Inverter that adjusts voltage command values and control method of inverter

A control device of an inverter comprising a plurality of series circuits, each of the series circuits being formed by two semiconductor switching elements being connected in series, a connection point between the two semiconductor switching elements being used as one of output terminals of polyphase alternate-current (AC) electrical power, the series circuits being connected in parallel with each other with respect to a capacitor connected in parallel with a direct-current (DC) voltage source,

• the control device being configured, in generating PWM pulses for controlling the semiconductor switching elements by comparing output voltage command values of respective phases with a carrier,
• to generate modified PWM pulses of respective phases based on an output of a counter common to the respective phases;
• and
• to control the semiconductor switching elements by using the modified PWM pulses,
• wherein each of the modified PWM pulses is configured such that, in a period corresponding to one or more cycles of the carrier, a sum of one or more ON periods of the modified PWM pulse is substantially equal to a sum of one or more ON periods of a PWM pulse of a corresponding phase among the respective phases, the PWM pulse being obtained by comparing a voltage command value with the carrier, and
• at least one of a generation timing and a generation frequency of the ON periods of at least one of the modified PWM pulses is different from the PWM pulse, exceeding a necessary extent for control.

An inverter comprising a plurality of series circuits, each of the series circuits being formed by two semiconductor switching elements being connected in series, a connection point between the two semiconductor switching elements being used as one of output terminals of polyphase alternate-current (AC) electrical power, the series circuits being connected in parallel with each other with respect to a capacitor connected in parallel with a direct-current (DC) voltage source,

• the inverter being configured, in controlling the semiconductor switching elements by using PWM pulses obtained by comparing output voltage command values of respective phases with a carrier,
• to generate modified PWM pulses of respective phases based on an output of a counter common to the respective phases;
• and
• to control the semiconductor switching elements by using the modified PWM pulses,
• wherein each of the modified PWM pulses is configured such that, in a period corresponding to one or more cycles of the carrier, a sum of one or more ON periods of the modified PWM pulse is substantially equal to a sum of one or more ON periods of a PWM pulse of a corresponding phase among the respective phases, the PWM pulse being obtained by comparing a voltage command value with the carrier, and
• at least one of a generation timing and a generation frequency of the ON periods of at least one of the modified PWM pulses is different from the PWM pulse, exceeding a necessary extent for control.