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3상 AC/DC PWM 컨버터의 IGBT 개방고장 진단에 관한 연구
임원상,김장식,김장목,이동춘,이교범 대한전기학회 2011 대한전기학회 학술대회 논문집 Vol.2011 No.4
본 논문에서는 3상 AC/DC PWM 컨버터에서 스위치 개방 고장을 검출하는 기법에 대해 연구하였다. 그 동안 전압원 인버터의 스위치 개방고장에 관한 많은 연구들이 진행되었지만, AC/DC 컨버터의 고장진단에 관한 연구는 미비하다. AC/DC 컨버터와 인버터는 전류 흐름이 반대이며 스위칭 고장발생 시 상전류 패턴에도 차이점이 나타나기 때문에 기존의 인버터의 개방 고장 기법들을 AC/DC 컨버터에 그대로 적용하기는 어렵다. 이 논문은 기존의 인버터 고장진단 기법을 해석하고 이를 컨버터 고장진단에 적용하였을 때의 문제점들을 파악하였다. 그리고 컨버터에 적합한 기법들을 제안하였다.
Diagnosis Methods for IGBT Open Switch Fault Applied to 3-Phase AC/DC PWM Converter
임원상,김장식,김장목,이동춘,이교범 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.1
Fault diagnosis technique of electrical drives is becoming more and more important, since voltage fed converter system has become industrial standard in many applications. Many studies have been conducted an inverter fault diagnosis for induction motors. However, there are few researches about fault diagnosis of 3-phase ac/dc PWM (Pulse Width Modulation) converter compared to the dc/ ac inverter. The ac/dc converter is the opposite of dc/ac inverter at current flow. Also, inverter and converter have different current patterns under the same condition of IGBT (Insulated gate bipolar transistor) open switch fault. Therefore, it is difficult to apply intact diagnosis methods of inverter to the converter. This paper proposes modified fault detection methods for IGBT open switch fault in 3-phase ac/dc PWM converter by modifying established fault diagnostic methods for dc/ac inverters.
Torque Maximization Control of 3-Phase BLDC Motors in the High Speed Region
임원상,김종필,백광렬,김장목 전력전자학회 2010 JOURNAL OF POWER ELECTRONICS Vol.10 No.6
This paper proposes a new torque control algorithm for BLDC motors to get the maximum torque in the high speed region. The delay of the phase currents is severe due to the stator reactance. The torque fluctuations of BLDC motors increase and the average torque is decreases due to a slow rise in the phase current when compared to the back EMF. In this paper, the phase current of BLDC motors under the high speed condition is analyzed and a torque maximization control is developed on the basis of using numerical analysis. Computer simulations and experimental results show the usefulness of the proposed control algorithm.
Compensation of Current Offset Error in Half-Bridge PWM Inverter for Linear Compressor
김동윤,임원상,황선환,김장목 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.6
This paper proposes a novel compensation algorithm of current offset error for single-phase linear compressor in home appliances. In a half-bridge inverter, current offset error may cause unbalanced DC-link voltage when the DC-link is comprised of two serially connected capacitors. To compensate the current measurement error, the synchronous reference frame transformation is used for detecting the measurement error. When an offset error occurs in the output current of the half-bridge inverter, the d-axis current has a ripple with frequency equal to the fundamental frequency. With the use of a proportional-resonant controller, the ripple component can be removed, and offset error can be compensated. The proposed compensation method can easily be implemented without much computation and additional hardware circuit. The validity of the proposed algorithm is verified through experimental results.
김형섭,임원상,김장목,이동춘,이교범 대한전기학회 2012 대한전기학회 학술대회 논문집 Vol.2012 No.4
본 논문에서는 3개의 전압센서를 가지는 3상 AC/DC PWM 컨버터에서 전압센서의 고장진단 기법에 대해 연구하였다. 전압센서는 컨버터를 제어하기 위한 교류입력 전원의 정보를 획득할 수 있는 중요한 장치이다. 그 동안 3상 AC/DC 컨버터에 대한 많은 연구들이 진행되었지만, 컨버터의 전압센서 고장진단에 관한 연구는 미비하다. 이 논문은 전압센서에 고장이 발생했을 때 고장진단 기법을 통해 고장을 검출하고 컨버터가 정상적으로 동작할 수 있는 방법을 제안한다.
A Capacitance Estimation of Film Capacitors in an LCL-Filter of Grid-Connected PWM Converters
허홍준,임원상,김장식,김장목 전력전자학회 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.1
A capacitor deterioration of LCL-filter grid-connected PWM converters is progressed by the self-healing mechanism. It leads to the degradation of the filter performance and drop of power factor. Thus, it is required to diagnose fault-point of capacitors and determine the replacement time. Typically, the fault of capacitors is determined when the capacitance is reduced up to 80% from initial value. This paper proposes algorithm to the determine capacitor replacement time of an LCL filter. The algorithm takes the advantage of change of the response on the injected resonant frequency corresponding to 80% value from the initial capacitance. The results of the algorithm are demonstrated through simulations and experiments.
Classification and Compensation of DC Offset Error and Scale Error in Resolver Signals
이원,문종주,임원상,박준호,김장목 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.3
This study proposes a classification and compensation algorithm of two non-ideal output signals of a resolver to reduce position errors. Practically, a resolver generates position errors because of amplitude imbalance and quadrature imperfection between the two output signals of the resolver. In this study, a digital signal processor system based on a resolver-to-digital converter is used to reconstruct the two output signals of the resolver. The two output signals, “sin” and “cos,” can be represented by a unit circle on the xy-plot. The classification and compensation of the errors can be obtained by using the radius and area of the circle made by the resolver signals. The method computes the integration of the areas made by the two resolver output signals to classify and compensate the error. This system cannot be applied during transient response given that the area integration during the transient state causes an error in the proposed method. The proposed method does not need any additional hardware. The experimental results verify the effectiveness of the proposed algorithm.
An Optimal Current Distribution Method of Dual-Rotor BLDC Machines
김성중,박제욱,임원상,정현우,김장목 전력전자학회 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.2
This paper proposes an optimal current distribution method of dual-rotor brushless DC machines (DR-BLDCMs) which have inner and outer surface-mounted permanent-magnet rotors. The DR-BLDCM has high power density and high torque density compare to the conventional single rotor BLDCM. To drive the DR-BLDCM, dual 3-phase PWM inverters are required to excite the currents of a dual stator of the DR-BLDCM and an optimal current distribution algorithm is also needed to enhance the system efficiency. In this paper, the copper loss and the switching loss of a DR-BLDCM drive system are analyzed according to the motor parameters and the switching frequency. Moreover, the optimal current distribution method is proposed to minimize the total electrical loss. The validity of the proposed method was verified through several experiments.
계통연계형 3상 PWM 컨버터에서 LCL필터의 필름 커패시터 열화 진단
김장식(Jang-sik Kim),임원상(Won-sang Im),김장목(Jang-mok Kim),오형식(Hyung-Shic Oh),최철(Cheol Choi) 전력전자학회 2011 전력전자학술대회 논문집 Vol.2011 No.7
3상 PWM 컨버터에서 LCL필터 필름 커패시터는 Selfhealing 메커니즘에 의해 열화가 진행되며, 이는 시스템의 필터성능과 역률 저하로 이어진다. 따라서 계통측 커패시터의 고장을 판단하고 교체시기를 결정하는 것이 필요하다. 본 논문에서는 정전용량의 80%에 해당하는 공진주파수를 한 주기 동안 주입하였을 때 나타나는 응답의 변화를 통해 커패시터의 열화고장진단 알고리즘을 제안하였다.