• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.6
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• pp.526-533
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• 2015

A new algorithm is proposed for the estimation of equivalent grid impedance at the point of common coupling of a grid-tie inverter output. The estimated impedance parameter can be used for the improvement of the performance and the stability of the distributed generation system. The estimation error is inevitable in the conventional estimation method because of the axis rotation due to PLL. In the conventional estimation error, the d-q voltage and current are used for the calculation of the impedance with active and reactive current injections. Conversely, in the proposed algorithm, the negative sequence current is injected, and then the negative sequence voltage is measured for the impedance estimation. As the positive and negative sequence current controller is independent and the PLL is based on the positive sequence component only, the estimation of the equivalent impedance can be achieved with high accuracy. Simulation and experimental results are compared to validate the proposed algorithm.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.2
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• pp.114-126
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• 2013

In this paper, we present a set of methodologies to model the electromagnetic susceptibility (EMS) testing of I/O buffers for mobile system memory based on the bulk current injection (BCI) method. An efficient equivalent circuit model is developed for the current injection probe, line impedance stabilization network (LISN), printed circuit board (PCB), and package. The simulation results show good correlation with the measurements and thus, the work presented here will enable electromagnetic susceptibility analysis at the integrated circuit (IC) design stage.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.332-334
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• 2005

This paper presents a dynamic simulation of the unified power flow controller (UPFC) using a current injection method. Flexible AC Transmission System (FACTS) devices give more flexibility of control for security and economic operation of power systems. Diffculties of modeling UPFC in the conventional dynamic simulation programs arise from the fact that the injected voltage by the series inverter is superimposed on the shunt inverter side voltage. A solution can be a current injection method, in which a serial part of UPFC is converted to a parallel equivalent circuit using source transformation, and two current sources affect each other at every time step. To verify efficiency of this method, the proposed model is applied for the transient analysis of an example power system.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1582-1589
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• 2016

In this paper the integration of Distributed Generation (DG) in radial distribution system is investigated by computing the optimal site and size of DG to be placed. An analytical expression based on equivalent current injection has been derived by utilizing topological structure of radial distribution system to find optimal size of DG to minimize losses. In the presented formulation, the optimal DG placement is obtained without repeatedly computing the load flow. The proposed formulation can be used to find the optimal size of all types of DGs namely Type-I, Type-II, Type-III and Type-IV DGs. The investigations are carried out on IEEE 33-bus and 69-bus radial distribution systems. The optimal DG placement results into reduction in active and reactive power losses and improvement in voltage profile of the buses.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.4
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• pp.436-447
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• 2013

In this paper, Integrated circuit(IC) electromagnetic(EM) conducted immunity measurement and simulation using bulk current injection(BCI) and direct power injection(DPI) methods were conducted for 1.8 V I/O buffers. Using the equivalent circuit models developed for IC electromagnetic conducted immunity tests, we investigated the reliability of the frequency region where IC electromagnetic conducted immunity test is performed. The insertion loss for the noise injection path obtained from the simulation indicates that using only one conducted immunity test method cannot provide reliable conducted immunity test for broadband noise. Based on the forward power results, we analyzed the actual amount of EM noise injected to IC. We propose a more reliable immunity test methods for broad band noise.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.2
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• pp.202-211
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• 2014

The bulk current injection (BCI) and direct power injection (DPI) method have been established as the standards for the electromagnetic susceptibility (EMS) test. Because the BCI test uses a probe to inject magnetically coupled electromagnetic (EM) noise, there is a significant difference between the power supplied by the radio frequency (RF) generator and that transferred to the integrated circuit (IC). Thus, the immunity estimated by the forward power cannot show the susceptibility of the IC itself. This paper derives the real injected power at the failure point of the IC using the power transfer efficiency of the BCI method. We propose and mathematically derive the power transfer efficiency based on equivalent circuit models representing the BCI test setup. The BCI test is performed on I/O buffers with and without decoupling capacitors, and their immunities are evaluated based on the traditional forward power and the real injected power proposed in this work. The real injected power shows the actual noise power level that the IC can tolerate. Using the real injected power as an indicator for the EMS test, we show that the on-chip decoupling capacitor enhances the EM noise immunity.

• Advanced Composite Materials
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• v.16 no.1
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• pp.1-10
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• 2007

Composite materials consisting of crushed carbon fiber reinforced plastics (CFRP) pieces and acrylonitrile-butadiene-styrene (ABS) resin were prepared by an injection mold method to solve the problem of recycling of CFRP. The electrical properties, such as electrical resistivity, alternating current impedance and electromagnetic interference (EMI) shielding effect, were measured for the composites. The electrical resistivity of the composites showed a percolation type of conduction behavior and no difference between parallel and perpendicular to the injection direction was observed for CFRP content higher than the critical value. Measurement of alternating current impedance revealed that the conduction mechanism is attributed to the direct conductive paths generated by distributed carbon fibers; however, strong frequency dependence of the impedance was observed for the CFRP content near the critical one. The frequency dependence of the impedance is caused by the inter-fiber connection and can be expressed as a simple equivalent circuit. The absorption component of shielding effect (SE) was smaller than the expected value estimated from its resistivity. The decline of SE is thought to be caused by the decrease in effective thickness due to fiber orientation.

• Proceedings of the KIPE Conference
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• 1996.06a
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• pp.63-66
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• 1996

An micro model for the power insulated Gate Bipolar Transistor(IGBT) is developed. The model consistently described the IGBT steady-state current-voltage characteristics and switching transient current and voltage waveform for all loading conditions. The model is based on the equivalent circuit of a MOSFET with supplies the base current to a low-gain, high-level injection, bipolar transistor with its base virtual contact at the collector and of the base. Model results are compared with measured turn-on and turn-off waveform for different drive, load, and feedback circuits.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.11
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• pp.36-43
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• 2015

A pixel-level readout circuit is studied for 2-dimensional microbolometer focal plane arrays (FPAs). A current mirroring injection (CMI) input circuit with 2-step current-mode bias suppression is proposed for a pixel-level architecture with high responsivity and long integration time. The proposed circuit has been designed using a $0.35-{\mu}m$ 2-poly 4-metal CMOS process for a $320{\times}240$ microbolometer array with a pixel size of $50{\mu}m{\times}50{\mu}m$. The proposed 2-step bias-current suppression has sufficiently low calibration error with wide calibration range, and the calibration range and error can be easily optimized by controlling some design parameters. Due to high responsivity and a long integration time of more than 1 ms, the noise equivalent temperature difference (NETD) of the proposed circuit can be improved to 26 mK, which is much better than that of the conventional circuits, 67 mK.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.6
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• pp.546-552
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• 2012

This paper presents an active anti-islanding detection method using negative sequence voltage injection to the grid through a three-phase photovoltaic inverters. Because islanding operation mode can cause a variety of problems, the islanding detection of grid-connected photovoltaic inverter is the mandatory feature. The islanding mode is detected by measuring the magnitude of negative sequence impedance calculated by the negative sequence voltage and current at the point of common coupling. Simulation and experimental test are performed to verify the effectiveness of the proposed method which can detect the islanding mode in the specified time. The test has been done in accordance with the condition on IEEE Std 929-2000.