An online estimation method of the filter inductance for a predictive current control

An online estimation method for the filter inductance is proposed in this paper in order to solve the phase error of output current and the system stability problem caused by the parameter mismatch of the filter inductance for a conventional predictive current control. The equivalent circuit for a small-scale single-phase grid-connected distributed generation system is simplified, and the dead-time effect near the zero-crossing current for an inverter is considered, the online estimated equation of the average filter inductance in the positive and negative sampling sectors in one cycle of the utility grid voltage is given based on the three-point median filter. Simulations and experiments are carried out in some conditions such as filter inductance change, magnitude change of output current and injected harmonic current, magnitude change of utility grid voltage and injected harmonic voltage, the results verify the proposed method is feasible.