Development of Communicationless Hot-Swap Paralleling for Single-Phase UPS Inverters based on Adaptive Droop Method

This paper presents an improved controller for parallel connected single-phase UPS inverters in distributed generation application areas. The proposed control strategy needs only locally measurable feedback signals with communicationless between each inverter. It also shows how the improved adaptive droop method can be easily adapted to account for the operation of parallel inverters, providing good performance under the variation and disturbance of loads. And it uses adaptive integral loop gain to provide the motivation for sharing the current distortion components induced by nonlinear loads, as well as improve power sharing accuracy of inverters. Two DSP-based single-phase paralleling inverters are designed and implemented. Simulation and experimental results are all reported, confirming the validity of the proposed control technique.