| 摘要 |
PROBLEM TO BE SOLVED: To eliminate the unbalance of load of each AC electric motor by a simple and inexpensive means, and freely increase and reduce the speed without limitation, when one machine device is driven by a number of AC electric motors controlled by respective inverter devices. SOLUTION: In a shield excavator 1 for driving a cutter 4 by a number of AC electric motors 2 controlled by respective inverter devices 7, an uniform torque command value 81 is given to each inverter device 7 to uniform the torque in the AC electric motors 2. Further, the speed signal S2 of the cutter 4 or the control signal 83 from the inverter device 7 is properly switched and fed back to perform a speed control. |
