the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 15 Sep 2026
A Systematic Design Methodology for Electromagnetic Brakes Applied to Low-Power Wind Turbines Using Analytical Modeling, Numerical Validation, and Experimental Verification
Abstract. Low-power wind turbines require reliable braking systems to ensure safe operation during emergency conditions, maintenance procedures, and high wind speeds. Among the available alternatives, eddy-current electromagnetic brakes offer an attractive solution because they operate without mechanical contact, thereby reducing component wear and maintenance requirements compared with conventional braking systems. However, existing studies have primarily focused on the analysis of electromagnetic behavior, the optimization of specific configurations, or industrial applications, while relatively few have addressed a comprehensive methodology for the design and experimental validation of electromagnetic braking systems for low-power wind turbines. This study proposes a reproducible design methodology for an eddy-current electromagnetic brake intended for a 1 kW wind turbine. The proposed methodology integrates the definition of design requirements, the development of an analytical model for electromagnetic sizing, three-dimensional finite element analysis (FEA), and the experimental validation of a prototype manufactured according to the obtained design parameters. The proposed methodology was assessed through three complementary validation stages: analytical modeling, finite element simulation, and experimental testing using a dedicated test bench. The comparison of the obtained results demonstrated good agreement among the analytical predictions, numerical simulations, and experimental measurements, with a relative difference of 1.18 % between the magnetic flux density predicted by the analytical model and that obtained from the finite element analysis. Furthermore, the developed prototype successfully achieved complete rotor stoppage under the prescribed design conditions, confirming the effectiveness of the proposed braking system. The main contribution of this work lies not only in the development of an electromagnetic braking device but also in the formulation and validation of a systematic design methodology that integrates analytical modeling, numerical validation, and experimental verification into a unified design framework. The proposed methodology provides a reproducible approach for the development of electromagnetic brakes for low-power wind turbines and establishes a foundation for future protection strategies, speed regulation systems, and scaling to higher-power wind energy applications.
- Preprint
(4415 KB) - Metadata XML
- BibTeX
- EndNote
Status: open (until 08 Nov 2026)
-
RC1: 'Comment on wes-2026-153', Anonymous Referee #1, 11 Oct 2026
reply
-
AC1: 'Reply on RC1', Jesús Antonio Enriquez Santiago, 13 Oct 2026
reply
We sincerely thank the reviewer for the positive assessment of our study and for the constructive comments. We appreciate the opportunity to clarify the points raised. Our responses are provided below.
Comment 1.
Table 1 specifies a rated power of 1000 W, an angular velocity of 55.95 rad/s, a rated torque of 17.8 N·m, and a generator efficiency of 82%. The design torque is calculated using Eq. (2), whereas the electrical power available from the generator is subsequently considered in the excitation system design. The authors should clarify whether the rated power refers to the mechanical input power or the electrical output power of the generator and explain how the generator efficiency is accounted for in these calculations. A consistent definition of the mechanical and electrical power quantities would improve the accuracy and transparency of the design methodology.Response:
We thank the reviewer for pointing out this ambiguity. The rated power of 1000 W reported in Table 1 corresponds to the rated three-phase electrical output power of the generator, rather than its mechanical input power. The generator is a three-phase machine; this information was not explicitly stated in the original description and will be added in the revised manuscript.At the rated angular velocity of 55.95 rad /s, the rated electrical output power corresponds to an equivalent electromagnetic torque of approximately 17.8 N m:
T_e = P_e / w_r = 1000/55.95 (approx 17.87 N m).
This equivalent electromagnetic torque was adopted as the reference torque for the electromagnetic brake design. Considering the generator efficiency of 82 %, the corresponding mechanical input power is approximately 1.22 kW, and the mechanical shaft torque at the same angular velocity is approximately 21.8 N m. Thus, the mechanical and electrical quantities are related through the generator efficiency, while the brake sizing presented in this work is referenced to the equivalent electromagnetic operating condition of the generator.
In the revised manuscript, Table 1 and the corresponding methodology will explicitly distinguish the rated electrical output power, equivalent electromagnetic torque, mechanical input power, and mechanical shaft torque, thereby removing the ambiguity identified by the reviewer.
Comment 2.
