Brushless DC (BLDC) motors are increasingly used in industrial applications due to their high efficiency, reliability, and low weight. However, their performance strongly depends on the electromagnetic properties of stator and rotor core materials. This study evaluates six BLDC motor configurations, employing materials such as M19 electrical steel, 1010 low-carbon steel, magnetic PLA, and ABS, and analyzes their impact using FEMM 4.2 finite element simulations. Key electromagnetic characteristics—including flux linkage, Back-EMF, torque, and torque ripple—were compared across configurations. The reference motor with M19 steel stator and 1010 steel rotor achieved ~7 mWb flux linkage, ~39 V pk–pk Back-EMF, and 1.44 Nm torque with ~49% ripple, confirming the suitability of laminated steels for high-power-density designs. Substituting M19 with 1010 steel in the stator reduced torque by less than 10%, indicating material interchangeability with minimal performance loss. By contrast, polymer-based designs exhibited drastic degradation: magnetic PLA yielded only 3.5% of the baseline torque with sixfold ripple increase, while ABS delivered nearly zero torque and >700% ripple. Hybrid configurations improved PLA-based results by 15–20%, though they remained far below ferromagnetic cores. Overall, results demonstrate a nearly linear relationship between material permeability and both flux linkage and Back-EMF, alongside a sharp rise in torque ripple at low permeability. The findings highlight the advantages of ferromagnetic and laminated steel cores for efficiency and stability, while polymer and hybrid cores are limited to lightweight demonstrator applications.

The main aim of this study is the concept of the magnet holder for the THz undulator utilized in the PolFEL superradiant light source. To achieve maximum flux at high K values (radiation frequencies ranging from 0.5 THz to 5 THz, and K values exceeding 3), it is necessary to use large permanent magnets with dimensions of 100 × 100 × 39.9 mm. For the above assumptions and parameters and specific requirements for magnet positioning, existing design solutions in the literature were found to be insufficient. The main challenges in the design of this holder included the following: (a) the unusually large size of the magnets, (b) requirements of wide-range calibration, and (c) large magnetic forces acting on each magnet, which can approach almost 4 kN. Taking into consideration these challenges, the prototype of the magnet holder was developed and manufactured. The paper presents the findings from both numerical and experimental studies aimed at validating the mechanical behavior and deformation of the proposed magnet holder. The measurements were conducted using two methods—traditional with the use of dial indicators and a novel approach based on the application of the Digital Image Correlation. The results from these numerical and experimental studies indicate that all specified requirements have been satisfactorily met. The study confirms the capability for accurate magnet positioning, demonstrating stable deformation of the holder under a magnetic load. Additionally, it was proved that the positioning of the magnets is both linear and repeatable, with calibration achievable within a range of at least ±0.25 mm.