Inovance MD330, Руководство пользователя

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Chapter 2 Tension Control Principles
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2.2 Tension control scheme
There are two ways for tension control: to control the output torque of
the motor and to control the rotation speed of the motor. MD330 is
designed with two tension control modes for the two methods.
1. Open-loop torque control mode
Open loop means that there is no tension feedback signal, and the
inverter can realize the control through the output frequency or torque
only, which will not be affected if the inverter is in open loop vector
mode or close loop vector mode. The torque control mode means that
the inverter controls the motor’s torque rather than its frequency, and
the output frequency changes automatically following the speed of the
materials.
According to the formula F=T/R (where: F is the material tension, T is
the torque of the wind-up roll, R is the curling radius), if the torque of the
wind-up roll can be adjusted based on the change of the curling radius,
the tension of the materials can be controlled. This is the principle for
tension control in open loop torque mode. The reason for its feasibility is
that the tension of the material is from the torque of the wind-up roll only,
and the torque of the wind-up roll is mainly imposed on the materials.
The MD series inverter can correctly control the output torque of the
motor in closed loop vector mode (with speed sensor vector control).
However, to use this control mode, encoder must be installed (the
inverter shall be equipped with PG card).
2. Function modules related to open loop torque mode