Comparison of 8-kW CCTT IM and Discrete Inductor Interleaved Boost Converter for Renewable Energy Applications

Abstract

This paper presents a comparison of two magnetic component topologies for use in a high-power high-current dc-dc boost preregulator for renewable applications. The industry-standard two-phase (2L) interleaved dc-dc boost converter consisting of two discrete toroid magnetic components is considered as the baseline design. A 3C92 CCTT-core split-winding integrated magnetic (CCTT IM) is developed and compared for similar conditions. The topologies are compared for the same worst case phase-current ripple conditions. First, the baseline industry-standard 2L design is presented, which consists of a toroidal magnetic component along with stranded copper conductors, which are used to reduce the effects of ac copper loss. The CCTT IM component is designed for the same worst case phase-current ripple as this allows for a size saving with respect to the baseline design. The CCTT IM boxed volume is investigated as the number of turns is varied, but for a like-for-like comparison, the final CCTT IM design has the same number of turns and copper cross-sectional area as the 2L baseline design. A 2D finite element analysis (FEA) is used in order to validate and optimize the designs. The 8-kW experimental results are presented that indicate that the CCTT IM option allows for an approximate reduction of 50% in both magnetic mass and boxed volume with respect to the 2L toroid inductors. Critically, this size saving does not come at the expense of reduced efficiency, and the CCTT IM exhibits greater efficiency than the 2L baseline design. The IM does require additional input capacitance compared to the 2L design. The overall $LC$ filter of the IM design, comprising the boost magnetics and input capacitance, is reduced by approximately 20% in volume and 44% in mass compared to the 2L design.