• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.1
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• pp.67-74
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• 2017

This study proposes a novel random pulse-width modulation (PWM) technique with a constant switching frequency utilizing a random offset voltage. The proposed PWM technique spreads switching harmonics by varying the position of an active voltage vector without a switching frequency variation. The implementation of the proposed PWM technique is simple because it does not require additional hardware and complex algorithm. The proposed random PWM technique is compared with the conventional PWM technique on the factors of harmonic spectrum, total harmonic distortion, and harmonic spread factor to confirm the harmonic spread effect. The validity of the proposed method is verified by simulations and experiments on a three-phase inverter drive system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.4
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• pp.98-107
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• 2005

Brushless DC motor(BLDCM) can be driven by 120[^{\circ}]$ square wave voltage and use PWM pulse patterns in two-phase feeding scheme to control the speed of the motor. This Paper introduces four PWM modes used BLDCM control system, and analyzes their different influences on the motor performances using a time-stepped voltage source finite element method. To verify the proposed computational method, we built the prototype motor for electrical power steering(EPS) and compared the predicted and the measured back EMF and phase current.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1088-1091
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• 1992

Programmed PWM(Pulse Width Modulated) generation techniques eliminating several low order harmonics have been widely used in the inverter circuit which produces minimum current ripple, reduced torque pulsation and thereby improves overall system performance. However, the applications of the programmed PWM technique are limited to CVCF(Constant Voltage Constant Frequency) applications and various motor drives. Although the programmed PWM produces a lower harmonic distorted waveform than the carrier modulated PWM, real-time programming is not possible because of the complicated calculation required for the gating signal. In this paper, a new programmed PWM technique named TAM (time averaging model) is developed to compensate for the demerits of the conventional programmed PWM technique with moderate harmonic distortion. Computer simulations are performed to verify the performance of the proposed algorithm.

• Journal of Electrical Engineering and Technology
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• v.11 no.1
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• pp.125-134
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• 2016

We propose an efficient high voltage level shifter for a high side Buck converter driving a light-emitting diode (LED) lamp. The proposed circuit is comprised of a low voltage pulse width modulation (PWM) signal driver, a coupling capacitor, a resistor, and a diode. The proposed method uses a property of a PWM signal. The property is that the signal repeatedly transits between a low and high level at a certain frequency. A low voltage PWM signal is boosted to a high voltage PWM signal through a coupling capacitor using the property of the PWM signal, and the boosted high voltage PWM signal drives a p-channel metal oxide semiconductor (PMOS) transistor on the high side Buck converter. Experimental results show that the proposed level shifter boosts a low voltage (0 to 20 V) PWM signal at 125 kHz to a high voltage (370 to 380 V) PWM signal with a duty ratio of up to 0.9941.

• Journal of Advanced Marine Engineering and Technology
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• v.11 no.2
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• pp.37-50
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• 1987

In an effort to conserve electric power, variable voltage variable frequency pulse width modulated (PWM) inverters are being applied increasingly to the variable speed control of the induction motors. The use of the PWM technique in motor drive applications is considered advantageous in many ways. For industrial applications, the PWM drive obtains its DC input through simple uncontrolled rectification of the commercial AC line and is favored for its good power factor, good efficiency, its relative freedom regulation problem, and mainly for its ability to operate the motor with nearly sinusoidal current waveforms. The purpose of this paper is to design a three phase natural sampled PWM inverter using microprocessor with simple control algorithm and hybrid control circuit has been built to implement this PWM scheme. In this system, the microprocessor can be used only for calculations directly related to motor control tasks by the design of hybrid circuit which sends PWM signals to the motor.

