This paper presents a Voltage imbalance issues in series stacking of UCs are addressed by increasing the conversion gain of MMCC. The selection of conversion gain involves balancing UC capacitance, the number of parallel stacks, and cost considerations. The thesis provides detailed guidelines for determining the optimal voltage gain of MMCC, considering these factors. Additionally, a failure mode analysis of the MMCC converter highlights its performance under fault conditions. A comprehensive comparative study of EVs employing Battery Energy Storage Systems (BESS) and hybrid energy storage systems is presented to elucidate the advantages of HESS. Economic feasibility assessments of BESS and HESS underscore the effectiveness of Li-ion battery/UC HESS. The converter topology and energy management control schemes proposed in this thesis are expected to pave the way for novel approaches to hybridizing energy sources for EV applications.