• Journal of Power Electronics
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• v.18 no.6
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• pp.1912-1919
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• 2018

The output capacitance of power semiconductor devices is important in determining the switching losses and in the operation of some resonant converter topologies. Thus, it is important to be able to accurately determine the output capacitance of a particular device operating at elevated power levels so that the contribution of the output capacitance discharge to switch-on losses can be determined under these conditions. Power semiconductor switch manufacturers usually measure device output capacitance using small-signal methods that may be insufficient for power switching applications. This paper shows how first principle methods are applied in a novel way to obtain more relevant large signal output capacitances of Gallium-Nitride (GaN) FETs using the drain-source voltage transient during device switch-off numerically. A non-linear capacitance for an increase in voltage is determined with good correlation. Simulations are verified using experimental results from two different devices. It is shown that the large signal output capacitance as a function of the drain-source voltage is higher than the small signal values published in the data sheets for each of the devices. It can also be seen that the loss contribution of the output capacitance discharging in the channel during switch-on correlates well with other methods proposed in the literature, which confirms that the proposed method has merit.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.3
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• pp.313-321
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• 2009

This paper describes the downlink design of a transportable small-sized KOMPSAT ground station using sub-carrier signal. Based on the analysis of the transmission modes of satellite real-time telemetry and range measurement signals, the downlink channel design of KOMPSAT ground station using sub-carrier signal was processed. By considering the threshold signal-to-noise ratio of real-time 2 kbps telemetry signal and the required signal-to-noise ratio for satellite range measurement, the small-sized KOMPSAT downlink channel with G/T value of 6.5 dB/K was designed. The real G/T of implemented ground station was proven to be 6.62 dB/K when measured using the Sun. Moreover, through interface test with KOMPSAT, the ground station has shown the required link performance for real-time telemetry acquisition using sub-carrier and was consequently evaluated to be adequate for a transportable small-sized KOMPSAT ground station.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.357-360
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• 2000

This paper describes a parameter extraction method for HBT(Heterojunction Bipolar Transistor) equivalent circuit model without measurements of special test structures or numerical optimizations. Instead, all equivalent circuit parameters are calculated analytically from small-signal S-parameters measured under different bias conditions. These values being extracted from the cutoff mode can be used to extract intrinsic parameters at the active mode. This method yields a deviation of about 1.3 % between the measured and modeled S-parameters.

• Proceedings of the KIEE Conference
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• 2006.11a
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• pp.387-389
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• 2006

This paper describes new on-line small signal stability assessment and its application using the time series simulated phasor measurement data. Using FFT technique and optimization method, the suggested method can effectively identify all of mode frequencies involved in measured data and calculate the damping ratio with accuracy.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2518-2521
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• 1999

A Full-bridge zero-voltage zero-current switching (ZVZCS) converter using transformer auxiliary winding is analyzed. A complete small-signal model for the control scheme is developed. The propoed model is accurate up to half the switching frequency. The dynamic characteristics are compared with those of the zero-voltage switching converter and buck converter. Model predictions are confirmed by experimental measurements.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.1149-1152
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• 1999

A gain controllable precision full-wave rectifier for the measurements of small-signal voltage is presented. It consists of gain controllable inverter superdiode and noninverter superdiode. The results of simulation with PSpice and experiment on breadboard show that the proposed rectifier has the characteristic of precise rectification and amplification for small signal voltage.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.37 no.6
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• pp.376-382
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• 1988

A small-signal low-frequency disturbance of the input line affects the regulated-output voltage of the series resonant converter. To mitigate the detrimental effect, the output feedback PI-controller is employed. Small-signal linear models are represented to characterize the closed loop series resonant converter system. Design equations for the PI-controller which satisfy stability and percent ripple conditions are derived from the closed-loop linear model. Experimental results are presented which show excellent correlation with theory.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.957-960
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• 2000

A novel extraction method of high frequency small-signal model parameters for MOSFETS is proposed. From S-parameter measurement, this technique accurately extracts the model parameters including the charge conservation capacitance parameters. To consider charge conservation, nonreciprocal capacitance is considered. The modeled parameters fit the measurements very well without any optimization.

• Journal of Electrical Engineering and Technology
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• v.11 no.5
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• pp.1165-1178
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• 2016

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.321-322
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• 2014

In this paper, a zero-voltage switching (ZVS) phase shift full-bridge converter is analyzed. The small-signal model is derived to design a digital controller. PLECS simulation shows how sampling method effects on transfer function of ZVS phase shift full-bridge converter.