Voltage Distribution in the Windings of Medium-Frequency Transformers Operated With Wide Bandgap Devices

The short rise time observed in the PWM voltages generated by ultrafast wide bandgap devices increases amplitude of voltage harmonics at higher frequencies. These can excite resonances medium-frequency transformers (MFTs), resulting overvoltages inside windings during continuous operation. Without further measures, these lead to unexpectedly high electric fields insulation material, which result partial discharge, accelerated aging, and possible failure MFT. To avoid effects, mechanism causing has be understood quantified design process. Based on this, MFT designed a way that vanish or are tolerable. Therefore, distribution is analyzed fully coupled multiconductor transmission line model, includes damping effect electromagnetic losses litz wire core. This method verified measuring transfer functions ground individual turns their waveforms indicate repeating windings. A guideline for verification simplified approach speed-up modeling process presented.