Analysis of Voltage Equalization Control Capability of Three-level DC/DC Converter

Three-level DC/DC converter can reduce the harmonic content of output voltage, improve the ability to carry unbalanced load, reduce the voltage stress at both ends of the switching tube, reduce the volume of passive devices, and can realize soft-switching technology to meet the needs of high-power conversion. Therefore, it has a wide range of application in the field of power electronics such as electric vehicles, renewable energy systems, and power adapters. In order to play the advantages of the topology, effectively reduce the voltage stress at both ends of the switch tube and extend the service life of the device, three-level DC/DC converter needs to carry out voltage equalizing control on the upper and lower bus capacitors to maintain the stable potential of the midpoint of the bus. In this paper, the mechanism of the traditional voltage balancing control strategy is analyzed from the perspective of modulation, the relationship between voltage balancing capacity and circuit parameters is established, the relationship between load unbalance degree and circuit parameters and circuit input and output is calculated, and a simulation model is built to verify the relationship.