| 摘要 |
PURPOSE:To eliminate discharge circuit by performing output frequency reduction control for an inverter at voltage drop side and balancing the voltage with power regenerated through an AC motor. CONSTITUTION:AC motors 3, 13 are operated through inverters 2, 12 connected in series with a DC power source 1. Voltages across capacitors C1, C2 are detected through voltage detectors 4, 14, then the differences between the capacitor voltages and a voltage VS, which is half of source voltage, are fed through integrator/amplifiers A1, A2 to the output of a frequency setter VR with the polarity being inverted. Since the frequency command for one of the capacitors C1, C2, having lower voltage, drops and the inverters 2, 12 are controlled by the dropped frequency command, corresponding one of the capacitors C1, C2 is charged with power regenerated through the AC motors 3, 13 thus maintaining voltage balance. |
