• 조명전기설비학회논문지
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• 제20권1호
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• pp.34-40
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• 2006

본 논문에서는 포워드형 3상 PWM 정류기를 이용한 새로운 DC 48[V] 통신용 전원시스템을 제안하여 역률과 효율, 리플 전압의 개선에 관하여 서술하였다. 제안된 DC 48[V] 통신용 전원시스템은 각 선간에 스위치와 인덕터 그리고 콘덴서가 조합된 전력변환장치로 구성되며, 전력변환장치내의 각 스위치의 턴-온시 제어 주기내의 도통시간을 조정하여 역률 1의 정현파 전류를 얻었다. 그리고 일반적인 PWM 정류기를 포워드 형태의 PWM 정류기로 구성함으로써 스위치의 온-오프시 발생되는 피크 전류를 작게 하여 변환 효율 92.1[%]을 얻었다. 또한 고조파 입력전류 규제값(IEC61000-3-2 Class-A)을 만족하는 입력 전류를 가지며, 3상 전원의 왜곡이 중첩되는 상태에서도 출력 전압의 맥동성분을 저감시켰다.

• 전력전자학회논문지
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• 제19권5호
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• pp.440-449
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• 2014

This study proposes an LLC series resonant converter with a current doubler using a coupled inductor as a rectification circuit for the secondary side. The current doubler circuit is generally used for a high-voltage input and low-voltage output circuit to obtain high efficiency with small transformer turn ratio. However, an inductive circuit is not generally used in the secondary side of an LLC series resonant converter. If inductive components exist on the secondary side, the resonant characteristics are changed through the secondary inductive circuit. Mathematical analysis shows that the secondary-side current doubler with coupled inductor is not affected by the resonant characteristic of the primary LLC if leakage inductance occurs in the coupled inductor. Results of the analysis are proven by simulation; an experiment is also conducted for the proposed circuit.

• Journal of Power Electronics
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• 제12권6호
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• pp.895-903
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• 2012

This paper presents a fast switching direct torque control (FS-DTC) using only a single DC-link current sensor. In FS-DTC, six new active voltage complex space vectors (CSVs) are synthesized by the conventional active voltage space vectors (SVs). The corresponding sectors are rotated in the anticlockwise direction by 30 degrees. A selection table is defined to select the CSVs. Based on the "Different Phase Mode", the output sequence of the selected CSV is optimized. Accordingly, a reconstruction method is proposed to acquire the phase currents. The core of the FS-DTC is that all of the three phase currents can be reliably reconstructed during every two sampling periods, which is the result of the fast switching between different phases. The errors between the reconstructed and actual currents are strictly limited in one sampling period. The FS-DTC has the advantages of the standard DTC scheme such as simple structure, quick torque response and robustness. As can be seen in the analysis, the FS-DTC can be thought of as an equivalent standard DTC scheme with 86.6% of the maximum speed, 173.2% of the torque ripple, and 115% of the response time of the torque. Based on a dSPACE DS1103 controller, the FS-DTC is implemented in an induction machine drive system. The results verify the effectiveness of the FS-DTC.

• 전기전자학회논문지
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• 제23권1호
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• pp.261-265
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• 2019

기존 양방향 컨버터와 출력 커패시터를 추진용 배터리 쪽으로 이동시킨 양방향 컨버터의 고장률 변화를 분석한다. 두 컨버터의 회로 구조적 동일성과 차이점을 분석하여 커패시터 위치 변경으로 동작전압이 저감됨을 확인한다. 전압스트레스 인자와 동작온도에 따른 커패시터 부품 고장률을 구하고 양방향 컨버터의 고장나무에 적용하여 컨버터 전체 고장률을 구한다. 동작온도와 커패시턴스 값에 따른 고장률과 평균고장시간을 비교 분석하여 설계 변경으로 인한 장 단점을 분석한다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권10호
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• pp.581-586
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• 2002

To improve the current waveform of diode rectifiers, we propose a new operating principle for the voltage-doubler diode rectifiers. In the conventional voltage-doubler rectifier circuit, relatively large capacitors are used to boost the output voltage, while the proposed circuit uses smaller ones and a small reactor not to boost the output voltage but improve the input current waveform. A circuit design method is shown by experimentation and confirmed simulation. The experimental results of the proposed diode rectifier satisfies the harmonic guide lines. A high input power factor of 97(%) and an efficiency of 98[%] are also obtained. The new rectifier with no controlled switches meet the harmonic guide lines, resulting in a simple, reliable and low-cost at-to dc converters in comparison with the boost-type current-improving circuits. This paper proposes a nonlinear impedance circuit composed by diodes and inductors or capacitors. This circuit needs no control circuits and switches, and the impedance value is changed by the polarity of current or voltage. And this paper presents one of these applications to improve the input current of capacitor input diode rectifiers. The rectifier using the nonlinear impedance circuit is constructed with four diodes and four capacitors in addition to the conventional rectifiers, that is, it has eight diodes and five capacitors, including a DC link capacitor. It makes harmonic components of the input current reduction and the power factor improvement. Half pulse-width modulated (HPWM) inverter was explained compared with conventional pulse width modulated(PWM) inverter. Proposed HPWM inverter eliminated dead-time by lowering switching loss and holding over-shooting.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.373-374
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• 2017

