###### Abstract  
Rising greenhouse gas emissions stemming from fossil fuel-driven vehicles are causing damage to the environment. To counteract this, one solution is the adoption of electric vehicles (EV) for transportation requirements. In this regard, one category of EVs that requires special attention is light electric vehicle (LEV), mainly because of their wide potential in public transportation--especially in developing countries. To realise widespread adoption of LEVs for this purpose, it is imperative to make their charging systems more robust. Consequently, the subject of LEV charging has gained considerable traction, and numerous research works have been reported on this subject in recent years. Hence, this paper aims to chronicle recent research developments on LEV charging techniques, by placing special attention on DC-DC converter topologies used in both on-board and off-board chargers. This review explores recent LEV charger DC-DC converters in literature by segregating them into isolated and non-isolated topologies. Lastly, this work explores challenges and emerging trends in LEV charging, which can potentially be explored by researchers in the future. light electric vehicle; DC-DC converter; on-board charger; off-board charger; isolated converter; non-isolated converter +
Footnote †: journal: selected  
To cope with the increasing number of LEVs, it is imperative to make their charging system more robust and widespread. A partial list of commercially available LEVs is given in Table 1[5; 6; 7; 8; 9; 10]. It can be seen from this table that most LEVs have battery ratings in the range of 48 to 72 V and have capacities ranging up to 180 Ah. Hence, LEV charging requirements are simple compared to other EVs, with most requiring a simple connection to residential AC supply. Hence, LEV charging requirements are simple compared to other EVs. Another key takeaway from this table is that the average normal charging time of the given vehicles is in the range of 3-5 h, with only a few supporting fast charging. Hence, availability of fast charging should be a point of priority for two/three-wheeler EV manufacturers. Figure 1: Electric vehicle sales trend in various regions. (**a**) Growth from 2019 to 2021 (**b**) Projected sales by 2030 [1]. While recent literature has tangentially reviewed LEV charging aspects [3; 11], there is still a deficiency of review papers that are dedicated to LEV charging. Whereas DC-DC converter topologies for EV charging have been covered in depth elsewhere in literature [12; 13], works detailing a summary of DC-DC converters are lacking for LEVs. This paper aims to fill this deficiency by reviewing recent trends in DC-DC converters used for LEV charging--highlighting salient features and areas of improvement of each. Furthermore, this paper addresses recent issues with respect to LEV charging and possible future research directions. The main contributions of this paper are summed up as shown:  
* This paper fills the gap in research by reviewing recent works on DC-DC converter topologies used for LEV charging--critiquing each implementation. Finally, areas of improvement and future research objectives are suggested in this regard. * Furthermore, this paper also describes recent issues and potential future areas of research in LEV charging. This intends to encourage researchers to take up research which will aim to address these issues and open up research avenues. Such a review is necessary as it provides perspective on the current standing of research on power electronics for LEV charging applications. Understanding this perspective is necessary to identify gaps and issues that can provide hindrance to the expansion of LEV usage. Considering that LEVs are an attractive, cost-effective choice for public mobility, such hindrances must be well-understood and be kept at a minimum. The subsequent paper is set up in the following manner: Section 2 deals with basic concepts in LEV charging. Section 3 lays out the methodology of review.