A ZVS Realization Method for Bidirectional Buck/Boost Converter Based on Current Zero-Crossing Prediction

To implement zero-voltage switching (ZVS) in bidirectional Buck/Boost converters, the critical conduction mode (CRM) is a widely adopted solution. Traditionally, zero-current detection (ZCD) with dedicated detection circuits has been extensively used to achieve CRM. However, these methods suffer from issues such as time delay, complex auxiliary circuits, bulky volume, and increased power loss. To address these issues, this paper proposes a novel method to realize ZVS based on current zero-crossing prediction. An analytical model is established to forecast current zero-crossing point. By employing synchronous rectification (SR) extension on all GaN HEMTs, full-range ZVS can be achieved without the need for a high-speed current sensor or detection signals, resulting in simplified hardware design. Finally, a 200W GaN-based prototype is designed to validate the proposed concept. Full-range ZVS has been realized without current sensor at frequency over 1MHz switching frequency.