Two-Stage System of CRM PFC Converter and LLC Resonant Converter to Reduce Frequency Interference in Integrated Transformers

Abstract An LLC resonant converter is used with a power factor correction (PFC) converter to receive a stable DC output from an AC power supply. The conventional boost PFC converter has a simple structure, but conduction and switching losses occur and low efficiency can be obtained. The bridgeless b...
Ausführliche Beschreibung

Abstract An LLC resonant converter is used with a power factor correction (PFC) converter to receive a stable DC output from an AC power supply. The conventional boost PFC converter has a simple structure, but conduction and switching losses occur and low efficiency can be obtained. The bridgeless boost PFC converter has a lower number of active elements than a conventional boost PFC converter, and a critical conduction mode (CRM) of the PFC converter is used to reduce the switching loss, thereby achieving high efficiency. The power density and integration are increased by integrating the inductor of the PFC converter and the transformer of the LLC resonant converter into one core, and the switching frequency of each converter is designed according to the influence of the magnetic flux generated in the core. A current sensor is required for the CRM operation mode. However, this study applied a bridgeless boost PFC converter and LLC resonant converter based on digital control without a current sensor. This system was verified through a PSIM simulation and an experiment. Ausführliche Beschreibung