Driving apparatus of electric motor for reduction roll

A driving apparatus of electric motors for reduction rolls in a twin drive rolling mill in which top and bottom reduction rolls are individually driven by an upper electric motor and a lower electric motor, characterized by comprising an upper electric motor speed controller that obtains an upper electric motor torque current reference by inputting a deviation of an actual upper electric motor speed from an upper electric motor speed reference, an upper electric motor torque current limiter and an upper electric motor current controller that control a torque of the upper electric motor so that the deviation of the actual upper electric motor speed from the upper electric motor speed reference becomes zero, a lower electric motor speed controller that obtains a lower electric motor torque current reference by inputting a deviation of an actual lower electric motor speed from a lower electric motor speed reference, a lower electric motor torque current limiter and a lower electric motor current controller that control a torque of the lower electric motor so that the deviation of the actual lower electric motor speed from the lower electric motor speed reference becomes zero, and a torque distribution controller that is provided between the upper and lower electric motor speed controllers and between the upper and lower electric motor torque current limiters, compares the upper and lower electric motor torque current references with a torque current limit value, and obtains a desired rolling torque, in a case where either of the upper and lower torque current references exceeds the torque current limit value, by adding an amount in excess of the torque current limit value to the other torque current reference, thereby minimizing a speed decrease amount during material entry.