Experimental Comparison of Solid-Rotor and Slitted-Rotor Switched Reluctance Machine

In a solid-rotor switched reluctance machine (SRM), the rotor is made from a single piece of magnetic material. This type of rotor is a viable option for applications involving high speeds and high shaft temperatures. However, solid-rotor SRM suffers from high core losses due to the absence of laminations. This paper proposes a slitted-rotor SRM, which is also crafted from a single piece of ferromagnetic material, as a solution to reduce core losses. The proposed slitted-rotor SRM is compared and evaluated against the existing solid-rotor SRM under static and no-load conditions. Under static conditions, the simulated and measured flux-linkage characteristics and torque characteristics at various currents, excitation frequencies, and rotor positions are presented. The static measurements reveal the superior flux-linkage characteristics, lower core losses, and higher torque-producing capability of the slitted-rotor SRM over the solid-rotor SRM. The measured static torque characteristics at different frequencies demonstrate that the slitted-rotor SRM has lower sensitivity to the excitation frequency relative to the solid-rotor SRM. Under no-load running conditions, the measured losses at different speeds are significantly lower for the proposed SRM. At the rated speed of 10,000 rpm, the no-load loss is found to be an acceptable value of 150 W, which is approximately 3% of the designed rated power. Additionally, under loading conditions at speeds of 200 rpm and 1000 rpm, the proposed SRM produces an output torque of 4.5 Nm and 3.7 Nm, respectively, which correspond to 95% and 78% of the designed rated torque of the machine (i.e., 4.7 Nm).