Minimizing Both Leakage Inductance and Winding Capacitance in a 1:1 High-frequency Transformer Using Fully Interleaved and Interposed Winding

It is desirable to reduce the parasitics of a high-frequency transformer to ensure reliable operation of high power isolated converters. However, conventional design approaches don’t provide the necessary degrees of freedom to simultaneously minimize the transformer parasitics, such as leakage inductance and winding capacitances. This objective is achieved in this paper by employing a fully interleaved and interposed winding configuration for a high-frequency high power transformer having unity turns ratio. This helps reducing the adverse effects of transformer parasitics at high dv/dt, such as current ringing, spikes in transformer current during turn on and off, etc. In addition to minimizing both leakage inductance and winding capacitance, the proposed winding method also reduces the eddy current effects at high frequency. This lowers the ac resistance of multilayer windings, thereby reduces the winding loss and improves the transformer efficiency. Benefits of the proposed winding strategy are verified using experimental results derived from 8 kW, 100 kHz transformers built using conventional (axially sandwich continuous winding) and proposed (fully interleaved and interposed winding) schemes.