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

In this paper, a proposed pulse width modulation (PWM) control method for the isolated current-mode resonant DC-DC converter with MHz level switching frequency is presented. The circuit topology is same as a conventional resonant converter with synchronous rectification and without any additional components. The control technique for the output voltage regulation is proposed with the unique PWM control for synchronously-rectifying switches. By using the transformer´s leakage inductance and the PWM control, the boost conversion can be realized. In addition, to achieve the zero-voltage switching (ZVS) operation, phase-shift between primary and secondary-side switches is adapted. The ZVS operation can maintain for primary-side switches. In this paper, proposed technique for achieving stable ZVS operation has been discussed. Some experiments have been done with 5MHz isolated DC-DC converter which has Gallium Nitride field effect transistor (GaN-FET), and the total volume of the circuit is 16.14cm³. The data show that the maximum power efficiency is 89.4%.