The transportation industry is experiencing a switch towards electrification. Availability of electric vehicle (EV) charging infrastructure is very critical for broader acceptance of EVs. The increasing use of OBCs, due to their cost-effectiveness and ease of installation, necessitates addressing key challenges. These include achieving high efficiency and power density to overcome space limitations and reduce charging times. Additionally, the growing interest in bidirectional power flow, allowing EVs to supply power back to the grid, highlights the importance of innovative OBC solutions. This review article provides a thorough analysis of the current advancements, challenges, and prospects in EV on-board charger technology. It aims to offer a comprehensive review of OBC architectures, components, technologies, and emerging trends, guiding future research and development. Addressing these challenges is essential to enhance the efficiency, reliability, and integration of OBCs within the broader EV ecosystem.
The global transition towards a sustainable and carbon-neutral future highlights the critical role of electric vehicles (EVs) in mitigating climate change and reducing greenhouse gas emissions. Policy initiatives such as the European Green Deal, which aims for net-zero carbon emissions by 2050, and India’s commitment at the 26th climate change conference to achieving net-zero emissions by 2070 highlight the urgency of this transition. This shift is driven by environmental regulations, advancements in battery technology, and innovative propulsion systems, leading to an increasing preference for EVs over traditional internal combustion engine (ICE) vehicles. This statement is supported by the reports, according to which 14% of all car sales in 2022 were electric vehicles, almost 9% more than sales in 2021.
We can broadly classify EVs as into the following categories: Battery electric vehicles (BEVs) consist of a battery powered electric motor. For charging purpose, BEVs need to be plugged into a wall outlet. Plug-in Hybrid Electric Vehicles (PHEVs) consist of an electric motor and an ICE powered by a battery and some fuel respectively. PHEVs are either charged from an outlet or make use of regenerative braking. Hybrid Electric Vehicles (HEVs) make use of an ICE along with one or more electric motors. The ICE and regenerative braking are used for charging purposes. Fuel Cell Electric Vehicles (FCEVs) use fuel cell technology to produce the electricity. They employ a propulsion system which converts hydrogen energy into electrical power. The primary subject of this study is battery electric vehicles (BEVs).
Even though conventional ICE vehicles have been dominant in transportation, they still pose significant environmental threats and face many technological problems. They have a major impact on greenhouse gas emissions and air pollution. Additionally, only 20–30% of the fuel energy in ICEs is converted into productive work. This low efficiency results in higher fuel consumption and increases operational costs. The mechanical complexity of ICE vehicles, with numerous moving parts, also leads to higher maintenance requirements and costs. Components such as exhaust systems, fuel injectors, and oil filters need regular servicing and replacement, adding to the overall cost of ownership. The reliance on fossil fuels further exacerbates the problems associated with ICE vehicles. Fluctuations in fuel prices, geopolitical tensions, and the finite nature of fossil fuel reserves create economic and energy security concerns. The extraction, transportation, and refining of fossil fuels also have significant environmental footprints, contributing to habitat destruction, oil spills, and water contamination.
In contrast, EVs offer a promising solution to these challenges. They produce zero tailpipe emissions, drastically reducing air pollution and greenhouse gas emissions. In Figure 1, a comparison of emissions from the use of different fuel sources is shown. From the manufacturing to the time an EV starts to run, the process is environmentally friendly. Electric drivetrains are significantly more efficient than internal combustion engines, converting a higher percentage of stored energy into motion, which translates to lower operational costs. Figure 1 gives us an idea about cost savings while using different fuels for same vehicle. From Figure 1, it can be inferred that for same vehicle among various fuels (gasoline, ethanol-85, diesel, LPG, and electricity), the maximum savings are experienced by using electricity. For the interpretation of the graph in Figure 1, we consider gasoline as fuel that results in maximum cost per kilometer. The cost-saving percentages mentioned for all other fuels are calculated in comparison to gasoline. The simpler mechanical design of EVs, with fewer moving parts, reduces maintenance needs and enhances reliability. The natural wear and tear due to vibrations and gasoline corrosion is absent in electric vehicles. As a result, there are fewer cases of breakdowns. Furthermore, the use of renewable energy sources for electricity generation can further minimize the environmental impact of EVs.
