Sensorless phase shift control for phase shifted DC-DC converters for eliminating DC transients from transformer winding currents

The paper presents a two phase shift control strategy for Dual Active Bridge(DAB) and Triple Active Bridge(TAB) converter to eliminate the dc transients from the high frequency transformer winding currents during operating phase angle change from one cycle to the next cycle. The proposed two phase shift method controls the alternating nature of high frequency current in transformer windings in one switching cycle without using any high frequency current sensor. The proposed control strategy applies two different phase shift angles during positive and negative half cycles in order to eliminate the dc transients from transformer winding currents during steady state phase angle change. The control strategy is analyzed and applied for power flow direction reversal of Dual Active Bridge Converter and for changing power flow mode from three port scenario to two port scenario in case of Triple Active Bridge converter. The proposed control strategy study has been verified by performing experimental study on a hardware prototype.