| 摘要 |
PROBLEM TO BE SOLVED: To reduce current overshoots of an AC motor by adding quasi- impulsive voltages to q-phase command voltage of two-phase command voltages. SOLUTION: When performing current control of an AC motor 11, the AC motor 11 is driven by a PWM-type power converting means 12, while sensing its three-phase currents Ia, Ib, Ic with a three-phase current sensor 13, sensing an electric angleθe with an encoder 14, and sensing a sensed speedωe with a sensed-speed computing means 21. Then, from the information of the sensed electrical angleθe by a three-phase/two-phase coordinate transforming means 15, the coordinate transformation of three-phase sensed currents Iafb, Ibfb, Icfb is performed. Furthermore, after subtracting two-phase sensed currents Iqfb, Idfb from two-phase command currents I*q, I*d to calculate two-phase error currentsΔIq,ΔId, two-phase command voltages V*q, V*d are calculated by a proportional integral controller 17-a. Then, from the information of the electrical angleθe by a two-phase/three-phase coordinate transformation calculating means 18, the two-phase/three-phase coordinate transformation from the two-phase command voltages V*q, V*d to three-phase command voltages V*a, V*b, V*c is performed. Thereby, current overshoots of an AC motor can be much suppressed.
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