Transformerless three-phase on-line UPS with high performance

Transformerless three-phase on-line UPS with
high performance
E.-H. Kim J.-M. Kwon B.-H. Kwon
Department of Electronic and Electrical Engineering, Pohang University of Science and Tech, Republic of Korea
E-mail: znight@postech.ac.kr
Abstract: A transformerless three-phase on-line uninterruptible power supply (UPS) is proposed. The proposed
UPS is composed of a rectifier, an inverter and a battery charger/discharger. The rectifier regulates a DC-link
voltage and performs power factor correction. On the other hand, the inverter provides a regulated sinusoidal
output voltage and has the current-limiting capability for an impulsive load. The battery charger/discharger
reduces the number of battery and supplies the power demanded by the load in the event of the input
power failure or abrupt decrease of the input voltage. Since both neutral lines of the input and output
voltages are connected at the centre of the DC-link, the need for an isolation transformer is eliminated and
the size, weight and cost of the system are significantly reduced. Additionally, new control algorithms of the rectifier, the charger/discharger and the inverter are proposed.
LINK
http://www.mediafire.com/view/7yl5uqoj5e3eq4s/TRANSFORMERLESS-UPS.pdf