Eddy current brakes (ECBs) are widely used in heavy vehicles because of their excellent noncontact braking characteristics. However, the torque decay is inevitable when ECB is continuously braking, which involves the interaction between electromagnetic field and temperature field. Especially in the extreme condition of high-power continuous braking, there is a serious decline in braking torque, and even the problem of coils insulation burning out due to high temperature. In response to the above issues, this paper proposes a fully water-cooled ECB structure and establishes an electromagnetic-thermal coupling model (ETCM) considering the current decay caused by coils temperature. Through 3D electromagnetic field numerical analysis, the rule of heat generation rate of the stator and the coils was obtained. The temperature distributions of the stator and the coils were calculated by the finite difference method. The average temperature was used to modify three factors of the conductivity, the permeability and the current of the coil in the electromagnetic field model. The simulation and experimental results showed that the ETCM can accurately calculate the thermal decline of the ECB. The proportion of torque decline caused by the three factors is analyzed, among which the conductivity and current have a greater effect on the torque decline. The influence of the coil cooling mode and the wire material on the coils heat dissipation is analyzed. The method of the water-cooled coil is proposed to decrease the torque decline and further optimize the continuous braking performance of ECBs.

The main aim of this project is to develop an alternative emergency braking system and brake failure identifier for vehicles. In this proposed method, an eddy current braking is used for alternative emergency braking system and the brake failure is identified by placing the ultrasonic sensor opposite to brake pads of the vehicles, that detects the thickness of the brake pad and notifies the driver with a visual and audible alert if there is a tear or brake pads are detached. The performance of the alternative emergency braking system is evaluated with different tests the first test is using aluminium and copper disk; and second test is of different magnets that is neodymium and ferrite magnet. The time taken for the speed of the motor to reduce the speed is up to 65% in 5 seconds using the aluminium disk and neodymium magnet. However, the speed reduction of the motor is only 50% in 5 seconds of time using the copper disk and ferrite magnet. Overall, the system proved to be very accurate in terms of braking efficiency and braking force generated by the eddy currents when the aluminium disk and neodymium magnet is used.

This paper proposes a novel hybrid brake system designed to improve the safety and performance of personal e-mobility devices, specifically electric kick scooters (e-scooters). The system integrates a foot brake and an axial flux eddy current brake (ECB) utilizing a linear Halbach magnet array to enhance braking power over a wide range of operating speeds. A comparative analysis of two ECB topologies, a circular permanent magnet array (ECB-CPM) and a linear PM with Halbach array (ECB-LPM), demonstrated the superior braking torque of the ECB-LPM in finite element analysis (FEA) simulations. The optimization of the ECB-LPM is achieved through a stochastic algorithm based on surrogate modeling and adaptive sampling techniques, resulting in improved performance metrics while maintaining compactness and cost-effectiveness. The experimental results verify the 3D FEA simulation results, demonstrating the hybrid system’s ability to achieve braking performance comparable to conventional mechanical brakes, with the added benefits of reduced maintenance and noise.

This paper examines promising areas for the development of braking systems for high-speed trains using eddy current braking. The relevance of the study is driven by increasing rail speeds and the need to improve the safety, energy efficiency, and reliability of braking systems. Eddy current braking, based on electromagnetic induction, is a promising alternative to traditional friction and rheostatic systems, as it reduces wear on mechanical components and improves braking smoothness. The research methods are based on a literature review of modern experimental studies on the use of various types of braking systems in high-speed transport. Particular attention is paid to combined systems combining eddy current braking with other technologies. The results demonstrate the need to modernize existing braking systems to meet modern safety and energy conservation requirements. Key development areas are identified, including optimization of eddy current brake design, integration of energy recovery systems, and the use of new materials to improve efficiency. The practical significance of this research lies in its proposal of specific solutions for the implementation of eddy current brakes on high-speed rolling stock. Implementation of these developments will improve rolling stock reliability, reduce operating costs, and ensure compliance with international safety standards. The results can be used in the design of new rail transport models.

Research on water cooling control strategies and factors influencing disc-type eddy current brakes

When the linear motor of a High-Temperature Superconducting Pinning Levitation (HTSPL) train fails, eddy current braking is required. This paper establishes a longitudinal dynamic model that accounts for bounded stochastic aerodynamic resistance, induction plate irregularity, and time delays. A basic controller was first designed based on braking acceleration. However, this approach did not consider the relative errors between maglev bogies. To address this limitation, a ‘look-forward' sliding mode control strategy was introduced. This paper adjusts the sliding mode controller according to different random disturbances and performs multi-objective optimisation within the constraints of Lyapunov stability to determine the optimal control parameters. Simulation results comparing the braking performance under different controllers show that minimising the effects of gradient and response time on the initial braking state is essential. While all controllers achieve the desired braking process, the simple controller produces significant high-frequency fluctuations in longitudinal acceleration and force, with relatively large amplitudes. In contrast, the sliding mode controllers effectively suppresses these vibrations. By selecting appropriate controller for different random disturbances, the system’s cost-effectiveness can be improved. However, when time delays become substantial, further refinement of the control method is necessary.

