Design optimization for ultrahigh efficiency buck regulator using wide bandgap devices

This paper discloses the design optimization for 99.5% plus ultrahigh efficiency buck regulator. Rather than using silicon devices, the switching losses can be dramatically reduced by properly selected wide bandgap devices such as gallium nitride (GaN) high-electron-mobility transistor (HEMT) and silicon carbide (SiC) Schottky diode. A 100-kHz switching four-phase interleaved inverse buck converter with 400-V input dc, 370-V output dc, and 2-kW rated output power was built to verify the design. Besides using wide-band-gap devices, the interleaved technique for reducing the input and output current ripples and inverse-coupled inductors are adopted to further reduce the input and output capacitors' ESR power losses and inductor core losses, respectively. From the experimental results, the efficiencies are above 98.5% at 10% load and over 99.5% from 50% to full load.