In Section 2.3.3, the design excitation current is defined as equal to the current available at the rectifier output (Eq. 9). However, the authors also introduce a DC–DC current-regulation stage, which means that the rectifier output current and electromagnet winding current are not necessarily identical?Response:
We thank the reviewer for identifying this ambiguity. We agree that the rectifier output current and the electromagnet winding current are not necessarily identical because the proposed electrical architecture includes a DC–DC current-regulation stage between the rectifier/DC link and the electromagnet.Equation (9) was used to estimate the DC current available under the rated generator operating condition, considering the rated electrical output power of the generator, the rectifier efficiency, and the rectified DC-link voltage. The resulting value of 12.41 A was subsequently adopted as the upper design reference for the electromagnet excitation current; it was not intended to imply an intrinsic equality between the rectifier output current and the electromagnet winding current.
The DC–DC stage regulates the actual excitation current supplied to the electromagnet within the established design range. Once the required excitation current is established, the corresponding steady-state winding voltage is determined from the winding resistance. In the revised manuscript, Section 2.3.3 and the interpretation of Eq. (9) will be clarified to explicitly distinguish the DC-link current from the regulated electromagnet excitation current.
Comment 3.
The finite element results demonstrate good agreement with the analytical prediction of magnetic flux density, with a reported relative difference of 1.18%. However, the numerical model is developed under magnetostatic conditions, and the authors explicitly state that the transient eddy-current braking response is not simulated. Therefore, the agreement primarily validates the magnetic circuit design rather than the braking torque prediction. The authors are encouraged to distinguish these two aspects more clearly when discussing the numerical validation. Additionally, a brief description of the mesh convergence assessment and the procedure used to extract the magnetic flux density for comparison would further improve the credibility of the numerical results.Response:
We thank the reviewer for this important observation. We agree that the magnetostatic finite element analysis primarily assesses the consistency of the analytical magnetic-circuit design and the predicted magnetic flux density, rather than directly validating the transient eddy-current braking torque. This distinction will be made explicit in the revised manuscript.The magnetic flux density used for the analytical–numerical comparison was extracted at a representative point within the region of interest at the air-gap–conductive-disc interface, rather than from the global maximum magnetic flux density of the finite element solution. The local numerical value was approximately 0.154 T, compared with the analytical prediction of 0.1522 T, resulting in the reported relative difference of approximately 1.18 %. This extraction procedure will be explicitly described in the revised manuscript.
The numerical model was discretized using a free tetrahedral mesh. We acknowledge that a formal mesh-independence study involving successive mesh refinements was not performed. Therefore, we will clarify this limitation rather than claim numerical mesh convergence. Accordingly, the finite element results will be interpreted specifically as supporting the consistency of the magnetic-circuit design, while the braking response is assessed separately through the experimental results.
We thank the reviewer again for these comments, which will help us improve the clarity and technical consistency of the manuscript.
Citation: https://doi.org/10.5194/wes-2026-153-AC1
-
AC1: 'Reply on RC1', Jesús Antonio Enriquez Santiago, 13 Oct 2026
reply
Viewed
| HTML | XML | Total | BibTeX | EndNote | |
|---|---|---|---|---|---|
| 284 | 84 | 42 | 410 | 50 | 46 |
- HTML: 284
- PDF: 84
- XML: 42
- Total: 410
- BibTeX: 50
- EndNote: 46
Viewed (geographical distribution)
| Country | # | Views | % |
|---|
| Total: | 0 |
| HTML: | 0 |
| PDF: | 0 |
| XML: | 0 |
- 1
Overall, it is a good study, but there are somewhere I am confuded , hoping authors could answer.
1. Table 1 specifies a rated power of 1000 W, an angular velocity of 55.95 rad/s, a rated torque of 17.8 N·m, and a generator efficiency of 82%. The design torque is calculated using Eq. (2), whereas the electrical power available from the generator is subsequently considered in the excitation system design. The authors should clarify whether the rated power refers to the mechanical input power or the electrical output power of the generator and explain how the generator efficiency is accounted for in these calculations. A consistent definition of the mechanical and electrical power quantities would improve the accuracy and transparency of the design methodology.
2. In Section 2.3.3, the design excitation current is defined as equal to the current available at the rectifier output (Eq. 9). However, the authors also introduce a DC–DC current-regulation stage, which means that the rectifier output current and electromagnet winding current are not necessarily identical?
3. The finite element results demonstrate good agreement with the analytical prediction of magnetic flux density, with a reported relative difference of 1.18%. However, the numerical model is developed under magnetostatic conditions, and the authors explicitly state that the transient eddy-current braking response is not simulated. Therefore, the agreement primarily validates the magnetic circuit design rather than the braking torque prediction. The authors are encouraged to distinguish these two aspects more clearly when discussing the numerical validation. Additionally, a brief description of the mesh convergence assessment and the procedure used to extract the magnetic flux density for comparison would further improve the credibility of the numerical results.