• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.481-482
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• 2016

병렬 운전 시 인터리빙 기술은 인버터 최종 출력 전류에 포함되는 스위칭 주파수 성분의 고조파를 제거하는 장점을 가지고 있지만 이로 인해 고주파 성분의 영상분 순환 전류를 만든다. 따라서 이 성분을 억제하기 위해 커플드 인덕터가 같이 사용된다. 하지만 커플드 인덕터를 사용할 경우에는 파라메타의 오차로 인해 안정성에 문제가 발생 할 수 있다. 따라서 본 논문에서는 인터리빙 및 커플드 인덕터를 사용한 병렬 운전 인버터 시스템에서 전류 품질 개선을 위해 고조파 보상을 할 경우 발생 할 수 있는 안정성 문제에 대한 원인을 규명하고 새로운 순환전류 제어 방법에 대해 제안하고 실험을 통해 검증하였다.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.6
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• pp.551-557
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• 2006

The electrical frequency synchronized periodic torque ripple exits in the AC motor. There are various sources of torque ripple in AC motor such as current measurement error, dead time, etc. This paper proposes a compensation algorithm which suppresses undesired side effect known as the periodic torque ripple of AC motor. The torque ripple compensation classified as the speed ripple detector and torque ripple compensator. This paper proves a speed ripple minimization at steady state by analysis of torque ripple compensator. A new speed ripple detector improves the performance of torque ripple compensation algorithm. The simulation and experimental results show that the compensation algorithm is effective and the torque ripple compensation method improves the performance of speed ripple detector by eliminating torque ripples effectively.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.700-701
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• 2015

본 논문은 함정 피탐지 성능 개선을 위하여 함정의 효율적인 탈자 프로토콜 탐색 기법에 관한 연구를 하였다. 탈자 프로토콜은 정해진 장비와 시간내에서 영구자기장 성분을 최소화 해야하는 방법으로써 본 논문에서는 탈자 초기 전류와 탈자 종료 전류의 자화 방향을 이용하여 최적의 탈자 프로토콜을 탐색하는 기법에 대하여 연구하였다. 실험을 위해서 탈자 처리 시설을 제작하였으며, 실험의 오차를 줄이기 위하여 지구자기장을 보상하는 3축방향의 코일을 이용하였다. 실험 결과 초기 전류와 종료 전류의 자화방향을 이용하여 최적의 탈자 프로토콜을 탐색할 수 있었다.

• Journal of IKEEE
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• v.26 no.2
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• pp.271-279
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• 2022

This paper proposes an advanced dead-time compensation method for dual inverter with a floating capacitor. The dual inverter with floating capacitor is composed of double two-level inverters and a bulk electrolytic capacitor. The output voltage of the dual inverter is dropped by the conduction voltage of the power semiconductors. The voltage drop and dead-time cause the fundamental and harmonic distortions of output currents. When supplied power for OEW-load is low, the dual inverter operates as single inverter for effective operation. The dead-time compensation method for the dual inverter operated as single inverter is needed for reliability. The proposed method using band pass filter in this paper compensates dead-time, dead-time error and changed voltage drop error of power semiconductors for the dual inverter and dual inverter operated as single inverter. The effectiveness of the proposed method is verified by simulation results.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.3
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• pp.279-284
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• 2014

This paper proposes a novel OLED pixel circuit to compensate the threshold voltage variation of p-channel low temperature polycrystalline silicon thin-film transistors (LTPS TFTs). The proposed 5-TFT OLED pixel circuit consists of 4 switching TFTs, 1 OLED driving TFT and 1 capacitor. One frame of the proposed pixel circuit is divided into initialization period, threshold voltage sensing and data programming period, data holding period and emission period. SmartSpice simulation results show that the maximum error rate of OLED current is -4.06% when the threshold voltage of driving TFT varies by ${\pm}0.25V$ and that of OLED current is 9.74% when the threshold voltage of driving TFT varies by ${\pm}0.50V$. Thus, the proposed 5T1C pixel circuit can realize uniform OLED current with high immunity to the threshold voltage variation of p-channel poly-Si TFT.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.35-36
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• 2013

