Power Management Unit With Its Control for a Three-Phase Fuel Cell Power System Without Large Electrolytic Capacitors

This paper investigates a three-phase four-wire fuel cell power system. The system is sensitive to the load characteristic in a stand-alone mode, because variation or unbalance of the three-phase load will affect the safety and lifespan of the fuel cell. A novel power management unit (PMU) with its control strategy is proposed. The PMU can compensate fuel cell slow dynamics. In addition, the PMU acts as dc bus capacitors to deal with the low-frequency current ripple. Therefore, the large dc bus electrolytic capacitors can be eliminated in the fuel cell power system. The control strategy of the PMU is derived and the whole system is verified by the experimental results.