To overcome the delayed dynamic response of fuel cell (FC), generally battery and ultracapacitor (UC) are preferred to be integrated in a fuel cell electric vehicle (FCEV) powertrain. However, to achieve improved power diversification among multiple energy sources of contrasting power & energy characteristics, independent regulation of each energy source becomes challenging. Aiming at this, an ultra flexible quad-port converter (UFQC), comprising of three input ports and one output port is proposed in this work. The proposed UFQC is capable of providing high flexibility in dynamic power flow management among the three energy sources, catering to diverse range of load power events encountered in a FCEV. Moreover, the UFQC exhibits the feature of charging both battery and UC from the FC and charging of UC from battery. Furthermore, the converter ensures single stage power processing across all power flow scenarios with the ability of simultaneous power transfer between multiple ports. All these features are attained by utilizing only two inductors and three high frequency switches, resulting in judicious utilization of magnetics with simplified gate driving. The flexible operation of UFQC across dynamic power flow scenarios is validated through simulation and preliminary experimentation performed in a laboratory scale hardware prototype.