UPS flux compensation techniques for transformer inrush reduction

This paper presents two flux compensation designs for the uninterruptible power supply system. The objective of the flux compensation is to reduce the potential inrush current of the uninterruptible power supply-fed load transformer in the event of grid disturbances and load transformer engagement. The proposed methods utilize the existing voltage and current sensors, and voltage and current control loops of the uninterruptible power supply system for easy implementation. The application scenario is explained, and details of the flux compensation techniques are presented Laboratory test results are provided for validation.