Comparison of full pitch and concentrated coil switched reluctance machines

While the switched reluctance machine (SRM) is traditionally a concentrated coil machine, efforts with full pitch windings have spurred interest. With the full pitch winding, twice the area of copper is energized at any given time as compared to the concentrated winding SRM, leading to potentially higher machine efficiency. This paper investigates the performance of 15 kW full pitch winding SRM under the following three current excitation patterns: unipolar, bipolar 120-degree conduction, and bipolar 180-degree conduction. In addition, the full pitch winding SRM is compared with the standard concentrated coil SRM. Finite element analysis (FEA) shows the highly nonlinear behavior of the mutual inductance of full pitch winding SRM. It is shown that the mutual inductance and self inductance change significantly depending on the current excitation patterns. Simulation results based on Simulink for each full pitch topology and concentrated coil SRM are presented at low and high speeds.