In this study, a new modulation method is proposed to reduce the harmonics at the output voltage due to dead time in uninterruptible power supply (UPS) applications. In UPS applications, it is desirable to have low-output voltage harmonics. Dead-time effects in a three-level UPS were investigated for various load conditions. Analysis and simulations related to the proposed method are given and the optimum solution is found by iteration. The validity of the proposed modulation method is tested on two different UPS systems. UPS1 is 20 kVA NPC type, and UPS2 is 160 kVA T type. It is observed that the theoretical and experimental results are in good agreement, and the total harmonic distortion value caused by dead time is significantly reduced at ohmic loads. The proposed method is activated at power factor >0.95 and it improves the output voltage quality as much as the ideal case where the dead time is zero.
Cite this article as: F. Zengin, H. Kelebek and A. F. Bakan, “A novel dead-time compensation method for three-level uninterruptible power supply,” Turk J Electr Power Energy Syst., 2023; 3(3), 125-132.