Novel analysis of the influence of tolerances in geometry and material on the equivalent circuit of a LLC transformer

Abstract:
Magnetic and electrical components always have unavoidable tolerances that must be taken into account when designing power converters. The data sheets of transformer cores, bobbins and magnetic materials give tolerances in geometry and material parameters. This paper investigates the influence of these tolerances on the equivalent circuit of a two-winding transformer. The magnetic field calculations are performed with the numerical field calculation method of boundary elements. The knowledge of possible deviations is crucial for the design of resonant converters such as the LLC-converter using integrated magnetics.