| 摘要 |
PURPOSE:To simplify a modulation circuit, and to obtain a low-cost variable speed gear by pulse-width modulating only one side of a switching arm while being separated from operation by a frequency signal and manufacturing the AC power of desired frequency and effective voltage. CONSTITUTION:Frequency signals omegaou, omegaov, omegaow are divided into switching signals UP-2, VP-2, WP-2 for an upper section and switching signals UN-2, VN-2, WN-2 for a lower section, to which the delay time is added, and output in order to prevent the short circuit of upper and lower switching by a modulation circuit 9. When the switching signal UP-2 for the upper section output from the modulation circuit 9 is at 'H', a transistor 12 is turned ON, a transistor 13 is turned ON, and a switching bridge 2 is turned ON. When the switching signal UP-2 for the upper section is at 'L', the transistor 12 and the transistor 13 are turned OFF, and the switching bridge 2 is turned OFF. Likewise, switching bridges 4 and 6 are turned ON/OFF by the switching signals VP-2, WP-2 for the upper section. |
