Dual Active Bridge DC-DC Converter with Symmetric Bipolar Output

The bipolar DC grid has a slight advantage over unipolar DC grids due to its multiple voltage levels and higher system efficiency. Unbalanced pole voltages resulting from uneven load distribution in the poles are the primary disadvantage of DC bipolar grid operation. However, this voltage level can be stabilized by a voltage balancer circuit. Blending a DC-DC converter with a voltage balancer circuit makes the system more complex. It is very crucial if the DC-DC converter can self regulate the bipolar voltage levels. A DC-DC converter based on Dual Active Bridges (DABs) that can self-regulate the pole voltages under various load scenarios is demonstrated in this work. In the DAB system, two full bridge converters are utilized for this purpose. In DAB, the power transmission is managed using a straightforward phase shift modulated switching mechanism. By sensing the voltage and current at the pole terminals, the programmable logic devices are used to create the phase-shifted gate pulses for the full bridge converters.