Dissimilar metal joining for rotors of high-speed axially laminated anisotropic synchronous reluctance machines

Abstract

High-speed electrical machines play a key role in enhancing the efficiency of energy conversion systems. Among them, axially laminated anisotropic synchronous reluctance machines (ALASynRMs) stand out due to their magnetless design, high-speed capability, and good efficiency. While the electromagnetic performance of ALASynRMs has been extensively studied, their mechanical performance—particularly the rotor structure—has received limited attention.

This dissertation investigates the mechanical behavior of ALASynRM rotors constructed using laminated materials with metallic joints. It focuses on the properties of the laminated material, the interface between laminated and solid materials, and the feasibility of integrating solid shafts into the rotor structure. This approach enables a novel rotor design that reduces the volume of laminated material while maintaining mechanical integrity.

A combination of experimental and simulation-based methods is used. Metallographic techniques assess the microstructure of the laminated material, while mechanical testing evaluates the strength. Full rotor behavior is analyzed through experimental methods, including experimental modal analysis, and with simulation models.

The findings demonstrate that laminated materials with metallic joints possess sufficient strength for high-speed operation. Solid materials can be reliably joined to laminates, enabling robust hybrid rotor structures. A well-chosen combination of rotor materials can ensure that the rotor’s mechanical properties—such as stiffness and thermal expansion—are effectively isotropic. This supports the suitability of ALASynRMs for high-speed applications despite the rotor’s inherent electromagnetic anisotropy.