| 摘要 |
<p>The present invention is provided with: an inverter circuit in which a plurality of switching devices are configured to use a direct-current voltage (+Ed, -Ed) as a power source, and to output the PWM voltage waveform at three levels (+Ed, 0, and -Ed); and a control circuit for turning the plurality of switching devices on and off, and generating the PWM voltage waveform on the basis of the output of the inverter circuit. The control circuit: controls the amplitude of the fundamental frequency component of the PWM voltage waveform in proportion to a prescribed modulation factor (M); during one cycle of the fundamental frequency component, fixes the output voltage of the inverter circuit at +Ed, 0, or -Ed relative to a specified phase angle range for the fundamental frequency component; fixes the output voltage of the inverter circuit at all of the voltages +Ed, 0, and -Ed in the specified phase angle range when the modulation (M) is 2/3 or greater; and fixes the output voltage of the inverter circuit at a voltage of 0 in the specified phase angle range when the modulation (M) is less than 2/3.</p> |
