Abstract: A current component, in which a phase angle is different by a predetermined reference angle from a magnetic flux occurring in an inductive load, is brought to a q-axis current. The q-axis current is computed on the basis of phase current. A phase angle of the magnetic flux is detected. A q-axis-current control phase and a reference potential phase are determined on the basis of the result of pulse-width-modulation computation and the phase angle. The q-axis-current control phase is controlled in a pulse-width-modulation manner. A potential of the remaining reference potential phase if fixed to a reference potential. Thus, interference among the phases is prevented to reduce current ripple.

Abstract: Method and system of controlling an inverter are disclosed. A reference rotary magnetic flux as a desired magnetic flux of an AC motor is so determined as to make a uniform rotary motion, an actual magnetic flux of the AC motor is detected, voltage vectors are selected such that a deviation between this reference rotary magnetic flux and the magnetic flux of the AC motor may be a value held within a tolerance, and switching elements of the inverter are on-off controlled so that the voltage vectors thus selected can be obtained.