## 1 Introduction
This study focused mainly on the magnetic field density produced by air gaps, but the researchers did not pay attention to the influence of the magnetic field. Another study stated that the change in the position of the magnetic field affects the braking performance [15]. These changes indicate that changes in the location of the shoe pole result in the change of braking performance by the ECB. Figure 1: Axial unipolar eddy current brake (ECB): (**a**) design unipolar ECB; (**b**) eddy currents. The limitation of using the ECB at low speeds is due to the induced currents, in which the magnitude is affected by the speed. To improve this performance, the ECB can be integrated with other systems that can provide braking at low speeds. [PERSON] et al. [16] investigated hybrid braking, combining the ECB and the magnetic track brake. The ECB can provide good braking at high speeds and reduce mechanical contact, therefore reducing the possibility of braking system failure. At low speeds, the braking system uses magnetic track braking, which uses braking pads coated with braking material. A similar study was also carried out by [PERSON] et al. [15]. They combined the ECB with mechanical braking using a hydraulic system. The distance between the magnetic field source and the rail uses an electrically controlled hydraulic system. Furthermore, [PERSON] et al. [17] developed the system by adding the design optimization using non-magnetic barriers to reduce the flux leak age. Providing a barrier to leakage increases the density of the magnetic field in the air gap and increases the braking force. [PERSON] et al. [18] examined the current settings to obtain the optimal braking torque. To activate the ECB, an external source of electricity and/or a permanent magnet are necessary, leading to a high total cost. To overcome these issues, an ECB system in which the source of the magnetic field is generated not by a permanent magnet but by an electromagnet from the electricity generated from a pack battery has been made. This system can save energy and reduce costs, as has been studied by [PERSON] et al. [1]. A self-generation system to improve energy efficiency was also evaluated by [PERSON] [2] by adopting capacitors. The capacity of the capacitor seemed to influence the energy efficiency. Previous studies have examined how to improve performance without consideration of the size of the magnets used. The results of the existing studies show improvements in performance without considering the limitations of the size of the vehicle used. Unipolar research is still limited to the use of one magnet. There has been no research on the use of more than one magnetic field source with a unipolar design. This research further analyzes the effect of certain parameters. The magnetic field is generated by using an electromagnet, allowing for the possibility of controlling the current. This research focuses more on the study of the ECB braking system by making changes to the source of the magnetic field that is adopted. In addition, the use of more than one magnetic field sources is also evaluated further in this study. Both experimental and calculation analyses are conducted to validate the result. The purpose of this research is to make a good ECB for hybrid applications with conventional brakes for a lightweight vehicle. The ECB does not replace the conventional brake but supports it, so that increases the lifetime of conventional brakes.