Current Self-Balancing Mechanism in ZVS Full-Bridge Converters

Full-bridge converters are widely used in isolated dc-dc conversion and wireless power transfer systems. A full-bridge converter can operate in zero-voltage-switching (ZVS) mode with the assistance of an inductive branch that connects the two switch nodes in parallel with the load. The inductive bra...

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Bibliographic Details
Main Authors: Li, Hongchang, de Rooij, Michael A., Fang, Jingyang, Yang, Haoxin, Tang, Yi
Format: Conference Proceeding
Language:English
Subjects:
Capacitance
Capacitors
Current balancing
dead time
full-bridge converters
Negative feedback
Resistance
Steady-state
Switches
Zero voltage switching
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Summary:Full-bridge converters are widely used in isolated dc-dc conversion and wireless power transfer systems. A full-bridge converter can operate in zero-voltage-switching (ZVS) mode with the assistance of an inductive branch that connects the two switch nodes in parallel with the load. The inductive branch provides a ZVS current and has a very low resistance. A tiny volt-second imbalance between the switch nodes may cause a large current bias on the branch. However, it can be demonstrated experimentally that the current on the branch can be almost self-balanced without any de blocking capacitor or balancing control. This paper quantitatively studies the current self-balancing mechanism and shows that the dead-time switch-node voltage can give a strong negative feedback effect that pushes the current bias toward zero. Experimental verification was carried out on a gallium-nitride device-based converter.
ISSN:2150-6086
DOI:10.23919/ICPE2019-ECCEAsia42246.2019.8797240