DC-Bias Reduction in High-Frequency Dual Active Bridge DC-DC Converters through Slow DC Measurements

Abstract:
This paper addresses the issue of DC bias in high-frequency Dual Active Bridge DC/DC converters. A new method to identify and reduce the DC bias by measuring only the DC-link voltage at each switching event is proposed. Experimental results confirm that the DC bias causes DC-link voltage ripple between both switching events during one period. This ripple is extracted by an analog circuit that allows a slow DC measurement as possible with many uC-interpreted ADCs. This DC value corresponds to the DC bias and can be eliminated by controlling the Dual Active Bridge with duty cycle control in addition to the phase shift control.