• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1807-1809
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• 2002

In this study, asolid-state laser system adopting a firing time control(FTC) method in which three flashlamps are turned on consecutively was designed and fabricated to examine the pulse width and the pulse shape of the laser beams depending upon the changes in the lamp turn-on time. That is, this study shows a technology that makes it possible to make various pulse shapes by turning on three flashlamps consecutively on a real-time basis with the aid of a PIC one-chip microprocessor With this technique, the lamp turn-on delay time can be varied more diversely from 0 to 10 ms and the real-time control is possible with an external keyboard enabling various pulse shapes. In addition longer pulses can be more widely used for industrial processing and lots of medical purposes.

• Journal of Power Electronics
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• 제15권1호
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• pp.65-77
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• 2015

Resonant converters are well suited for induction heating (IH) applications due to their advantages such as efficiency and power density. The control systems of these appliances should provide smooth and wide power control with fewer losses. In this paper, a simple phase locked loop (PLL) based variable duty cycle (VDC) pulse density modulation (PDM) power control scheme for use in class-D inverters for IH loads is proposed. This VDC PDM control method provides a wide power control range. This control scheme also achieves stable and efficient Zero-Voltage-Switching (ZVS) operation over a wide load range. Analysis and modeling of an IH load is done to perform a time domain simulation. The design and output power analysis of a class-D inverter are done for both the conventional pulse width modulation (PWM) and the proposed PLL based VDC PDM methods. The control principles of the proposed method are described in detail. The validity of the proposed control scheme is verified through MATLAB simulations. The PLL loop maintains operation closer to the resonant frequency irrespective of variations in the load parameters. The proposed control scheme provides a linear output power variation to simplify the control logic. A prototype of the class-D inverter system is implemented to validate the simulation results.

• Journal of Advanced Marine Engineering and Technology
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• 제17권3호
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• pp.60-69
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• 1993

The speed control associated with dc servo motors for direct-drive applications of mobile robot is considered in this study. Robot is moved by power wheeled steering of two dc servo motors mounted to it. In order to cooperate with micro-computer and to achieve the high-performance operation of dc servo motor, speed control system is composed of a digital Phase Locked Loop and H-type drive circuit. And the motor is driven by Pulse Width Modulations. In controlling PWM, it is modified to compose of H-type drive circuit with feedback diodes and switching transistor and design of control sequence so that it may show linear characteristics. As a result, speed characteristics of motor showed linear features. In order to get data on design of PLL control system, the parameters of 80[W[ motor & robot device is measured by simple software control. The PLL speed control system is schemed and designed by leaner drive circuit and measured parameters. A complete speed control system applied to 80[W] dc servo motor showed good linearity, stability and high response. Also, it is verified that the PLL speed control system has good compatibility as a mobile robot driver.

• 대한전기학회논문지:시스템및제어부문D
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• 제55권10호
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• pp.458-463
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• 2006

The purpose of this work is to investigate the fundamental properties of the gradual muscle force potentiation. We investigated the dependence of force potentiation on both the pulse-amplitude and the pulse-duration with different ramp-up time. The experimental results showed that the force increment ratio (FIR) during constant electrical stimulation decreased with pulse-amplitude and also with pulse-duration. The FIR was greater with short ramp-up time in both the pulse-amplitude and pulse-width modulation. The feasible mechanism might be that the myosin light chain phosphorylation induces the force potentiation and it occurs only in the fast type muscle fibers which are recruited first. These observations indicate that muscle potentiation must be understood well for the accurate control of muscle force.

• International Journal of Aeronautical and Space Sciences
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• 제16권1호
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• pp.102-109
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• 2015

In Korea, Lunar exploration program has been prepared with the aim of launching in the 2020's. As a part of it, a lunar lander demonstrator was developed, which was the model for verifying the system such as structure, propulsion, and control system, before launching into the deep space. This paper deals with the path tracking performance of the lunar lander demonstrator with respect to the thruster controller based on Pulse Width Pulse Frequency Modulator (PWPFM) and Pulse Width Modulator (PWM). First, we derived equations of motion, considering the allocation of the thrusters, and designed the path tracking controller based on Euler angle. The signal generated from the path tracking controller is continuous, so PWPFM and PWM modulator are adopted for generating ON/OFF signal. Finally, MATLAB simulation is performed for evaluating the path tracking ability. We compared the path tracking performances of PWPFM and PWM based thrust controller, using performance measures such as the total impulse and the position error with respect to the desired path.

