Decoupled EPS Control Utilizing Magnetizing Current to Achieve Full Load Range ZVS for Dual Active Bridge Converters

A decoupled extended phase shift (EPS) control is proposed to decrease the control complexity and achieve full load range zero-voltage-switching (ZVS) for dual active bridge (DAB) dc-dc converters. In the proposed solution, full load range ZVS is achieved by adding an extra small fixed duty cycle and utilizing the magnetizing current. In addition, the two control variables are decoupled, since the control of the duty cycle is only determined by the voltage conversion ratio and is independent of the phase shift angle, which avoids the detection of operation mode and switching of control laws. The ZVS model considering junction capacitors and magnetizing inductance, ZVS region under full load range, and derivation of control law are analyzed in detail. Finally, the effectiveness of the proposed solution is experimentally verified on a 500W, 250kHz GaN-Based prototype.