• Journal of IKEEE
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• v.24 no.3
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• pp.803-813
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• 2020

This paper presents a high efficiency resonant flyback converter using a single-chip microcontroller. The proposed converter primary performs the resonant switching by applying the asymmetrical pulse-width modulation (APWM) to the half-bridge power topology. And the converter secondary uses the diode flyback rectifier as its power topology and operates with the zero current switching (ZCS). Thus the proposed converter achieves high efficiency. The total structure of proposed converter is very simple because it uses a single-chip microcontroller and bootstrap circuit for its control and drive, respectively. First, this paper describes the converter operation according to each operation mode and shows its steady-state analysis. And the software control algorithm and drive circuits operating the proposed converter are explained. Then, the operation characteristics of proposed converter are shown through the experimental results of an implemented prototype based on each explanation.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.9 s.351
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• pp.23-30
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• 2006

This paper presents a design of a high-efficiency CMOS DC-DC boost converter using a current-sensing feedback method. High-precision current-sensing circuity is incorporated in order to sense the current flowing in the inductor, which determines the switching scheme of the pulse-width modulation. The external components or large chip area for the frequency compensation can be avoided while maintaining the stable operations of the converter. Various input/output voltage levels can be available through the external resistor strings. The designed DC-DC converter is fabricated in a 0.18-um CMOS technology with a thick-gate oxide option. The converter shows the maximum efficiency over 90% for the output voltage of 3.3V and load current larger than 200mA. The load regulation is 1.15% for the load current change of 100mA.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.6
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• pp.2747-2753
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• 2011

In this paper, a PWM current-mode DC-DC boost converter for mobile phone flash application has been proposed. The converter which is operated with 5 Mhz high switching frequency is capable of reducing mounting area of passive devices such as inductor and capacitor, consequently is suitable for compact mobile phones. This boost converter consists of a power stage and a control block. Circuit elements of the power stage are inductor, output capacitor, MOS transistors and feedback resistors. Meanwhile, the control block consists of pulse width modulator, error amplifier, oscillator etc. Proposed boost converter has been designed and verified in a $0.5\;{\mu}m$ 1-poly 2-metal CMOS process technology. Simulation results show that the output voltage is 4.26 V in 3.7 V input voltage, output current 100 mA which is larger than 25 ~ 50 mA in conventional 500 Khz driven converter when the duty ratio is 0.15.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.4
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• pp.707-714
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• 2016

Active driving safety systems for vehicle, such as the front collision avoidance, lane departure warning, and lane change assistance, have been popular to be adopted to the compact car. For improving performance and competitive cost, FMCW radar has been researched to adopt a phased array or a multi-beam antenna, and to integrate the front and the side radar. In this paper we propose several efficient methods to implement the signal processing module of FMCW radar system using low cost DSP. The pulse width modulation (PWM) based analog conversion, the approximation of time-eating functions, and the adoption of vector-based computation, etc, are proposed and implemented. The implemented signal processing board shows the real-time performance of 1.4ms pulse repetition interval (PRI) with 1024pt-FFT. In real road we verify the radar performance under real-time constraints of 10Hz update time.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.764-765
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• 2010

The medical treatment X-ray machineries used in diagnosis of the human body is possible to diagnosis inside of the human body with the method of noninvasive so that it has shared a very important role in diagnosis from the medical institution. High voltage occurrence system which is most important in occurrence of X-ray has mainly been used the existing type of high voltage transformer, however it has a low efficiency of X-ray occurrence since it is a big and heavy, and a high ripple ratio of the direct current high voltage come to the X-ray tube. In order to solve this problem, the research has been advanced about the high voltage power supply system, and the inverter type of the high voltage occurrence system which occurs a high voltage by increasing the power frequency from about ten times to about hundred times with the inverter has currently used mainly. Also, the operation of tube voltage and tube current was controlled by using PWM method and the operation results were identified using an oscilloscope.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.2
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• pp.129-135
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• 2014

In the paper, we propose a design method for the logistics transportation system using magnetic levitation that has a good characteristics without mechanical friction, noise and dust. The proposed transportation system consists of a levitation control system and a propulsion control system. Magnetic levitation system is an electromagnetic suspension system in which electromagnet generates magnetic attractive force and the attractive force pulls the rail. We design a PID controller for the current control of electromagnets. We use linear induction motors for propulsion of the proposed logistics transportation system and adapt the space vector PWM method for the propulsion control system. The proposed transportation system using magnetic levitation is verified performances through levitation and propulsion experiments.

