Optimal idling control strategy for three-port full-bridge converter

Multi-port converters (MPCs) are the prospective alternative in the hybrid power system, which can simplify the system structure and reduce the cost. In some operation conditions, one port may quit from the system, leaving this idling port at zero power. Under the exclusive operation, different control strategies can be used. Based on the analysis of the soft-switching ranges and the conduction losses, this paper proposed an optimal idling control strategy that combines the phase-shift control with the PWM control. In order to ensure the conduction losses be minimum, the duty cycle of the idling port is regulated in real time referring to the voltage of the port and the total output power. As an additional benefit, the converter can operate under a wide soft-switching range. Finally, a 1kW prototype converter has been built to verify the theoretical analysis.