# Design of Magnetic Concrete for Inductive Power Transfer System in Rail Applications
## 4 Results and Discussion
### Shielding Analysis of IPT Systems  
This section presents the results of the shielding effectiveness of two coupler designs: one using traditional ferrite cores and the other using a magnetic concrete slab. The simulations were conducted using Ansys Maxwell. Figure 16a shows the magnetic field distribution in the W-I ferrite core design (Coupler Design 1). The color-coded magnetic flux density (B-field) is represented in the unit of  
Figure 14: Thermal distribution for Coupler Design 3 with normal concrete. Figure 15: Thermal images of IPT system during operation. (**a**) Receiver coil thermal distribution using ferrite bar. (**b**) Transmitter coil thermal distribution with magnetic concrete. micro-Tesla (uT). The denser and closely spaced field lines indicate stronger magnetic fields, primarily concentrated around the ferrite cores. This visualization highlights the effective magnetic flux concentration achieved by ferrite materials, demonstrating their high magnetic permeability and efficiency in guiding magnetic fields. In contrast, Figure 16b shows the magnetic field distribution in Coupler Design 2, which utilizes a magnetic concrete slab. Magnetic concrete guides the magnetic flux efficiently, reducing the magnetic flux density on the ground. This reduced distribution of magnetic fields indicates a more uniform flux distribution, which is beneficial for protecting various sensors installed along the railway tracks, such as condition monitoring, acceleration, temperature, and rotation rate sensors. The magnetic concrete design shows an ability to guide the magnetic flux away from the ground and critical areas, reducing electromagnetic interference and enhancing the overall safety of the railway system. Figure 17 provides a cross-sectional visualization of the magnetic field flux for the IPT system with a magnetic concrete slab. The color-coded streamlines represent the magnetic flux density in the system. Regions with denser and closely spaced field lines indicate stronger magnetic fields. Notably, the red lines highlight areas with higher magnetic flux density, primarily concentrated around the coil within the magnetic concrete slab. This simulation reveals how the magnetic concrete slab influences the magnetic flux lines, demonstrating its effectiveness in guiding the magnetic field. The magnetic concrete's ability to concentrate the magnetic flux within the desired paths enhances the efficiency of power transfer and reduces unwanted magnetic field leakage. The simulations confirm that the magnetic concrete slab not only enhances the durability and structural integrity of the IPT system but also provides effective shielding comparable to or better than that of traditional ferrite cores. The relative shielding efficiency computed for the magnetic concrete is about 51.5% for the closest region near the two railroad tracks. From our prior studies, W-I coupler systems have met the threshold of the electromagnetic field effect for human safety [30]. The current magnetic concrete-based coupler system also met the requirements. The ferrite cores in Coupler Design 1 offer high magnetic permeability and effective shielding but are fragile and can degrade over time, especially in dynamic railway environments. In contrast, Coupler Design 2 with a magnetic concrete slab shows a significant ability to guide magnetic flux efficiently, reducing the magnetic flux density on the ground. This reduction in flux density is advantageous for safeguarding sensors along the railway tracks, ensuring the reliability and safety of railway operations. Figure 16: Electromagnetic flux distributions presented in 2D view. As described by several studies [3, 21, 31, 64], the IPT system improves the aesthetics, safety, and costs for short-distance transits such as light rails, street cars, and trans. The current study further demonstrates that the findings from these simulations are instrumental in validating the theoretical benefits of using magnetic concrete slabs in IPT systems.