• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.8 s.173
• /
• pp.64-70
• /
• 2005

The development of an accurate and energy saving pneumatic regulator that may be applied to a variety of practical pressure control applications is described in this paper. A novel modified pulse width modulation(MPWM) valve pulsing algorithm allows the pneumatic regulator to become energy saying system. A comparison between the system response of conventional PWM algorithm and that of the modified PWM(MPWM) algorithm shows that control performance is almost the same, but energy saving is greatly improved by adopting this new MPWM algorithm. The effectiveness of the proposed control algorithm are demonstrated through experiments with various reference trajectories.

• Journal of Power System Engineering
• /
• v.3 no.2
• /
• pp.70-78
• /
• 1999

The vector controlled induction motor(I.M) with speed sensor has been widely used for variable speed drive systems. In these application fileds, speed sensorless control are expected strongly to progress reliability, simplicity and cost performance of I.M and to expand its application part. This paper describes a novel speed sensorless control method of I.M based on feedforward quick torque response control technique. Especially, this paper aimed at the realization of sensorless control in the very low speed region, The proposed method can be formulated simply from a motor circuit equation and conducted easily by detecting primary motor currents and a voltage command at every sampling time. Throughout some results of numerical simulations with the assumption of using a pulse width modulation(PWM) voltage source inverter, the validity of the method was successfully confirmed.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.8
• /
• pp.86-93
• /
• 2003

The development of a fast, accurate, and inexpensive position-controlled pneumatic actuator that may be applied to a variety of practical positioning applications with various external loads is described in this paper. A novel modified pulse width modulation (MPWM) valve pulsing algorithm allows on/off solenoid valves to be used in place of costly servo valves. A comparison between the system response of standard PWM technique and that of the novel modified PWM technique shows that the control performance is significantly increased. A state feedback controller with position, velocity and acceleration feedback is successfully implemented as the continuous controller. Switching algorithm of control parameter using learning vector quantization neural network (LVQNN) is newly proposed, which estimates the external loads of the pneumatic actuator. The effectiveness of the proposed control algorithms are demonstrated through experiments with various loads.

• Journal of Advanced Marine Engineering and Technology
• /
• v.23 no.3
• /
• pp.369-378
• /
• 1999

This paper presents position control of an electro-hydraulic servo system whoch is operated by four 2-2way high speed on-off valves with either PWM PID control method or sliding mode control method, The advantages of using high speed on-off valves instead of electo-hydraulic servo valves or electro-hydraulic proportional valves are low price robustness for oil contamination and direct control without a D/A converter. The system consists of load cylinder inertia car potentiometer and external load cylinder. The experiments were carried out under several conditions and the results were compared. As a result the sliding mode method has shown good control performance and the robust and stable positioning of the elector-hydraulic servo system can be achieved accurately.

• Journal of the Korean Society of Radiology
• /
• v.6 no.3
• /
• pp.207-215
• /
• 2012

As one of photo dynamic therapies, the existing LED photo irradiation method with 635 nm continuous wave has most frequently been used for acne treatment, it suffered from a low energy efficiency and generation of a large amount of heat in tissues requiring improvement measures. In this thesis, a LED photo irradiation system for acne treatment has been designed using PWM(Pulse Width Modulation) mode to enhance the energy efficiency and prevent thermal destruction in tissues. System configuration consisting largely of timer module, PWM module, and photo transfer device has been designed with the use of 1 W LED at a wavelength of 660 nm for the photo transfer device to increase skin penetration depth for treatment of acne. Frequency and wave form generated by using PWM control was verified along with confirmation of output energy of 660 nm LED and surface temperatures of tissues, followed by evaluation of stable energy outputs and stability of tissues. The results indicated that whereas power loss was high and thermal destruction in tissues was exhibited when C.W mode was used to obtain the optical energy of 1 W LED at a wavelength of 660 nm for acne treatment, realization of PWM mode allowed lowering of power consumption for LED through pulse width modulation, and no occurrence of thermal destruction in tissues, suggesting that PWM mode is safer and more effective for treatment of acne than C.W mode.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.14 no.2
• /
• pp.142-149
• /
• 2009

