| 摘要 |
PROBLEM TO BE SOLVED: To allow predetermined currents to surely flow to an AC motor in the case of controlling the driving of the AC motor by using a power conversion device which converts direct currents into three-phase currents by using pulse width modulation by a switching element, and supplies the currents to the AC motor, and to surely suppress the occurrence of a voltage distortion across a whole speed range to the highest speed.SOLUTION: A carrier frequency setting section 60A for setting a carrier frequency as the frequency of a carrier to be used for pulse width modulation in response to a primary frequency, in which a carrier frequency is set so as not to exceed an upper limit value to be determined in accordance with the cooling capability of the switching element of a PWM invertor 2 which supplies a three-phase AC power to an AC motor 1 and the scale of currents flowing to the AC motor, and such that its rate to the primary frequency does not fall below a predetermined value is arranged in a control device 3A which controls the PWM invertor 2. |
