Influence of Stator Winding Reconnection and Bipolar Excitation on the Performance Characteristics of Solid-Rotor Switched Reluctance Machine

The rotor in a solid-rotor Switched Reluctance Machine (SRM) is made from a block of magnetic material, suitable for extreme operating conditions like high shaft temperature and corrosive environments. However, the lack of laminations reduces torque output due to eddy currents and hysteresis losses. This paper investigates improving the performance of the solid-rotor SRM through a mutually coupled winding connection with bipolar excitation. The article examines the flux-linkage characteristics of a solid-rotor SRM with Double Layer Conventional (DLC) and Double Layer Mutually Coupled (DLMC) windings under sinusoidal excitations at various frequencies. Experimental findings demonstrate that the DLMC winding has a larger loop area enclosed between unaligned and aligned flux linkage curves for a given peak current across all frequencies. Static torque measurements show the robustness of the DLMC winding to excitation frequency, consistently generating higher static torque than the DLC winding. The study presents static core and copper loss characteristics for both windings at different frequencies, with the DLMC winding exhibiting higher static core losses for a given peak current. The investigation examines the back-emf characteristics, indicating that the DLMC winding achieves nearly double the peak back-emf and peak torque of the DLC winding under a given current injection. Finally, a comparison of average torque output shows that the DLMC winding with bipolar excitation delivers higher torque than the DLC winding with unipolar excitation for a given peak current injection in the solid-rotor SRM.