Leakage inductance and termination effects in a high-power planar magnetic structure

The leakage inductance of planar magnetic structures designed for high-frequency power electronics applications is a critical performance parameter that significantly effects circuit operation. This paper presents numerical models for a particular high power (100-500 W) transformer designed for low-profile applications. The impact that secondary winding terminations have on the leakage characteristics of the device is examined using a set of laboratory measurements. It is shown that the effective inductance the transformer presents to the circuit can be several times the inductance calculated or measured based on an ideal short-circuited winding. These results point toward some general design guidelines that are useful for minimizing leakage inductance for planar structures