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Gwan-Bon Koo,Tae-Sung Kim,Gun-Woo Moon,Myung-Joong Youn 한국과학기술원 인간친화 복지 로봇 시스템 연구센터 2002 International Journal of Assistive Robotics and Me Vol.3 No.4
It is proposed that a capacitor be inserted in the main power flow of the primary side of a phase shift full bridge converter with series-connected two transformers (PSFBC with SCTT) for high efficiency in this paper. This method overcomes the disadvantage of conventional PSFB converter share with PSFBC with SCTT, conduction loss by a circulating current during the freewheeling mode. The primary voltage across the transformers increases due to the voltage across the inserted capacitor, allowing the turn ratio of the transformers to be increased. Furthermore, because of the capacitor, the primary current can be diminished nearly to zero during the freewheeling period so that the circulation energy during that period is reduced. As a result, the efficiency of the proposed converter is higher than that of the PSFBC with SCTT. A mode analysis and experimental results are presented to validate the proposed converter.
Online Load Torque Compensator for Single Rolling Piston Compressor
Bon-Gwan Gu,Jun-Hyuk Choi,In-Soung Jung 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
A single rolling piston compressor (SPRC) is commonly applied to the low power room air-conditioning system because of the low cost. The SRPC has only one compression and discharge process per each mechanical rotation. During compression process of the refrigerants, the load torque is quite high. On the other hand, during discharge process, of the refrigerant from the compressor room, the load torque is low. This load torque variation makes speed ripple and induce severe vibration, which causes fatigue failures of pipes and compressor parts at low speed. To relieve the vibration, the compressor usually operates in the high speed range where the rotor and piston inertia reduce the vibration phenomenon. Or a predefined feed-forward load torque compensator is used at low speed to minimize the speed ripple and vibration. However, since the load torque variation varies depending on the temperature, pressure, and speed, the predefined load torque table, based on one operating condition, is not appropriate to all. In this paper, an on-line load torque observer for SRPC is proposed. The proposed method utilizes the speed ripple as load torque ripple factor. The speed ripple is transformed into frequency domain and compensates each frequency harmonic term in a feed-forward way independently. Experimental results are presented to verify the proposed method.
Analysis and Design of a Phase Shift Full Bridge Converter With Series-Connected Two Transformers
Gwan-Bon Koo,Tae-Sung Kim,Gun-Woo Moon,Hyun-Soo Kim,Myung-Joong Youn 한국과학기술원 인간친화 복지 로봇 시스템 연구센터 2002 International Journal of Assistive Robotics and Me Vol.3 No.3
A new phase shift full bridge (PSFB) converter with series-connected two transformers is proposed. The main feature of the proposed converter is the zero voltage switching (ZVS) down to a very light load using the magnetizing currents of the transformers. Furthermore, no inductor is needed in the secondary side of the proposed converter since the two transformers can replace both a main transformer and an output inductor. Therefore, it is well suited for an on-board converter of a few hundreds watts, which requires a high efficiency and high power density. A mode analysis, design equations through the large signal modeling, and experimental results are presented to verify the validity of the proposed converter.
Start-Up Current Control Method for Three-Phase PWM Rectifiers with a Low Initial DC-Link Voltage
Bon-Gwan Gu,Jun-Hyuk Choi,In-Soung Jung 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.4
When a PWM rectifier has a low DC-link voltage during startup, the output voltage vector cannot be high enough to regulate the input current. This lack of a PWM rectifier output voltage vector can cause an unregulated inrush current when the rectifier operation starts. This paper presents a PWM rectifier start-up current control algorithm for when it starts operation with a lower DC-link voltage than unloaded condition case. To avoid the unregulated inrush current caused by a lack of DC-link voltage, the proposed control scheme regulates the one phase current with one switch chopping and it generates the current command considering the uncontrolled current magnitude information, which is calculated in advance. Simulation and experiment results support the validity of the proposed method.
