Abstract Due to the rapid development in modern power industrial applications such as renewable energy, photovoltaic, laptop adapters and electric vehicles, DC/DC resonant converters have gained the attention of many researchers. The rise of the potential of this industry has since led to a plethora of studies on resonant converter topologies with the aim to enhance the features of soft switching, high power density, smooth waveforms and high efficiency. The efficiency of these converters has been proven, thus are undoubtedly favored over hard switching conventional converters because of their ability to both work at high frequency and reduce switching losses. Researches are still being continued to significantly reduce the cost and number of components, besides improving areas such as high power density, high efficiency, wide load variations, and reliability. This paper presents the principles of resonant power converters (RPCs) and their classifications based on their DC-DC converter family, and ability to achieve soft switching. Several recent research trends have focused on the development of their constructions, operational principles, merits and demerits. The study of different resonant DC–DC converter topologies suggests that there is no single topology which can achieve all requirements. Therefore, further research is required to produce a power circuit that can eliminate the addressed limitations as many as possible.