Optimization of LCL filter based on THD estimation model

LCL filter has the advantage of small size and strong inhibition of high frequency harmonic currents. The parameter design of LCL filter mostly considers switching frequency harmonics. The attenuation of single-time harmonic current is always treated as optimization target. Thus the designed parameters may too large. What´s more, the THD requirement is not easy to verify. This paper proposes an optimization method of LCL filter based on the estimation of THD. The THD estimation model is established for Design of Experiments (DOE) instead of real LCL filter model. An 18kW three-phase converter with LCL filter has been established and tested. Simulation and experimental results verify the theoretical analysis.