• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1696-1698
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• 1998

Pulsed Nd:YAG laser using Nd:YAG crystal operates stably in the thermal conductivity, mechanical, optical condition. That is used broadly in material processings because of easy reaction to the materials, and the maintenance is very easy because of lamp excitation. In these material processings, power dinsity control is very important to improve processing technology. Power density is controled by inductance and capacitance or repetition rate. Therefore we are going to control laser power density as One-Chip Microprocessor(PIC16C55) and 8051. We have been experimented at the pulse repetition rate range of 10pps to 60pps(pulse per second).

• 한국전기전자재료학회논문지
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• 제21권4호
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• pp.289-295
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• 2008

In this paper, we designed the off-line PWM(Pulse width modulation) control IC for flyback type power converter to reduce the standby power consumption. In normal state, this off-line PWM IC generates the output pulse with $40\sim60kHz$ frequency and duty ratio of $20\sim88%$. When SMPS operates in standby mode, this IC generates the output pulse with 33kHz frequency and duty ratio of 1 %. SPICE simulation was performed to verify the standby power consumption of the power converter with designed of-line PWM IC. Power converter with designed off-line PWM IC consumes less than 0.3W when it operates in standby mode condition.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.40.3-40
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• 2001

The pulsed Nd:YAG laser is the most commonly used type of solid-state laser in many fields. In material processing and medical treatment, the power density control of a laser beam Considered to be significant, which depends on the flashlamp current pulse width and pulse repetition rate. For general laser power supply to control the laser power density, the secondary of the power transformer is connected to the rectifier and filter capacitor. The output of a rectifier is applied to a switching element in the secondary of the transformer. So power supply is complicated and the loss of switching is considerably. In addition, according to increasing pulse repetition rate, charged energy of energy-storage capacitor bank is not transferred sufficiently to flashlamp, and laser output efficiency decreases. In this study, we have ...

• 제어로봇시스템학회논문지
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• 제17권11호
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• pp.1179-1182
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• 2011

RC servos are electro-mechanical devices that respond to a control signal, which instructs them to move their output shaft to a certain position. A servo is normally plugged into a radio receiver with a three pin connector. The three wires are a power (usually 4.8V to 6.0V), a ground, and a signal wire. The signal wire carries a PWM (Pulse-Width Modulation) signal consisting of a 1-2msec pulse repeated 50 times a second. A 1.5msec pulse will tell the servo to move to its output shaft to the center position, 0 degrees. For a servo with a 180 degree of motion, a 1msec pulse will move the servo to -90 degrees, and a 2msec pulse will move the servo to +90 degrees. In order to development a humanoid robot, mechanical design, fixtures design, analysis of kinematics, implementation moving program, selection of RC servo motor and controller are required. This study was performed to experimentally compare the rotation range of RC servo motors according to change of a periods.

• 전력전자학회논문지
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• 제20권5호
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• pp.421-428
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• 2015

An advanced direct torque control (DTC) with pulse width modulation (PWM) method is presented in this paper. The duty ratio calculation of the selected voltage vector is based on the voltage functions of the selected voltage vector according to the sector angle. The proposed DTC uses a conventional DTC scheme with six sector divisions and switching rules. However, the winding voltages are supplied by the PWM approach. Furthermore, the duty ratio of the switching voltage vector is determined by the flux, torque error, and motor speed. The base voltage that shall determine the duty ratio can be calculated by approximate voltage functions according to the voltage angle. For the calculation of base voltages, second-order quadratic functions are used to express the output voltage of the selected voltage vector according to voltage angle. The coefficients for the second-order quadratic functions are selected by the voltage vector, which is determined by the switching rules of the DTC. In addition, the voltage functions are calculated by the coefficients and voltage angle between the voltage vector and rotor position. The switching voltages from the calculated duty ratio can supply the proper torque and flux to reduce the ripple and error. The proposed control scheme is verified through practical experimental comparisons.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 춘계종합학술대회
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• pp.947-950
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• 2005

본 논문에서는 전차 포탑의 선회, 고저를 담당하던 기존의 유압시스템을 모터를 사용하는 전기시스템으로 대체한 후 이 시스템에 벡터제어기법을 적용하였다. 모터의 각 상에 원하는 교류 전류를 공급하기 위한 전압원 인버터의 스위칭 방법으로는 주로 사용하는 공간벡터 PWM 변조방식 보다는 연산량이 적어서 빠른 연산을 수행할 수 있는 MIN-MAX PWM 변조방식을 사용하였으며 디지털 필터를 설계 적용하였다. 설계된 전류제어기는 전차의 환경시제에서 전류제어, 속도제어, 주파수응답 및 속도 궤적 추종 실험을 하였으며 그 성능을 입증하였다.

