• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.38-39
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• 2017

This paper proposes a new control method for an AC-DC Buck converter which is utilized as a front-end converter of a 2-stage high power density adapter. In the conventional adapter applications, 2-stage configuration shows higher power transfer efficiency and higher power density than those of the single stage flyback converter. In the 2-stage AC-DC converter, the boost converter is widely used as a front-end converter. However, an efficiency variation between high AC line and low AC line is large. On the other hand, the proposed conduction band control method for a buck front-end converter has an advantage of small efficiency variation. In the proposed control method, switching operation is determined by a band control voltage which represents output load condition, and an AC line voltage. If the output load increasesin low AC line, the switching operation range is expanded in half of line cycle. On the contrary, in light load and high line condition, the switching operation is narrowed. Thus, the proposed control method reduces switching loss under high AC line and light load condition. A 60W prototype which is configured the buck and LLC converter with the proposed control method is experimented on to verify the validity of the proposed system. The prototype shows 92.16% of AC-DC overall efficiency and 20.19 W/in 3 of power density.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.125-128
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• 2006

This paper presents a novel type soft switching PWM power frequency AC-AC converter using bidirectional active switches or single phase utility frequency AC-high frequency AC matrix converter. This converter can directly convert utility frequency AC (UFAC, 50Hz/60Hz) power to high frequency AC (HFAC) power ranging more than 20kHz up to 100kHz. A novel soft switching PWM prototype of high frequency multi-resonant PWM controlled UFAC-HFAC matrix converter using antiparallel one-chip reverse blocking IGBTs manufactured by IXYS corp. is based on the soft switching resonance with asymmetrical duty cycle PWM strategy. This single phase UFAC-HFAC matrix converter has some remarkable features as electrolytic capacitor DC busline linkless topology, unity power factor correction and sine-wave line current shaping, simple configuration with minimum circuit components, high efficiency and downsizing. This series load resonant UFAC-HFAC matrix converter, incorporating bidirectional active power switches is developed and implemented for high efficiency consumer induction heated food cooking appliances in home uses and business-uses. Its operating performances as soft switching operating ranges and high frequency effective power regulation characteristics are illustrated and discussed on the basis of simulation and experimental results.

• 전력전자학회논문지
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• 제20권1호
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• pp.51-58
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• 2015

In order to decrease the size of a switch mode power supply, high switching frequency can be an efficient way to reduce the size of passive components in the converter. In this paper, a 500-kHz high-frequency LLC resonant converter is proposed with an accurate design method of magnetizing inductance, as well as the relationship between the switching frequency and the size of the passive components. Simulation and experimental results are presented to verify the proposed methods and equations, including the temperature data of each passive and active device of the converter. Using those results, dominant power losses in the prototype converter under 500-kHz high-frequency operation are investigated, compared with the results from a 100-kHz converter. In addition, operating waveforms and power conversion efficiency will be shown to obtain design considerations for the high switching frequency LLC resonant converter.

• 전력전자학회논문지
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• 제18권2호
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• pp.138-144
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• 2013

Most of the DC loads have had the sensitive characteristics electrically for input voltage. In this system, power converter is operated after connecting with DC loads to minimize the overshoot of the control voltage that may occur during connection of the loads. But whenever starting the power converter, parameters in circuit are different because power converter has been connected with diverse load types at each startup time. This is cause of a disadvantage to PI controller design of power converter. In this paper, the novel voltage control method using sliding mode control theory has proposed. This control method minimizes the overshoot of control voltage at startup of power converter. Despite the variations of the system parameters, the proposed voltage controller has fast response and robustness characteristics such as PI and sliding mode controllers. The proposed controller was applied to the three-phase AC/DC converter and each performance of controller was verified.

• 전력전자학회논문지
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• 제23권3호
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• pp.190-198
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• 2018

This paper proposes a nonisolated, bidirectional, soft-switching DC - DC converter with PWM plus phase shift (PPS) control. The proposed converter has an input-parallel/output-series configuration and can achieve the interleaving effect and high voltage gains, resulting in decreased voltage ratings in all related devices. The proposed converter can operate under zero-voltage switching (ZVS) conditions for all switches in continuous conduction mode. The power flow of the proposed converter can be controlled by changing the phase shift angle, and the duty is controlled to balance the voltage of four high voltage side capacitors. The PPS control device of the proposed converter is simple in structure and presents symmetrical switching patterns under a bidirectional power flow. The PPS control also ensures ZVS during charging and discharging at all loads and equalizes the voltage ratings of the output capacitors and switches. To verify the validity of the proposed converter, an experimental investigation of a 2 kW prototype is performed in both charging and discharging modes under different load conditions and a bidirectional power flow.

