• Journal of Power Electronics
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• v.6 no.3
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• pp.195-204
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• 2006

This paper presents a new compensating system, consisting of series and shunt active filters, for mitigating voltage and current disturbances. The shunt filter is used to compensate for unbalanced and distorted load currents. The series filter comprises two inverters, used to suppress voltage disturbances and handle source currents independently. This configuration is devised to reduce the overall cost of active compensators by using low-frequency high-current switches for the latter inverter. The filters are controlled separately using a novel control strategy. Since voltages at the point of common coupling contain interharmonics, conventional methods cannot be used for extracting voltage references. Therefore, voltage references are obtained from generated sinusoidal waveforms by a phase-locked loop. Current references are detected based on rotating frame vector mapping. Simulation results are presented to verify the system.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.4
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• pp.323-329
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• 1998

In this paper, we compose of the utility interactive photovoltaic(PV) generation system with a PWM stepdown chopper and a current source inverter. The stepdown chopper is controlled by the several gate pulses (twice frequency of utility voltage, square pulse and without the chopper) of chopper part to reduce pulsation of DC current and size of DC reactor. PV current only is measured for maximum power point tracking without any influence on the variation of insolation and temperature. Therefore, we can control modulation factor of the chopper to operate at maximum power point of solar cell. And, the utility interactive photovoltaic generation system supplies an AC power to the load and the utility power system.

• Journal of Power Electronics
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• v.4 no.2
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• pp.102-111
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• 2004

This paper is concerned with a deadbeat current control implementation of shunt-type three-phase active power filter (APF). Although the one-dimensional deadbeat control method can attain time-optimal response of APF compensating current, one sampling period is actually required fur its settling time. This delay is a serious drawback for this control technique. To cancel such a delay and one more delay caused by DSP execution time, the desired APF compensating current has to be predicted two sampling periods ahead. Therefore an adaptive predictor is adopted for the purpose of both predicting the control error of two sampling periods ahead and bringing the robustness to the deadbeat current control system. By adding the adaptive predictor output as an adjustment term to the reference value of half a source voltage period before, settling time is made short in a transient state. On the other hand, in a steady state, THD (total harmonic distortion) of the utility grid side AC source current can be reduced as much as possible, compared to the case that ideal identification of controlled system could be made.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.995-998
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• 1992

A fully software-controlled pulse-width modulatioed (PWM) rectifier with current link is presented. Line power factor is controlled, while maintaining dc current. The input fitter of the PWM rectifier is analyzed and its analysis, shows that unity power factor is achieved with lagging of the input current of the PWM rectifier with respect to the source voltage. The PWM technique is developed using a space vector modulation and is implementation is carried out with a minimal control hardware structure based on one 16-bit single-chip microcomputer. It is shown via experimental results that the proposed sheme gives good performance for the PWM rectifier with current link.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.12
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• pp.2273-2277
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• 2010

In this paper a 2.4GHz CMOS colpitts type microwave oscillator was designed and fabricated using H-spice and Cadence Spetre. There are 140MHz difference between the oscillation frequency and the resonance frequency of a tank circuit of the designed oscillator. The difference is seemed to be due to the parasitic component of the transistor. The inductors used in this design are the spiral inductors proposed in other papers. Cascode current source was used as a bias circuit of a oscillator and the output transistor of the current source is used as the oscillation transistor. A common drain buffer amplifier was used at the output of the oscillator. The measured oscillation frequency and output power of the oscillator are 2.173GHz and -5.53dBm.

• 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.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.395-397
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• 1999

This paper presents a method of improving the power factor and the waveform of A.C line currents and the out waveforms of AC to DC fully bridge converter systems which is achieved by connecting converters in series and parallel. The results of simulation show that the power factor and the source voltage and current waveforms are improved by the method of connecting converter in series, and the controlled input voltage and current waveform using a current limit controller.

• Journal of Satellite, Information and Communications
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• v.9 no.3
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• pp.15-21
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• 2014

An electrostatic discharge (ESD) protection device, so called, N-type embedded silicon controlled rectifier (NESCR), was analyzed for high voltage operating I/O applications. A conventional NESCR standard device shows typical SCR-like characteristics with extremely low snapback holding voltage, which may cause latch-up problem during normal operation. However, our modified NESCR_CPS_PPW device with proper junction/channel engineering such as counter pocket source (CPS) and partial P-well structure demonstrates highly latch-up immune current-voltage characteristics with high snapback holding voltage and on-resistance.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.6
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• pp.262-270
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• 2003

In this paper, the characteristics of single-phase line-start permanent magnet synchronous motor driven by constant voltage are analyzed on d-q axis vector diagram and compared with that of current controlled motor. The coupled method of symmetrical coordinates and d-q axis voltage equation are applied to the analysis method like the analysis of single-phase induction motor. From the result of the analysis, it is seen that motors driven by constant voltage source have effects on not only the amplitude of current and torque but also current and current phase angle, so overall characteristics such as power factor and load angle are affected by circuit parameters. For precise analysis and design of single-phase line-start synchronous motor, its characteristics should be analyzed on d-q axis vector plan in consideration of the variation of circuit parameters.

• JSTS:Journal of Semiconductor Technology and Science
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• v.4 no.4
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• pp.269-274
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• 2004

Current delivery system, in which the analog current produced by a unique DAC circuit is stored into a current-memory circuit and delivered in a time-divided sequence, shows variation of output current as low as 4% in a current source data-driver IC for AM-OLED driven by a current-programmed method without any fuse repairing after fabrication. This driver IC has 54 outputs and can sink constant current as low as 3 ${\mu}A$ with 6-bit analog levels. Such a low current level without variation can hardly be obtained by an ordinary MOS transistor because the current level is in the sub-threshold region and changes exponentially with threshold voltage variation. Thus we adopted a current mirror circuit composed of bipolar transistors to supply well-controlled current within a nano-ampere range.