2. Unified Boundary Trapezoidal Modulation Control for Dual Active Bridge DC–DC Converter

The unified boundary trapezoidal modulation (TZM) control utilizing fixed duty cycle compensation and magnetizing current design for dual active bridge DC–DC converter is proposed in this chapter. The fixed duty cycle compensation and magnetizing current design are firstly introduced to achieve the zero-voltage switching (ZVS) of the power switches, which cannot be ensured with the conventional TZM control. As a result, all the power switches of dual active bridge DC–DC converter can achieve ZVS and four switches can be turned off with very low current. Besides, based on the revealed power transfer characteristic, the power control variables including the duty cycles and phase shift ratio can be unified without look-up tables or operation region division. With the proposed boundary TZM control, circulating current losses can be reduced and non-active power is significantly suppressed according to the mathematic analysis, resulting in decrease of the conduction loss. A 1.6 kW laboratory prototype is built to verify the theoretical analysis and effectiveness of the proposed control.