Improvement of yoke materials for a PM stepping motor

Recently, there are growing demands for motors that feature greater mechanical output, higher speed, and lower power consumption. Improvement of electric machine conversion efficiency of PM stepping motors is required to satisfy these needs. This paper reports on the examination of the efficiency improvement of a PM stepping motor. We examined yoke materials and magnetic annealing conditions to reduce iron losses, which are divided into eddy current losses and hysteresis losses. As a result, we found a better yoke material and annealing conditions that were able to decrease eddy current losses and hysteresis losses of the motor. The optimized PM stepping motor posted an efficiency of 63%, compared to the 40-45% efficiency of a conventional PM stepping motor.