• Journal of IKEEE
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• v.13 no.1
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• pp.19-29
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• 2009

For two input ESD protection schemes utilizing the NMOS protection device or the lvtr_thyristor protection device, which is suitable for high-frequency CMOS ICs, we attempt an in-depth comparison study on the HBM ESD protection level in terms of lattice heating inside the protection devices and the peak voltage applied to the gate oxides in the input buffer through DC, mixed-mode transient, and AC analyses utilizing the 2-dimensional device simulator. For this purpose, we suggest a method for the equivalent circuit modeling of the input HBM test environment for the CMOS chip equipped with the input ESD protection circuit. And by executing mixed-mode simulations including up to four protection devices and analyzing the results for five different test modes, we attempt a detailed analysis on the problems which can be occurred in a real HBM test. In this procedure, we explain about the strength and weakness of the two protection schemes as an input protection circuit for high-frequency ICs, and suggest guidelines relating to the design of the protection devices.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.333-334
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• 2014

Converters employing IGCTs usually require di/dt snubber and Over Voltage Protection (OVP) circuit for the protection of IGCTs and fast diodes. In these IGCT-based converters, conventional di/dt snubber and OVP circuit dissipates a significant amount of power loss. To reduce this loss of conventional di/dt snubber and OVP circuit, this paper proposes a flyback type snubber circuit with di/dt limiting characteristic for IGCT-based converters in medium voltage wind turbines. This flyback type snubber circuit simply consists of a flyback type transformer and diode. The proposed circuit reduces loss and simplifies conventional di/dt snubber by adopting the flyback type transformer. Loss analysis of conventional di/dt snubber and OVP circuit is performed for the 3-level NPC type back-to-back VSC supplied from grid voltage of 6.9kV. The proposed flyback type snubber circuit can save the loss of conventional snubber circuit in the 3L-NPC type back-to-back VSC in multi-MW MV wind turbine. The proposed snubber circuit has a fewer number of components and improved efficiency leading to a reliable and efficient wind turbine systems.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.6
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• pp.427-432
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• 2018

High-capacity secondary batteries can cause explosion hazards owing to microcurrent variations or current surges that occur in short circuits. Consequently, complete safety cannot be achieved with general protection that is limited to a mere current fuse. Hence, in the case of secondary batteries, it is necessary for the protector to limit the inrush current in a short circuit, and to detect the current during microcurrent variations. To serve this purpose, a fuse can be employed for the secondary battery protection circuit with current detection. This study aims at designing a protection device that can stably operate in the hazardous circumstances associated with high-capacity secondary batteries. To achieve the said objective, a detecting fuse was designed from an alloy of low melting point elements for securing stability in abnormal current states. Experimental results show that the operating I-T and V-T characteristic constraints can be satisfied by employing the proposed current detecting self-contained low melting point fuse, and through the resistance of the heating resistor. These results thus verify that the proposed protection device can prevent the hazards of short circuit current surges and microcurrent variations of secondary batteries.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.106-110
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• 2005

In this paper, LED traffic signal lamp's operating circuit using Flyback converter and PFC IC has been presented. Most power conversion circuits use PFC IC for Power Factor Correction. The design parameter's value of Flyback converter has been proposed and the error amplifier which regulates the output voltage has been designed Besides, the under voltage protection circuit and the over voltage protection circuit for protecting the operating circuit kin unbalance of common electric power source and the temperature compensation circuit for fixed optical output power have been proposed.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1298-1305
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• 2016

This paper presents the development of a short-circuit protection mechanism on a high voltage switch (HVS) board which is built by a series connection of semiconductor switches. The HVS board is able to quickly detect and limit the peak fault current before the signal board triggers off a gate signal. Voltage clamping techniques are used to safely turn off the short-circuit current and to prevent overvoltage of the series-connected switches. The selection method of the main devices and the development of the HVS board are described in detail. Experimental results have demonstrated that the HVS board is capable of withstanding a short-circuit current at a rated voltage of 10kV without a di/dt slowing down inductor. The corresponding short-circuit current is restricted to 125 A within 100 ns and can safely turn off within 120 ns.

