Laser Additively Manufactured Magnetic Core Design and Process for Electrical Machine Applications

Abstract

Additive manufacturing (AM) is considered the enabling technology for topology optimized components, with its unparalleled, almost free-form design freedom. Over the past decade, AM of electromagnetic materials has evolved into a promising new area of research. Considerable efforts have also been invested by the electrical machine (EM) research community to develop and integrate novel additive components. Several challenges remain, however, in printing soft magnetic flux guides—most prominently, reducing the induced eddy currents to achieve competitive AM core efficiency. This paper demonstrates the workflow of laser additive manufacturing magnetic cores with superior magnetic properties to soft magnetic composites (at 50 Hz excitation): describing the workflow, parameter tuning for both printing and annealing, and shape optimization. Process optimization yielded the optimal energy density of 77 J/mm3 and annealing temperature of 1200 °C, applied to prepare the samples with the highest relative density (99.86%), lowest surface roughness Rz (0.041 mm), minimal hysteresis losses (0.8 W/kg at 1.0 T, 50 Hz), and ultimate yield strength of 420 MPa. For Eddy current suppression, the sample (5 × 5 × 60 mm toroid) with bi-directional grading reached specific core losses as low as 1.8 W/kg (W10,50). Based on the findings, the advantages and disadvantages of AM graded cores are discussed in detail.

Additively Manufactured Transverse Flux Machine Components with Integrated Slits for Loss Reduction

“…The narrow slits, on the other hand, are less continuous due to the manufacturing process, resulting in spatially larger eddy currents due to bridges between the slits. These results are consistent with other studies where the integration of slits oriented along the flux direction in 3%SiFe ring samples also resulted in lower iron losses [23][24][25][26][27]. However, the slits in these studies are provided with several bridges due to mechanical stability and therefore not continuous.…”

“…As a result, the proportion of hysteresis losses in the total losses decreases after the annealing. This effect was also observed by Tiismus et al [23,24]. The reduction of iron losses by heat treatment has a somewhat greater effect on components without or with only narrow slits, since in these cases a larger contiguous defective magnet volume is restored or improved.…”

Recent Advances in Additive Manufacturing of Soft Magnetic Materials: A Review

“…Silicon steels (Fe–Si) have long been the standard industrial material for the manufacture of electric motor cores, generator cores, and transformer cores due to their remarkable electromagnetic properties and cost-effectiveness, making them highly competitive in the industry [ 39 , 50 , 137 ]. They are typically produced with a silicon content ranging from 2.0% to 7.0% wt.…”

Magnetic Properties of High DC Bias Performance Fe-Si-B-C-Cr Amorphous Soft Magnetic Composites

“…Soft magnetic composites (SMCs) are widely used in a variety of electromagnetic applications due to their superior magnetic properties, including high permeability and low coercivity. − Non-crystalline or amorphous materials have unique properties that make them attractive for use in SMCs. , Amorphous SMCs (ASMCs) have received significant attention due to their high saturation induction, low eddy current losses, and excellent frequency-dependent magnetic properties. , Research on ASMCs has mainly focused on the preparation of ASMCs, the characterization of their microstructure, and their magnetic properties. − Various preparation methods have been proposed, such as powder metallurgy, hot pressing, spark plasma sintering, and additive manufacturing. − Among these methods, powder metallurgy is the most widely used technique. , Researchers have explored the effects of different preparation parameters on the microstructure and magnetic properties of ASMCs, including particle size, compaction pressure, annealing temperature, and cooling rate. − These parameters can significantly affect the magnetic properties of ASMCs, such as permeability, coercivity, power loss, and saturation induction.…”