5. Blocking-Cap-Based DAB Converters

Blocking-cap-based dual active bridge (DAB) converter with wide voltage conversion gain is studied in this chapter. The DC blocking capacitor, which is used for avoiding the DC flux bias in the transformer of conventional DAB converter, is utilized to achieve better performance under wide voltage gain range. By changing PWM generating method under different voltage input, the converter can work in half-bridge and full-bridge mode correspondingly with presented hybrid control. To simplify the PWM generating method, the duty cycles of primary and secondary bridges are fixed as 50%. The power transfer characteristics, ZVS region, and RMS current are analyzed and are compared with the DAB converter using single-phase shift (SPS) control. The theoretical analysis and conclusion of the converter with the hybrid control are verified by experimental results from a 1 kW prototype.