• Journal of the Korean Society of Industry Convergence
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• v.21 no.6
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• pp.265-271
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• 2018

DC-DC buck converter is a critical building block in the power management integrated circuit (PMIC) architecture for the portable devices such as cellular phone, personal digital assistance (PDA) because of its power efficiency over a wide range of conversion ratio. To ensure a safe operation, avoid unexpected damages and enhance the reliability of the converter, fully-integrated protection circuits such as over voltage protection (OVP), under voltage lock out (UVLO), startup, and thermal shutdown (TSD) blocks are designed. In this paper, these three fully-integrated protection circuit blocks are proposed for use in the DC-DC buck converter. The buck converter with proposed protection blocks is operated with a switching frequency of 1 MHz in continuous conduction mode (CCM). In order to verify the proposed scheme, the buck converter has been designed using a 180 nm CMOS technology. The UVLO circuit is designed to track the input voltage and turns on/off the buck converter when the input voltage is higher/lower than 2.6 V, respectively. The OVP circuit blocks the buck converter's operation when the input voltage is over 3.3 V, thereby preventing the destruction of the devices inside the controller IC. The TSD circuit shuts down the converter's operation when the temperature is over $85^{\circ}C$. In order to verify the proposed scheme, these protection circuits were firstly verified through the simulation in SPICE. The proposed protection circuits were then fabricated and the measured results showed a good matching with the simulation results.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.2
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• pp.130-136
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• 2015

This study describes the structure and operation modes of vertical stabilization (VS) converter for international thermonuclear experimental reactor (ITER) and proposes a protection method. ITER VS converter supplies voltage (${\pm}1000V$)/current (${\pm}22.5kA$) to superconducting magnets for plasma current vertical stabilization. A four-quadrant operation must be achieved without zero-current discontinuous section. The operation mode of the VS converter is separated in 12-pulse mode, 6-pulse mode and circulation current mode according to the magnitude of the load current. Protection measures, such as bypass and discharge, are proposed for abnormal conditions, such as over current, over voltage, short circuit, and voltage sag. VS converter output voltage is controlled to satisfy voltage response time within 20 msec. Bypass operation is completed within 60 msec and discharge operation is performed successfully. The feasibility of the proposed control algorithm and protection measure is verified by assembling a real controller and implementing a power system including the VS converter in RTDS for a hardware-in-loop (HIL) facility.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.1979-1985
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• 2016

A protection algorithm using a voltage-controlled overcurrent element for a looped collection circuit in a wind farm is suggested in this paper. Because the proposed algorithm uses voltage relaying signals as well as current relaying signals, any fault in the looped collection circuit can be cleared by voltage-controlled overcurrent relays located at the two adjacent relaying points, the nearest place in each direction from the fault point. The algorithm can also distinguish the external faults which occur at the outside of a wind farm from the internal faults. It means that the proposed algorithm can provide the proper ability of protection coordination to the relays in the looped collection circuits of a large wind farm. The performance of the proposed algorithm is verified under various fault conditions using PSCAD/EMTDC simulations.

• Journal of the Institute of Convergence Signal Processing
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• v.11 no.2
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• pp.163-168
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• 2010

This paper presents the practical implementation of an over-temperature protection system for power semiconductor devices. In the proposed system, temperature variation is provided with just using $R_{ds(on)}$ characteristics of power MOSFET, while extra device such as a temperature sensor or an over-temperature detection transistor is needed to monitor the temperature in the conventional method. The proposed protection technique is experimentally tested on IRF840 power MOSFET. The PIC microcontroller PIC16F877A is used for the implementation of the proposed protection algorithm. The built-in 10-bit A/D converter is utilized for detecting voltage variance between a drain and a source of IRF840. The induced temperature-resistance relationship based on the measured drain-source voltage, supplies a gate signal to the power MOSFET. If detected temperature's voltage exceeds any a protection temperature's voltage, the microcontroller removes the trigger signal from the power MOSFET. These test results showed satisfactory performances of the proposed protection system in term of accuracy within 1.5%.

