Innovative perspectives on energy management strategies for bidirectional DC-DC converters with hybrid storage integration in HEVs

• The review article is primarily dedicated to examining bidirectional DC-DC converters, which are crucial components in HEV energy systems. • The efficient energy transfer and management within HEV systems: Proton Exchange Membrane Fuel Cells and Direct Methanol Fuel Cells (DMFCs) in HEVs are discussed. • The effective energy management systems of electric vehicles (EVs) and a crucial literature gap in research are addressed. • Bidirectional DC-DC converters' potential and significant contribution are highlighted. This review provides a thorough analysis of energy management strategies (EMS) used in bidirectional DC-DC converters for HEVs, focusing primarily on the incorporation of hybrid energy storage systems (HESS) that include fuel cells, such as Direct Methanol Fuel Cells (DMFC) and Proton Exchange Membrane Fuel Cells (PEMFC), lithium-ion batteries, and ultra capacitors. Several converter topologies and sophisticated EMS techniques, including optimization-based algorithms, fuzzy logic control, model predictive control (MPC), and equivalent consumption minimization strategy (ECMS), are assessed in this work. These strategies are assessed for their capabilities in delivering effective power exchange, voltage regulation, and real-time responsiveness. The aim is to critically analyze how these methodologies contribute to improved energy efficiency, enhanced system stability, and optimal control in dynamic driving conditions. The paper presents a critical comparison of these strategies based on control complexity, energy efficiency, scalability, and implementation feasibility in real-world HEV applications. Key technical challenges, including energy balancing, harmonics mitigation, interface standardization, and thermal management, are also addressed. By evaluating the strengths and limitations of current methodologies, this review aims to guide the design of robust and intelligent EMS frameworks. The study concludes by identifying research gaps and future directions to support the development of sustainable, reliable, and intelligent electric mobility systems.