• Proceedings of the KIPE Conference
• /
• 2015.07a
• /
• pp.235-236
• /
• 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 the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.22 no.7
• /
• pp.555-558
• /
• 2009

This paper presents a step-down converter IC for automotive applications. This device was designed for a 40 V/1 A high-power output for voltage reference of automotive IC. It provides 250kHz PWM (pulse width modulation) and PFM(pulse frequency modulation) according to load conditions. This device was simulated spectre of IC-design-tools and fabricated Dong-bu Hitec 0.35um BD350BA process.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.05a
• /
• pp.546-551
• /
• 2001

Space Test Department at KARI(Korea Aerospace Research Institute) plans to carry out the GVT(Ground Vibration Test) for the KSR(Korea Sounding Rocket)-III FM(Flight Model) which is being developed by Space Technology R＆D Division. KSR-III will be an intermediate to the launch vehicle capable of carrying satellites to their orbits. GVT offers very important information to predict the behavior of KSR in its operation, and to develop the flight control and aerodynamic analysis. For development of test facilities, testing and analysis methods which can be used for the future test, Space Test Department has performed the GVT with KSR-II PFM(Proto-Flight Model) at Satellite Integration ＆ Test Center of KARl This paper discusses the procedures, techniques and the results of it. In this test, to simulate free-free condition, test object hung in the air by 4 bungee cords specially devised. The GVT was carried out using pure random excitation technique with MIMO(Multi-Input-Multi-Output) method with three electromagnetic shakers, and poly-reference parameter estimation was used to identify the modal parameters. As the result of the test, 11 mode shapes and modal parameters below 200㎐ were identified and compared with analytical results.

• Journal of Power Electronics
• /
• v.16 no.3
• /
• pp.840-848
• /
• 2016

A primary-side regulation AC-DC converter operating in the PFM (Pulse Frequency Modulation) mode with a high precision output current is designed, which applies a novel inductance compensation technique to improve the precision of the output current, which reduces the bad impact of the large tolerance of the transformer primary side inductance in the same batch. In this paper, the output current is regulated by the OSC charging current, which is controlled by a CC (constant current) controller. Meanwhile, for different primary inductors, the inductance compensation module adjusts the OSC charging current finely to improve the accuracy of the output current. The operation principle and design of the CC controller and the inductance compensation module are analyzed and illustrated herein. The control chip is implemented based on a TSMC 0.35μm 5V/40V BCD process, and a 12V/1.1A prototype has been built to verify the proposed control method. The deviation of the output current is within ±3% and the variation of the output current is less than 1% when the inductances of the primary windings vary by 10%.

• Proceedings of the IEEK Conference
• /
• 2002.06e
• /
• pp.207-210
• /
• 2002

This paper describes a design of multiple-mode single-output DC/DC converter which can be used in both up and down conversion. Proposed up/down converter does not produce a negative voltage which is generated in conventional buck-boost type converter. Three types of operation mode(up/down/bypass) are controlled by the input voltage sense and command signals of target output voltage. PFM(pulse frequency modulation) control is adopted and modified for fast tracking and for precise output voltage level with an aid of output voltage sense. Designed DC/DC converter has the performance of less than 5 % ripple and higher than 80 % efficiency. Chip area is 3.50 mm ${\times}$ 2.05 mm with standard 0.35 $\mu\textrm{m}$ CMOS technology.

• Proceedings of the KIPE Conference
• /
• 2001.10a
• /
• pp.295-300
• /
• 2001

A variety of high voltage DC power supplies employing the high frequency inverter are difficult to achieve soft switching considering a quick response and no overshoot response under the wide load variation ranges which are used in medical-use x-ray high voltage generator from 20kV to 150kV in the output voltage and from 0.5mA to 1250mA, respectively. The authors develops soft switching high voltage DC power supply designed for x-ray power generator applications, which uses series resonant inverter circuit topology with a multistage voltage multiplier instead of a conventional high voltage diode rectifier connected to the second-side of a high-voltage transformer with a large turn ratio. A constant on-time dual mode frequency control scheme operating under a principle of zero-current soft switching commutation is described. Introducing the multistage voltage multiplier, the secondary transformer turn-numbers and stray capacitance of high-voltage transformer is effective to be greatly reduced. It is proved that the proposed high-voltage converter topology with dual mode frequency modulation mode control scheme is able to be the transient response and steady-state performance in high-voltage x-ray tube load. The effectiveness of this high voltage converter is evaluated and discussed on the basis of simulation analysis and observed data in experiment.

• Journal of IKEEE
• /
• v.24 no.3
• /
• pp.853-858
• /
• 2020

This paper proposes a 2-ch DC-DC converter for OLED display with immunity against RF noise inserted from communication device. For RF signal immunity, an input voltage variation reduction circuit that attenuates as much as the input voltage variation is embedded. The boost converter for positive voltage V_POS operates in SPWM-PWM dual mode and has a dead time controller to increase power efficiency. The inverting charge pump for negative voltage V_NEG is a 2-phase scheme and operates in PFM using VCO to reduce output ripple voltage. Simulation results using 0.18 ㎛ BCDMOS process show that the overshoot and undershoot of the output voltage decrease from 10 mV to 2 mV and 5 mV, respectively. The 2-ch DC-DC converter has power efficiency of 39%~93%, and the power efficiency of the boost converter is up to 3% higher than the conventional method without dead time controller.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.1
• /
• pp.226-239
• /
• 2018

In this paper, design and control method ZVT Interleaved Bidirectional LDC(IB-LDC) for mild-hybrid electric vehicle is proposed. The IB-LDC is composed of interleaved buck and boost converters employing an auxiliary inductor and auxiliary capacitors to achieve zero-voltage-transition. Operating principle of IB-LDC according to operation mode is introduced and mathematically analyzed in buck and boost mode. Moreover, PFM and phase control are proposed to reduce circulating current for low power range. Passive components design such as main inductor, auxiliary inductor and capacitors is suggested, considering ZVT condition and maximizing efficiency. Furthermore, a 600W prototype of ZVT IB-LDC for MHEVs is built and tested to verify validity.

• Proceedings of the IEEK Conference
• /
• 2008.06a
• /
• pp.537-538
• /
• 2008

A step-down DC-DC converter with On-chip Compensation for battery-operated portable electronic devices which are designed in 0.18um CMOS standard process. In an effort to improve low load efficiency, this paper proposes the PFM (Pulse Frequency modulation) voltage mode 1MHz switching frequency step-down DC-DC converter with on-chip compensation. Capacitor multiplier method can minimize error amplifier compensation block size by 20%. It allows the compensation block of DC-DC converter be easily integrated on a chip and occupy less layout area. But capacitor multiplier operation reduces DC-DC converter efficiency. As a result, this converter shows maximum efficiency over 87% for the output voltage of 1.8V (input voltage : 3.3V), maximum load current 500mA, and 0.14% output ripple voltage. The total core chip area is $mm^2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.04b
• /
• pp.83-84
• /
• 2009

This paper presents a step-down converter IC for automotive applications. This device was designed for a 40V/1A high-power output for voltage reference of automotive IC. It provides 250kHz PWM(pulse width modulation) and PFM(pulse frequency modulation) according to load conditions. This device was simulated Spectre of IC Design Tool And fabricated Dong-bu Hitec 0.35um BD350BA process.