본 논문은 EV(Electric Vehicle)에 사용되는 배터리의 충/방전 전류에 따른 SOC(State of Charge) 및 전압특성을 Matlab Simulink로 구현하였으며, 검증을 위해 양방향 DC-DC 컨버터를 설계하여 실험을 하였다. 배터리 모델에 사용된 파라미터는 Randles등가회로를 기반으로 펄스방전을 통해 추출하였고, 단자전압 계산부에 3D Look-up 테이블을 이용해 적용하였다. SOC계산부는 전류에 따른 용량변화를 보상하기 위해 Peukert Effect를 적용하였으며, FTP-75 전류패턴으로 온도($0^{\circ}C$, $25^{\circ}C$, $40^{\circ}C$)에 따라 실험한 결과 시뮬레이션의 오차율은 5%로 높은 정확도를 갖는 것을 확인을 통해 검증 하였다.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.935-939
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• 2015

This paper describes sensorless speed control of brushless DC motors by using direct torque control. Direct torque control offers fast torque response, robust specification of parameter changes, and lower hardware and processing costs compared to vector-controlled drives. In this paper, the current error compensation method is applied to the sensorless speed control of a brushless DC motor. Through this control technique, the controlled stator voltage is applied to the brushless DC motor such that the error between the stator currents in the mathematical model and the actual motor can be forced to decay to zero as time proceeds, and therefore, the motor speed approaches the setting value. This paper discusses the composition of the controller, which can carry out robust speed control without any proportional-integral (PI) controllers. The simulation results show that the control system has good dynamic speed and load responses at wide ranges of speed.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.156-157
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• 2017

본 논문은 전차원 자속 관측기를 이용한 대용량 매입형 영구자석 동기전동기(IPMSM)의 센서리스 제어 기법을 제안한다. 기존의 전차원 자속 관측기를 사용한 제어 방식은 IPMSM의 자속 모델을 표면 부착형 영구자석 동기전동기(SPMSM)의 자속 모델처럼 해석하기 때문에 추정되는 회전각의 오차가 발생한다. 특히 릴럭턴스 토크가 큰 대용량 IPMSM 구동 시에는 회전각 오차가 크게 나타나므로 단위 전류당 발생하는 최대토크를 감소시켜 정밀한 MTPA 제어가 불가능하다. 제안하는 알고리즘은 전차원 자속 관측기를 통해 추정된 회전각의 오차를 보상하여 대용량 IPMSM의 정밀한 센서리스 제어를 가능하게 한다. 제안하는 기법의 타당성은 시뮬레이션을 통해 확인하였으며, 기존의 알고리즘과 비교하였다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.1
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• pp.7-13
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• 2008

This paper proposes a newly structured circuit that can compensate current deviation of a data driver circuit for OLED. A conventional data drivel circuit for OLED cannot compensate the current deviation at the data drivel circuit output terminal generated by MOS process change, but the proposed data drivel circuit can authorize uniform value of current to an OLED panel by calibrating the current deviation at the output terminal. The proposed circuit can minimize current deviation of the output current via process change by connecting the circuit for data output current with a common interconnect line through addition of a switching transistor to the existing data output circuit. The circuit proposed in this paper has been designed based on an OLED panel supporting $128{\times}128$ resolution, and the process used for driver circuit development is 0.35um. As a result of the experiment in this study, the output current of the data driver circuit proposed here has 1% range of error, while 9% range of severe changes was demonstrated in the case of the previous data driver circuit. When using the data driver circuit for OLED proposed in this paper, high definition OLED display can be actualized and the circuit can be applied to mobile display devices requiring high quality display features.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.3
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• pp.283-292
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• 2016

The performance of 4-switch 3-phase inverter(: FSTPI) which replace two switches of 6-switch 3-phase inverter(: SSTPI) is mainly affected by the compensator unbalanced voltages and output voltage control method. This paper proposes a DC offset current injection method to compensate the capacitor unbalanced voltages for FSTPI. A simplified SVPWM method which can be applied to FSTPI is also proposed. The validity of the proposed methods is verified by simulation and experiment using SPMSM.