Serial multi-module UPS system control method considering battery module balancing

Abstract

In this paper, serial multi-module UPS system control considering battery module balancing is proposed. Because of the organization, the UPS system has some properties. One of them is output voltage is sum of each UPS module output voltage. Thus, each UPS module output voltage respective control can accomplish each battery module balancing according to SOCs of each battery module. As SOC is high or low, output power of each module is controlled proportionally to equalize SOC of the battery modules. And the reference of the output powers is compensated according to magnitude of SOC difference. Eventually, utilization of the batteries can be increased by preventing over-charge and over-discharge problem. The proposed control is verified by simulation and experimental result.