• 한국수산과학회지
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• 제50권5호
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• pp.605-615
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• 2017

A multi-resonant broadband acoustic transducer with six Tonpilz elements operating at different resonant frequencies in a transducer assembly was fabricated, tested, and analyzed. A compensated transducer, modified by adding series inductance to the developed multi-resonant broadband transducer, was shown to provide improved bandwidth performance with a relatively more uniform frequency response compared with the uncompensated transducer. By controlling the series inductance, flat frequency response characteristics at two frequency bands were obtained over the range 38-52 kHz with 1.1 mH inductance and 50-60 kHz with 0.4 mH inductance. These results suggest that the operating frequency of the developed multi-resonant broadband transducer in a chirp echo sounder can be shifted to a different frequency band that is optimized according to the environment for more effective echo surveys of fishing grounds.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.370-372
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• 2008

A resonant converter suitable for applications of wide input variation is proposed. A half-bridge converter and a phase-shift converter are combined in primary and the secondaries of each transformer are connected in series which makes four voltage levels. Furthermore, by adopting resonant converter scheme, a resonant capacitor is connected with the secondaries of the transformers in series and an output inductor is removed. Zero voltage switching is achieved from full load to no load. The analysis of the resonant converter and experimental results of 200W prototype is presented to verify the features of the converter.

• Journal of Electrical Engineering and Technology
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• 제9권5호
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• pp.1632-1642
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• 2014

This paper presents an interleaved resonant converter to reduce the voltage stress of power MOSFETs and achieve high circuit efficiency. Two half-bridge converters are connected in series at high voltage side to limit MOSFETs at $V_{in}/2$ voltage stress. Flying capacitor is used between two series half-bridge converters to balance two input capacitor voltages in each switching cycle. Variable switching frequency scheme is used to control the output voltage. The resonant circuit is operated at the inductive load. Thus, the input current of the resonant circuit is lagging to the fundamental input voltage. Power MOSFETs can be turn on under zero voltage switching. Two resonant circuits are connected in parallel to reduce the current stress of transformer windings and rectifier diodes at low voltage side. Interleaved pulse-width modulation is adopted to decrease the output ripple current. Finally, experiments are presented to demonstrate the performance of the proposed converter.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.169-171
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• 2005

In this paper, a novel type of auxiliary switched capacitor assisted edge resonant soft switching PWM series load resonant high frequency inverter with two auxiliary edge resonant lossless inductor snubbers is proposed for small consumer induction heating appliances. The operation principle of this high frequency inverter is described using the switching mode equivalent circuits. The practical effectiveness of the newly proposed soft switching inverter are discussed as compared with the conventional soft switching high frequency inverters based on simulation and experimental results from an application point of view.

• 전력전자학회논문지
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• 제11권3호
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• pp.216-223
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• 2006

태양광 발전 시스템을 위한 무접점 변압기 적용 고효율 Full-bridge LLC 공진컨버터를 제안하였다. 제안된 LLC 공진컨버터는 직렬 커패시터와의 직렬공진을 위해 무접점 변압기의 누설인덕턴스와 자화인덕턴스를 이용하였다. 제안된 LLC 공진컨버터는 공진주파수 보다 높은 스위칭영역에서 연속 공진전류로 동작하는 기존 직렬공진 컨버터와는 달리 공진주파수 아래의 좁은 주파수 범위에서 불연속 공진전류로 동작한다. 이러한 불연속모드 공진전류 때문에 제안된 컨버터는 어떤 보조회로 없이 무접점 변압기 1차측 주스위칭 소자의 영 전압 스위칭(ZVS)과 2차측 다이오드의 영 전류 스위칭(ZCS)을 얻을 수 있고, 높은 전압이득특성을 갖는다. 본 논문에서는 무접점 변압기 적용 Full-bridge LLC 공진컨버터를 이용한 무접점 전원장치에 대한 이론적 해석 및 시뮬레이션을 통해 150W급 시제품을 제작하여 태양광 발전 전원시스템에 적용 실험한 결과를 서술했다.

