Thermal Management of Switched Reluctance Machines
Thermal management is a complex but crucial aspect in electric machine design. For example, high temperature results in higher resistance and, hence, higher copper losses in the windings. An ineffective cooling system can lead to faster insulation degradation and increased winding failure rates due to increased thermal cycles and peak temperatures. It is a rule of thumb that a 10° Celsius increase in temperature will reduce the life expectancy of the windings by half. Temperature rise in a switched reluctance machine is caused by power losses generated by different physical mechanisms. Copper loss is a major loss component in all electric machines, especially at higher torque operation. The copper loss increases as the resistance increases with temperature. The temperature of the overhang conductors is typically higher than the active conductors. The active conductors in the slots are surrounded by electrical steel, which has higher thermal conductivity.