• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.4
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• pp.493-500
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• 2015

A flyback converter operates with either pulse width modulation (PWM) or pulse frequency modulation (PFM) control scheme depending on the load current. At light load condition, PFM control is employed to reduce the switching frequency and thereby minimize the switching power loss. For heavier load, PWM control is used to regulate the output voltage of the flyback converter. The flyback controller has been implemented in a $0.35{\mu}m$ BCDMOS process and applied to a 40-W flyback converter. The light-load power efficiency of the flyback converter is improved up to 5.7-% comparing with the one operating with a fixed switching frequency.

• Journal of IKEEE
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• v.23 no.3
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• pp.1104-1107
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• 2019

This paper proposes a DC-DC boost converter for wearable AMOLED display using dead time controller to reduce dead time and improve power efficiency. Also the DC-DC boost converter adopts PWM-SPWM (set-time variable pulse width modulation) dual-mode to enhance power efficiency under light load and decrease output voltage ripple. The proposed circuit has been designed using $0.18{\mu}m$ BCDMOS process. Simulation results show that the circuit has power efficiency of 39%~96% and output ripple voltage of 2 mV under load current range of 1 mA~70 mA. The power efficiency of the proposed circuit is up to 2% higher than the previous PWM-SPWM method and up to 8% higher than only PWM method.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.6
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• pp.453-460
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• 2008

This paper proposes a new multi-output LLC resonant converter by using single control IC, which has the tight-regulated dual output voltage without additional power devices and controller. The proposed converter has master and slave outputs, of which regulations are achieved by the PWM(pulse width modulation) and PFM(pulse frequency modulation), respectively. Different from the conventional dual-output LLC resonant converter, the proposed converter has no additional post-regulators like a boost converter. Therefore, it features a low cost, small size, and high efficiency. To confirm the validity and prove the superiority of proposed converter, simulated and experimental results on a 50" FHD PDP power set prototype are presented.

• Journal of Electrical Engineering and Technology
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• v.6 no.1
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• pp.133-138
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• 2011

This paper proposes a simple but robust self-tuning fuzzy logic controller for the speed regulation of a dual star induction machine based on indirect field oriented control. For feed the two star of this machine, two voltage source inverters based on sinus-triangular pulse-width modulation techniques are introduced. The simulation results show the robustness and good performance of the proposed controller.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.235-236
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• 2015

본 논문에서는 universal line 입력 및 전 부하영역에서 영전압 스위칭(Zero Voltage Switching) 보장을 통한 500kHz 고 주파수 구동의 Dual Mode control LLC 컨버터를 제안한다. 제안 회로는 전 부하영역에서의 ZVS(영전압 스위칭)보장으로 고주파 구동이 가능하여 전원회로의 부피 중 상당량을 차지하는 수동소자의 부피를 대폭 저감 할 수 있다. 또한, 소용량 전원회로는 PFC(Power Factor Correction)의 규제가 없기 때문에 universal line 입력에 대응이 가능해야하므로, 제안회로는 변화하는 입력전압과 출력전류에 따라 PFM과 PWM의 두 가지 모드로 동작하여 universal line 입력 및 전 부하 영역에서 정확한 출력전압 제어가 가능하다. 최종적으로 제안 회로의 타당성 검증을 위하여 60W급 adapter의 전원회로를 위한 시작품을 제작하여 고찰된 실험 결과를 제시한다.

• Journal of IKEEE
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• v.15 no.4
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• pp.319-323
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• 2011

In this paper presents a new model of dual-mode synchronous buck converter with dynamic control for mobile applications was proposed. The proposed circuit can operate at 2.5MHz with supply voltage 2.5V to 5V for low ripple and minimum inductor and capacitor size, which is suitable for single-cell lithium-ion battery supply mobile applications. For high efficiency, the proposed circuit adopts synchronous type and dynamic control. The proposed circuit is designed by using the device parameter of TSMC 0.18um BCD process and the performance is evaluated by Cadence spectre. Experimental board level results show the maximum conversion efficiency is 96% at 100mA load current.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.4
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• pp.366-373
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• 2005