• Journal of IKEEE
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• v.22 no.3
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• pp.836-841
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• 2018

In this paper, This paper is based on the conventional ESD protection circuits SCR and LVTSCR. Also, the SCR-based ESD protection circuit, which is different from the conventional structure, is presented and tested for variations in the trigger voltage and holding voltage. Due to the insertion of additional N +, P + regions, the newly added SCR-based protection circuit have improved electrical characteristics. To discuss the electrical characteristics of the proposed circuit, Synopsys T-CAD simulation data was shown.

• Proceedings of the KIEE Conference
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• 2004.05b
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• pp.227-230
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• 2004

The Co-Gen System which maximize energy efficiency was installed at the industrial plants at the initial stage. However Small Scale Co-Gen System was expanded even to the general end-users such as housing and building owing to ESCO business recently. For this SSC, inter-connected operation to the utility is desirable due to voltage and frequency fluctuation following to unbalance between power output and load. Then voltage unbalance with utility system, frequency, increase of short circuit capacity, reclosing, and ALTS etc. should be fully considered for the inter-connected operation. Voltage variation, protection coordination, Co-Generators single running, and short circuit capacity should also be solved. For Con-Gen users, the several protection relays are recommended to install at the user's main incoming panel by the guide lines and/or instructions of the interconnected utility Then user's main CB(Circuit Breaker) have the chance to be tripped by some of this recommended relays and users have to undergo the unexpected blackout. So the circuit breaker trip schemes targeted to trip with these protection relays are reconsidered and the study result is hereunder proposed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.12
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• pp.1619-1625
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• 2018

Portable electronic devices secondary batteries can cause fire and explosion due to micro-current change in addition to the situation of short-circuit inrush current, safety can not be secured with a general operation limited current fuse. Therefore, in secondary battery, it is necessary for the protector to satisfy both the limit current type operation in the open-short-circuit inrush current and the current detection operation characteristic in the micro current change situation and for this operation, a fuse for the current detection type secondary battery protection circuit can be applied. The purpose of this study is to design a protection device that operates stably in the hazardous situation of small capacity secondary battery for portable electronic devices through the design of low melting fuse elements alloy of sensing type fuse and secures stability in abnormal current state. As a result of the experiment, I-T and V-T operation characteristics are satisfied in a the design of the alloy of the current sensing type self-contained low melting point fuse and the resistance of the heating resistor. It is confirmed that it can prevent accidents of short circuit over-current and micro current change of secondary battery.

• Journal of IKEEE
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• v.25 no.2
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• pp.280-284
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• 2021

In this paper, a new ESD protection circuit is proposed to improve the snapback characteristics. The proposed a new structure ESD protection circuit applying the conventional SCR structural change and stack structure. The electrical characteristics of the structure using penta-well and double trigger were analyzed, and the trigger voltage and holding voltage were improved by applying the stack structure. The electron current and total current flow were analyzed through the TCAD simulation. The characteristics of the latch-up immunity and excellent snapback characteristics were confirmed. The electrical characteristics of the proposed ESD protection circuit were analyzed through HBM modeling after forming a structure through TCAD simulator.

• Journal of the Korea Society for Simulation
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• v.4 no.2
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• pp.41-60
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• 1995

The IGBT(Insulated Gate Bipolar Transistor) is a power semiconductor device that has gained acceptance among circuit design engineers for motor drive and power converter applications. IGBT devices(International Rectifier, Proposed proposed model etc) have the best features of both power MOSFETs and power bipolar transistors, i.e., efficient voltage gate drive requirememts and high current density capability. When designing circuit and systems that utilize IGBTs or other power semiconductor devices, circuit simulations are needed to examine how the devices affect the behavior of the circuit. The interaction of the IGBT with the load circuit can be described using the device model and the state equation of the load circuit. The voltage rise rate at turn-off for inductive loads varies significantly for IGBTs with different base life times, and this rate of rise is important in determing the voltage overshoot for a given series resistor-inductor load circuit. Excessive voltage overshoot is potentially destructive, so a snubber protection circuit may be required. The protection circuit requirements are unique for the IGBT and can be examined using the model. The IGBT model in this paper is verified by comparing the results of the model with experimented results for various circuit operating conditions. The model performs well and describes experimented results accurately for the range of static and dynamic condition in which the device is intended to be operated.