## 1 Introduction  
Wireless power transfer (WPT) technology is considered essential for ensuring a continuous power supply to all IoT devices. From smartphones, wearable devices, and home appliances to mobility units, such as automobiles, IoT devices are increasingly integrating more functions, placing them at the forefront of modern technological innovation. WPT, which eliminates the need for physical connections, offers significant experiential advantages to users. Furthermore, it operates across various environments, including smart homes, smart cities, industrial automation, and autonomous vehicles. In these settings, WPT overcomes limitations related to charging time and location, making it a critical enabler for the intelligent operation of devices through an uninterrupted power supply [1, 2, 3, 4, 5]. Particularly, DWPT technology for dynamic wireless charging enables continuous charging even during movement, addressing challenges related to battery capacity and charging infrastructure. As such, it has been actively studied for electric vehicle (EV) applications [6, 7, 8]. However, DWPT technology is not limited to EVs. It is a necessary technology that should be developed to provide a continuous power supply across all power-consuming devices, including industrial robots, equipment, smart appliances, and IoT devices. Since the power requirements vary across applications, appropriately sized WPT couplers must be designed. For instance, EV wireless charging, which typically demands outputs ranging from several kW to tens of kW, requires WPT coupler coils with widths exceeding 0.2 m [9; 10; 11]. In contrast, couplers for mobile robots, which operate at an output level of approximately 24-50 W, should be practically smaller than 0.2 m [12; 13]. Furthermore, a coreless track-based wireless charging system capable of transmitting and receiving over 100 W has been studied to support the free movement of robots [14]. These technologies are based on inductive wireless power transfer (IPT) using magnetic induction and magnetic resonance. Initially proposed by an MIT research team in 2007, IPT has since been extensively studied [15]. This approach, like the aforementioned studies, achieves high efficiency at close transmitter-receiver distances. However, the strong electromagnetic fields generated by IPT systems cannot be overlooked due to their potential impacts on other electronic devices and human health [16; 17]. Additionally, the induced voltage caused by magnetic fields can lead to malfunctions in other devices [18; 19; 20; 21]. Given these potential risks, international guidelines regulating electromagnetic exposure limits have been updated [22]. Based on these standards, studies have also been conducted to analyze the electromagnetic fields induced within the human body [23]. In contrast, capacitive wireless power transfer (CPT) using electric resonance is free from these issues [24]. Notably, designing a DWPT system based on IPT requires complex structures [25; 26], whereas CPT allows for relatively simpler and more efficient system designs [27; 28]. The structure of a four-plate CPT coupler is categorized into parallel and stacked configurations [29]. Generally, the parallel structure features two transmitting metal plates and two receiving metal plates arranged to face each other [30]. In the stacked structure, the two transmitting plates are stacked vertically, and the receiving plates are arranged in the same manner, with the two plates on each side layered on top of each other [31]. These two configurations can be designed and applied according to specific objectives [32; 33]. Dynamic wireless capacitive power transfer (DCPT) systems also apply these structures [34; 35; 36]. As illustrated in Figure 1, mutual coupling is formed between the transmitter plate and receiving plate, both composed of metal, facilitating power transfer through electric field coupling. Figure 1: Dynamic wireless-charging systems for mobile robots.