• Proceedings of the Safety Management and Science Conference
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• 2001.05a
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• pp.67-75
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• 2001

Circuitry to be connected to a Telecommunication Network consists of SELV CIRCUITS or TNV CIRCUITS. So International Standards, like as ITU-T Recommendation K.11, UL 1950, CSA C22.2 950 have been taken to reduce the risk that the Overvoltages from the power lines and from electrictraction lines, that may be received from the telecommunication network. Legal requirements may exist regarding permission to connect equipment having PTC components to a telecommunication network. Surge suppressors that bridge the insulation shall have a minimum d.c. sparkover voltage of 1.6 times the rated voltage or 1.6 times the upper voltage of the tared voltage range of the equipment. If left in place during electric strength testing of insulation, they shall not be damaged. In this work, The Conception ＆ Fail-Mode Analysis of PTC components for Over-Current Protection is proposed. It guarantees the protection for PL Claim about this Subject.

• 전자공학회논문지 IE
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• v.49 no.1
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• pp.18-23
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• 2012

In this paper, a potable device application for DC-DC converter was designed for voltage protection circuit. Voltage protection circuit to offer the under voltage lock out and over voltage protection consists of a comparator and bais circuits were implemented using. XFAB 1um CMOS process, SPICE simulations was confirmed through the characteristics. Simulation results, under voltage lock out input voltage is 4.8 V higher when the turn-on and, 4.2 V less when turn-off. When the input voltage is low voltage is applied can be used to prevent malfunction of the circuit. Over voltage protection is 3.8 V reference voltage when the output voltage caused by blocking circuit prevents device destruction can be used to improve the stability and reliability. The virtual control circuits of the DC-DC converter connected. According to the results of the abnormal voltage, voltage protection circuit behavior was confirmed. The proposed voltage protection circuit of the DC-DC converter cell is useful are considered.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.5
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• pp.340-344
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• 2012

Protected Circuit Module protects battery from over-charge and over-discharge, also prevents accidental explosion. Therefore, power MOSFET is essential to operate as a switch within the module. To reduce power loss of MOSFET, the on state voltage drop should be lowered and the switching time should be shorted. However there is trade-off between the breakdown voltage and the on state voltage drop. The TDMOS can reduce the on state voltage drop. In this paper, effect of design parameter variation on electrical properties of TDMOS, were analyzed by computer simulation. According to the analyzed results, the optimization was performed to get 65% higher breakdown voltage and 17.4% on resistance enhancement.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.2
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• pp.91-96
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• 2015

There are provision for risk analysis in IEC standards. It is to determine the need for installation of a surge protection device (SPD) in order to protect the low-voltage electrical installations from overvoltages caused by atmospheric phenomena and the like. However, scattered many related standards, the lack of details are not easy to apply it in the field. We investigated the relevant domestic and international standards for applies to the international standards in domestic. And we proposed the flow chart for determining the need for protection of the low-voltage electrical installations from overvoltage due to atmospheric phenomena and it set the appling target facility.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.293-295
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• 2003

KEPCO's high voltage distribution power line laid under the ground near to the J-booster pumping station that supply water for living. Lightening rod equipment does not installed at the J-booster pumping station because KEPCO's over head ground wire for protection functions as a lightening rod equipment. In this study, it is concerned whether KEPCO's over head ground wire for protect the distribution power line affect to the J-booster pumping station which is installed for reduce the damage from the direct and indirect lightening. If KEPCO's protection area does not affect to the J-pumping station, it is plan to examine the construction method of lightening rod protection angle and lightening rod equipment and to suggest the optimum protection plan using the surrounding structure based on the suitability of protection area.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.6
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• pp.562-567
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• 2020

In this paper, this is a study on the correction of protection relays to monitor temporary power facilities for storage tanks especially transformers to block and protect faults such as insulation breakdown. When an abnormality such as a short circuit or a ground fault occurs in the power system, it is important to detect this quickly cut off the device and equipment in which the fault occurred and separate it from the power system to correct the protection relay so that it does not interfere with power supply. In addition the fault current calculation that accurately applies the fault type and the cause of the fault for protection cooperation will be the most important factor in the correction of the protection relay. For protection coordination a study was conducted on the method of coordination for protection of power facility protection for storage tanks such as over current relay, ground over current relay, under voltage relay, and ground over voltage relay applied to temporary.