A Topology-Reconfigurable LLC Resonant Converter for Wide Output Range Applications

A novel topology-reconfigurable LLC resonant converter for wide output range applications is proposed in this article. In the proposed wide output converter, a reconfigurable topology based on matrix transformer is presented, the primary sides of the matrix transformer are connected in parallel, the connection of the secondary sides can be changed by controlling the selector switch on the secondary side, which are categorized into HV and LV operation mode and suitable for different output levels. The HV operation mode whose secondary rectifiers are connected in series is employed for the high output level, while the LV operation mode whose secondary rectifiers are connected in parallel is employed for the low output level. Consequently, the output range is widened by configuring the connection structure. What's more, the switching frequency range can be reduced. Furthermore, the magnetizing current will be reduced by the parallel connection of the primary sides, and soft-switching operation is realized on all of the switches over the full operation range. Therefore, the proposed converter features a wide output voltage range along with high efficiency. Finally, an experimental prototype with 400 VDC input and 150 VDC/14 A-500 VDC/4.2 A output is fabricated and tested to verify the feasibility and effectiveness of the converter.