Research on Asymmetric Modulation Scheme with Minimum RMS Inductor Current Stress

Dual active bridge (DAB) has become a popular interface circuit between energy storage systems and the DC bus because of its advantages of bidirectional transmission, wide voltage adjustability, and simple modulation scheme. To reduce the power loss, lower current stress and a wider soft switching area need to be realized. Under the condition of light load or high voltage gain, the traditional modulation method can’t guarantee the wider soft switching area while optimizing the current stress. To solve this problem, on the one hand, this paper uses an asymmetric modulation (AM) method, which combines phase-shift modulation with asymmetrical duty modulation on the primary side to strike a balance between high efficiency and low control complexity. On the other hand, the root-mean-square (RMS) current stress is selected as the optimization target and optimized by the fmincon function in MATLAB. Compared with the existing work, the optimization method has better effect. Finally, the effectiveness of the modulation Scheme is verified on a DAB prototype.