Two-stage optimization procedure of LCL filters for the design of high-efficiency grid inverters

Abstract

Grid inverters with resonant LCL filters allow to exchange energy with the utility grid while achieving high power quality. The design of resonant LCL filters is a challenging task because it requires considering many different constraints such as distortion, cost, losses and robustness. In terms of optimization, it is computationally complex because it involves dealing with many discrete components. The paper deals with these challenges by proposing a two stage constrained optimization procedure that allows compute efficiently the best filter that optimizes the design objective and satisfy the constraints. Given the maximum allowed distortion and budget (cost, volume, mass, etc.), the filter that minimizes the total converter system losses is found. It is shown that the losses can be substantially reduced following the proposed approach. The numerical comparison with two existing approaches shows that lower losses are achieved at equal budget equal distortion. The approach is validated experimentally.