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In a PWM-controlled, variable voltage/variable frequency inverter, a pulse mode, which is identified by a number of voltage pulses within one cycle of an output AC voltage of the inverter, is changed in accordance with a frequency of the output AC voltage and an output AC voltage factor, which is a

In a PWM-controlled, variable voltage/variable frequency inverter, a pulse mode, which is identified by a number of voltage pulses within one cycle of an output AC voltage of the inverter, is changed in accordance with a frequency of the output AC voltage and an output AC voltage factor, which is a ratio of an output AC voltage to be produced by the inverter at that time to a maximum value of the output AC voltage which can be produced under a then-present value of a voltage of a DC voltage source for the inverter.

대표청구항 ▼

A control apparatus for an inverter, which is fed with a DC voltage and supplies an induction motor with a variable voltage/variable frequency output AC voltage produced in accordance with a PWM control, comprising: detection means for detecting a frequency (an output frequency) of the output AC vol

A control apparatus for an inverter, which is fed with a DC voltage and supplies an induction motor with a variable voltage/variable frequency output AC voltage produced in accordance with a PWM control, comprising: detection means for detecting a frequency (an output frequency) of the output AC voltage of the inverter; output AC voltage factor calculating means for calculating an output AC voltage factor, which is a ratio of an output AC voltage to be produced by the inverter at that time to a maximum value of the output AC voltage, which can be produced by the inverter under a then present DC voltage, on the basis of the output frequency from said detection means and the DC voltage; pulse mode determining means for determining a pulse mode in the operation of the inverter, in which a particular number of voltage pulses is maintained within one cycle of the output AC voltage, on the basis of the output frequency from said detection means and the output AC voltage factor from said output AC voltage factor calculating means modulation factor calculating means for producing the modulation factor on the basis of the output AC voltage factor from said output AC voltage factor calculating means and the pulse mode signal from said pulse mode determining means; and PWM control means for producing gate signals for the inverter on the basis of the modulation factor and the output frequency in accordance with the pulse mode determined in said pulse mode determining means.