Modeling, Analysis, and Implementation of Parallel Multi-Inverter Systems With Instantaneous Average-Current-Sharing Scheme

Parallel multi-inverter systems can be designed to have the advantages of expandable output power, improved reliability, and easy N + X redundancy operation. However, a current-sharing control scheme has to be employed to enable the inverters to share the load current equally. A multi-inverter system with instantaneous average-current-sharing scheme is presented in this paper. By introducing a disturbance source to represent all the sources that may cause current unbalances, a model of the system can be built. Some key issues are discussed based on the model, including stability of the current-sharing controller, impedance characteristics and voltage regulation. Three experimental 110 Vac/I.I KVA inverters are built and paralleled to verify the theoretical predictions.