• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.125-127
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• 2003

Brake forces due to eddy-currents induced by the relative motion of a conductor and a magnetic devices: motors, brakes and magnetically levitated vehicles. In particular, the practicality of using permanent magnet in eddy-current brakes system is obviously recent, due to the manifold improvement in magnet materials and technology. For such a system we give analytical formulas considering eddy-current distribution as variables: flux density for each region and forces.

• Journal of Power Electronics
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• v.8 no.1
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• pp.74-80
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• 2008

This paper develops a direct torque control method (DTC) using a matrix converter fed induction motor. The advantages of matrix converters are combined with the advantages of the DTC technique; under the constraint of the unity input power factor, the required voltage vectors are generated to implement the conventional DTC method of induction motor. The proposed DTC algorithm is applied to induction motors and the experimental results are given in steady-state and transient conditions, while the discussion about the trend of the DTC method using the MC is also carried out. Furthermore, the entire system of the matrix converter configuration using 7.5kW IGBT module is explained in detail.

• Journal of Power Electronics
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• v.9 no.6
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• pp.960-968
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• 2009

This paper presents a design optimization process for interior permanent magnet synchronous motors (IPMSM) for hybrid electric compressors (HEC) which are applied to hybrid electrical vehicles. A hybrid electric compressor is composed of an electric motor driving section and an engine driving section which is connected to the engine by a pulley belt. A hybrid electric compressor driving motor requires half of the full driving power of a compressor. Even though an engine is not operated at the idling stop mode, the electric motor drives the air-conditioner compressor by itself so that the air conditioning system can produce its minimum cooling capacity. In this paper, the design optimization of an IPMSM for a 42 (V) applied voltage system is studied using the design of experiment (DOE) and response surface method (RSM) of 6sigma. The driving characteristics of this motor drive system are measured and analyzed by experiment.

• Journal of Power Electronics
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• v.7 no.4
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• pp.271-277
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• 2007

In this paper, an induction motor rotor fault diagnosis system using current signals, which are measured using the axis-transformation method is presented. Inverter-fed motor drives, unlike line-driven motor drives, have stator currents which are rich in harmonics and therefore fault diagnosis using stator current is not trivial. The current signals for rotor fault diagnosis need precise and high resolution information, which means the diagnosis system demands additional hardware such as a low pass filter, high resolution ADC, an encoder and additional hardware. Therefore, the proposed axis-transformation method is expected to contribute to a low cost fault diagnosis system in inverter-fed motor drives without the need for any additional hardware. In order to confirm the validity of the developed algorithms, various experiments for rotor faults are tested and the line current spectrum of each faulty situation, using the Park transformation, is compared with the results obtained from the FFT(Fast Fourier Transform).

• Journal of Power Electronics
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• v.16 no.4
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• pp.1387-1395
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• 2016

A method for the identification of mechanical parameters based on integral calculation is presented. Both the moment of inertia and the friction constant are identified by the method developed here, which is based on well-known mechanical differential equations. The mechanical system under test is excited according to a pre-determined low-frequency sinusoidal motion, minimizing the distortion, and increasing the accuracy of the results. The parameters are identified using integral calculation, increasing the robustness of the results against measurement noise. Experimental data are supported by simulation, confirming the effectiveness of the proposed technique. The performance improvements shown here are of use in the design of speed and position controllers and observers. Owing to its simplicity, this method can be readily applied to commercial inverter products.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1346-1354
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• 2016

This paper proposes a design guideline for the feedback gain of the adaptive full-order observer in the speed sensorless control of induction machines. The performance of the adaptive full-order observer is dependent on its feedback gain. This paper presents a pole placement method for the observer feedback gain design to improve the estimation performance of the speed adaptive observer. In the proposed method, the observer poles can be chosen independently of the induction motor poles. Instead, they can be positioned according to the operating speed. An analysis and experimental results obtained with the proposed method reveals better performances under general operating conditions.

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.59-60
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• 2017

본 논문에서는 하이브리드 / 전기 자동차의 견인용 전동기로 널리 쓰이는 영구자석 동기 전동기를 실시간으로, 실제 전력 상황에서 모의하는 실시간 부하 모의 장치(Real-Time Emulator, RTE)의 구동에 필요한 직류단 전압의 크기에 대하여 분석한다. 운전 주파수 및 스위칭 주파수 전류 모의까지 가능한 부하 모의 장치에서, 모의 전류 및 모의 운전 속도에 따라 필요한 직류단 전압을 구하는 방법을 이론적으로 전개하고, '도요타사(社)'의 하이브리드 자동차 '프리우스'에 내장된 견인 전동기의 모의를 위해 필요한 직류단 전압의 계산에 이를 적용해본다. 실제 물리적 지표를 반영하기 위해 모의하고자 하는 전동기에 대하여 유한요소법 (Finite Element Method, FEM)을 실행하여 얻은 값들을 사용하였다.

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.67-69
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• 2017

본 논문에서는 철도차량용 매입형 영구자석 동기전동기의 저속영역에서 구동을 위해 센서리스 제어 기법을 적용하였다. 저속영역에서 센서리스 제어는 회전하는 전동기에 연속적인 고주파 신호를 인가하고 그 신호에 대한 응답을 이용한다. 매입형 영구자석 동기전동기의 회전자 인덕턴스 변화와 자기적 돌극성을 이용하므로 특정 전동기에 대해 우수한 성능을 나타낸다. 따라서 본 논문에서는 동기좌표계 d축 전압에 정현파 신호와 구형파 신호를 주입하여 두 방식에 대한 결과를 시뮬레이션을 통해 분석하였다.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.296-297
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• 2011

Many applications involving induction motors that are controlled using variable frequency drives require the ability to stop quickly. These applications include emergency stops, quick stopping of fans, centrifuges, presses, etc. The technique that is widely accepted in the industry for achieving quick stopping makes use of brake resistors in series with a power semiconductor switch. The switch-resistor combination (brake-unit) is applied across the dc bus. The fastest decelerating time achievable depends on the size of the resistors and the switch employed. In this paper, the authors propose a novel method of achieving quick stopping times without the use of any brake-unit. Experimental test results with and without this method on a large inertia motor-load combination show that the proposed stopping method is able to reduce the stopping time significantly compared to normal decelerated stop without the need for a braking unit.

• Proceedings of the KAIS Fall Conference
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• 2009.12a
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• pp.531-533
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• 2009

본 연구에서는 E-EGR Valve 내에 퇴적물이 쌓여 디젤엔진의 성능을 저하시키는 문제를 해결하기 위하여 CRDI 직분식 4기통 엔진에 장착된 E-EGR 밸브를 대상으로 형상변화에 따른 유동해석을 통하여 퇴적물 축적과 작동불량을 감소 시켜줄 새로운 형상을 제시하고자 하였다.