• Proceedings of the KIPE Conference
• /
• 2007.07a
• /
• pp.95-97
• /
• 2007

This paper studies on operating limit curve of low voltage electric machinery with respect to source voltage variation or sag. Also, it discusses electric machine and compensation equipment design methodology based on voltage quality effect assessment technology. Voltage quality standards, such as SEMI47, CBEMA, ITIC curve are regarded to examine the relation between time constants of load and sagging time of sag generator, the load(low voltage electric machinery) study. Voltage sag characteristics of loads, time constant and sag relation voltage-time operating limits are tested and verified.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.33-35
• /
• 2007

This paper studies on operating limit curve of low voltage electric machinery with respect to source voltage variation or sag. Also, it discusses electric machine and compensation equipment design methodology based on voltage quality effect assessment technology. Voltage quality standards, such as SEMI47, CBEMA, ITIC curve are regarded to examine the relation between time constants of load and sagging time of sag generator, the load(low voltage electric machinery) study. Voltage sag characteristics of loads, time constant and sag relation voltage-time operating limits are tested and verified.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.14 no.6
• /
• pp.797-801
• /
• 2014

This research presented the concept of employing the punch-through diode triggered SCRs (PTTSCR) for low voltage ESD applications such as transient voltage suppression (TVS) devices. In order to demonstrate the better electrical properties, various traditional ESD protection devices, including a silicon controlled rectifier (SCR) and Zener diode, were simulated and analyzed by using the TCAD simulation software. The simulation result demonstrates that the novel PTTSCR device has better performance in responding to ESD properties, including DC dynamic resistance and capacitance, compared to SCR and Zener diode. Furthermore, the proposed PTTSCR device has a low reverse leakage current that is below $10^{-12}$ A, a low capacitance of $0.07fF/mm^2$, and low triggering voltage of 8.5 V at $5.6{\times}10^{-5}$ A. The typical properties couple with the holding voltage of 4.8 V, while the novel PTTSCR device is compatible for protecting the low voltage, high speed ESD protection applications. It proves to be good candidates as ultra-low capacitance TVS devices.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.3
• /
• pp.1392-1397
• /
• 2018

The potentiometric measurement result for a high resistance up to $100P{\Omega}$ using a low resistance, a low voltage source and a commercial digital multimeter(DMM) is presented. With the method, a resistance can be easily, fast and economically measured. Using the method, resistance ranges over the $10G{\Omega}$ range which is difficult to measure using a commercial DMM and resistance ranges between $100T{\Omega}$ and $100P{\Omega}$ which cannot measure using an insulation tester were measured within accuracy of a few percent. It is expected that it can be useful to determine the temperature and voltage effect of a high resistance and an insulation material because it uses a reference resistance with a low resistance, very low temperature and voltage effect. Besides, it is expected that it can be useful to calibrate a dc high voltage divider with a large resistance ratio and a very low resistance because arbitrary resistance ratio measurements are possible with it.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
• /
• v.2B no.3
• /
• pp.81-89
• /
• 2002

The sensorless AC motor drive is a popular topic of study due to the cost and reliability of speed and position sensors. Most sensorless algorithms are based on the mathematical modeling of motors including electrical variables such as phase current and voltage. Therefore, the accuracy of such variables largely affects the performance of the sensorless AC motor drive. However, the output voltage of the SVPWM-VSI, which is widely used in sensorless AC motor drives, has considerable errors. In particular, the SVPWM-VSI is error-prone in the low speed range because the constant DC link voltage causes poor resolution in a low output voltage command and the output voltage is distorted due to dead time and voltage drop. This paper investigates a novel high-performance strategy for overcoming these problems in a sensorless ac motor drive. In this paper, a variation of the DC link voltage and a direct compensation for dead time and voltage drop are proposed. The variable DC link voltage leads to an improved resolution of the inverter output voltage, especially in the motor's low speed range. The direct compensation for dead time and voltage drop directly calculates the duration of the switching voltage vector without the modification of the reference voltage and needs no additional circuits. In addition, the proposed strategy reduces a current ripple, which deteriorates the accuracy of a monitored current and causes torque ripple and additional loss. Simulation and experimentation have been performed to verify the proposed strategy.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.36 no.6
• /
• pp.598-602
• /
• 2023

