A Harmonic Circulation Current Reduction Method for Parallel Operation of UPS with a Three-Phase PWM Inverter

Kyung-Hwan Kim; Wook-Dong Kim; Dong-Suk Hyun

A Harmonic Circulation Current Reduction Method for Parallel Operation of UPS with a Three-Phase PWM Inverter

Kyung-Hwan Kim

Wook-Dong Kim

Dong-Suk Hyun

Vol. 5, No. 2, pp. 160-165, Apr. 2005

10.6113/JPE.2005.5.2.160

parallel operation UPS(Uninterruptible Power Supply)

PWM synchronization

circulation current

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Abstract

In a parallel operation of UPS, there are two types of circulating currents between UPS. One is the low order circulating current with a fundamental frequency caused by the amplitude and phase differences of UPS output voltages, and the other is the harmonic circulating current with PWM switching frequency caused by non-synchronized PWM waveforms among UPS. The elimination of the low order circulating current is essential for optimal load sharing in parallel operations of UPS, which can be accomplished by the phase and magnitude control at each UPS. The harmonic circulating current may cause troubles and deteriorate in performance of the controller for optimal load sharing in parallel operation of UPS. This paper presents a PWM synchronizing method to eliminate the harmonic circulation current in parallel operation of UPS. The effectiveness of the proposed scheme has been investigated and verified through experiments by a 50kVA UPS.

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Cite this article

[IEEE Style]

K. Kim, W. Kim, D. Hyun, "A Harmonic Circulation Current Reduction Method for Parallel Operation of UPS with a Three-Phase PWM Inverter," Journal of Power Electronics, vol. 5, no. 2, pp. 160-165, 2005. DOI: 10.6113/JPE.2005.5.2.160.

[ACM Style]

Kyung-Hwan Kim, Wook-Dong Kim, and Dong-Suk Hyun. 2005. A Harmonic Circulation Current Reduction Method for Parallel Operation of UPS with a Three-Phase PWM Inverter. Journal of Power Electronics, 5, 2, (2005), 160-165. DOI: 10.6113/JPE.2005.5.2.160.