Interleaved LLC half bridge series resonant converter with integrated transformer
ABSTRACT High efficiency and simple structure are the main reasons for the widespread use of LLC converters. Nowadays, the application of LLC converters is still in development. In general, increasing the power level to use a parallel converter is quite popular. However, this method uses a separate transformer, which will lead to an obvious decrease in power density. Moreover, the separate transformer will also cause current imbalance due to the error of the magnetic material characteristic. Therefore, this study proposes an integrated transformer for a conventional interleaved LLC converter. This proposed structure can effectively increase the power density and decrease the problem of current imbalance. The operating principle of the interleaved LLC converter and an analysis of the integrated transformer are presented. Finally, experimental results are recorded for a prototype converter. The specifications are as follows: DC input voltage is 380 VDC, output voltage is 12 VDC, maximum output current is 50 A, output power is 600 W, and maximum conversion efficiency is approximately 95.5%