• Journal of Power Electronics
• /
• v.18 no.3
• /
• pp.892-901
• /
• 2018

SiC MOSFETs have been used to improve system efficiency in high frequency converters due to their extremely high switching speed. However, this can result in undesirable parasitic oscillations in practical systems. In this paper, models of the key components are introduced first. Then, theoretical formulas are derived to calculate the switching oscillation frequencies after full turn-on and turn-off in clamped inductive circuits. Analysis indicates that the turn-on oscillation frequency depends on the power loop parasitic inductance and parasitic capacitances of the freewheeling diode and load inductor. On the other hand, the turn-off oscillation frequency is found to be determined by the output parasitic capacitance of the SiC MOSFET and power loop parasitic inductance. Moreover, the shifting regularity of the turn-off maximum peak voltage with a varying switching speed is investigated on the basis of time domain simulation. The distortion of the turn-on current is theoretically analyzed. Finally, experimental results verifying the above calculations and analyses are presented.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.20 no.4
• /
• pp.41-46
• /
• 1983

The current-fed DC-DC converter has only one energy storage reactor in series with the input for any number of outputs and is insensitive to transformer volt-second unbalance. It is considered that these properties of the converter are considerable advantages over other maltiple-output circuits. The steady-state and dynamic characteristic and stability for the current-fed DC-DC con-verter are analyzed in detail. The analysis is carried out by the state-space averaging method for the operation with the duty ratio less than 50% and is confirmed by the experiment. From the evaluation of stability it is identified that the stability of this converter is excellent as compared with that of the conventional buck type converter.

• Proceedings of the KIEE Conference
• /
• 1993.07b
• /
• pp.704-706
• /
• 1993

This paper, introduces a Current-fed type High-Frequency Inverter with self turning devices. By replacing Thyrisors used for power source of heat treatment with high speed switching element, MOSFET in current type Inverter, the proposed Inverter makes high speed performance with several 100kHz. This paper also depicts some operating principles of the proposed circuits and general operating characteristics. Steady state solution on state variables in analysis of the proposed circuit is described generally by using normalized parameter and its characteristics depending on separate ratio(n) is also shown.

• Progress in Superconductivity and Cryogenics
• /
• v.7 no.1
• /
• pp.25-31
• /
• 2005

Since the discovery of the high temperature superconductors many researches have been performed for the practical applications of superconductivity technologies in various fields. As results, significant progress has been achieved. Especially, Superconducting Fault Current Limiter (SFCL) offers an attractive means In limit fault current in power systems. HTS resistive type SFCL is based on the ultra fast transition from the superconducting (non resistive) state to the normal (resistive) state by overstepping the critical current density, In this study, the simulation method of resistive type superconducting fault current limiter using EMTDC is proposed and the developed EMTDC model of SFCL is applied to the modeled power network using the Parameters of real system.

• Proceedings of the KIEE Conference
• /
• 1999.07e
• /
• pp.2155-2157
• /
• 1999

This paper describes a new measurement method of resistive current and the technique of deterioration diagnosis for ZnO element. The consequence of current increasing (resistive current) with time is the eventual attainment of a state of thermal instability that may lead to arrester failure. So, it is very important to measure a leakage current of ZnO arrester installed at on-state. For the high-precision and more reliability, an iron core, which has a very high relative permeability, was used for increasing detection sensitivity, and we also used the personal computer for the data storage and program and analysis. And we have verified the reliability and performance of the sensing device through several laboratory tests.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.24 no.4
• /
• pp.229-236
• /
• 2019

This study proposes a DC-DC converter topology of solid-state transformer for low-voltage DC distribution. The proposed topology consists of a voltage balancer and bipolar DC-DC converter. The voltage and current equations are obtained on the basis of switching states to design the controller. The open-loop gain of the controller is achieved using the derived voltage and current equations. The controller gain is selected through the frequency analysis of the loop gain. The inductance and capacitance are calculated considering the voltage and current ripples. The prototype is fabricated in accordance with the designed system parameters. The proposed topology and designed controller are verified through simulation and experiment.

• International journal of advanced smart convergence
• /
• v.13 no.1
• /
• pp.206-211
• /
• 2024

This study used a total of 205,565 datasets of 'voltage', 'current', '℃', and 'time(s)' to systematically analyze the properties and performance of solid electrolytes. As a method for characterizing solid electrolytes, a linear regression model, one of the machine learning models, is used to visualize the relationship between 'voltage' and 'current' and calculate the regression coefficient, mean squared error (MSE), and coefficient of determination (R^2). The regression coefficient between 'Voltage' and 'Current' in the results of the linear regression model is about 1.89, indicating that 'Voltage' has a positive effect on 'Current', and it is expected that the current will increase by about 1.89 times as the voltage increases. MSE found that the mean squared error between the model's predicted and actual values was about 0.3, with smaller values closer to the model's predictions to the actual values. The coefficient of determination (R^2) is about 0.25, which can be interpreted as explaining 25% of the data.

• Journal of Power Electronics
• /
• v.17 no.4
• /
• pp.1027-1036
• /
• 2017

The brushless doubly-fed induction generator (BDFIG) is a new type of dual stator winding induction generator. In such a generator, both the power winding (PW) and the control winding (CW) are housed in the stator. This paper presents the performance characteristics of a stand-alone BDFIG operation system. A new T-type steady-state model of a BDFIG is proposed. This model is more suitable for the performance analysis of stand-alone BDFIGs than the conventional Π-type steady-state model and the simplified inner core steady-state model. The characteristics of the power flow and CW current are analyzed by detailed mathematical derivations on the basis of the proposed T-type steady-state model. The analysis results are verified by experiments, which are carried out on a prototype BDFIG. The results of the performance analysis contribute to simplifying the control circuit, improving the control performance, and selecting an appropriate BDFIG for actual industrial applications.

• Progress in Superconductivity and Cryogenics
• /
• v.4 no.2
• /
• pp.27-30
• /
• 2002

One dimensional conduction equation is solved by finite difference method, to analyse the stability of Au/YBCO film deposited on a sapphire substrate. Joule heat is included in the case of current sharing state. The analysis shows the quench and recovery of superconductor depending on the amount of thermal disturbance release on the center surface of superconductor. The critical disturbance energies for different filling factor and operating current are calculated.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.37 no.8
• /
• pp.534-539
• /
• 1988

The dynamic chatacteristics and stability including steady state characteristic of the currentfed DC-to-DC converter with multiouput, which has a considerable advantage about the multioutut circuit,are analyzed in this paper. It is performed by using the steady state averaging method. As result, we know that the error, which is caused by secondary winding resistance of the transformer, exists between the two outputs in the steady state characteristics. Furthemore, it is verified that the current-fed DC-to-DC converter has also excellent stability in the multioutput application.