• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.6
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• pp.433-440
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• 2007

Recently, the reduction of standby power consumption is significantly issued in electronic and electrical industry for the conservation of environment. In the case of a switched mode power supply (SMPS), it is demanded high efficiency at extremely low output power conditions by consumers. However, it is very different from high efficiency techniques at full load conditions. In addition, many SMPSs are designed as a multi-output circuit for various loads because of cost down. This circuit is difficult to implement both high efficiency and good cross regulation performance, simultaneously. In this paper, secondary side post regulator (SSPR), current mode control method, and power sequence control technique are proposed to reduce standby power consumption and to improve cross regulation performance of the multi-output SMPSs which consist of single or multiple converter. The proposed methods are analyzed by their operational principles and optimal designs verified by experimental results with 110[W] and 270[W] SMPSs.

• Journal of IKEEE
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• v.14 no.2
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• pp.90-97
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• 2010

The high efficiency power management IC(PMIC) with DTMOS(Dynamic Threshold voltage MOSFET) switching device and DTMOS Error Amplifier is presented in this paper. PMIC is controlled with PWM control method in order to have high power efficiency at high current level. Dynamic Threshold voltage CMOS(DT-CMOS) with low on-resistance is designed to decrease conduction loss. The control parts in Buck converter, that is, PWM control circuits consist of a saw-tooth generator, a band-gap reference circuit, an DT-CMOS error amplifier and a comparator circuit as a block. the proposed DT-CMOS Error Amplifier has 72dB DC gain and 83.5deg phase margin. also Error Amplifier that use DTMOS more than CMOS showed power consumption decrease of about 30%. DC-DC converter, based on Voltage-mode PWM control circuits and low on-resistance switching device is achieved the high efficiency near 96% at 100mA output current. And DC-DC converter is designed with Low Drop Out regulator(LDO regulator) in stand-by mode which fewer than 1mA for high efficiency.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.6
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• pp.434-440
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• 2023

This paper propose the method that measure the main system parameters for current control of a.c. motor adopting the vector control technique. The automatical method that tuning PI control gains for current control of servo motors are used frequently through the information of main system parameters, wire resistance and inductance. In this study, the techniques to measure these two system parameters through the control of 3-phase inverter are presented. These control and measuring method are implemented by measuring output phase current obtained as a results of the step current control using simple proportional feedback input. Moreover, this method use freewheeling current of inverter at special switching mode for measuring inductance. This analytic strategy is could measure and calculate the system parameters without the complex measurement algorithm and new additional measuring circuits. That is could measure the total resistance and total inductance including wiring resistance and conduction resistance of switching devices using real driving circuits to control the motors.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.10
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• pp.40-47
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• 2016

In this paper, a dual mode buck converter with an ability to change mode is proposed, which is suitable particularly for portable device. The problem of conventional mode control circuit is affected by load variation condition such as suddenly or slowly. To resolve this problem, the mode control was designed with slow clock method. Also, when change from the PFM(Pulse Frequency Modulation) mode to the PWM(Pulse Width Modulation) mode, to use the counter to detect a high load. And the user can select mode transition point in load range from 20mA to 90mA by 3 bit digital signal. The circuits are implemented by using BCDMOS 0.18um 2-polt 3-metal process. Measurement environment are input voltage 3.7V, output voltage 1.2V and load current range from 10uA to 500mA. And measurement result show that the peak efficiency is 86% and ripple voltage is less 32mV.

