高次高調波を重畳した励磁における電磁鋼板の磁気ひずみ

抄録

Effects of superposition of higher harmonics on magnetostriction of non-oriented electromagnetic steel sheets were examined. Magnetostriction was measured using base-less semiconductor strain gauges applied at four points on ring specimens.
Higher harmonic components of magnetostriction were markedly observed by the PWM inverter excitation, although magnetic flux contained only a small amount of higher harmonic components. They have been considered to be the main cause of noise in the electrical machine driven by the inverter.
To evaluate contribution of the superimposed higher harmonic magnetization, specimens were magnetized at power frequency superimposed with the 49th higher harmonic frequency. Magnetostrictive components at the superimposed frequency resulted in about 100 times higher value than that obtained from magnetization at the frequency corresponding to higher harmonics. This fact means that the superimposed higher harmonics is supported by the rotational components of magnetization such as the 90° wall movement, which is in part included in magnetizing processes at the fundamental frequency.