• JSTS:Journal of Semiconductor Technology and Science
• /
• 제15권4호
• /
• pp.484-492
• /
• 2015

This paper proposes a PWM phase-shift circuit to make that the LED lighting system distributes the channel currents evenly for any number of LED strings by generating evenly phase-shifted PWM signals for multiple LED driver ICs. The evenly distributed channel currents reduce the peak current, the decoupling capacitor size, and EMI noise. The PWM phase-shift circuit makes an arbitrary degree of PWM phase-shift by using a resistor and a capacitor. It measures the RC delay once. It reduces the number of external resistors and capacitors by providing zero and 180 degree phase-shift modes requiring no resistor and capacitor. An LED driver IC with the PWM phase-shift circuit was fabricated with a $0.35{\mu}m$ BCDMOS process. The PWM phase-shift circuit receives a PWM signal of 50 Hz~20 kHz at $f_{CLK}=450kHz$ and it generates a $0{\sim}360^{\circ}$ phase-shifted PWM signal with $R=0{\sim}1.1M{\Omega}$ at C=1 nF and $f_{PWM}=1kHz$. The measured phase errors are 1.74~3.94% due to parasitic capacitances.

• 제어로봇시스템학회논문지
• /
• 제21권10호
• /
• pp.910-916
• /
• 2015

A sensorless motor control scheme with conventional back-Electro Motive Force (EMF) sensing based on zero crossing point (ZCP) detection has been widely used in various applications. However, there are several problems with the conventional method for effectively driving sensorless brushless motors. For example, a phase mismatch of 30 degrees occurs between the ZCP and commutation time. Additionally, most of the motor speed/current controls are achieved based on a pulse width modulation (PWM) method, which generates significant noise that distracts the back-EMF sensing. Due to the PWM switching, the ZCP is not deterministic, and thus the efficiency of the motor is reduced because the phase transition points become uncertain. Moreover, the motor driving performance is degraded at a low speed range due to the effect of PWM noise. To solve these problems, an improved back-EMF detection method based on a differential line method is proposed in this paper. In addition, the proposed sensorless BLDC driver addresses the problems by using a variable voltage driver generated from a buck converter. The variable voltage driver does not generate the PWM switching noise. Consequently, the proposed sensorless motor driver improves 1) the signal-to-noise ratio of back-EMF, 2) the operation range of a BLDC motor, and 3) the torque characteristics. The proposed sensorless motor driver is verified through simulations and experiments.

• 한국콘텐츠학회논문지
• /
• 제7권1호
• /
• pp.116-123
• /
• 2007

본 논문은 OLED 패널 소스 구동회로에서 구동 전류의 크기와 폭을 조절하는 새로운 amplitude width modulation(AWM) 방식을 제안하였다. 기존의 소스 구동회로에서 pulse amplitude modulation(PAM) 방식은 DAC 회로 추가로 인해 크기가 커진다는 단점이 있고, pulse width modulation(PWM) 방식은 낮은 그레이 신호 레벨에서 발광 효율이 나쁜 단점이 있다. 이와 같은 단점을 개선하기 위해 본 논문에는 색상 데이터 비트의 MSB를 이용하여 구동 전류의 레벨을 제어하고, 데이터 비트의 LSB를 이용하여 구동 전류의 폭을 조정하는 구동방식을 제안하였다. 제안된 구동 방식은 $0.35-{\mu}m$ 3-poly 4-metal CMOS high voltage 공정을 사용하여 구현하였다. 시뮬레이션 결과는 제안된 AWM 구동 회로가 PAM 방식에 비해 회로 크기를 줄였고 신호 레벨이 낮은 영역에서 PAM과 거의 동일한 발광 효율을 얻었다.

• Journal of Power Electronics
• /
• 제12권6호
• /
• pp.886-894
• /
• 2012

This paper presents a secondary-side, dual-mode feedback LLC resonant controller IC with dynamic PWM dimming for LED backlight units. In order to reduce the cost, master and slave outputs can be generated simultaneously with a single LLC resonant core based on dual-mode feedback topologies. Pulse Frequency Modulation (PFM) and Pulse Width Modulation (PWM) schemes are used for the master stage and slave stage, respectively. In order to guarantee the correct dual feedback operation, Phased-Locked Loop (PLL)-based automatic duty control circuit is proposed in this paper. The chip is fabricated using $0.35{\mu}m$ Bipolar-CMOS-DMOS (BCD) technology, and the die size is $2.5mm{\times}2.5mm$. The frequency of the gate driver (GDA/GDB) in the clock generator ranges from 50 to 425 kHz. The current consumption of the LLC resonant controller IC is 40 mA for a 100 kHz operation frequency using a 15 V supply. The duty ratio of the slave stage can be controlled from 40% to 60% independent of the frequency of the master stage.

• 전력전자학회논문지
• /
• 제14권3호
• /
• pp.243-250
• /
• 2009

본 논문은 조명용 LED 구동 장치를 위한 새로운 방식의 Two-stage LED 구동 회로를 제안한다. 제안된 회로는 PFC flyback 회로의 다중 출력을 이용하여 LED 양단에 전압을 인가하여 LED 구동 회로의 출력 전압을 획기적으로 낮출 수 있어 LED 구동 회로에 사용되는 반도체 소자의 전압 스트레스를 크게 줄일 수 있다. 제안된 회로는Universal input에서 25 [W] 이상 조명 장치에 적용되는 IEC 61000-3-2 class C 규제를 만족하고, PWM 디밍을 사용하여 넓은 범위의 휘도 조절이 가능하다. 본 논문에서는 제안 회로의 동작 원리를 설명하고, 시뮬레이션 및 LED에 실제 적용 실험하여 제안 회로의 유용성을 입증하였다.

