Multi-phase series resonant DC to-DC converters

DC-to-DC converters are applied in may different applications. This work focuses on a class of DC-to-DC converters which are characterized by a fixed input-to-output voltage ratio, a galvanic isolation between input and output side and an output power larger than approximately one kilowatt. This class of DC-to-DC converters is called multi-phase series resonant DC-to-DC converters (SRCM). The SRCM comprises a multi-phase input converter, a series-resonant link consisting of transformers and resonant capacitors and an output diode rectifier. The multi-phase series resonant DC-to-DC converter offers many advantages. The low number of components keep the costs low. Additionally, zero voltage and near zero current switching (ZVS-NZCS) of the electronic switches guarantees a high efficiency and a high reliability. Furthermore, the power density is high, because the passive components, such as the input capacitor, the resonant capacitors, the transformers and the output capacitors, can be designed smaller, due to the resonant behavior and the multiphase operation. This work describes and investigates multi-phase series resonant DC-to-DC converters. Design rules for the components are derived for stationary and for transient operation. The obtained analytical models are verified with experiments taken from a three-phase series resonant DC-to-DC converter (SRC3).