A control method for uninterruptible power supply in weak current systems based on virtual impedance

Abstract

If there is a significant voltage control error in the uninterruptible power supply (UPS) of weak current systems, it will seriously reduce the stability of the power supply. Therefore, a virtual impedance based UPS control method for weak current systems is proposed. Firstly, analyse the basic structure of weak current systems and uninterruptible power supplies. Secondly, an inverter output inductor current feedback is added outside the voltage and current dual loop control of the UPS to form a virtual impedance loop. Finally, virtual impedance is used to suppress the inverter circulating current of the UPS in the weak current system, thereby completing the control of the UPS. The experimental results show that the maximum voltage control error of the proposed method does not exceed ±0.331 V. Therefore, it indicates that the UPS control performance of this method is good.