My application: a horizontal strip accumulator (looper) tension control.

Components: PLC S7 412 ->Profibus network -> Simovert Masterdrives VC DC-AC -> 55kW motor

Via PLC and Profibus I set P486 (S.Torque Setp) and P506 (S.Torq Add) with fixed value, and P587 (Slave). see attachment Drivemonitor file.

When rotation of motor is in first direction (forward movement of looper train - positive speed of motor) the torque is about 4 tones ( measured with LORENZ tension sensor ).

When the rotation is changed ( reverse movement - negative speed of motor) the torque is about 7 tones ( is higher than first direction). The current of motor is same for both direction of rotation.

I didn't change any parameters for time when the speed is negative.

Any time the speed reference is 100% positive.

At point of change speed direction, the real torque change ( 4 tones for positive speed and 7 tones for negative speed).

Please, help me to solve this problem.

Thanks for your answer Ahmed.

Torque setpoint comming from PLC is same for both direction ( one fixed value). I verified in Simovert, P486 (S.torque Setp) and P506 (S.torq Add) stay fixed.

The PLC transmit to Simovert same datas all the time.

The data, that is send by PLC to Simovert, is not depend of rotation direction.