A 30Mhz Isolated Push-Pull Resonant Converter

Abstract

An isolated Push-Pull (PP) resonant converter suitable for Very High Frequency (VHF, 30-300 MHz) power conversion is proposed in this paper. The primary side of the converter is a PP topology derived from the Class EF2 inverter. The secondary side is a Class E based low dv/dt full-wave rectifier. The important thing is that when the isolation is realized, more applications requiring isolation can be well matched to the VHF converters. Moreover, the turns ratio provides more design flexibility to wide input and voltage range. The challenge of the gate driver is to provide two complementary drive signals precisely and minimize the gate drive loss at VHF. Therefore, a new dual-channel RGD is proposed to reduce VHF gate drive loss. Other features of the proposed converter include: 1) the power MOSFETs are under ZVS condition and the rectifier diodes are under ZCS condition for high efficiency; 2) the voltage stress of the MOSFET is much reduced compared to topologies such as Class E; 3) the parasitic inductance and capacitance can be absorbed and fully utilized. The commercial available Si power MOSFETs are used in the hardware implementation for low cost and the hysteresis control is applied to ensure the fast dynamic response taking advantage of VHF. A 36 V input, 50 W/ 24 V output, For Peer Review 30 MHz prototype was built to verify the advantages of the proposed converter.