Search

Inductors are important energy storage elements that are used as filters in switching power converters. The operating efficiency of power inductors depend on the initial design choices and they remain as one of the most inefficient elements in a power converter. The focus of this paper is to explore the inductor design procedure from the point of efficiency and operating temperature. A modified form of the area product approach is used as starting point for the inductor design. The equations which estimate the power loss in core and copper winding are described. The surface temperature of the inductor is modelled using heat transfer equations for radiation and natural convection. All design assumptions are verified by actual experimental data and results show a good match with the analysis.

Design of higher order LCL filters that are used in grid-connected inverter applications involves multiple constraints. The filter requirements are driven by tight filtering tolerances of standards such as IEEE 519-1992 and IEEE P1547.2- 2003. Higher order LCL filters are essential to achieve these regulatory standard requirements at compact size and weight. This paper discusses the design procedure for these higher order LCL filters. The design procedure is analysed in per-unit basis so results can be generalized for different applications and power levels. This paper also gives guidelines for actual construction of the inductor based on a proposed fringing flux model. Experimental results of filtering characteristics show a good match with analysis in the frequency range of interconnected inverter applications.