Nonlinear C_oss-V_DS Profile based ZVS Range Calculation for Dual Active Bridge Converters

Generally, power electronic converters are designed to obtain the highest efficiency at rated power while they are most often operated under partial loading conditions. For dual active bridge converters, the zero-voltage-switching (ZVS) conditions can be impaired under light load situations. While load depending ZVS operation has been introduced by prior-art approaches, the nonlinear characteristic of the output capacitance in a power device is often not considered and its effect on operating boundaries of ZVS is neglected. In this letter, based on practical switching transients, an improved method of calculating the ZVS range is introduced. By taking into account the nonlinearity of output capacitance, the method is developed from a detailed analysis of real switching transients. A 2.5-kW prototype is built, and a comprehensive comparison with prior-art approaches is conducted to validate the accuracy of the proposed method.