Simple Lead Angle Adjustment for Brushless DC Motors
Bon-Gwan Gu,Jun-Hyuk Choi,In-Soung Jung 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.3
This paper presents a simple lead angle adjustment method for brushless DC motors. The proposed method is based on the motor current dynamics analysis during the current commutation interval. With the proposed scheme, the phase current and phase back-EMF voltage are in phase and the BLDC motor and drive system have a high efficiency induced by the reduced copper and conduction losses. Experimental results are shown to validate the proposed method.
Bon-Gwan Gu,Jun-Hyuk Choi,In-Soung Jung IEEE 2014 IEEE transactions on power electronics Vol.29 No.4
<P>In this study, interturn short fault models of permanent magnet synchronous motors (PMSMs) employing series and parallel winding connections are developed using deformed flux models based on both fault winding flux information and inductance variations caused by cross flux linkages that depend on the distribution of same phase windings. As these models take into account fault winding within a three-phase winding dynamics analysis, they constitute fourth-order assessments. In the parallel-winding model, an additional dynamical analysis is used to describe variations in current distribution caused by the parallel connection between fault and healthy windings. Based on deformed flux modeling and positive sequence current assumptions, the proposed model is derived in both positive and negative sequence synchronous reference frames. A finite-element method-based simulation is applied to validate the proposed PMSM model.</P>
Single rotary compressor의 저진동 저속제어를 위한 자동 부하 보상 알고리즘
구본관(Bon-Gwan Gu),최준혁(Jun-Hyuk Choi),정인성(In-Soung Jung) 전력전자학회 2010 전력전자학술대회 논문집 Vol.2010 No.11
저용량 에어컨의 압축기에 많이 사용되는 Single rotary 방식은 하나의 피스톤만을 채용하여 가격적인 면에서 큰 이점을 가진다. 그러나, 압축기 모터가 1회전할때 마다 압축과 토출을 단 1회 거치게 되므로, 부하변동을 심하여 진동이 많이 발생하는 단점이 있다. 이러한 단점을 보완하기 위하여 Single rotary를 사용하는 에어컨 제품에서는 저속에서의 운전을 회피하거나 하나의 운전점에 대한 전향보상기를 채용하여 진동을 저감시켜왔다. 본 논문에서는 모든 운전점에서 보상이 가능하도록 압축과 토출로 인한 부하의 패턴에서 각 주파수 성분을 분석하여 자동으로 부하 토크를 보상하는 알고리즘을 제안한다. 제안된 방법은 가장 영향이 큰 1차와 2차 주파수 성분의 속도 리플의양을 FFT 하고, 그 양이 작아지는 방향으로 부하 토크를 전향제어방식으로 인가하는 방식이다. 제안된 방식을 이용하여 저속 운전에서 진동이 저감 되는것을 실험을 통하여 보였다.
단일 전력단 단상 공진형 영전류 스위칭 역률 개선 회로
구관본(Gwan-Bon Koo),이준영(Jun-Young Lee),윤명중(Myung-Joong Youn) 전력전자학회 1999 전력전자학술대회 논문집 Vol.1999 No.7
An Integrated zero current switching (ZCS) quasi-resonant converter( QRC) for power factor correction and high efficiency with single switch is proposed in this thesis. Boost integrated circuit operating discontinuous conduction mode(DCM) and QRC are used for power factor correction and reducing switching loss, respectively. A prototype converter has been designed and experimented At rated condition, the THD in the Input current waveform of this prototype has approximately 18%. The efficiency is obtained about 70%, the power factor is about 0.985 as well.<br/> Therefore, the proposed converter IS suitable for a low power level converter with operating switching frequency above several hundred kHz.
Simple Lead Angle Adjustment Method for Brushless DC Motors
Gu, Bon-Gwan,Choi, Jun-Hyuk,Jung, In-Soung The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.3
This paper presents a simple lead angle adjustment method for brushless DC motors. The proposed method is based on the motor current dynamics analysis during the current commutation interval. With the proposed scheme, the phase current and phase back-EMF voltage are in phase and the BLDC motor and drive system have a high efficiency induced by the reduced copper and conduction losses. Experimental results are shown to validate the proposed method.