최근 개발 및 출시되고 있는 전기자동차(EV) 충전시스템은 3상 AC전원을 입력받아 입력역률개선과 고효율 AC/DC변환을 위한 Interleaved PFC컨버터, Bridgeless PFC컨버터, 3-Level 비엔나정류기(VIENNEA Rectifier) 등의 Topology가 사용되고 있으며, 변환된 DC전압을 입력받아 배터리를 충전하기 위한 절연된 고주파 DC/DC컨버터로 LLC 공진컨버터, 3레벨 컨버터 등이 사용되어 사이즈저감 및 경량화를 꾀하고 있다. 본 논문은 기존 입력역률 개선을 위한 PFC 컨버터와 배터리 충전을 위한 절연형 DC/DC 컨버터 2단으로 구성되어진 충전시스템 대신에 사이즈저감 및 효율개선 그리고 넓은 범위의 출력전압제어(200Vdc~430Vdc)에 대응 할 수 있도록 '단일전력단 3레벨 하이브리드 AC/DC 컨버터'를 제안하였고, 2kW 시제품을 제작하여 실험을 통해 적용 가능성을 입증하였다.

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.207-216
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• 2017

Wind energy conversion systems (WECS) which consist of wind turbines with permanent magnet synchronous generator (PMSG) and full-power converters have become widespread in the field of renewable power systems. Generally, conventional diode bridge rectifiers have used to obtain a constant DC bus voltage from output of PMSG based wind generator. In recent years, together advanced power electronics technology, Pulse Width Modulation (PWM) rectifiers have used in WECS. PWM rectifiers are used in many applications thanks to their characteristics such as high power factor and low harmonic distortion. In general, L, LC and LCL-type filter configurations are used in these rectifiers. These filter configurations are not exactly compensate current and voltage harmonics. This study proposes a hybrid passive filter configuration for PWM rectifiers instead of existing filters. The performance of hybrid passive filter was tested via MATLAB/Simulink environment under various operational conditions and was compared with LCL filter structure. In addition, neuro-fuzzy controller (NFC) was preferred to increase the performance of PWM rectifier in DC bus voltage control against disturbances because of its robust and nonlinear structure. The study demonstrates that the hybrid passive filter configuration proposed in this study successfully compensates current and voltage harmonics, and improves total harmonic distortion and true power factor.

• 전기학회논문지
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• 제66권2호
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• pp.328-338
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• 2017

In this paper, a zero torque control scheme adopting current sharing function (CSF) used in integrated Switched Reluctance Motor (SRM) drive with DC battery charger is proposed. The proposed control scheme is able to achieve the keeping position (KP), zero torque (ZT) and power factor correction (PFC) at the same time with a simple novel current sharing function algorithm. The proposed CSF makes the proper reference for each phase windings of SRM to satisfy the total charging current of the battery with zero torque output to hold still position with power factor correction, and the copper loss minimization during of battery charging is also achieved during this process. Based on these, CSFs can be used without any recalculation of the optimal current at every sampling time. In this proposed integrated battery charger system, the cost effective, volume and weight reduction and power enlargement is realized by function multiplexing of the motor winding and asymmetric SR converter. By using the phase winding as large inductors for charging process, and taking the asymmetric SR converter as an interleaved converter with boost mode operation, the EV can be charged effectively and successfully with minimum integral system. In this integral system, there is a position sliding mode controller used to overcome any uncertainty such as mutual inductance or DC offset current sensor. Power factor correction and voltage adaption are obtained with three-phase buck type converter (or current source rectifier) that is cascaded with conventional SRM, one for wide input and output voltage range. The practicability is validated by the simulation and experimental results by using a laboratory 3-hp SRM setup based on TI TMS320F28335 platform.

• 전력전자학회논문지
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• 제12권5호
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• pp.394-399
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• 2007

본 논문에서는 소프트 스위칭에 의한 새로운 고효율의 벅-부스트 DC-DC 컨버터에 대해 연구된다. 제안된 벅-부스트 컨버터는 기존의 벅-부스트 DC-DC 컨버터에서 문제가 되는 제어용 스위치의 스위칭 손실증대를 해결하기 위해 새로운 소프트 스위칭 기법이 적용된다. 소프트 스위칭 회로는 구조적으로 기존의 컨버터에 사용되는 벅-부스트용 인덕터와 스너버 회로를 변형 설계한 구조로써 회로구성이 간단하다. 제안된 컨버터에 사용된 제어스위치들은 부분공진의 동작에 의해 소프트 스위칭을 이룬다. 또한 컨버터의 출력전압은 제어스위치의 PWM 제어에 의해 조정되고 벅-부스트용 인덕터에 흐르는 전류는 불연속모드로 제어되어 제어회로와 제어기법이 간단한 장점이 주어진다. 제안된 벅-부스트 컨버터는 기존의 벅-부스트 컨버터와 비교되어 해석되고 컴퓨터 시뮬레이션과 실험을 통해 그 해석적 타당성이 입증된다.

• 전기학회논문지
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• 제64권1호
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• pp.196-200
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• 2015

The switching noise in the power electronics of the power conversion equipment (Power Conditioning System) for large energy storage devices are generated. Since the burst-level transient noise from being generated in the power system at a higher power change process influences the control circuit of the low voltage driver circuit. Noise may cause the malfunction of the control device even if no dielectric breakdown leads to a control circuit. To overcome this, this paper proposes the installation of an additional nano-surge protection device on the power supply DC output circuit of the battery management unit.