• Journal of Power Electronics
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• 제10권2호
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• pp.155-164
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• 2010

This paper presents a voltage control algorithm for a hybrid multilevel inverter based on a staged-perception of the inverter voltage vector diagram. The algorithm is applied to control a three-stage eighteen-level hybrid inverter, which has been designed with a maximum number of symmetrical levels. The inverter has a two-level main stage built using a conventional six-switch inverter and medium- and low- voltage three-level stages constructed using cascaded H-bridge cells. The distinctive feature of the proposed algorithm is its ability to avoid the undesirable high switching frequency for high- and medium- voltage stages despite the fact that the inverter's dc sources voltages are selected to maximize the number of levels by state redundancy elimination. The high- and medium- voltage stages switching algorithms have been developed to assure fundamental switching frequency operation of the high voltage stage and not more than few times this frequency for the medium voltage stage. The low voltage stage is controlled using a SVPWM to achieve the reference voltage vector exactly and to set the order of the dominant harmonics. The inverter has been constructed and the control algorithm has been implemented. Test results show that the proposed algorithm achieves the desired features and all of the major hypotheses have been verified.

• Journal of Power Electronics
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• 제17권3호
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• pp.653-663
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• 2017

Multilevel active neutral-point-clamped (ANPC) converter combines the advantages of three-level ANPC converter and multilevel flying capacitor (FC) converter. However, multilevel ANPC converter often suffers from capacitor voltage balancing problems. In order to solve the capacitor voltage balancing problems for five-level ANPC converter, phase-shifted pulse width modulation (PS-PWM) is used, which generally provides natural voltage balancing ability. However, the natural voltage balancing ability depends on the load conditions and converter parameters. In order to eliminate voltage deviations under steady-state and dynamic conditions, the active voltage-balancing control (AVBC) methods of floating capacitors and dc-link capacitors based on PS-PWM are proposed. First, the neutral-point current is regulated to balance the neutral-point voltage by injecting zero-sequence voltage. After that, the duty cycles of the redundant switch combinations are adjusted to balance the floating-capacitor voltages by introducing moderating variables for each of the phases. Finally, the effectiveness of the proposed AVBC methods is verified by experimental results.

• Journal of Power Electronics
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• 제19권1호
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• pp.244-253
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• 2019

Finite control set model-predictive control (FCS-MPC) has received increasing attentions due to its outstanding dynamic performance. It is being widely used in power converters and multilevel inverters. However, FCS-MPC requires a lot of calculations, especially for multilevel-cascaded H-bridge (CHB) static synchronous compensators (STATCOMs), since it has to take account of all the feasible voltage vectors of inverters. Hence, an improved five-segment space vector pulse width modulation (SVPWM) method based on the non-orthogonal static reference frames is proposed. The proposed SVPWM method has a lower number of switching states and requires fewer computations than the conventional method. As a result, it makes FCS-MPC more efficient for multilevel cascaded H-bridge STATCOMs. The partial cost function is adopted to sequentially solve for the reference current and capacitor voltage. The proposed FCS-MPC method can reduce the calculation burden of the FCS-MPC strategy, and reduce both the switching frequency and power losses. Simulation and experimental results validate the excellent performance of the proposed method when compared with the conventional approach.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 영호남학술대회 논문집
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• pp.74-77
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• 2000

A pulsed Nd:YAG laser has been used in a wide variety of fields : measuring, material processing and so on. In a material processing, it is very important to control the laser energy density. A pulse repetition rate and a pulse width are regarded as the most dominant factors to control the energy density of laser beam. In this study, pulsed Nd:YAG laser system was designed and manufactured to control the laser output usefully and easily. This system adopted the sequential charge and discharge circuit is controlled by 80196 micro- processor. As a result, it is found that laser output is controlled minutely by changing laser input and pulse repetition rate, and usefully by using 80196 microprocessor.