• 조명전기설비학회논문지
• /
• 제28권12호
• /
• pp.65-73
• /
• 2014

In this paper, the detection scheme of the voltage variation using a two difference voltage is proposed. The conventional sag detector is from a single-phase digital phase-locked loop (DPLL) that is based on a d-q transformation using an all-pass filter (APF). The APF generates a virtual q-axis voltage component with $90^{\circ}$ phase delay but the APF cannot generate the virtual q-axis voltage depending on the phase of the grid voltage. To overcome the problem, q-axis voltage component is generated from difference between the current and previous value of d-axis voltage component in the stationary reference frame. However, the difference voltage around the zero crossing is not enough to detect the voltage sag. Therefore, the new detection scheme using the two difference voltage which can detect the sag around the zero crossing voltage is proposed.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1996년도 하계학술대회 논문집 B
• /
• pp.949-952
• /
• 1996

The ultrasonic motor(USM) has good characteristics such as compact size, silent motion, low speed, high torque and high speed response. The USM is driven by 2-phase AC electricity. The control parameters of USM are voltage, phase difference, frequency of input power, etc. In this paper, we propose voltage difference control. And we designed USM controller to adjust voltage and phase using pLSI(programmable Large Scale Integration). Voltage difference control has many advantages that are lower current, lower power than phase difference control. Especially there is nearly zero ampere at the zero point of speed and torque. we can apply this voltage difference control to the compliance control of DD manipulator.

• 대한기계학회논문집A
• /
• 제24권4호
• /
• pp.874-880
• /
• 2000

In this paper, a DC potential drop measurement system was used to find the position of the flaw on a simple thin plate. Four-point probe test was evaluated and used for this study. In the four-point probe test, the more distance between current pins provides the more measurable scope, the less voltage difference, and the more voltage difference rate. In the other hand, the more distance between voltage pins provides the less voltage difference and the less voltage difference rate. An optimized four-point probe was applied to measure the relation between voltage and the relative position of flaw to the probe. The Maxwell 21) simulator was used to analyze the electromagnetic field, and it showed that the analytical result was similar to the experimental result within 11.4% maximum error.

• 조명전기설비학회논문지
• /
• 제28권1호
• /
• pp.96-104
• /
• 2014

The all pass filter generates a virtual q-axis voltage component with $90^{\circ}$ phase delay but the virtual q-axis voltage cannot detect the voltage depending on the phase of the grid voltage. To overcome the problem, q-axis voltage component is generated from difference between the current and previous value of d-axis voltage component in the stationary reference frame. However, the difference voltage between the current and previous value around the zero crossing voltage is not enough to detect the voltage sag. Therefore, the new detection scheme which can detect the sag around the zero crossing voltage is proposed.

• Journal of Korean Society for Atmospheric Environment
• /
• 제23권E1호
• /
• pp.29-38
• /
• 2007

A cylindrical tube connection that has a voltage difference and is separated electrically by an insulator was modelled. The penetration efficiencies of charged particles passing through the connector tube were investigated. Typically, as the particle size decreases and the applied voltage difference increases, the penetration efficiency decreases. To assess the effect of the electrode geometry, various lengths of electric insulator and aerosol flow rate with a fixed tube length and tube diameter were used when calculating penetration efficiencies. The comparison of penetration efficiencies for various electrode geometry setups suggests that the penetration efficiency can be described as a function of the product of applied voltage and electrical mobility of charged particles. The diffusion loss from this and previous studies are compared. Further, an explicit form for penetration efficiency is provided as a function of a new non-dimensional parameter, $Es(=Z_pV/U_{avg}W);\;P_{es}=0.2{\cdot}{\exp}(-Es/0.6342)+0.8{\cdot}{\exp}(-Es/4.7914)$.

