Average Current Sharing Control Strategy for Parallel Operation of UPS with Low Bandwidth Communication

摘要

This paper analyzes the stability of average current sharing (ACS) control for parallel uninterruptible power supply (UPS) with low bandwidth communication (LBC). In the ACS method, the LBC causes the instability problem due to its phase lags. Also, it is related to the system output impedance because it appears on the poles which may cause instability issues. To analyze the output impedance effect in the ACS, dual-loop voltage controller which has different output impedance as different inner feedback currents, is adopted. Simulations and experimental results on the two parallel 15 kVA three phase inverters show the validation of stability analysis and effectiveness of the proposed method.