• The Transactions of the Korean Institute of Power Electronics
• /
• v.27 no.5
• /
• pp.367-375
• /
• 2022

Generally, a proportional-resonant controller is used to eliminate steady-state errors during the voltage-current control of a double-conversion uninterruptible power supply (UPS) in a stationary reference frame. Additionally, the feed-forward control compensating for the load current, which can be considered a disturbance of the voltage controller, can be used to improve the disturbance rejection performance. However, during the parallel operation of UPSs, circulating current can occur between UPS modules when performing both feed-forward control and droop control because feed-forward control reduces the circulating current impedance. This study proposes a feed-forward compensation technique that considers the impedance of circulating current. An additional feed-forward compensation technique is developed to enhance the disturbance rejection performance. The validity of the proposed feed-forward compensation technique is verified by the experiment results of the parallel operation of a 500 W double-conversion UPS module.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.20 no.1
• /
• pp.11-18
• /
• 2015

This paper proposes a high-efficiency 3-kW hybrid ESS with emergency power supply. The proposed system enables efficient use of power from photovoltaic (PV) cells and energy storage system (ESS). The proposed system can operate as an uninterruptible power supply (UPS) when grid fault occurs, providing seamless transfer from grid-connected mode to stand-alone mode. The LLC converter for PV achieves ZVS turn-on of switches and ZCS turn-off of diodes, and the isolated bidirectional DC-DC converter for ESS achieves ZCS turn-off regardless of load condition, resulting in high efficiency. The efficiency and performance of the proposed hybrid ESS has been verified by a 3-kW prototype.

• Proceedings of the KIPE Conference
• /
• 2014.07a
• /
• pp.253-254
• /
• 2014

본 논문에서는 무정전전원장치(UPS : Uninterruptible Power Supply 이하 UPS)에서 사용되는 단상인버터의 전압 제어기의 낮은 대역폭으로 인하여 발생될 수 있는 전압 위상 지연 문제를 해결한다. 제안하는 방법은 전압 명령에 대한 전향보상을 이용한 새로운 전압 제어기를 제안하고 이를 MATLAB Simulink를 사용한 시뮬레이션을 통하여 효과를 입증하였다.

• Proceedings of the KIPE Conference
• /
• 2000.07a
• /
• pp.744-747
• /
• 2000

This paper aims at developing remote control system to control and monitor distribute various devices through internet or information communication network. So far for managing UPS(Uninterruptible Power Supply) serial communication system has been used. This paper proposes managing method of UPS monitoring using SNMP. It consists of SNMP agent network board SNMP manager PC software serial communication software and UPS. The proposed method can be applied to various devices with communication network remotely.

• Journal of the Architectural Institute of Korea Structure & Construction
• /
• v.35 no.11
• /
• pp.129-136
• /
• 2019

Non-structural elements are vulnerable to earthquake ground motion. In this study, an experimental study for the electrical non-structural element was performed using tri-axial shaking table tests. A 100kVA UPS(Uninterruptible Power Supply system) was used as the test specimen. The test specimen was anchored to the concrete slab using the conventional installation detail. The input acceleration were generated in accordance with ICC-ES AC156 code. Scale factors of the input acceleration with respect to the required response spectrum defined in ICC-ES AC156 were from 25% to 600%. Based on the test results, damage and dynamic characteristics of UPS were evaluated and analyzed including natural frequency, damping ratio, acceleration time history response, dynamic amplification factor and relative displacement.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.17 no.1
• /
• pp.1-7
• /
• 2012

This paper describes the performance comparison results for current controller of a single-phase PFC converter with 1-switch voltage doubler strategy for single-phase double-conversion UPS(Uninterruptible Power Supply). A single-phase PFC converter with 1-switch voltage doubler strategy needs a diode bridge and one bidirectional active switch. Thus it is possible to reduce the material cost. However, the study results of current controller design and comparison of current control method has not been known after the converter circuit was proposed. For the performance comparison of current control, single-phase 3 kVA double-conversion UPS was tested. The performance of PI and PR current controller is experimentally confirmed with followings - input current reference tracking, input power factor correction and input current THD suppression.

• Proceedings of the KIPE Conference
• /
• 2013.07a
• /
• pp.137-138
• /
• 2013

This paper proposes the single-phase double-conversion UPS(Uninterruptible Power Supply) with ESS(Energy Storage System). The Proposed system is operating in three modes, which are normal mode, battery mode, and bypass mode. Not only in black-out but also in peak load times, the system is operating in battery mode which is using the stored energy of the battery to manage the power effectively. The validity of proposed system could be verified by simulations and experiments.

• Proceedings of the KIEE Conference
• /
• 2005.07e
• /
• pp.88-90
• /
• 2005

There are a lot of troubles during the transfer of the source of electric power in UPS (uninterruptible power supply system) which is indispensable to the industrial equipments. They cause blackout accidents, resulting in a great economic loss. After measuring and analyzing the transient phenomena happening during the transfer, this paper presents the solution of the troubles. The solution can be used as a basic material for maintenance and it can minimize the troubles occurring in UPS and enhance the reliability of it.

• Proceedings of the KIEE Conference
• /
• 1997.07f
• /
• pp.1919-1923
• /
• 1997

Superconducting magnet energy storage(SMES) offers lower loss and more capacity than other energy storage systems. This paper deals with a configuration and a control method of uninterruptible power supply(UPS) with SMES, Proposed system is constituted of three partsinverter, dc chopper and superconducting coil. The control system is implemented with a general-purpose DSP, TMS320C31. The results of simulation and experiment with a 10kVA prototype show the validity of the system configuration and the control method.

• Proceedings of the KIEE Conference
• /
• 1999.11a
• /
• pp.56-60
• /
• 1999

This paper presents the high performance real time control system of PWM inverter for uninterruptible power supply(UPS). This system is based on a digital control scheme which calculates the pulse widths of the inverter switches for the next sampling time in digital signal processor(DSP). A PI compensator is used to eliminate the voltage error caused by the difference between the actual values of LC filter and those designed. Double regulation loops which are the inner current loop and the outer voltage loop are used to make the transient response time reduce in load disturbance and nonlinear load. This method makes it possible to obtain better response in comparison to conventional digital control system. The proposed scheme provides good performance such as stable operation, low THD of the output voltage, and good dynamic response for load variations and nonlinear load.