A Control Scheme for Mitigating the Impact of Variations in Device Parameters for Phase-Modulated Converters

In the full-bridge converter, DC-current in the transformer exists due to unequal forward voltage drops in the semiconductor devices. A conventional peak current mode control is used to mitigate this DC-current in duty controlled full-bridge converter. In phase-modulated full-bridge converter, unlike duty controlled converter, conventional peak current control is not viable to mitigate the DC-current. A novel control scheme to mitigate this DC-current is proposed which retains the performance characteristics of the converter. With the proposed control scheme, output regulation and DC-current mitigation are implemented in a decoupled manner, therefore output voltage is unaltered during the process of DC-current mitigation. The impact of variations in on-state resistance of the lagging and leading leg MOSFETs on the DC-current magnitude is analyzed. From the analysis, it is observed that the variation in the on-state resistance of the lagging leg MOSFETs causes larger DC-current compared to leading leg. The simulation and experimental results verifying the proposed control scheme is presented.