A Combined DC-DC Converter Suitable for Wide Output Voltage Range

This paper proposes a three level DC/DC converter for wide output voltage range. The converter consist of two parallel main bridge arm and auxiliary bridge arm, and a main transformer and an auxiliary transformer connected in cascade. The converter has two operation modes: low voltage mode and high voltage mode. The auxiliary bridge turned-off to reduce the converter loss at low voltage mode and turned-on to improve the output voltage at high voltage mode. Compared with the conventional converter, the main transformer of the proposed has a lower turn ratio. This paper analyzes the loss of conventional converter, comparing the efficiency between proposed converter and conventional converter at different output voltage modes, and concluding that the proposed converter is more efficient at low voltage mode. A prototype of 2000W is built. The experimental data show that the proposed converter efficiency can still be 94% at low voltage mode, is with 3% higher efficiency than that of the conventional converter, verifying the correctness of the theoretical analysis.