Superconductivity for railway applications: A review

Eddy current braking is an effective emergency braking method for maglev trains; however, the normal forces generated during the braking process can affect the stability of the levitation system of the train. To explore methods for suppressing the normal force, this study employs a nonlinear iterative calculation approach based on the magnetic permeability stratification of the induction plate to analytically compute the normal force of eddy current braking. This approach addresses the challenges in analytical calculations due to the variation in the magnetic permeability of ferromagnetic induction plates owing to magnetic saturation, a problem that traditional subdomain methods are unable to solve. During the calculation process using the subdomain method, the induction plate is divided into N layers of equal thickness and an iterative calculation method is employed to determine the magnetic permeability of each layer, thereby improving the computational accuracy. Subsequently, a finite element simulation is used to verify the analytical calculation results. The influence of various parameters on the normal force is analyzed. Aiming at the demand for emergency braking for high-speed maglev, the parameters are optimized to suppress the normal force.

The overwinding protection device serves as the final braking measure in the operation of the mine hoisting system, playing a crucial protective role. However, when implemented in ultra-deep mines, traditional over-winding protection devices encounter issues such as frictional wear and decreased braking efficiency. This paper proposes a hybrid over-winding protection strategy that combines Permanent Magnet Eddy Current Brakes (PMECB) and friction braking to address these challenges. First, this paper analyses the braking characteristics of the axial PMECB, drum friction brake and hydraulic disc brake, and designs a collaborative working strategy based on these characteristics. Subsequently, finite element simulations were conducted to investigate the braking performance under various operating conditions. The simulation results show that, compared with traditional friction devices, the hybrid braking strategy reduces the wear issues and shortens the over-winding distance. The advantages of the hybrid braking strategy are more obvious at higher initial speeds. Finally, hybrid braking experiments were conducted to validate the accuracy of the simulation model and confirm the advantages of the hybrid braking strategy in over-winding protection.

The linear eddy current braking (LECB) system is suitable for use as an emergency braking system to ensure the safe and stable operation of high-speed maglev trains. This paper analyzes the adverse effects of the normal force generated by eddy currents on the stable levitation of the electrodynamic suspension (EDS) train. From the perspective of electromagnetic mechanisms, it elucidates the intrinsic relationship between the magnetic field distribution and the resulting eddy current electromagnetic forces. Based on this theoretical framework, a novel parallel hybrid excitation (PHE) eddy current braking electromagnetic structure is proposed for EDS train,. The aim is to suppress the normal force without reducing braking force. Using the subdomain method and the principle of equivalent magnetic vector potential, a spatiotemporal distribution model of magnetic flux density, along with analytical models for the eddy current braking force and normal force, are developed. Key parameters influencing the system’s electromagnetic performance are identified. The analytical model’s accuracy is validated through 3D finite element simulations, confirming the effectiveness of the proposed structure and providing a theoretical basis for its application in EDS trains.

Maglev train speeds exceed 600 km/h, with significant longitudinal impact between vehicles during braking and acceleration affecting ride comfort. Studying the unsteady aerodynamic and longitudinal impact characteristics of a 600 km/h high-speed maglev train during plate braking with and without crosswind, we realized braking plate motion using dynamic grid technology and simulated the flow field around the train using the time-averaged Reynolds equation and shear-stress-transport k–ω turbulence model, which were verified by wind tunnel test data. Braking force of the plate under crosswind stabilized faster than under no crosswind. Meanwhile, the aerodynamic drag fluctuation of the plate under the crosswind was more severe, particularly the top braking plate of the middle car. Aerodynamic drag fluctuation of plate 4 on top of the middle car increased by 90% under crosswind, intensifying the longitudinal impact between vehicles. Plate braking effectively assists the eddy current braking system in performing emergency braking under high-speed conditions, reducing the load on the eddy current braking system. To address the longitudinal impact issue stemming from the combined emergency braking of plate and eddy current under crosswind, the impact was effectively mitigated by strategically placing longitudinal dampers between the vehicles, optimizing their damping value through particle swarm optimization. After optimization, positive peak value of longitudinal deceleration of the middle car 1, with the worst stability under crosswind, decreased by ∼8%, and negative peak increased by ∼14%, reducing maximum impact amplitude by ∼22%. The results provide reference for the emergency braking and longitudinal impact issues of high-speed maglev trains.

