Dual-frequency-controlled C-TPTL DC−DC converter for high and wide input voltage applications

Traditional three-level (TL) DC−DC converters are suitable for the power conversion with high-input voltage, but the performance of the converter is difficult to be optimized within a wide-input-voltage range. A combined three-phase TL (C-TPTL) DC−DC converter suitable for high and wide input-voltage applications was investigated, and the topology consists of a TL clamping cell and a three-phase full-bridge (TPFB) sub-converter cell. The TL clamping cell ensures that the voltage stress on switches is half of the input voltage, and the TPFB cell reduces the current rating of switches and the output filter requirement. Meanwhile, the C-TPTL converter can operate in the half-input-voltage mode and full-input-voltage mode by controlling the switching sequence of the TL clamping cell. The relationship between the input and output voltages, and the choice of the boundary between different operation modes were discussed. Also, the loss analysis to achieve the optimal efficiency was included. A 200–600 V input and 48 V–20 A output prototype was fabricated and tested in the lab, and the experimental results can effectively verify the theoretical analysis and the performance of the C-TPTL converter.