| 摘要 |
PURPOSE:To balance a plurality of input voltages and to prevent an overvoltage due to unbalance of the input voltages by connecting a plurality of power converters in series with a DC power source, and controlling it based on the differential voltage of the input voltages. CONSTITUTION:A positive terminal of a DC power source 1 is connected in series with a first 3-phase inverter 6 and a second 3-phase inverter 7. 3-phase induction motors 8A, 8B are connected to the inverters 6, 7. The difference of the input voltages of the inverters 6, 7 is detected by a differential voltage detector 19, and input to a frequency controller composed of an absolute value calculator 20 and a subtracter 22. A frequency controller controls the frequencies of the AC powers of the inverters 6, 7. Thus, generation of an overvoltage is prevented to prevent the damage of the inverter. |