Abstract During high-speed operation, a high-temperature superconducting pinning levitation (HTSPL) train must rely on independent eddy current brakes on its maglev bogies for distributed braking in the event of linear motor failure. To investigate the braking process and enhance its performance, the train is modeled as an interconnected system, with the modularly designed maglev bogies treated as subsystems. A comprehensive longitudinal dynamic model of the train is developed. Based on the desired braking acceleration corresponding to the current speed, combined with displacement and velocity feedback, control currents are applied to the brakes to achieve eddy current braking. However, this simple control strategy does not account for relative errors between maglev bogies or the transmission of longitudinal vibrations between carriages, posing safety risks. To address these issues, a ‘Look-Forward’ sliding mode control strategy is implemented under the same feedback conditions. A braking current control law is designed, and the range of control parameters is determined through Lyapunov stability analysis. Numerical simulations compare the braking performance of the two strategies. Results show that both strategies achieve a complete stop within acceptable time (135 s) and distance (9 km), although the time and distance under sliding mode control are slightly longer. With simple control, longitudinal acceleration and force exhibit superimposed vibrations at approximately 5 Hz and 30 Hz, adversely impacting train reliability and passenger comfort. In contrast, the ‘Look-Forward’ sliding mode control significantly reduces vibrations, achieving the desired synchronized braking effect among maglev bogies. However, there is room for parameter optimization, and other advanced control methods could be explored to address more complex operating conditions.

In this paper, a novel dual-winding rail eddy current braking system with AC excitation is proposed. First, the structure and the working principle of the braking system are elaborated. Second, the 2-D subdomain model is built to obtain the braking characteristics of the proposed brake. Third, the effects of the slip and the excitation capacitance value on the braking characteristics are analyzed by the 2-D finite-element method (FEM).

With the development of application and research of eddy current brakes (ECB) in various fields, the application of ECB in large braking machines targeting strong impact load is beginning to be explored. When braking against strong impact load, a high acceleration phase will exist, and sometimes under this special condition, a high peak of electromagnetic resistance will appear, which can disturb the braking effect of the ECB. The effect of high acceleration on the electromagnetic resistance characteristics of ECB under such special application conditions is of concern. In this paper, the change of electromagnetic field under high acceleration is analyzed. Combining the working principle of eddy current brake with the data obtained from FEM model, the principle equation and explanation analysis are given. By comparing the electric field distribution with and without high acceleration, effects of high acceleration at different velocity stages on the eddy current electric field are discussed. In order to be able to better predict the resistance of the ECB under strong impact loads, an electric field strength incremental considering high acceleration was introduced according to a simplified analytical model combining the MEC model with the equivalent electric field approach. Numerical modeling was performed based on the data obtained from FEM models, and the final model obtained is verified by comparison with experimental results. In this paper, combining analytical modeling, finite element modeling and numerical modeling, an analytical model of electromagnetic resistance and braking process considering high acceleration is proposed, and the braking process can be simulated quite accurately. Future research can use this model to optimize the design of the ECB mechanism to obtain a more efficient braking force and a smoother braking process.

The integration of electromagnetic braking (EMB) and regenerative braking systems (RBS) presents an innovative approach to enhancing braking efficiency in electric vehicles (EVs). This study proposes a hybrid braking system that leverages ferrite and neodymium magnets to induce eddy currents in an aluminum brake disc. The generated eddy currents create an opposing force that slows down the vehicle without mechanical contact, reducing wear and maintenance costs. Additionally, a galvanometer-based system is incorporated to detect and quantify the induced current between the braking surfaces, demonstrating the feasibility of energy recovery. Experimental and simulation analyses validate the effectiveness of the proposed system, showing improvements in braking efficiency, heat dissipation, and energy recovery. The results suggest that integrating eddy current braking with regenerative braking enhances overall energy efficiency and contributes to sustainable transportation solutions. Key Words: Electromagnetic Braking (EMB), Regenerative Braking System (RBS), Electric Vehicles (EVs), Braking Efficiency, Energy Recovery, Eddy Currents, Kinetic Energy, Battery Recharge, Wear Reduction, Sustainability.

