## 7 Challenges and Future Perspectives  
Numerous technical, economic, and other challenges must be overcome in order to make _DC-DC_ and _DC-AC_ converters popular and successful in a variety of applications. In this section, the challenges that may face some of the mentioned converters in terms of configuration and design are discussed. * The _DAB-IBDCs_ is one of the types of bidirectional converters, as mentioned above, and due to the advantages of _DAB-IBDCs_, such as the ease of implementation of soft switching, bidirectional power transfer capabilities, modular and symmetric structure, and so on, they have garnered increasing attention in recent years. Numerous studies conducted globally so far have concentrated on fundamental characterization, topology and soft-switching solutions, control strategies, and hardware design and optimization. The design and performance optimization of _DAB-IBDCs_ based on silicon carbide and gallium nitride _SiC/GaN_ power devices, as well as system-level _DAB-IBDCs_ solutions for high-frequency link (_HFL_) power conversion systems, will be the trend in the future, with other major concerns including: (1) Electrical optimization design methods of the topology, electrical parameters, and control approach of _DAB-IBDCs_ based on _SiC/GaN_ power devices in order to fully exploit their high-temperature, high-frequency, and low-loss properties. (2) Mechanical optimization design methods of _DAB-IBDCs_ based on _SiC/GaN_ power devices in order to further increase the efficiency, power density, modularity, and reliability of _HFL_ power conversion systems. (3) Multipurpose, modular, and intelligent _HFL_ power conversion system solutions with high efficiency and high power density, which utilize _DAB-IBDCs_ as the core circuit [172]. * Today's power converters must deliver increased power while maintaining high efficiency over a wide load range. As a result of the zero voltage switching (_ZVS_) for the primary side's _MOSFETs_ or _IGBTs_ and zero current switching (_ZCS_) for the secondary side's power devices, the _LLC_ resonant is a type of resonant converter topology that can address these challenges and is advantageous in front-end _DC-DC_ conversion applications. Additionally, it has a narrow switching frequency range to facilitate control, a quick transient response, and low cost because the leakage inductance of the transformer serves as the resonant inductor [173]. * The series resonant converter has become attractive for switched-mode power supply, not just because running at a high switching frequency increases power density, but also because of the decreased switching losses. In addition to its historical and technological significance, the resonant converter series has created a large family of high-density _DC/DC_ mode resonant converters, all of which have been widely used in several practical applications [174]. In the last few years, the growing interest in resonant power converters suggests more potential exploration of these converters. Although resonant converters have some superior features compared to conventional converters, studies have identified some issues that must be addressed to carry on [16]. To address the challenges facing the resonance part regardless of its type and structure, the assigned and selected parameters must be considered. The voltage gain, frequency ratio, load values, and inductance ratio must be understood. Finally, future studies should focus on the optimization of the control of such topologies. * Power flow. One-directional power flow can be handled with a traditional buck-boost converter, but the power flow in bidirectional converters is in both directions. With bidirectional _DC-DC_ converters, voltage levels can be either stepped up or down based on the flow control capacity in either direction. According to galvanic isolation, there are two types of bidirectional converter: the first is the isolated bidirectional converter, and the second is the empty of isolation or non-isolated converter [175; 176; 177; 35].