Clamp mode forward ZVS-MRC with self-driven synchronous rectifier

The clamped-mode (CM) forward zero-voltage-switching multi-resonant power converter (ZVS-MRC) with a self-driven synchronous rectifier is studied. The loss at the synchronous rectification stage of the power converter is analyzed and compared with the loss at the conventional Schottky diode rectification stage of the power converter. From the results of the analysis, it is known that the use of MOSFETs as a synchronous rectifier effectively reduces the loss at the rectification stage over the whole load range. In order to verify the validity of the analysis, the authors have built a 33 W (3.3 V/10 A) CM forward ZVS-MRC with a self-driven synchronous rectifier, with a switching frequency of 1 MHz, and tested its performance. From these experimental results, synchronous rectification achieved about a 3 W improvement in losses at the rectification stage and about 3% in the efficiency of the power converter as compared with conventional Schottky diode rectification.