Summary Torsional stick/slip vibrations are a significant cause of drillstring damage and failure. Using damping subs distributed along the drillstring has been demonstrated in both simulations and laboratory experiments as a viable solution to reduce stick/slip in drilling. The effectiveness in mitigating stick/slip can be further improved through active control of the damping strength of one or several subs. This paper evaluates a control scheme, which relies only on local downhole measurements, for various operating conditions simulated with a drillstring mechanics model. Damping subs with sleeves supported on bearings and incorporated eddy current brakes are installed along the drillstring, adding viscous damping to the system to mitigate torsional vibrations. The damping amount is proportional to the relative rotational speed between the sleeve and the pipe and therefore maximized when the sleeves are nonrotating. However, if the braking force surpasses the static friction holding the sleeve in place, the sleeve slips and reduces its braking abilities. To counteract this, an on-off-based control scheme with proportional control (P-off controller) is implemented at the level of each sub to manipulate the value of its damping coefficient. The off condition is triggered when local measurements indicate slipping of the sleeve. Simulations of various drilling scenarios conducted with a coupled axial and torsional drillstring model show that the P-off controller can reduce stick/slip in the system in both off-bottom and on-bottom conditions. The results indicate that the average damping coefficient, and implicitly the torque added to the system, can be greatly reduced compared with a passive damping system, consisting of the same number and positioning of subs but with constant damping coefficients. Also, the settling time of the downhole rotational speed is significantly reduced compared with the passive system. The damping subs can also be used in combination with a surface stick/slip mitigation system. The control scheme is decentralized as it relies only on local knowledge, such as pipe rotational speed inferred from an inertial measurement unit, to estimate the topdrive revolutions per minute (RPM) setpoint. Therefore, communication with the surface or with neighboring subs is not a requirement for the control implementation. The controller also shows robustness against variations in the topdrive RPM and noisy downhole measurements, which is important for a real-world application. The presented approach differs from existing downhole torsional vibration damping solutions, as it does not rely on a single tool placed inside or near the bottomhole assembly, but on several subs distributed along the drillstring, with their damping strength adjusted directly downhole in a decentralized manner.

Development and Experiment of Superconducting Eddy Current Braking Prototype Device

Accurate analytical calculation of electromagnetic field is the basis of research and optimization of axial magnetic flux eddy current brake, and structural optimization design is the key to improving system performance and reducing engineering construction costs. In order to establish an accurate analytical calculation model of electromagnetic field of axial magnetic flux eddy current brake, based on the two‐dimensional analytical calculation model of electromagnetic field, this paper comprehensively considers the influence of non‐ideal factors such as core saturation, transverse dynamic end effect and secondary skin effect on the electromagnetic characteristics of axial magnetic flux eddy current brake, and obtains an improved analytical calculation model of electromagnetic field by introducing corresponding correction coefficients, and verifies the accuracy of the analytical calculation model of electromagnetic field by comparing with the numerical calculation results of three‐dimensional electromagnetic field finite element model. On this basis, an improved multi‐objective particle swarm optimization algorithm is adopted to optimize the system design, so as to increase the electromagnetic braking torque, reduce the electromagnetic axial force and reduce the secondary mass. Finally, the accuracy of the above electromagnetic field analytical calculation model and optimization design results is verified on the experimental research platform of axial magnetic flux eddy current brake, which can provide theoretical basis for subsequent researchers to design and optimize the electromagnetic scheme. © 2025 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Eddy current brakes have been recently used for functional resistance training in individuals with neurological and orthopaedic disorders. These devices consist of a gearbox, a conductive disc, and permanent magnets that can be moved relative to the disc to alter resistance. However, current devices use a commercial planetary gearbox with a tall profile that sticks out from the leg, which affects wearability. This is coupled with the large system inertia, which together impedes potential device transition to clinical and in-home use. In this study, we developed a low-profile, pancake-style planetary gearbox that greatly reduces the protrusion of the device from the leg. We performed a design analysis and optimization to minimize the thickness and inertia of the device while ensuring that it could withstand the maximum expected torque (50 Nm). We then performed human subjects experiments to examine the effectiveness of our new design for functional resistance training. The results indicated that all leg muscles showed a significant increase in activation during resisted conditions. There were also significant after-effects on medial hamstring activation. These results indicate that the new design is a feasible method for functional resistance training and may have a potential clinical value in gait rehabilitation.

In this article, the magnetic analysis of a rail eddy current brake (ECB) with ring structure winding and ac excitation is presented. Differing from the ECBs with dc excitation, the proposed ECB can generate electricity and reduce rail heating. First, the structure and working principle are described. Second, the three-dimensional (3-D) analytical model (AM) is established considering the nonlinear permeability of the secondary rail and the transverse end effect. Third, the accuracy of AM is verified by the finite-element method and experimental results. Furthermore, the ECB's braking force and power characteristics are analyzed based on the finite-element analysis. Finally, four different winding schemes possibly suitable for ECBs are compared to determine the superiority of the ring structure winding.