| 摘要 |
PROBLEM TO BE SOLVED: To change the electromagnetic sound of PWM from noisy monochromatic sound quality to white noise by changing the time ratio of the half cycle of a plurality of PWM modulations in the sample period for controlling current. SOLUTION: When the cycle and the current control cycle of PWM modulation are to be synchronized by a PWM inverter, the sample period of current control is set to two times larger or more than the half cycle of a PWM carrier. Then, the sample cycle period itself is made constant, and a plurality of half cycle periods of PWM included in it are distributed with a certain ratio instead of being equally distributed, thus changing time width for each half cycle and hence modulating a carrier frequency and changing the electromagnetic sound of PWM from noisy monochromatic sound quality to white noise for reducing noise in terms of auditory sensation. |