• Journal of Digital Contents Society
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• v.19 no.8
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• pp.1603-1615
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• 2018

In order to achieve the low complexity and area, power in the design of Optical Image Stabilization (OIS) suitable for the smart phone, this paper presents the following design explorations, such as; optimization of gyroscope sampling rate, simple and accurate gyroscope filters, and reduced operating frequency of motion compensation, optimized bit width in ADC and DAC, evaluation of noise effects due to PWM driving. In experiments of gyroscope sampling frequencies, it is found that error values are unvaried in the frequency above 5KHz. The gyroscope filter is efficiently designed by combining the Fuzzy algorithm, to illustrate the reasonable compensation for the angle and phase errors. Further, in the PWM design, the power consumption of 2MHz driving is shown to decrease up to 50% with respect to the linear driving, and the imaging noises are reduced in the driving frequency above 2MHz driving frequency. The operating frequency could be reduced to 5KHz in controller and 10KHz in driver, respectively, in the motion compensation. For ADC and DAC, the optimized exploration experiments verify the minimum bit width of 11bits in ADC as well as 10bits in DAC without the performance degradation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.4
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• pp.81-94
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• 2010

This paper presents a high efficiency resonant asymmetrical half-bridge flyback converter. The primary half-bridge circuit of the converter operates by a soft-switching type using the asymmetrical pulse-width modulation (PWM) method with the resonant capacitance and transformer leakage inductance. The secondary flyback circuit of the proposed converter utilizes a synchronous rectifier, which operates by a new voltage-driven method with a simple drive circuit. Thus the proposed converter improves the total efficiency. This paper explains the operational principle of the proposed converter by each mode and shows the converter design consideration and a design example for the prototype converter, respectively. After that, the proposed simple driving technique of the synchronous rectifier by a voltage-driven method is explained, briefly. The designed prototype converter has wide input voltage (AC $V_{in,rms}$=75~265[V]), 5[V] DC output voltage, and 100[W] output power. To verify the excellent performance of the proposed converter, the designed prototype is implemented and experimented. The good performance of the proposed converter is shown through the experimental results.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.2
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• pp.17-28
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• 2015

In this paper, it is accomplished to design a control method for such an actuation system of simplified ON/OFF mechanism with actuation command limit. First of all, based on experimental data, the modeling works for nonlinear/linear actuation dynamics are performed, which are govern by PWM command as a control input. Using the linearized model, a classical PI control method is designed to satisfy the aimed control performance requirements, and a control algorithm is proposed to realize the required control performance in the effective control region through resolving the issue for the PWM command limit which reduces the control performance. Finally, through control simulations, the design method is verified and the corresponding control performance improvement is evaluated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11B
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• pp.1501-1509
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• 2001

Recently, the use of wireless communication systems has been rapidly increasing, which results in a difficult problem in efficient control of limited frequency resources. As a way of solving this problem, the ultra wideband time hopping impulse radio system attracts much attention. The impulse radio system communicates pulse position modulated data using Gaussian monocycle pulses of very short duration less than 1 nsec. Thus the transmitted signal has very low power spectral density and ultra wide bandwidth from near D.C. to a few GHz. It is blown that it hardly interferes with the existing communication systems because of its very low power spectral density. The purpose of this paper is to characterize multipath propagation of the impulse radio signal and to evaluate the performance of the correlator-based receiver for the multipath environments. In this paper, we consider the deterministic two-path model and the statistical indoor multipath model of Saleh and Valenzuela. For the two-path model the output of the correlator with the ideal reference waveform varies according to the relative difference between the indirect path delay and the time interval of PPM, and to the indirect path gains. In addition, the characteristics of bit error rates is measured for the two models through computer simulation. The simulation results indicate that the performance of the impulse radio system depends both on the relative difference between the indirect path delay and the time interval of PPM, and on the indirect path gains. Furthermore, it is observed that the reference signal designed for the AWGN channel can not be applied to the multipath channels.