• Journal of Power Electronics
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• v.15 no.1
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• pp.227-234
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• 2015

This paper presents the application of bee colony optimization (BCO) to obtain the optimal switching angles for single phase PWM AC choppers. The optimal switching angles are found in the region of 0-${\pi}$ based on the asymmetrical PWM technique. This PWM process results in improvements of the total harmonic distortion of the output voltage and in the input power factor. Simulation and experimental results are compared with the conventional PWM to verify the performance of the proposed PWM process.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.6
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• pp.1-9
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• 2008

This paper suggests the triple-mode CMOS DC-DC converter that has temperature/voltage variation compensation techniques. The proposed triple-mode CMOS DC-DC converter is used to generate constant or variable voltages of 0.6-2.2V within battery source range of 3.3-5.5V. Also, it supports triple modes, which include Pulse Width Modulator (PWM) mode, Pulse Frequency Modulator (PFM) mode and Low Drop-Out (LDO) mode. Moreover, it uses 1MHz low-power CMOS ring oscillator that will compensate malfunction of chip in temperature/voltage variation condition. The proposed triple-mode CMOS DC-DC converter, which generates output voltages of 0.6-2.2V with an input voltage sources of 3.3-5.5V, exhibits the maximum output ripple voltage of below 10mV at PWM mode, 15mV at PFM mode and 4mV at LDO mode. And the proposed converter has maximum efficiency of 93% at PWM mode. Even at $-25{\sim}80^{\circ}C$ temperature variations, it has kept the output voltage level within 0.8% at PWM/PFM/LDO modes. For the verification of proposed triple-mode CMOS DC-DC converter, the simulations are carried out with $0.35{\mu}m$ CMOS technology and chip test is carried out.

• The Journal of the Acoustical Society of Korea
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• v.36 no.3
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• pp.179-185
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• 2017

The problem that occurred in the design/fabrication/testing of the wideband transmitting power amplifier for an embedded active SONAR (Sound Navigation and Ranging) system operating underwater was analyzed and the solution of the problem was proposed in this paper. Wideband acoustic SONAR systems had been developed in order to improve the underwater detection performance. The underwater acoustic transmission system had been also developed to achieve the wideband SONAR system. In this paper, the wideband acoustic transmission signal was generated using a 2 Level sawtooth type Class D PWM (Pulse Width Modulation) which was not complicated to implement. When the sonar signals having two or more frequencies were simultaneously generated, parasitic frequencies were added to the original signals by integer multiples of the frequency difference of the original signal. To cope with this problem, we proposed a way to remove the parasitic frequency from the source signal through modeling and simulation of the implemented power amplifier and PWM control hardware using MATLAB and Simulink.

• Journal of IKEEE
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• v.23 no.3
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• pp.1104-1107
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• 2019

This paper proposes a DC-DC boost converter for wearable AMOLED display using dead time controller to reduce dead time and improve power efficiency. Also the DC-DC boost converter adopts PWM-SPWM (set-time variable pulse width modulation) dual-mode to enhance power efficiency under light load and decrease output voltage ripple. The proposed circuit has been designed using $0.18{\mu}m$ BCDMOS process. Simulation results show that the circuit has power efficiency of 39%~96% and output ripple voltage of 2 mV under load current range of 1 mA~70 mA. The power efficiency of the proposed circuit is up to 2% higher than the previous PWM-SPWM method and up to 8% higher than only PWM method.

• Journal of Power Electronics
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• v.14 no.2
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• pp.302-314
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• 2014

Due to advancements in power electronics and inverter topologies, the current controlled multilevel voltage-source pulse width modulated (PWM) inverter is usually preferred for accurate control, quick response and high dynamic performance. A multilevel topology approach is found to be best suited for overcoming many problems arising from the use of high power converters. This paper presents a comprehensive review and comparative study of several current control (CC) techniques for multilevel inverters with a special emphasis on various approaches of the hysteresis current controller. Since the hysteresis CC technique poses a problem of variable switching frequency, a ramp-comparator controller and a predictive controller to attain constant switching frequency are described along with its quantitative comparison. Furthermore, various methods have been reviewed to achieve hysteresis current control PWM with constant switching frequency operation. This paper complies various guidelines to choose a particular method suitable for application at a given power level, switching frequency and dynamic response.