• 전자공학회논문지
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• 제50권7호
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• pp.269-274
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• 2013

전해 산성이온수는 알칼리성 이온수에 비해 응용분야가 음용을 목적으로 하는 알칼리이온수와 많이 다르게 이용되고 있으며 ph 농도에 따라 강산성인 경우 잔류염소에 의한 살균 목적의 소독제로 사용되고, 중산성인 경우 세척과 세안으로 사용하고, 약산성인 경우 식재료와 혼합하여 요리에 널리 사용할 수 있다. 이런 산성이온수를 생성하기 위해서는 물을 전기분해 하여 사용하는데 전기분해 하는 과정에서 염소가스와 수산화나트륨 등의 물질로 살균력을 가지며, 전기분해시 +전극 쪽으로 -이온을 띤 염소, 인, 유황 등의 유기물이 모여져 산성이온수를 만든다. 또한 산성수와 알칼리수를 분리하기 위해서 격막을 사용했다. ph 농도변화의 구현방법은 Microprocessor를 이용하여 강산성에서 약산성 사이의 ph 농도를 PWM(pulse width modulation) 제어로 3종류의 PWM 전압을 전해조 전극에 인가하여 PWM제어에 의한 연속적으로 농도가 조절된 산성수가 생성되게 구현하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.751-753
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• 1999

In this paper, a simple SR method of AC motor has introduced. The method achived by appling the Pulse-Width Modulation(PWM) method to control the ON and OFF time of motor. The method is simple, practicable and has no problem of shift and out of control which is existed in SR method of SCR.

• Journal of Power Electronics
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• 제14권1호
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• pp.115-124
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• 2014

This paper presents the implementation of two-arm modulation (TAM) technique for the independent control of a two-induction motor drive fed by a five-leg inverter (FLI). A carrier-based space vector pulse width modulation technique for TAM is proposed to generate switching signals for FLI. Two independent three-phase space vector modulators are utilized to control two motors. The motor drive system applies two separate indirect field-oriented control methods. The stationary voltage outputs from the vector control are synthesized in the three-phase space vector modulator to generate switching signals for FLI. The performance of the independent control of the motors and the voltage utilization factor are likewise analyzed. Simulation and experimental results verify the effectiveness of the proposed method for the independent control of the two-motor drive system. The proposed technique is successfully validated by dSPACE DS1103 experimental work.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2002년도 춘계학술대회 및 임시총회
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• pp.10-13
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• 2002

본 연구에서는 다기능 휠체어 시스템을 개발하기 위해 제어부를 16bit의 마이크로 프로세서인 80C196KC 사용하였고, 조이스틱을 통해서 된 시스템을 제어하는 것을 구현하였다. 전체시스템은 제작된 전동 휠체어 기본 Plant를 사용하였으며, 모터에서 Encoder로 입력받아 MCU를 통해서 휠체어 회전수를 이용하여 제어시켰다. 휠체어 모터의 제어 방법은 PWM(Pulse Width Mudulation)을 이용하였으면, 여기에 H-브릿지 회로를 구성하였다. 조이스틱을 사람의 손으로 제어하는데 있어서 조이스틱 위치 변화에 따른 전동휠체어에 부착된 DC모터 동작을 퍼지 제어 알고리즘을 사랑하였으며, DC모터의 속력과 방향을 제어하고 아울러 위치 정보까지도 제어할 누 있게끔 하였다.

• 유공압시스템학회논문집
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• 제8권1호
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• pp.19-25
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• 2011

This study presents the design of digital amplifier.controller for a proportional control valve and the development of PID discrete control scheme by using RCP(Rapid Controller Prototyping) system. RCP system is the device to embed the control code developed in PC into the microcontroller on-site. Ramp input test using the digital amplifier.controller developed in this study was carried out for the proportional control valve of domestic production and Bosch Rexroth respectively. The instability problem occurred around maximum displacement of localized valve spool at ramp input test was solved by supplementing offset current to the duty ratio of PWM(Pulse Width Modulation) driving signal to the solenoid. The comparison of test results between localized proportional control valve and Bosch Rexroth's product shows that the characteristics obtained by ramp input test and static flow gains are alike each other. Two valves are about the same in dead bands and hysteresis characteristics.