• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.5
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• pp.787-794
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• 2001

In this paper, the development of large-signal model extractor for GaAs FET device through the Monolithic Microwave integrated Circuit(MMIC) is presented. The measurement program controlled by personal computer is developed for the processing of an amount of measured data, and the de-embedding algorithm is added to the program for voltage dropping as attached series resistance on measurement system. The small-signal model parameters are typically consisted of 7 elements that are considered as complexity of large-signal model and its the accuracy of the small-signal model is verified through comparing with measured data as varied bias point. The fitting function model, one of the empirical model, is used for quick simulation. In the process of large-signal model parameter extraction, one-dimensional optimization method is proposed and optimized parameters are extracted. This study can reduce the modeling and measuring time and can secure a suitable model for circuit.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.1119-1122
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• 2000

This paper describes on RF circuit simulation technique, especially on a RF modeling and a model extraction of a LDMOS(Lateral Diffused MOS) that has gate-width (Wg) dependence. Small-signal model parameters of the LDMOSs with various gate-widths extracted from S-parameter data are applied to make the relation between the RF performances and gate-width. It is proved that a source inductance (Ls) was not applicable to scaling rules. These extracted small-signal model parameters are also utilized to remove extrinsic elements in an extraction of a large-signal model (using HP Root MOSFET Model). Therefore, we can omit an additional measurement to extract extrinsic elements. When the large-signal model with Ls having the above gate-width dependence is applied to a high-power LDMOS module, the simulated performances (Output power, etc.) are in a good agreement with experimental results. It is proved that our extracted model and RF circuit simulation have a good accuracy.

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.217-220
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• 2001

CaN(gallium nitride) MODFET(modulation doped field effect transistor) large signal model was studied using Modified Materka-Kacprzak large signal MODFET model. using the Dambrine's method［3, at 45MHz-40㎓, Measured S-parameter and DC characteristics. based on measuring results, small signal parameter extraction was conducted. by the cold FET［4］method, measured parasitic elements were de-embedding. Extracted small signal parameters were modeled using modified Materka model, a sort of fitting function reproduce measuring results. to confirm conducted large signal modeling, modeled GaN MODFET's DC, S-parameter and Power characteristics were compared to measured results, respectively. by results were represented comparatively agreement, this paper showed that modified Materka model was useful in the GaN MODFET large signal modeling.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.141-143
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• 1998

A new small-signal model for the controlled on-time boost Power factor correction (PFC) circuit is Presented. The proposed small-signal model is valid up to high frequencies ever 1kHz. IF to remove the low-frequency ripple from the output a 120Hz notch filter is used the proposed model can be used for the control design of the PFC circuit to improve the dynamics of the output voltage. The accuracy of the model is confirmed by comparing the experimental results with the simulational result.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.609-614
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• 1998

A new small signal modeling of an average current mode control is proposed. In order to analyze the characteristics of the control scheme, the discrete and continuous time small signal models are derived. The derivation are mainly come from the analysis of the sampling effect presented in the current control loop. By the mathematical interpretation of practical sampler representing the sampling effect of a current control loop, the small signal models of an average current mode control can be easily derived. The instability of the current control loop, which gives rise to the subharmonic oscillation, can be identified by the proposed models. To show the usefulness of the proposed models, the simulation and experiment are carried out. The results show that the predicted results by the proposed model are much better agreed with the measured ones than that of the conventional model, even though the high gain of the compensation network of a current control loop is employed.

• Journal of Power Electronics
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• v.14 no.5
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• pp.1057-1068
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• 2014

Phase-locked loops (PLL) based on the synchronous reference frame (SRF-PLL) have recently become the most widely-used for grid synchronization in three phase grid-connected inverters. However, it is difficult to study their performance since they are nonlinear systems. To estimate the performances of a SRF-PLL, a canonical small-signal linearized model has been developed in this paper. Based on the proposed model, several significant specifications of a SRF-PLL, such as the capture time, capture rang, bandwidth, the product of capture time and bandwidth, and steady-state error have been investigated. Finally, a noise model of a SRF-PLL has been put forward to analyze the noise rejection ability by computing the SNR (signal-to-noise ratio) of a SRF-PLL. Several simulation and experimental results have been provided to verify and validate the obtained conclusions. Although the proposed model and analysis method are based on a SRF-PLL, they are also suitable for analyzing other types of PLLs.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.5
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• pp.422-430
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• 2014

This study proposes a small-signal model and control design for a two-stage DC-DC-AC converter to investigate its dynamic characteristics in relation to battery energy storage system. When the circuit analysis of the two-stage DC-DC-AC converter is attempted simultaneously, the mathematical procedure of deriving the dynamic equation is complex and difficult. The main idea of modeling the two-stage DC-DC-AC converter states that this topology is separated into a bidirectional DC-DC converter and a single-phase inverter with an equivalent current source corresponding to that of the inverter or converter. The dynamic equations for the separated converter and inverter are then derived using the state-space averaging technique. The procedures of building the small-signal model of the two-stage DC-DC-AC converter are described in detail. Based on the derived small-signal model, the individual controllers are designed through a frequency-domain analysis. The simulation and experimental results verify the validity of the proposed modeling approach and controller design.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.3
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• pp.192-199
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• 2022

In DC distribution systems, a TAB converter employing multiple transformers is one of the most widely used topologies due to its high power density, modularizability, and cost-effectiveness. However, the conventional control technique for a grid-connected mode in the TAB converter cannot maintain its reliability for an islanding mode under a blackout situation. In this paper, the islanding mode control technique is proposed to solve this issue. To verify the relative stability and dynamic characteristics of the control technique, small-signal models of both the grid connected and the islanding mode are derived. Based on the small-signal models, PI controllers are designed to provide suitable power control. The proposed control technique, the accuracy of small-signal models, and the performance of the controllers are verified by simulations and experiments with a 1-kW prototype TAB converter.

• Journal of Power Electronics
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• v.16 no.3
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• pp.849-860
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• 2016

The high-switching-frequency operation of power converters can achieve high power density through size reduction of passive components, such as capacitors, inductors, and transformers. However, a small-output capacitor that has small capacitance and low effective series resistance changes the small-signal model of the converter power stage. Such a capacitor can make the converter unstable by increasing the crossover frequency in the transfer function of the small-signal model. In this paper, the design and implementation of a high-frequency LLC resonant converter are presented to verify the power density enhancement achieved by decreasing the size of passive components. The effect of small output capacitance is analyzed for stability by using a proper small-signal model of the LLC resonant converter. Finally, proper design methods of a feedback compensator are proposed to obtain a sufficient phase margin in the Bode plot of the loop gain of the converter for stable operation at 500 kHz switching frequency. A theoretical approach using MATLAB, a simulation approach using PSIM, and experimental results are presented to show the validity of the proposed analysis and design methods with 100 and 500 kHz prototype converters.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.4
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• pp.551-561
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• 2001

In this paper, the large signal unified model is established for H4O GaAs pHEMT of GEC-Marconi using modified Curtice model. This unified model includes DC characteristic, small signal, and noise characteristic as various bias. Particularly, the model can simply and physically explain trans-conductance $(g_m)$ of pHEMT using modified Curtice model, and can tell the difference $g_m$, $R_ds$ at DC and these at AC through inclusion of internal RF-choke. The results of the established model built up using SDD in HP-Eessof show good agreement to the S/W measured data in DC, small signal, and noise characteristic. This model can also be applied to various computer aided analysis, such as linear simulation, 1-tone harmonic balance simulation, and multi-tone harmonic balance simulation, so the LNA(Low Noise Amplifier), oscillator, and mixer design has been shown using this model library.