Loss reduction of laminated core inductor used in on-board charger for EVs

Abstract

A laminated core has advantages such as low iron loss, high permeability, and high saturation flux density. For inductor applications, an air gap has to be inserted into the magnetic circuit to avoid saturation at lower magnetic field strengths. However, when an air gap is inserted, fringing flux leaks out of the air gap and concentrates on the surface of the core. As a result, the iron loss increases to 292% as compared with an ungapped core, and the inductance characteristic deteriorates. Although a core with chamfered edges is known as a prior art that reduces the iron loss to 147%, there is scope for improvement. In this paper, we propose a core with curved edges for loss reduction of the laminated core inductor. Consequently, the proposed shape reduces the iron loss to 113% and improves the inductance characteristic. Thus, the proposed method increases the efficiency and reduces the size of the on-board charger.