| 摘要 |
PROBLEM TO BE SOLVED: To precisely output/estimate voltage by adding correction values discriminated by phases and the polarity of the output current of the respective phases to the voltage commands of the respective phase, and making signal waves compared with a modulation wave. SOLUTION: A correction value storage unit 5ap stores a correction value when the current of an a-phase is positive and a correction value storage unit 5an stores the correction value when the current of the a-phase is negative. Correction value storage units 5bp, 5bn, 5cp and 5cn are similar. A switch 11a selects the output of the correction value storage unit 5ap when the current of the a-phase is positive and selects a value obtained by multiplying the output of the correction value storage unit 5an by -1 when the current of the a-phase is negative. The correction values of the respective phases selected by the switches 11a, 11b and 11c are added with the voltage commands of the respective phases, which are the outputs of a voltage command generator 3 in adders 4a, 4b and 4c. The outputs of the adders 4a, 4b and 4c are compared with the triangular wave of the output of a modulation generator 7 in comparators 10a, 10b and 10c. They are outputted to a PWM inverter 1 as switching signals. |
