• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.689-691
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• 1992

In this study, slip frequency control for a single-sided linear induction motor(SLIM) is discussed. We adopted variable slip frequency pattern in stead of constant slip frequency pattern under V/f constant mode, which is effective in improving driving efficiency of SLIM. And the dynamic characteristics are analyzed by using equivalent circuit during the accelerating time.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.1
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• pp.46-51
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• 2018

Constant slip frequency control has been conventionally used in thrust control of the linear induction motor(LIM) for magnetically levitated train. However in this paper variable slip frequency control method is presented to increase LIM efficiency according to change of driving notch. Thrust, attractive force, input power to inverter, regenerative power of the LIM are analyzed by finite element method when the train runs according to the presented control method. As a result it is proved experimentally that the electrical energy to inverter is reduced than the conventional method.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.135-138
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• 1991

In this study, a variety of characteristics is considered when LIM for transit is driven with acceleration and deceleration. From the characteristics of constant voltage, with V/f ratio fixed, slip frequency is derived. With slip frequency of 12[Hz] and objective velocity of 40[km/h], the robust control characteristics which are generated constant thrust and normal force, except for open-loop control interval, are obtained.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.1
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• pp.57-63
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• 2001

The wound rotor type induction motor(WRIM) control system which is widely used in the industry has many maintenance problem because of external resistors and magnetic contactors. In this paper, the simple sensorless vector control algorithm for WRIM is proposed without any additional devices except detecting rotor currents. Because the external resistors are disconnectd and the rotor slip rings are shorten, the power loss due to external resistors is removed and the maintenance problem is improved remarkably. Also, the vector control performance becomes better because the proposed sensorless vector control algorithm does not use the rotor resistance which is usually used to estimate the slip frequency in case of indirect vector control scheme. The proposed algorithm is verified by the digital simulation and the experiment.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.558-560
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• 2019

범용 인버터는 계통 전원의 전압 강하 또는 정전 발생 시, 정류기의 직류단 전압이 감소하여 인버터 고장(fault)이 발생한다. 보호 동작으로서 인버터는 일시적으로 전원 공급이 이루어 지지 않는 상태에서 제어 기능 및 관리가 이루어 질 수 있도록 Ride-Through 운전을 수행한다. 고장 발생 없이 제어 시스템 상태를 유지하여 전원 복구 후, 빠른 재기동이 가능하다. 본 논문에서 V/f 제어를 사용하는 범용 인버터를 고려한 Ride-Through 방법으로 KEB(Kinetic Energy Backup) 운전을 제안한다. KEB 운전은 순시 정전에 의한 인버터 고장 방지를 위해 요구되는 에너지를 계산하고 슬립 주파수를 조절하여 회생 운전을 통해 인버터의 직류단 전압을 일정하게 유지한다. 제안한 방법은 실험을 통해 유효성을 검증한다.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.5
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• pp.451-458
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• 2000

In wind power generating system connected in power grid, the value of stator flux has almost constant because the stator side of doubly fed induction machine(DFIM) is connected to power grid. Using the stator and rotor current, it is possible to estimate the slip angle and rotor speed. A stator flux orientation scheme and rotor slip estimator are employed to achieve control of generating power in stator side. To verify the theoretical analysis, a 5-hp DFIM prototype system and PWM power converter are built. Results of computer simulation and experiment are presented to support the discussion.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.3
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• pp.233-240
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• 2005

In this paper, AC electric vehicle propulsion system(Converter/Inverter) using high power semiconductor, IPM is proposed. 2-Parallel operation of two PWM converter is adopted for increasing capacity of system and the harmonic content is eliminated by the phase shaft between two PWM converters switching phase. VVVF inverter control is used a mixed control algorithm, where the vector control strategy at low speed region and slip-frequency control strategy at high speed region. The proposed propulsion system is verified by experimental results with a 1,350kW converter and 1,100kVA inverter with four 210kW traction motors.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.306-309
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• 1988

For the purpose of fast response and simplifing system angle control strategy is selected. And the analysis and dynamic performance of a slip frequency controlled current source inverter fed induction motor drive with stator frequency compensation (indirect torque angle control) is investigated. The current control loop including motor is modeled and speed control loop including the frequency compensation is analysed. And transfer function of overal system is simplified. Experimental results are given in support of the analytical procedure.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.2
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• pp.125-130
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• 1998

This paper describes a novel flux calculator for the estimation of real rotor flux angle which is indispensable to the field oriented control of induction motors. A pure integrator is used to estimate the real rotor flux precisely from voltage and current information. The proposed flux calculator adopts the new drift compensation method to overcome the drift problem of pure integrator. The motor speed is calculated using estimated flux angle and estimated slip frequency. The performance of this approach is verified through the experiment. The experimental results shows stable operation of proposed system even below 1/100 of rated speed.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.2
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• pp.125-131
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• 2001

This paper presents a application of vector control strategy to 1.2MVA traction drive for railway vehicle. The vector control required the control of the phase and amplitude of output voltage vector. But in case of traction system for railway vehicle, the one-pulse mode is used at high speed region in order to utilize the link voltage fully. So it is impossible to control the flux and torque axis current instantaneously and independently in the region. So this paper proposes a mixed control algorithm, where the vector control strategy at low speed region and slip-frequency control strategy at high speed region is used. And precise switching technique between the two different control strategy is proposed. The proposed strategy is verified by experimental results with a 1.2MVA traction drive system with four 210kW induction motors.