Current-Aware Adaptive Dead-Time Control for Extended Zero Voltage Switching in Dual Active Bridge for EV Chargers

Abstract

The acceptance of Electric Vehicles to address sustainable development goals 7,11 and 13 has motivated the necessity for high-efficiency, bidirectional charging units. The Dual Active Bridge (DAB) is the distinguished topology for the charging units because of its capabilities inter alia galvanic isolation, inherent Zero Voltage Switching (ZVS) and bidirectional power flow (V2G). However, traditional fixed dead-time control techniques bring critical trade-offs: satisfactory dead-time protects heavy loads but invariably results in excessive body diode conduction, while fixed dead-time fail to facilitate Zero Voltage Switching at light loads leading to hard-switching losses. This research outlines a comprehensive, current-aware adaptive dead-time control technique that dynamically modulates the dead-time interval grounded on the real-time sensing of the transformer leakage current. By dynamically tuning the blanking interval, the proposed method extends the soft-switching operating range, minimises reverse conduction losses, and mitigates voltage waveform distortion. Validations through MATLAB/Simulink modelling including a 10KW Electric Vehicle (EV) charger model demonstrate up to a 5% efficiency improvement under light to medium loads compared to conventional fixed dead-time techniques.