This paper presents two new circuit topologies of the dc busline side active resonant snubber assisted voltage source high frequency link soft switching PWM full-bridge dc-dc power converters acceptable for either utility ac 200V-rms or ac 400V-rms input grid. These high frequency switching dc-dc converters proposed in this paper are composed of a typical voltage source-fed full-bridge PWM inverter, high frequency transformer with center tap, high frequency diode rectifier with inductor input filter and dc busline side series switches with the aid of a dc busline parallel capacitive lossless snubber. All the active switches in the full-bridge arms as well as dc busline snubber can achieve ZCS turn-on and ZVS turn-off transition commutation with the aid of a transformer leakage inductive component and consequently the total switching power losses can be effectively reduced. So that, a high switching frequency operation of IGBTs in the voltage source full bridge inverter can be actually designed more than about 20 kHz. It is confirmed that the more the switching frequency of full-bridge soft switching inverter increases, the more soft switching PWM dc-dc converter with a high frequency transformer link has remarkable advantages for its power conversion efficiency and power density implementations as compared with the conventional hard switching PWM inverter type dc-dc power converter. The effectiveness of these new dc-dc power converter topologies can be proved to be more suitable for low voltage and large current dc-dc power supply as arc welding equipment from a practical point of view.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.10
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• pp.40-47
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• 2016

In this paper, a dual mode buck converter with an ability to change mode is proposed, which is suitable particularly for portable device. The problem of conventional mode control circuit is affected by load variation condition such as suddenly or slowly. To resolve this problem, the mode control was designed with slow clock method. Also, when change from the PFM(Pulse Frequency Modulation) mode to the PWM(Pulse Width Modulation) mode, to use the counter to detect a high load. And the user can select mode transition point in load range from 20mA to 90mA by 3 bit digital signal. The circuits are implemented by using BCDMOS 0.18um 2-polt 3-metal process. Measurement environment are input voltage 3.7V, output voltage 1.2V and load current range from 10uA to 500mA. And measurement result show that the peak efficiency is 86% and ripple voltage is less 32mV.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.2
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• pp.288-294
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• 2011

In this paper, the FPGA-based SoC board (Xilinx Virtex-4 ML401 EVM) is adopted to control electrical power inverter system. For marine application, its performance is shown on PC-based system for monitoring electrical characteristics of a power inverter using by the NMEA 2000 protocol. This power inverter system is achieved in Real-Time monitoring and control by dual micro-processor operation on embedded FPGA-based SoC board. One micro processor is for control (Control processor) electrical power inverter using by PWM signal. And the other microprocessor (Communication processor) is for communication with PC-based monitoring system. The two-processor is communicating each other using by dual-port ram (DPRAM). PC-based system user can control and monitor information of the electrical power inverter via NMEA 2000 based communication processor. Control and monitoring information includes the inverter status and configuration. SoC board converts this information to Parameter Group Numbers (PGNs) in the NMEA 2000 protocol. This system can be applied to marine power electronics for distributed power generation, transmission or regulation systems on the ship.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.790-802
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• 2017

This paper proposes the modeling and control strategy to track the MPPs of hybrid PV and Wind power systems, using a new dual input boost converter. The dual input power conditioning system with an independent MPPT control scheme is introduced with minimum number of circuit elements in order to reduce the switching loss, size and cost of the system. Since the operating conditions for the PV and Wind power systems are very distinct from each other, an efficient and superior control system is required to track the MPPs of both renewable sources with the use of a simply-structured single-ended single-inductor converter. The design of Power-Conditioning System (PCS) and detail control strategy are presented in this paper. To provide independent tracking of MPPs, a variable duty-cycle control strategy is employed for the wind system and a variable frequency strategy is employed for the PV system. Finally, the proposed dual-input converter for hybrid power conditioning system is implemented and the hardware test results are presented. From the hardware experiment, it is concluded that the proposed system successfully tracks the MPPs of both of the renewable power systems independently.