With the purpose of instilling an awareness of the safety of users of electrical equipment and inducing voluntary facility improvement through the safety rating system for general low voltage electrical equipment, simulation and field application of the safety rating of general low voltage electrical equipment were conducted. For the introduction and application of the safety rating system for general low-voltage electrical equipment, data related to domestic safety was investigated and analyzed, cases of introduction in other fields were reviewed, and for design, the 4M risk assessment method of the Korea Occupational Safety and Health Agency and the cases of safety index development in Korea were analyzed and standardized. Safety rating system simulations were conducted for general low-voltage electrical equipment, and problem improvement measures were prepared by analyzing the results through on-site verification and simulation applied to the initial design. Design standards for the introduction of the safety rating system for general low-voltage electrical equipment were prepared, and 394 youth training facilities were applied to the field to see if the design standards were practically applicable to the field. With the application of the safety rating system for low-voltage electrical equipment for general use, youth training facilities that had been classified as 'appropriate' were able to induce an upgrade to a higher level through voluntary facility improvement according to the application of grades (A to E). As a result of inducing voluntary repair projects based on the results of the 1st and 2nd inspection of youth training facilities, it was confirmed that 86 facilities received grade A, 225 facilities received grade B, and only 311 facilities received grade A to B out of a total of 394 facilities, and there was no grade E.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.10
• /
• pp.1432-1441
• /
• 2012

In this study, an improved LCCT(Inductor-Capacitor-Capacitor-Trans) Z-source inverter(Improved LCCT ZSI) with characteristics of Quasi Z-source inverter(QZSI) and LCCT Z-source inverter(LCCT ZSI) is proposed. The proposed inverter can also reduce the voltage stress and input current/capacitor voltage ripples compared with conventional LCCT ZSI and Quasi ZSI. A two winding trans in Z-impedance network of the conventional LCCT ZSI is replaced by a three winding trans in the proposed inverter. To verify the validity of the proposed inverter, a DSP controlled hardware was made and PSIM simulation was executed for each method. Comparing the current and voltage ripples of each method under the condition of input DC voltage 70[V] and output AC voltage 76[Vrms], the input current and capacitor voltage ripple factors of the proposed inverter were low as 11[%] and 1.4[%] respectively. And, for generation of the same output AC voltage of each method, voltage stress of the proposed inverter was low as 175[V] under the condition of duty ratio D=0.15. As mentioned above, we could know that the proposed inverter have the characteristics of low voltage stress, low ripple factor and low operation duty ratio compared with the conventional methods. Finally, the efficiency according to load change/duty ratio and the transient state characteristics were discussed.

• KIEE International Transactions on Power Engineering
• /
• v.5A no.2
• /
• pp.97-102
• /
• 2005

Voltage sags are the most widespread quality issues affecting distribution systems. This paper describes in some detail the voltage sag characteristics due to different types and locations of fault in a practical low voltage power distribution system encountered in the UK. The results not only give utility engineers very useful information when identifying parts of the system most likely to pose problems for customer equipments, but also assist the facility personnel to make decisions on purchasing power quality mitigation equipment.

• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.1018-1019
• /
• 2015

Recently, standby power reduction techniques of AC/DC adaptor were developed, consuming power almost arrived to 300mW level. The standby power losses are composed of the input filter loss 11.8mW, the control IC for AC/DC adaptor 18mW, the switching loss 9.53mW and the feedback loss 123mW. And there are the standby power reduction techniques. In this paper, in order to reduce the standby power of SMPS more, the loss due to a voltage difference between input and output is reduced by the control circuit which is composed of the low voltage driving circuit and voltage regulator. The low voltage driving circuit operates on the low voltage of input and off the high voltage. The low voltage driving IC was produced by the $1.0{\mu}m$, high voltage DMOS process.

• Journal of the Korean Society of Industry Convergence
• /
• v.24 no.4_1
• /
• pp.387-395
• /
• 2021

Distributed resources such as renewable energy sources and ESS are connected to the low voltage direct current(LVDC) distribution network through the power conversion system(PCS). Control power is required for the operation of the PCS. In general, controller power is supplied from AC power or DC power through switch mode power supply(SMPS). However, the conventional SMPS has a low input voltage, so development and research on high input voltage self-power suitable for LVDC is insufficient. In this paper, to develop Self-Power that can be used for LVDC, the characteristics of the conventional topology are analyzed, and a series-input single-output flyback converter using a flux-sharing transformer for high voltage is designed. The high input voltage Self-Power was designed in the DCM(discontinuous current mode) to reduce the switching loss and solve the problem of current dissipation. In addition, since it operates even at low input voltage, it can be applied to many applications as well as LVDC. The validity of the proposed high input voltage self-power is verified through experiments.