• 전력전자학회논문지
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• 제14권3호
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• pp.251-259
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• 2009

본 논문에서는 비접촉 시스템에 있어서 스위칭 소자의 영 전압 스위칭(ZVS)뿐만 아니라 2차측 정류 다이오드 역시 영 전류 스위칭(ZCS)을 이룰 수 있는 비접촉 변압기를 이용한 Half-Bridge 직렬 공진 컨버터 적용 비접촉 충전 시스템을 제안 적용하였다. 본 논문에서 제안한 비접촉 변압기 적용 Half-Bridge 직렬 공진컨버터는 공진 주파수보다 낮은 영역에서 스위칭 동작이 가능하기 때문에 불연속 공진전류에 의한 2차측 정류 다이오드의 영 전류 스위칭(ZCS)이 가능하다. 또한 좁은 주파수 영역에서 제어가 가능하며 높은 전압 이득특성에 따라 적은 턴-수비의 변압기를 사용할 수 있으므로 기존의 비접촉 시스템과 비교해 보았을 때 효율특성을 개선시킬 수 있다. 시뮬레이션과 이론적인 분석을 토대로 3.15W 시제품을 제작하고 실험내용을 서술했다.

• 한국산학기술학회논문지
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• 제11권11호
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• pp.4483-4488
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• 2010

LED는 다른 광원에 비해 동작수명이 길고, 친환경적이며, 에너지 효율이 높은 장점을 가지고 있다. 최근 LED 기술의 발전으로 인해 고휘도, 고용량의 LED가 개발됨에 따라, 표시장치에만 적용되던 LED를 조명장치에도 적용하는 기술이 확산되고 있다. 파워 LED는 동작의 안정성 및 신뢰성을 확보하기 위해 구동전류를 일정한 값 이하로 유지하는 전류제한기능이 필요한데, 본 논문에서는 전류제한기능을 포함한 하프브리지 LLC 직렬공진형 컨버터를 제안한다. 하프브리지 LLC 직렬공진형 컨버터는 다른 공진형 컨버터에 비해 상대적으로 입력전압 및 출력부하 범위가 광범위한 장점이 있으며, 변압기의 누설인덕턴스를 공진인덕터로 이용할 수 있기 때문에 마그네틱 소자를 줄일 수 있는 장점이 있다. 전류제한기능 및 역률개선기능을 포함하고 있는 출력전압 DC24[V], 200[W]급의 LED 조명장치 구동용 하프브리지 LLC 직렬공진형 컨버터의 설계 및 실험을 통해 타당성을 입증하였다.

• 전력전자학회논문지
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• 제23권1호
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• pp.24-31
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• 2018

An induction heating (IH) resonant converter, as well as its coil design method, is proposed in this study to improve the heat capability of low- and high-resistance IH vessels. Conventional IH resonant converters have been designed only for heating high-resistance containers designed for IH application. Thus, the primary current in the resonant tank becomes extremely high to transfer the rated power when the converter heats the low-resistance vessel. As a result, the rated power cannot be transferred due to overcurrent flows against the rated switch current. Hence, the optimal number of coil turns and proper operating frequency to heat high- and low-resistance vessels are proposed in this study by analyzing an IH load model. Simulation and experimental results using a 2.4 kW prototype resonant converter and its IH coil validate the proposed design.

• Journal of Power Electronics
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• 제14권5호
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• pp.882-889
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• 2014

This paper presents a zero voltage switching (ZVS) converter with three resonant tanks. The main advantages of the proposed converter are its ability to reduce the switching losses on the power semiconductors, decrease the current stress of the passive components at the primary side, and reduce the transformer secondary windings. Three resonant converters with the same power switches are adopted at the low voltage side to reduce the current rating on the transformer windings. Using a series-connection of the transformer secondary windings, the primary side currents of the three resonant circuits are balanced to share the load power. As a result, the size of both the transformer core and the bobbin are reduced. Based on the circuit characteristics of the resonant converter, the power switches are turned on at ZVS. The rectifier diodes can be turned off at zero current switching (ZCS) if the switching frequency is less than the series resonant frequency. Therefore, the reverse recovery losses on the rectifier diodes are overcome. Experiments with a 1.6kW prototype are presented to verify the effectiveness of the proposed converter.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제11B권3호
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• pp.104-111
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• 2001

The design procedures and experimental results of a single-stage electronic ballast using half-bridge resonant inverter are presented in this paper. The proposed topology is based on a single-stage ballast which combines a boost converter and a half-bradge series resonant inverter. High power factor is achieved by using the boost semi-stage operating in discontinuous conduction mode and inverter semi-stage operated above resonant frequency to provide zero voltage switching is empolyed to ballast the fluorescent lamp Experimental results from the ballast system with 36W fluorescent