Effects of the switching frequency of a grid converter on the LCL filter design

Abstract

The size of the LCL filter can be decreased significantly using higher switching frequencies enabled by next generation semiconductors. This paper studies the effects of the switching frequency of a grid converter on the LCL filter design. The goal in the design is to minimize the stored energy of the magnetic components. The core material of the converter-side inductor is selected based on the highest peak flux density within core-loss density limits. A laminated iron-core inductor is assumed on the grid side. For achieving higher accuracy during optimization, the grid-side inductor is modelled using an analytical high-frequency model. The proposed design method is evaluated using a 50-Hz 12.5-kVA SiC grid converter as an example case.