This interpretation is based on an approximation because the cost of various fuels can vary over time, as taxes and subsidies come into play. Therefore, for any cost-related comparison, we need to be extremely careful. The graph here gives us an idea about more effective technology in terms of cost only.
Despite these advantages, the widespread adoption of EVs faces several challenges. There are certain areas in the case of EVs that need improvement. The limited range of EVs, determined by the energy density of current battery technologies, remains a significant concern for consumers. A worldwide statistics report showed that the range of EVs has seen growth in the last 5–6 years. Although advancements have been made, such as the Tesla Model S achieving a range of up to 630 km, anxiety persists. The development of fast and accessible charging infrastructure is another critical area, as long charging times compared to the quick refueling of ICE vehicles hinder convenience. Range anxiety among drivers forces many to select a vehicle with higher battery capacity (in terms of kWh). Additionally, the high cost of lithium-ion batteries, driven by the need for large capacity to ensure adequate range, poses an economic barrier. Battery weight and thermal management are also critical issues. The substantial weight of batteries impacts vehicle efficiency and performance, while effective thermal management systems are essential to maintain battery health and safety, particularly under extreme conditions. Addressing these technical and infrastructural challenges is imperative for the broader acceptance of EVs.
One of the most critical components in EVs that requires significant attention is the on-board charger (OBC). The OBC is responsible for converting alternating current (AC) from the grid into direct current (DC) to charge the vehicle’s battery. The efficiency and performance of OBCs are vital as they directly impact the charging time, energy efficiency, and overall user experience. The increasing demand for high-efficiency and high-power-density OBCs presents several technical challenges. These include managing heat dissipation, reducing size and weight, and ensuring reliable operation under various environmental conditions. The limitations of current OBC technology can result in longer charging times, reduced energy efficiency, and higher costs, which in turn affect consumer acceptance and the practicality of EVs. The complexity of OBC design also poses significant challenges. High-power OBCs must handle substantial amounts of energy conversion while maintaining efficiency and safety. This requires advanced power electronics, thermal management solutions, and sophisticated control algorithms. Any failure in the OBC can lead to catastrophic consequences, including potential damage to an EV’s battery and overall vehicle malfunction. Therefore, improving OBC technology is crucial for the safe, efficient, and reliable operation of EVs.
Research and development efforts are focused on overcoming these barriers by advancing battery technology, improving energy efficiency, and developing intelligent thermal management systems. Innovations in high-power converters and control strategies aim to reduce charging times and enhance the reliability of EV charging systems. The integration of renewable energy sources with EV charging infrastructure is also being explored to maximize environmental benefits. Addressing the challenges of OBCs is particularly crucial, as advancements in this area will directly influence the overall performance, cost, and consumer acceptance of EVs.
In summary, while EVs present significant advantages over conventional ICE vehicles, addressing existing challenges, particularly in OBC technology, is crucial for their widespread adoption. Considering these requirements, this research focuses on innovations that are essential to realizing the full potential of EVs in achieving a sustainable and carbon-neutral transportation future. The article emphasizes current technologies and trends being researched, with a particular focus on improving OBCs, which will play a pivotal role in ensuring efficient energy conversion, reducing charging times, and enhancing the overall reliability and safety of EVs.
The major contributions of this literature are as follows:
The subsequent sections of the paper are organized as follows: Section 2 provides an overview of charging technologies of electric vehicles, which includes the different charging levels and charging methods available to us. Section 3 presents an analysis of all the relevant EV standards which comprise the safety, grid integration, and EV charging standards. In Section 4, the design considerations for OBCs and the targeted performance parameters are discussed. In Section 5, a summary of the present-day EV market is provided, with a detailed overview of the state-of-the-art OBCs. In Section 6, a summary of the present-day EV market is provided, with a detailed overview of the state-of-the-art OBCs.
