Research on Current Balance Control of Off-Grid Inverter with Asymmetric Load

Off-grid inverters can maintain the current output balance even when the load is asymmetrical, which is very important for the efficient and economical operation of the micro-grid system composed of new energy. In this paper, a single three-phase voltage source inverter with unbalanced load is taken as an example to study the unbalanced mechanism, and a simple and effective current balance control strategy is proposed. Firstly, the current output characteristics of off-grid inverter are analyzed when the load is asymmetric. Then, a negative sequence component extraction method based on SOGI is adopted, and an unbalanced current suppression method is designed on the basis of this extraction method. Finally, the PLECS simulation model is used to verify the results. The results show that this strategy can effectively suppress the output current distortion caused by load asymmetry, and obtain high quality current output waveform.