• 전력전자학회논문지
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• 제7권1호
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• pp.18-29
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• 2002

기존의 역률 개선 컨버터는 경 부하에서 높은 직류 링크 전압을 갖는다. 특히 라인 전압이 높고 부하가 작을 경우, 직류 링크 전압은 매우 높은 전압을 갖게 되어 실용상 문제가 존재한다. 본 논문에서 역률 개선 부로 벅 토폴로지를 갖는 새로운 단일 전력 단 역률 개선 컨버터를 제안하였다. 또한 제안된 컨버터의 타당성을 증명하기 위해 제안된 회로의 설계 예를 보였으며, 설계 시 고려되어야 할 사항들과 관련 설계 식을 유도하였다. 유도된 설계 식으로부터 정해진 회로 정수 값을 이용하여 실험을 실시하였고, IEC1000-3-2의 역률 규제를 만족함을 입증하였다. 본 논문에서 제안된 컨버터를 통하여 기존의 단일 전력 단 컨버터의 문제점인 경 부하 시 높은 직류 링크 전압 문제를 해결할 수 있었다.

• Journal of Power Electronics
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• 제6권2호
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• pp.131-138
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• 2006

An active clamp ZVS PWM forward converter using a secondary synchronous switch control is proposed in this paper. The proposed converter is suitable for low-voltage and high-current applications. The structure of the proposed converter is the same as a conventional active clamp forward converter. However, since it controls the secondary synchronous switch to build up the primary current during a very short period of time, the ZVS operation is easily achieved without any additional conduction losses of magnetizing current in the transformer and clamp circuit. Furthermore, there are no additional circuits required for the ZVS operation of power switches. Therefore, the proposed converter can achieve high efficiency with low EMI noise, resulting from soft switching without any additional conduction losses, and shows high power dens~ty, a result of high efficiency, and requires no additional components. The operational principle and design example are presented. Experimental results demonstrate that the proposed converter can achieve an excellent ZVS performance throughout all load conditions and demonstrates significant improvement in efficiency for the 100W (5V, 20A) prototype converter.

• 한국정보통신학회논문지
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• 제11권10호
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• pp.1894-1898
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• 2007

본 연구는 산업체에서 널리 사용되어지고 있는 기존의 3상 AC-DC 컨버터에서 무게와 부피를 획기적으로 줄일 수 있는 고역율 3상 AC-DC컨버터를 제안하였다. 제안된 고역율 3상 AC-DC 컨버터는 LC 필터를 제거 한 상태에서 효율성과 다탕성을 검증함으로써 경량화는 물론 저 비용을 실현할 수 있게 된다. 또한 LC 필터를 제거하였음에도 불구하고 성능 면에서 볼 때 기존의 AC-DC 컨버터와 비슷한 성능을 얻을 수 있으므로 고전력 밀도 및 고역율이 요구되는 항공 우주 분야에 응용이 가능해 질 것으로 기대된다.

• 전자공학회논문지A
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• 제31A권6호
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• pp.128-133
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• 1994

This paper proposes a new TTL-to-CMOS converter which has low power dissipation. This converter has no static power dissipation for typical TTL output voltage levels. The simulatio result shows that the power dissipation is reduced to about 1/20 of conventional level converter using CMOS inverters. It also has hysteresis due to the positive feedback which makes the converter noise immune. The logic threshold voltages in the hysteresis characteristic can be optimized by changing the size ratios of the transistors.

• 한국산학기술학회논문지
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• 제11권7호
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• pp.2570-2578
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• 2010

본 논문에서는 임계전류도통모드로 동작하는 디지털제어 단상 역률개선(PFC; power-factor correction) 컨버터를 제안한다. 제안한 컨버터는 PFC를 위하여 DC-DC 부스트 컨버터 구조를 이용하며 인덕터전류를 임계도통모드로 동작시킨다. 또한 제안한 컨버터는 마이컴을 이용하여 디지털적으로 제어되기 때문에 제어회로는 간단해지고 컨버터는 더욱 효과적으로 동작한다. 본 논문에서는 먼저 제안한 컨버터의 동작원리를 설명하고 회로를 해석한다. 그리고 본 논문은 제안한 컨버터의 구현방법을 소프트웨어와 회로설계 부분으로 구분하여 구체적인 설계예와 함께 설명한다. 또한 설계된 회로파라미터에 의한 프로토타입 컨버터의 실험결과로 제안한 컨버터가 단상 PFC 컨버터로써 좋은 동작 특성을 가지고 있음을 보인다.