5MHz PWM-controlled current-mode resonant DC-DC converter using GaN-FETs

In this paper, the method of the realization of a MHz level switching frequency DC-DC converter for high power-density is presented. For high power-density, Gallium Nitride field effect transistor (GaN-FET) and current-mode resonant DC-DC converter are adopted. In addition, the proposed pulse width modulation (PWM) control method which is suitable for the isolated current-mode resonant DC-DC converter operated at MHz level switching frequency, and the novel primary-side zero voltage switching (ZVS) turn on method for the proposed PWM control are presented. Some experiments have been done with 5 MHz isolated DC-DC converter which has GaN-FET, and the total volume of the circuit is 16.14 cm³. With the proposed PWM control method, input voltage range is 36-44 V, and maximum load current range is 8 A at V_i = 44 V. The primary-side ZVS turn on is confirmed, and the maximum power-efficiency is 89.4%.