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我国露天矿山现有的电动挖掘机为原动机－发电 机──电动机组的控制方式，该方式存在以下缺点：（１）系统中间继电器多，故障率高；（２）由于挖掘机特性，系统常处于过流运行状态，磁场调节难以控制，经常造成发电机过载而烧坏的现象；（３）机组在整个工作过程中不能停机，
The existing electric excavators in the open-pit mines of our country are the control mode of the prime mover-generator-motor unit, which has the following disadvantages: (1) the system has many intermediate relays and the failure rate is high; (2) due to the characteristics of the excavator Often in the over-current operation, the magnetic field is difficult to control, often causing the phenomenon of generator overload and burn out; (3) Unit in the entire process can not be shut down,