| 摘要 |
PURPOSE:To largely improve the power factor by connecting two inverters in series at low speed operating time and connecting two inverters in parallel at high speed operating time. CONSTITUTION:An electromagnetic switch 11 is excited in a high speed operation range, and the contacts (c) of changeover contactors 11a, 11b are connected at the contacts (a) side. Thus, the input terminals of inverters 6, 7 are connected in parallel, and DC current having voltage Ed an current Id/2 is flowed to the input terminals of the inverters 6, 7. On the other hand, the switch 11 is demagnetized in a low speed operation range, and the contacts (c) of the contactors 11a, 11b are connected at the contacts (b) side. In this manner, the input terminals of the inverters 6, 7 are connected in series, and a DC current having voltage Ed/2 and current Id is flowed to the input terminals of the inverters 6, 7. |
