# A Comprehensive Review of Developments in Electric Vehicles Fast Charging Technology
## 2 Fast Charging Techniques for Electric Vehicles
### Inductive Charging  
Inductive charging, known as wireless charging, eliminates the need for physical cables by transmitting energy through an electromagnetic field between a charging pad on the ground and a receiver on the electric vehicle [44]. While not as fast as some wired fast charging methods, wireless charging offers convenience, allowing drivers to park over a charging pad for automatic charging without connecting any cables [44]. [PERSON]'s experiment in 1910 at the Wardenclyffe Tower laid the groundwork for wireless power transfer (WPT) [45; 46]; smart cities with e-mobility mainly utilize WPT [47], employing methods like inductive power transfer (IPT) and capacitive power transfer (CPT). Improving IPT efficiency involves optimizing coil design, ensuring coil alignment, selecting appropriate batteries and charging standards, and using electromagnetic field shielding [45; 47; 48; 49]. Advanced optimization techniques and control strategies, such as adjusting charging frequency and monitoring alignment, enhance power transfer efficiency and safety. Inductive charging offers a convenient alternative to traditional plug-in charging methods, simplifying the connection process significantly. However, it is essential to consider potential safety risks, such as the possibility of foreign object hazards. While moderately weatherproof, inductive charging systems necessitate embedded charging pads for effective operation, influencing their integration with existing infrastructure. Moreover, compatibility is restricted to vehicles equipped with compatible receivers, posing a limitation on widespread adoption. Additionally, inductive charging may contribute to slightly accelerated battery degradation due to the heat generated during the charging process. Nonetheless, its scalability and upgradability are notable advantages, allowing for the incorporation of additional charging pads over time. It is worth noting, however, that inductive charging tends to exhibit a lower efficiency than traditional methods, which can be attributed to energy loss in the magnetic field.  
Static charging systems, similar to IPT, are commonly found in stationary locations like parking lots, traffic lights, and toll booths, as depicted in Figure 2a. These systems are more efficient and compatible with electric vehicles. However, in wireless EV charging, misalignment between the transmitter and receiver coils can lead to fluctuations in the coupling coefficient, reducing the system's efficiency and power output [50]. Researchers are working to address misalignment issues in static WPT systems [50; 51; 52; 53]. These systems typically have two stages: a high-frequency inverter converts input power to AC, which is then transferred to the primary coil to create an electromagnetic field. This induces AC power in the nearby receiver coil, which is then converted to DC power and stored in the vehicle's battery [45]. The system can achieve an efficiency of 85% or higher, with the individual stages reaching up to 97% efficiency.  
Figure 1: EV charging techniques.  
Dynamic inductive charging is a method that wirelessly charges a vehicle's battery while it is in motion, also known as on-the-go or road-based charging. This addresses the challenge of electric vehicles having a limited range for long-distance trips [54; 55]. It is an emerging technology that is currently being explored in various pilot projects and studies. In dynamic inductive charging, as depicted in Figure 2b, a primary coil buried along the road track and a secondary coil mounted on the vehicle chassis facilitate power transfer as the vehicle moves [47; 56]. The primary infrastructure components include the Power Supply Unit and the Inductive Transmitter Units embedded in the road [47]. This charging method has several advantages; the major disadvantages are shown in Table 1.