To improve the dynamic response of a polymer electrolyte membrane fuel cell (PEMFC), generally battery is preferred to be integrated in a fuel cell hybrid electric vehicle (FCHEV) powertrain. However, the wide terminal voltage of a PEMFC necessitates the use of a DC-DC converter with both step up (boost) and step down (buck) capability to regulate the power flow into the DC bus of a FCHEV powertrain. Aiming at this, a cascaded boost-buck converter (CBBC) with reduced capacitor rating having the ability to handle wide variations of PEMFC voltage is proposed in this work. Further, a modified modulation scheme is proposed, wherein anti-symmetrical carrier signals are provided for boost and buck stages of CBBC. This eventually facilitates in reduction of the RMS value of capacitor ripple current thereby minimizing the size of link capacitor. Analysis of direct and indirect energy transfer between the cascaded boost and buck stages is also carried out to evaluate the performance of modified modulation scheme in comparison with conventional modulation scheme. Furthermore, steady state analysis of CBBC in conjunction with modified modulation scheme is performed through simulation in MATLAB/Simulink platform and also through experimentation in a 5 kW laboratory scale hardware prototype.