This paper investigates operating characteristics of three-phase matrix converter with unity input power factor by direct duty-ratio pulse-width modulation in the case of balanced and unbalanced load. It can be found from the system analysis that (1) The control algorithm for unity power factor is not related to the variables of load sides but the input voltages, (2) With the balanced three-phase load except for the pure reactive load, the unity input power factor can be achieved, (3) In the case of the unbalanced linear load, the equivalent input characteristics of the matrix converter can be seen like the nonlinear resister, (4) When the input frequency and the output frequency have the specific relationship, each input phases have the same sharing of the average power. The feasibility and validity of the analysis were verified by simulation and experimental results.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.14 no.6
• /
• pp.129-135
• /
• 2015

This paper shows significant methods that improve the lifespan of LED modules as well as efficiently using an aluminum heat-sink for LED module in high power. It proposes a method that raises stability and lifespan to protect LED modules and the power unit when the LED module has been used for a long hours at high temperatures. During the research, we applied a method of pulse-width modulation (PWM) in order to prevent the phenomenon that the entire power of a system is turned off and the lifespan is reduced when the LED nodule reacts to the high temperatures. To protect the LED module and SMPS based on high efficiency, a temperature sensor is attached underneath the circuit board and the sensor measures the temperature of circuit board when the LED module is powered on. The electrical power connected to SMPS is controlled by PWM when the temperature of the LED module reaches a particular temperature.

• Journal of the Korean Society for Precision Engineering
• /
• v.23 no.10
• /
• pp.60-67
• /
• 2006

This paper presents the temperature control in aluminum plate with Peltier module. From the experimental work, Peltier module is used to control the temperature of small aluminum plate for both heating and cooling with the control of current and fan ON/OFF. And current control of Peltier module was accomplished by PWM method. As a result of experiments, it is proper that operate cooling fan only while cooling duration and there exist a proper cooling current to drop temperature rapidly. It takes about 125sec to control temperature of aluminium plate between $30^{\circ}C$ and $70^{\circ}C$ and about 70sec between $40^{\circ}C$ and $60^{\circ}C$, in ambient temperature $28^{\circ}C{\sim}29^{\circ}C$ while cooling fan is operated only cooling duration. With the cooling current, temperature control of aluminum plate was accomplished more rapidly in comparison without cooling current. Future aim is to realize more rapid temperature control and develop SMHA(special metal hydride actuator) by using Peltier module as a heating and cooling source.

• Journal of Drive and Control
• /
• v.13 no.3
• /
• pp.47-52
• /
• 2016

This paper presents a control method for the performance improvement of a proportional solenoid actuator using a Pulse Width Modulation (PWM) signal. It is very difficult to obtain excellent response performance from a proportional solenoid actuator using a simple proportional controller with no PWM signal or dither because the mass and structure of a proportional solenoid actuator changes according to the application target, friction force in the proportional solenoid tube, operating force and displacement range. To solve the above problems, first, a controller with a PWM function for experimenting with attraction force characteristics was designed and manufactured. Secondly, an experimental setup for solenoid performance measurement with a force sensor and a displacement sensor was also manufactured. The attraction force characteristics according to the frequency and duty ratio variations of a PWM signal were tested and the relationships among the frequency, duty ratio, plunger mass and friction characteristics were analyzed. Finally, response characteristics improvements for proportional solenoid actuators are discussed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2001.05a
• /
• pp.427-430
• /
• 2001

Computers and automated manufacturing processes in industry are very susceptible to voltage sags and surges. The need for greater power reliability makes the end-users to use the uninterruptible power supply and other electronic power conditioning means to maintain the stable voltage. In this paper, a single-phase buck ac-ac converter for Custom Power Applications is presented. The presented converter uses IGBT's as switching module and maintains the stable voltage through PWM technology in spite of the input voltage sags and load rejections. In this paper, the operation characteristics of the power converter at steady state are illustrated using PSPICE simulations.