• 한국조명전기설비학회지:조명전기설비
• /
• 제10권6호
• /
• pp.88-95
• /
• 1996

초음파 모터(ultrasonic motor : USM)는 압전 세라믹소자(piezoelectric ceramics)의 초음파 진동을 이용한 마찰 구동형 모터이다. 기존의 전자식 모터와는 달리 자기화로 즉 철심과 코일이 없는 단순 구조를 갖는 특수 소형 모터로서 저속 고토오크의 특성을 지니고 있으므로 다이랙트 드라이브 방식의 액츄에이터로 활용이 가능하다. 그리고 자장이 강한 특수 환경에서도 외란의 영향을 받지 않아도 산업계 전바에 걸쳐 제어용 모터로서 높이 평가받고 있다. 따라서 실용화를 위한 여러 가지 파라미터에 대한 특성 실험과 그에 따른 제어법 개발이 시급하다. 본 논문에서는 2상 입력 전원의 전압차 제어(voltags)를 제안한다. 먼저 전압차 제어에 의하여 이론적으로 고찰하고 초음파 모터의 구동원이 되는 고정자의 한 질점에서 발생하는 타원 궤적을 시뮬레이션을 통하여 알아봄으로써 초음파 모터의 속도와 토오크 특성을 예측하였다. 그리고 입력 전압워 전압차를 조절하여 초음파 모터의 속도와 토오트 특성을 실험하였다. 그 결과를 토대로 전압차 제어가 초음파 모터의 새로운 구동 방식이 될 수 있음을 밝혔다.

• 한국정보통신학회논문지
• /
• 제16권12호
• /
• pp.2716-2724
• /
• 2012

본 논문에서는 기존의 fractional-N 위상고정루프의 가장 큰 문제점인 fractional 스퍼를 억제하기 위해 위상차-전압 변환기(Phase Difference-to-Voltage Converter : PDVC)를 도입하였다. PDVC는 위상주파수 검출기 출력 신호의 위상차에 따라 전하펌프의 전류량을 조절한다. 제안한 구조는 위상 주파수 검출기(phase frequency detector) 신호들의 위상차가 커지면 전하펌프(charge pump) 전류를 감소시켜 fractional 스퍼를 줄일 수 있는 구조이다. 회로는 1.8V $0.18{\mu}m$ CMOS 공정의 파라미터를 이용하여 HSPICE로 시뮬레이션을 수행하고 회로의 동작을 검증하였다.

• 조명전기설비학회논문지
• /
• 제27권7호
• /
• pp.59-66
• /
• 2013

This paper proposes a new voltage reference generation method for Four-Switch Inverters(FSI) with compensation of the neutral DC-link voltage variation. Since FSIs have the split DC-link causing the inherent problem of voltage fluctuations in the upper and lower capacitors, it is required to take account the voltage difference between the top and bottom capacitors. In this paper, to reduce the effect by the voltage variation, reference voltages are modified by adding compensation voltages proportional to the voltage difference between upper and lower capacitors. Simulation results showing control performance of induction and permanent magnet motors demonstrate the validity of the proposed method.

• 제어로봇시스템학회논문지
• /
• 제19권6호
• /
• pp.508-512
• /
• 2013

In recent years, sensorless drive schemes have been proposed widely and most of them are based on the ZCP (Zero Crossing Point) detection of the BEMF (Back Electro-Motive Force). These schemes have two main problems. One is that ZCP may not be detected at low speed and thus a forced drive is required. The other problem is that there is $30^{\circ}$ phase difference between ZCP and the motor commutation instant and to ensure proper operation, this gap should be accounted for. To solve these problems a circuit is devised for detecting ZCP of the BEMF difference through the line voltage difference. Experimental results show that the output of this circuit is identical to that of the Hall sensor signal, and velocity control of a BLDC motor is possible without the sensor.

• 대한전기학회논문지
• /
• 제38권7호
• /
• pp.481-491
• /
• 1989

A compensation strategy for the phase-difference control method, which has been reported as a new driving method of a 2-phase inverter-fed induction motor, is proposed. The phase-difference control method extends the control range of the speed and eliminates the harmonic contents of the output voltage of the 2-phase inverter-fed induction motor. However, the phase-difference angle becomes narrower, motor efficiency deceases more and pulsating torque increases more. As the counterplan for these shortcomings of the phase-difference control method, a hybrid control method which combines the phase-difference control with the voltage control is proposed. The algorithm to realize a hybrid method is presented. As an example, a model composed of 5 regions has been analyzed by computer simulation in terms of motor performance and the results have been compared with experimental results.