Calculation of Dead Time in Full-Bridge Converters Considering MOSFET Parasitic Capacitance

Currently, the calculation of dead time in a full-bridge Class-D zero-voltage switching (ZVS) converter is mainly based on the snubber capacitance structure connected in parallel with the fixed capacitance switching devices. There are few analyzes for calculating the dead time for Class-D full-bridge converters using the parasitic capacitance of the switching devices as the snubber capacitance. Under high-frequency operating conditions, too short or too long a dead time can cause the Class-D full-bridge converter to lose ZVS, resulting in significant power loss or even damage to the device. Therefore, this paper analyzes the operation of a Class-D full-bridge converter using the parasitic capacitance of the switching devices as the snubber capacitance, and calculates a suitable dead time. Then, a prototype 4 MHz Class-D full-bridge converter based on silicon carbide devices is developed, and the experimental results show that setting the dead time according to the calculation method proposed in this paper ensures the operation of the prototype under ZVS conditions.