Design and construction of a rotor for switched reluctance motor to improve torque profile

In this article the effect of non-uniform air gap on a 4/2 switched reluctance motor is studied. In order to do this, two rotors are designed, optimized and fabricated. The first rotor has uniform air gap in aligned position and the second rotor in half of pole is the same as the first but in another half of pole, air gap can be non-uniform. The purpose of optimization is achieving a desired torque profile which reduces torque ripple in high speeds and at the same time increases the average torque. Finite element analysis is used for calculating torque profile and genetic algorithm is used for optimization, both by MATLAB. Optimization variables are rotor pole arc and width of rotor yoke. For the second rotor, another variable which determines the amount of uniformity of air gap is added. The analysis results show that the motor with non-uniform air gap is more coincident with the desired torque profile. Experimental results of prototype motor confirm the analysis results.