CONTROL APPARATUS, METHOD, AND CONTROL PROGRAM FOR THREE-PHASE INDUCTION MOTOR

PROBLEM TO BE SOLVED: To reduce the frequency of switching on a five-leg inverter in a technique to control an induction motor using a five-leg inverter. SOLUTION: A pulse width conversion means 14 converts line voltage commands Vu1v1* and the like into pulse widths Tu1v1 and the like. A pulse placement determining means 16 divides the first half and the second half of a modulation period T severally into segments T1, T2, T3, with the segment T2 being the segment, wherein all the line voltages Vu1v1 and the like become zero. The line voltage with the shortest pulse width is placed in the segment T1, and the line voltage with the next shortest pulse width is placed in the segment T3. The line voltage, having the longest pulse width, is divided and placed into the two segments T1, T3. A switching pattern selecting means 18 selects a switching pattern, that turns all three line voltages Vu1v1 and the like into zero, to achieve a minimum value for the total frequency of switching before and after the segment T2. COPYRIGHT: (C)2004,JPO