• Journal of Power Electronics
• /
• 제15권1호
• /
• pp.146-159
• /
• 2015

Since the power capacity needed for the propulsion of large ships is very large, a multiphase AC induction propulsion mode is generally adopted to meet the higher requirements of reliability, redundancy and maintainability. This paper gives a detailed description of the development of a 20MW fifteen-phase PWM driver for advanced fifteen-phase propulsion induction motors with a special third-harmonic injection in terms of the main circuit hardware, control system design, experiments, etc. The adoption of the modular design method for the main circuit hardware design can make the enclosed mechanical structure simple and maintainable. It can also avoid the larger switch stresses caused by the multiple turn on of the IGBTs in conventional large-capacity converter systems. The use of the distributed controller design method based on a high-speed fiber-optic ring net for the control system can overcome such disadvantages as the poor reliability and long maintenance times arising from the conventional centralized controller which is designed according to point-to-point communication. Finally, the performance of the 20MW PWM driver is verified by experimentation on a new fifteen-phase induction propulsion motor.

• 전력전자학회논문지
• /
• 제14권6호
• /
• pp.504-513
• /
• 2009

본 논문에서는 조명용 LED 구동 장치를 위한 새로운 방식의 LED 구동 모듈화 방법을 제안한다. 제안된 LED 구동 회로는 플라이백 컨버터를 이용하여 교류 입력 전원의 핫 접지와 LED 구동부의 콜드 접지를 절연한다. LED 전류 제어를 용이하게 하기위해 플라이백 컨버터를 동특성이 뛰어난 불연속 모드로 동작시키고, KIA2431을 이용하여 귀환 루프 제어를 한 후, 그에 대한 특성을 파악한다. 제안된 LED 구동 모듈은 폭넓은 교류 전원 입력 범위와 PWM 제어 IC를 직접 제어하여 버스트 디밍을 구현하고 넓은 범위의 LED 밝기 조절이 가능하게 하였다. 본 논문에서는 제안된 LED 구동 모듈에 대한 동작 원리를 설명하고 LED 구동 모듈을 실제로 구현 및 적용하여 제안된 구동 모듈의 유용성을 입증하였다. 또한, 소형화와 모듈화 된 LED 구동 모듈을 병렬로 연결한 다 채널 LED 구동 장치를 제안하고 그 타당성을 검증하였다.

• 전기전자학회논문지
• /
• 제16권3호
• /
• pp.203-210
• /
• 2012

기존의 DC-DC 부스트 변환기에 사용되는 non-overlapping gate driver는 dead-time이 고정되어 있기 때문에 body-diode conduction loss 또는 charge-sharing loss가 발생하는 문제점을 가지고 있다. 이러한 loss에 의한 효율 감소를 줄이기 위해 본 논문에서는 dead-time 적응제어 기능을 갖는 PWM DC-DC 부스트 변환기를 설계하였다. 제안된 DC-DC 부스트 변환기는 CMOS $0.35{\mu}m$ 공정으로 설계되었고, 입력전압 2.5V를 받아서 3.3V의 출력전압으로 승압시킨다. 스위칭 주파수는 500kHz이며, 최대효율은 97.3%이다.

• 한국정밀공학회지
• /
• 제26권2호
• /
• pp.54-62
• /
• 2009

The purpose of this study is to develop a piezo injector driver for common-rail direct injection diesel engines. In this research, we analyzed the electrical and mechanical characteristics of the piezo actuator through experiments. Current flow and charging voltage of the piezo injector are controlled by the PWM signal of variable duty ratio in order to realize both fast response and low peak current. The optimal switching duty ratio was designed by modeling and analyzing of the piezo driver circuit. In order to avoid resonance and unacceptably long settling time, appropriate frequency range of the PWM signal was derived based on the driver circuit model. The developed injector driver was validated by experiments under various fuel rail pressure, injection duration, and charging voltage.

• 전기학회논문지P
• /
• 제63권4호
• /
• pp.219-225
• /
• 2014

The purpose of this paper is to control of the low-speed, high-precision PMSM 2-axes pitch/turning. In this paper, apply the PAM-PWM inverter for it. However, The PAM-PWM inverter, control algorithms and hardware is complex. But it is possible to improve the performance in the low-speed operation can reduce the effect of the PWM ripple and Dead Time of inverter by applying suitable DC-bus voltage control. The direct driver PMSM(Permanent Magnet Synchronous Motor) configured to vector control part, PAM control part and the other controller. The vector control part includes PI current, speed control, additional space vector modulation. PAM control part has to have PI voltage controller and P current controller for DC-bus voltage control. Besides, the motor position estimator, the speed estimator and the counter electromotive force and Dead Time Compensation are added. With this arrangement, PMSM was driven with a low pole pitch/turning by performing the current control to the current command or torque command is the paper. As a result, it was possible to minimize the disturbance component that appears in the drive in proportion to the DC voltage magnitude. The use of a hydraulic drive method for a two-axis bubble column is a typical tank. When using the PWM PAM inverter driver is in the turret can be driven by high-precision, low vibration, low noise compared to the hydraulic drive may contribute to the computerization of the turret.