• Journal of Power Electronics
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• v.16 no.3
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• pp.840-848
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• 2016

A primary-side regulation AC-DC converter operating in the PFM (Pulse Frequency Modulation) mode with a high precision output current is designed, which applies a novel inductance compensation technique to improve the precision of the output current, which reduces the bad impact of the large tolerance of the transformer primary side inductance in the same batch. In this paper, the output current is regulated by the OSC charging current, which is controlled by a CC (constant current) controller. Meanwhile, for different primary inductors, the inductance compensation module adjusts the OSC charging current finely to improve the accuracy of the output current. The operation principle and design of the CC controller and the inductance compensation module are analyzed and illustrated herein. The control chip is implemented based on a TSMC 0.35μm 5V/40V BCD process, and a 12V/1.1A prototype has been built to verify the proposed control method. The deviation of the output current is within ±3% and the variation of the output current is less than 1% when the inductances of the primary windings vary by 10%.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.2
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• pp.175-180
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• 2017

The measurement of three-phase current is important to control the instantaneous torque of a interior permanent magnet synchronous motor(IPMSM) using a three-phase inverter. Therefore, shunt resistors are used in low-cost motor-driving systems to measure three-phase current instead of additional current sensors that are too expensive for these systems. However, in certain regions of a space vector plane, shunt resistors cannot reconstruct three-phase current in high-speed driving mode. In this paper, predictive current control is used to compensate for the three-phase current in those regions, which results in a reduction of current ripple in a three-shunt sensing inverter(TSSI) and torque ripple in IPMSM.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.677-681
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• 2005

This Paper presents a 6 pulse shift operation control mode of current-source-inverter to make improvement of efficiency and to reduce the frequency of inverter switching for photovoltaic generation system using PWM current-source-inverter. This system is connected solar cell energy directly without using a storage cell. The proposed circuit can maintain maximum voltage of photovoltaic generation of take advantage of six Buck-Boost converter and a full-bridge inverter determines the polarity of AC output. That is controlled by using digital signal processor TMS320F2812 for operation about a 6 pulse shift operation control of current-source-inverter, and it is verified through the experimental results.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.4
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• pp.265-271
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• 2000

A non-contact battery charger for cellular phone is designed using half-bridge series resonant converter. This converter utilizes series resonance to reduce the undesirable effect of large leakage inductance of the detachable transformer and ZVS operation can reduce switching loss and switching noise. In this paper, analysis and design procedure of half-bridge series resonant converter with detachable transformer is presented. The input voltage is 85VAC∼270VAC, and the output voltage and current is 4.1V and 800mA, respectively. Furthermore, a method of calculating the secondary current of the transformer to control the battery charging current in the constant current charging mode is proposed. The performance of the charger is verified through experiments.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.28-32
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• 2004

In this paper, the operational performance of SRM can be improved by using current hysteresis control method. This method maintains a generally flat current waveform. At the high speed, the current chopping capability is lost due to the development of the back-EMF. Therefore SRM operates in single pulse mode. By using zero-current switching and zero-voltage switching technique, the stress of power switches can be reduce in chopping mode. When the commutation from one phase winding to another phase winding, the current can be zero as fast as possible in this period because several times negative voltage of DC-source voltage produce in phase winding. This paper is compared to performance based on conventional C-dump converter topology and the proposed resonant C-dump converter topology Simulation and experimental results are presented to verify the effectiveness of the proposed circuit.

• Journal of Welding and Joining
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• v.21 no.3
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• pp.51-57
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• 2003

The metal transfer in $CO_2$ welding shows the transition of transfer mode from short-circuiting to repelled transfer will the increase of welding current. While the short-circuiting mode in $CO_2$ welding has been studied very extensively relating with droplet formation and spatter generation, the repelled transfer has little been understood. In this study, high current $CO_2$ welding has been performed with bead-on-plate welds along with the waveform analyzer and high speed camera. The image of high speed camera was synchronized with its waveform so that the moment of spatter generation could be realized during drop detachment. As a results of this study, it was found that welding arc changes its location either once or three times and thus single or double pulse signals were developed in the voltage waveform. Whenever the arc moved its location, new arc was developed in a explosive way and thus it caused spatter generation. Specially severe spattering took place when the waveform showed a double-peak pattern. As a consequence of these results, new waveform control techniques could be suggested for suppressing the spatter generation in the high-current $CO_2$ welding.