• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.369-372
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• 1994

In this paper, a voltage type dual PWM converter which achives the bidirectional power flow between a AC supply and a DC bus voltage is described. In PWM modulator, there exist a time difference between the sampling time and carrier wave, it achieves stable modulation even the disturbance in the synchronous AC source voltage. And this paper proposes the compensation method and the control method related a disturbance of synchronous signal using the low pass filter and phase shifter for the stable modulation. As a result the voltage type dual PWM converter makes the imput current wave as sinusoid, and performs the high power factor driving.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.09a
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• pp.34-37
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• 2001

This research suggested the new algorithm controlled by micro processor which is already stored by various PWM form of output voltage by using fundamental data of the carrier and signal. The determined PWM pattern is not concerned with the signal wave form and the new algorithm can obtain the desired pulse width by synchronous of carrier. The PWM wave can be controlled with real time by using extra hardware and digital software and to speed up program processing, the control signals to switch the power semi-conductor of three phase PWM inverter, simultaneously use the output signal by microprocessor and extra hardware, and control signal by software. In the end, this method was proved by applying to Three phase voltage source inverter.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.515-517
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• 1989

This PWM inverter are used bridge circuit of two pair complementary transistor at each phase. The operation signals are 3 level PWM wave of W type and M type modulation, Which were obtained from switching time data by switching position calculation of triangular and sine wave. The output voltage waveforms of this inverter have the 5 level phase voltage and the 9 level line voltage of PWM.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.12
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• pp.137-144
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• 1994

In this paepr, we present a soft switching PWM inverter as reducing switching loss and stress at high power application. The PWM inverter is designed by space voltage about 2$\sqrt{3}$ times (15%) than conventional SPWM method. To reduce switching loss and stress. The DC link requires a capacitor, an inductor and two additional switches. Therefore proposed inverter performs trun PWM operation under the soft switching condition. As a result of soft switching we can reduce switching loss and ensure stability of switching devices. For approach to real time, control system is realized by 8 bit single-chip microprocessor. Therefore, we can construct system is with simplified volumn and structure by eliminating carrier wave and referrence wave generator of conventional SPWM method.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.675-677
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• 2000

In the paper the eddy current loss in brushless DC motor due to switching frequency supplied by PWM inverter, is analyzed. The compensated conductivity is used in order to analyze the eddy current loss in brushless DC motor which has lamination structure. The eddy current loss is deceased when switching frequency supplied by PWM inverter is gradually increased from 1.2kHz up to 12kHz. The high switching frequency of PWM inverter make the output wave into a similar sine wave and this leads to the decreasing eddy current loss.

• Journal of the Korean Professional Engineers Association
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• v.22 no.4
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• pp.12-16
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• 1989

This paper presents a n analysis of the output voltage waveforms of the double sinusoidal modulated PWM inverter, and are studied on the driving characteristics through the 3 phase induction motor using 6502 microcomputer. The double sinusoidal modulated waves are produced during the interval 4$\pi$/3 [rad] for one cycle, and the switching loss can be reduced. The amplitude of fundamental wave of double sinusoidal modulated PWM inverter is 1.15 times higher than that of the sinusoidal PWM inverter, but the practical measured value by FFT analyzer is 1.13 times.

• Journal of ILASS-Korea
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• v.21 no.3
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• pp.155-161
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• 2016

Injected fuel pressure waves of a common rail injector with various current profiles supplied to the injecor were measured using Bosch method. In order to drive the common rail injector, the current in the solenoid should be controlled using what is known as a peak and hold pattern, which consists of a high current level with a short time duration (peak) in the first step and a low current level with a long time duration (hold) in the subsequent step. The current profile can be shaped by swithcing an injector driving power source with the peak and hold waves. The capture, compare and PWM (CCP) pin in the microprocessor was used to generate the combined peak and hold waves. The PWM square wave generated from the CCP pin has a duty ratio of 100% for the peak current and 10% or 30% for the hold pattern. Five patterns of the current profile were generated by combining the peak and hold wave. The common rail pressure is controlled at 75, 100, and 130 MPa. As the fuel rail pressure increases, the variations of the measured fuel injection pressure wave according to the current profiles decrease.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.5
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• pp.922-930
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• 2009

An optimized PWM switching strategy for an induction motor voltage control is developed and demonstrated. Space vector modulation in voltage source inverter offers improved DC-bus utilization and reduced commutation losses and has been therefor recognized the preferred PWM method especially in case of digital implementation. An optimized PWM switching strategy for an induction motor voltage control consists of switching between the two active and one zero voltage vector by using the proposed optimal PWM algorithm. The preferred switching sequence is defined as a function of the modulation index and period of a carrier wave. The sequence is selected by using the inverter switching losses and the current ripple as the criteria. For low and medium power application, the experimental results indicate that good dynamic response and reduced harmonic distortion can be achieved by increasing switching frequency.

• Journal of the Korean Society of Radiology
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• v.6 no.3
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• pp.207-215
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• 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 Electrical Engineers
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• v.39 no.2
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• pp.157-163
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• 1990

The PWM inverter investigated in this paper utilizes a bridge type current sharing reactor circuit with tow pairs of complementary transistor at each phase. The driving signals for this inverter are 3 level PWM waves of W type an M type modulation, which are obtained from a microprocessor based on the switching time data obtained by switching position calculation of triangular and sine modulation wave. The output voltage waveforms of this inverter have 5 level phase voltage and 9 level line voltage of PWM. The harmonics of the output voltage are reduced to half when it is compared with single CTI, and the occurrence of harmonics is also reduced.