| 摘要 |
PURPOSE:To simplify the structure and to reduce manufacturing cost by charging at least two backup power sources with regenerative power to be fed from a regenerative switch circuit through an inverter main circuit upon interruption of power supply from an AC power source. CONSTITUTION:A power interruption detecting circuit 41 detects power interruption and provides power interruption detecting signals to a control circuit 37 and a regenerative switch circuit 39. The control circuit 37, which is fed with power from a battery 38 for control circuit, gradually lowers the frequency of control signal being fed to an inverter main circuit 35 such that the frequency of the control signal will be lower than the frequency corresponding to the rotation of a motor 31. Consequently, regenerative power is fed from the motor 31 through the inverter main circuit 35 to the DC source line 34 side. The regenerative switch circuit 39 conducts between input and output terminals based on the power interruption detecting signal. By such arrangement, batteries 49a, 49b for bearing are fed with regeneration power from the inverter main circuit 35 through the regenerative switch circuit 39 and charging operation is started. |
