• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.246-248
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• 1994

This paper describes a bidirectional Voltage Source PWM Converter for an elevator. From the study of boost rectifier, the control circuit desisted by full digital DSP technique. The characteristic of control circuit is that implements of space-vector PWM method and has feedback loop of DC side load current which reduce DC voltage flucturation.

• Journal of Power Electronics
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• 제18권1호
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• pp.137-146
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• 2018

This paper describes a single pulse-width modulation control strategy using the Single Pulse-Width Modulation (SPWM) method with a soft-switching technique for a wide range of output voltages from a bidirectional Dual-Active Bridge (DAB) converter. This method selects two typical inductor current waveforms for soft-switching, and proposes a rule that makes it possible to achieve soft-switching without any compensation algorithm from the waveforms. In addition, both the step-up and step-down conditions are analyzed. This paper verifies that the leakage inductance is independent from the rule, which makes it easier to apply in DAB converters. An integrated algorithm, which includes step-up and step-down techniques, is proposed. The results of experiments conducted on a 50-kW prototype are presented. The system efficiency is experimentally verified to be from 85.6% to 97.5% over the entire range.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 전력전자학술대회 논문집
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• pp.165-166
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• 2015

본 논문은 새로운 단일전력변환 SEPIC(Single-Ended Primary-Inductor Converter)-ZETA 절연형 양방향 컨버터를 제안한다. 제안된 컨버터는 SEPIC과 ZETA 컨버터가 결합된 구조로 절연을 통해 안정성을 강화했고, DC측 리플 전류가 낮아 에너지 저장장치의 수명을 연장시킨다. 그리고 SEPIC 컨버터 모드(DC/AC)와 ZETA 컨버터 모드(AC/DC)에서의 입출력 전압비가 동일해 양방향 제어 알고리즘이 간단하다. 또한, 기존 two-stage 구성의 양방향 컨버터와 달리 회로가 단순하며, 단일전력변환을 통한 고효율 저비용의 장점을 가지고 있다. 본 논문에서는 이론적 해석 및 제안한 컨버터의 250W급 시작품을 이용한 실험결과를 통해 컨버터의 우수성 및 성능을 검증한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.994-995
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• 2008

It is possible to suppress voltage drops, power loading fluctuations and regeneration power lapses for DC railway systems by applying an energy storage system. A electric double layer capacitor (EDLC) of the rapid charge/discharge type has been developed and used in wide ranges. It has a long life, high efficiency and maintenance free/low pollution features as a new energy storage element. In this paper, an efficient charge and discharge control method of a bidirectional DC-DC converter using the supercapacitor is proposed.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.97-99
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• 2008

It is possible to suppress voltage drops, power loading fluctuations and regeneration power lapses for DC railway systems by applying an energy storage system. Recently the electric double layer capacitor (EDLC) of the rapid charge/discharge type has been developed and used in wide ranges. The on board energy storage system with supercapacitor for railway vehicles presented in this paper seems to be a reliable technical solution with an enormous energy saving potential. In this paper, an efficient charge and discharge control method of a bidirectional DC-DC converter using the supercapacitor is proposed.

• 전력전자학회논문지
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• 제21권4호
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• pp.302-311
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• 2016

This paper proposes a hybrid ESS that integrates an energy storage system (ESS) with an uninterruptible power supply (UPS). The hybrid ESS has a demand management and emergency power supply function while increasing the battery utilization of the UPS, which has just been used in a power failure. In addition to the critical load, the proposed system augments the capacity of emergency generation using an additional load, which has voltage and frequency-dependent characteristics to the grid side. The control algorithm of the AC-DC converter and bidirectional DC-DC converter is proposed for demand management and emergency power supply. Furthermore, seamless and autonomous transfer methods to alleviate the transient during mode transfer are proposed. To validate the proposed control scheme, experimental results from a 5 kW prototype are provided.

• 전력전자학회논문지
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• 제7권4호
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• pp.322-331
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• 2002

본 논문은 단상 반파 PWM 정류기와 3상 2-leg 인버터를 결합한 단상-삼상 컨버터 회로에서 전원전압의 센서를 제거하여 3상 유도전동기를 저가형으로 구동하는 방법을 제안하고자 한다. 전원전압의 센서를 제거하기 위해 전원 전류의 실측치와 제어기 내의 모델전류가 일치하도록 관측기를 구성하여 전원전압을 추정한다. 본 논문에서 제안한 기법을 사용할 경우 스위칭 소자와 센서 수를 줄이면서 직류전압 일정제어, 입력전류의 정현제어 및 단위 역률 제어가 가능하고 VVVF 교류전압을 얻을 수 있다는 장점이 있다. 3[Hp]의 3상 유도전동기의 V/f 구동에 적용한 실험결과로 제시된 알고리즘의 타당성을 검증한다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권11호
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• pp.561-568
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• 2005

This paper proposes a method that distributes the load power and stores the regenerated energy for a hoist-load system using the supercapacitor, an energy storage device. The crane, which is a representative hoist-load system, operates in two modes. The first is the hoist-up mode in which the load container is lifted up: the maximum power is required at the end of acceleration. The second is the hoist-down mode in which the load container is lifted down; the regenerated energy is wasted by the resistor In this paper, the supercapacitor stores the regenerated energy in the hoist-down operation and supplies the peak power demand in the hoist-up operation. The same structure as the commercially available three-phase inverter is proposed as a bidirectional do-dc converter to charge and discharge the supercapacitor. A power control algorithm is proposed to optimize the load sharing between the generator and the supercapacitor. Using the proposed method, it is effected that the generator size can be cut down to one third of the original one; it leads to the reduction of the fuel consumption, noise and air pollution. Simulation and experimental results verify the effectiveness of the Proposed method.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권3호
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• pp.298-304
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• 2014

In this paper, a novel topology for cascade multilevel converter is introduced, which has many levels with fewer number of power electronic components. Less number of the switches leads to the reduction of size, losses, simple control strategy and high efficiency. For proposed multilevel converter, a new algorithm for determination of dc voltage source values has been recommended. The performance and operation of the proposed multilevel converter has been evaluated with the simulation results of a cascade 25-level converter.

• 전력전자학회논문지
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• 제26권6호
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• pp.437-445
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• 2021

This paper proposes an operating frequency design method that limits the voltage applied to aload-side converter during the initial operation of a loosely coupled resonant dual-active bridge (LCR-DAB) converter and an initial operating strategy that applies it. The LCR-DAB converter uses two wireless power transfer coils instead of the high-frequency transformer of the general DAB converter. The wireless power coil has a physical distance of several tens of millimeter or more between the two coils; thus, the LCR-DAB converter is a bidirectional isolated power conversion system that can easily achieve high insulation performance. However, for the initial operation of the LCR-DAB, if the power-side converter is operated at the resonance frequency while the load-side converter is not operating, then a very high voltage due to resonance is applied to the load-side converter, thereby causing damage to the converter. Therefore, a method that can stably charge the DC link voltage of the secondary-side converter during the initial operation is needed. This paper proposes a method to initially charge the secondary-side DC link by operating the primary-side converter at a frequency with limited voltage gain rather than at a steady-state operating frequency. The validity of the proposed frequency design method and initial operating sequence is verified through simulation and experimentation of the 1 KW LCR-DAB converter.