To clarify the relation between the ON-voltage of power semiconductors in the inverter and the magnetic properties such as iron loss and the magnetic hysteresis curves, the PWM shaped voltage with the virtual ON-voltage is realized experimentally by means of an arbitrary function generator and an amplifier excitation. The iron loss and the width of the minor loop increase linearly with the increasing ON-voltage. Therefore, if the inverter made a virtual voltage waveform generated by a low ON-voltage of the power semiconductor, the iron loss would be reduced.