• The Transactions of the Korean Institute of Power Electronics
• /
• v.6 no.3
• /
• pp.223-230
• /
• 2001

This power proposes a new sensorless drive system for the trapezoidal brushless DC motor generally requiring mechanical position or speed sensor. For this an indirect rotor position sensing method from the back emf waveform of non-conducting phase is explained. Back emf waveform of non-conducting is obtained from analysing terminal voltage created by making Y-connection. And an experiment is implemented with a driving system which use 87c196mc microcontroller having a peripheral associated with 3-phase signals and inverter composed of Power MOSFET. The experimental results show the validity and practicality of the proposed sensorless drive.

• Proceedings of the KIPE Conference
• /
• 2018.07a
• /
• pp.452-453
• /
• 2018

이 논문은 Polymer Dispersed Liquid Crystal (PDLC) 필름 구동방식을 제안한다. 현재 시스템은 변압기를 사용하여 PDLC를 구동시켜 전압가변이 힘들어 ON/OFF 기능으로만 사용된다. 하지만 변압기를 사용하지 않고 인버터를 사용하면 전압가변이 용이하여 PDLC 필름의 투과도 조절이 용이하다. 인버터를 사용한 토플로지에서 출력전압을 정현파로 출력하게 되면 필터가 추가되어 하드웨어 제작 시 추가적인 비용이 발생하고 하드웨어의 부피가 증가하게 된다. 그래서 필터가 사용되지 않는 구형파 구동방식을 선정하였다. 이를 실험을 통해 보여준다.

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.7
• /
• pp.916-922
• /
• 2014

Diode rectifiers have been widely used for an AC to DC converter. But a big problem is that they include large harmonics components in the input currents. A 12-pulse configuration with phase shifting transformer is useful for reducing them. however, it still includes the ($12{\pm}1$)th (m; integer) harmonics in the input currents. In this paper, we propose a single-phase square wave auxiliary voltage supply which is inserted in the middle DC bus. It reduces harmonics especially the 11th and 13th and the harmonic characteristic becomes almost equivalent to a 24-pulse rectifier. Theoretical analysis of the combined 12-pulse diode rectifier with the auxiliary supply is presented and a control method of the auxiliary supply is proposed. The reduction in the input current harmonics is verified by simulation using software PSIM.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.9 no.3
• /
• pp.1-8
• /
• 1972

The characteristics of tunnel diode pair circuit biased within the negative resistance region has also the voltage-control type negative resistance region, and the voltage at the center point of negative resistance region is described as the square-wave relaxation oscillation. In this paper, the period T, positive duration T1, negative duration T2 of the pulse are obatined from the characteristic curve T, positive duration T1, negative duration T2 of the pulse are obtained from the characteristic curve and observed actually, considring the fact that the pulse width and the period of square-wave at the center point of the negative resistance region is able to be controlle dby the blas volgate. Mereover, the relationship between T, T1 or T2 and circuit parameters is searched for and the Circuit parameters that satisfy the conditions of T1-T2 being proportional to the variation of bias voltage with Teonstant are determined. Thereafter, the bias voltage and the signal voltage are inserted serially to the PWM circuit and the characteristics of that circuit is analyzed.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.6 no.2
• /
• pp.158-163
• /
• 2001

Current Source Inverter(CSI), operated in square wave mode, is more efficient thant the PWM CSI because of increased cost, greater complexity of control algorithm and substantial switching losses, EMI. But, the square wave output current of CSI, rich in low order harmonics produce motor torque ripples. Therefore, in this paper, describes active power filters for compensating square wave input current of current source induction motor. Also, notch filtering as compensation algorithm is employed. To confirm the validity of proposed system, PSIM simulation results are presented and discussed.

• Journal of the Korean Vacuum Society
• /
• v.12 no.1
• /
• pp.46-50
• /
• 2003

Characteristic properties of backlight arraying external electrode fluorescent lamps has been investigated indriving with a square wave from switch inverters. In the backlight of 17 inch-diagonal with 12 lamps, the efficiency of 65-70 1m/W with the luminance of 5,000-10,000 cd/$\textrm m^2$ has been achieved in the frequency range 40-80 kHz where the higher frequency provides the lower operating voltage in the range 1.0-2.0 kV. In the frequency above 80 kHz, a stable and an uniform luminance in the backlight panel can not be achieved.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.10 no.4
• /
• pp.323-330
• /
• 2005

In order to increase reliability and reduce system cost, this paper studies particularly applicable method for sensorless PM BLDCM drive system. The waveform of the motor internal voltages(or back emf) contains a fundamental and higher order frequency harmonics. Therefore the third harmonic component is extracted from the stator phase voltage. The resulting third harmonic signal keeps a constant phase relationship with the rotor flux for any motor speed and load condition, and is practically free of noise that can be introduced by the inverter switching, making this a robust sensing method. In addition, a simple starting method and a speed estimation approach are also proposed. Some experimental results are Provided to demonstrate the validity of the proposed control method.

• Proceedings of the KIEE Conference
• /
• 2005.07b
• /
• pp.1468-1470
• /
• 2005

본 논문에서는 오존발생시스템의 전원으로 사용하는 단상 풀브리지 인버터를 ATmega128을 이용하여 출력 주파수와 전압을 제어하였고, 전압제어 방식으로는 준구형파 방식이 사용되었다. 또한, 사용자가 오존발생시스템에서 키패드를 사용하여 출력 주파수와 전압값을 설정할수 있게 하였고, 사용자가 설정한 값을 LCD를 이용하여 디스플레이하였다.

• Proceedings of the KIPE Conference
• /
• 2009.11a
• /
• pp.179-181
• /
• 2009

고압 방전 램프는 점등 후부터 정상상태에 이르기까지 방전관 내부의 온도 및 압력이 광범위하게 변화하는 복잡한 동작 특성으로 모델링이 어렵다. 이러한 특성은 램프를 구동하는 안정기의 설계에 어려움이 따른다. 램프의 구동에는 초기 점화 시 높은 점화용 전압 펄스를 필요로 한다. 점화 후에 정상상태에 다다르면 램프 전극의 소모를 줄이기 위해 교류로 구동되어야 한다. 하지만 램프를 교류로 구동하게 되면 음향 공진 현상이 발생할 수 있다. 음향 공진 현상은 램프 구동 전류의 맥동성분이 큰 경우에도 발생을 할 수 있으므로 구동 전류의 맥동 성분의 크기는 최소화 돼야 한다. 램프의 수명시간을 길게 하려면, 안정기는 램프를 정격전력으로 구동하여야 한다. 따라서 안정기에서는 정전력 제어가 필요하게 된다. 램프 전류의 극성이 변화할 때, 램프 전류는 spike전류와 중첩이 된다. 본 논문에서는 spike 전류를 저주파구형파 램프 전류의 포락범위 안에 유지하고, 고주파 스위칭시손실을 줄이기 위해 소프트 스위칭 기법을 이용한 회로 설계를 제안했다. 제안된 방법은 시뮬레이션 및 이론적 수식적 방법으로 검증 했다.

• 전자공학회논문지 IE
• /
• v.44 no.1
• /
• pp.1-5
• /
• 2007

This experiment was analysed the discharge characteristics of FFL(flat fluorescent lamp). FFL is operated by sine and pulse wave source. We use FFL which has the electrodes covered with dielectric, observed the discharge characteristics of FFL by V-Q Lissajous' figure. When FFL is operated with pulsed, the discharge current flows after the applied voltage is risen. When the duty ratio increases, the number of metastable xenon atoms seem to increase. Consequently, the 172nm radiation becomes strong as the duty ratio increases.