors just like in the case of an axial magnetic bearing, while the other motions are passively stable. For rotation, It follows the theory of a four-pole three-phase synchronous motor. This paper Introduces schemes for design and control of the self-bearing motor and shows some experimental results to Prove the feasibility of application for the axial Pump.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.351-354
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• 1987

In this paper, an adaptive control scheme is applied to the speed control system of a synchronous AC servo motor. The adaptive control system using Ioannou's modified adaptation law is shown to be robustly stable in the presence of current control error and load torque disturbance. The computer simulation demonstrates the rapid compensation of rotor speed deviation due to load torque disturbance.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.930-932
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• 2003

As Synchronous Reluctance Motor gives reluctance torque, An inductance is an important parameter that is proportional to torque. To achieve the high performance in sensorless control, it is necessary to consider exact inductance values because the inductance is not a constant parameter anymore. Therefore, this paper shows the inductance measurement using DC current decay test, AC standstill test, and AC standstill test considering Cross Magnetization. This inductance has also been compared with the result that is analyzed by FEM.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.193-196
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• 1999

The current boost type atatic excitation system for synchronous generator that can sustain prope output voltage level even at fault condition is proposed. The proposed excitation system is capabl of supplying level 60% of the rated voltage. The proposed system is verified and tested using computer simulations as well as load tests. The load tests are performed with a 5KVA synchronous generator driven by a ac motor. The actual tests results indicated a good performance.