Goodrive350A series high-performance multifunction VFD
Basic operation guidelines
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regulation improvement.
(4) Material feeding interrupt detection and processing module: The function is valid when material
feeding interrupt detection has been enabled.
(5) Pre-drive: This function is applied to automatic reel change. After the VFD is started if the
pre-drive function terminal is valid, the roller runs at the set linear speed. If the terminal is invalid, the
VFD will automatically switch to the corresponding control mode after a period of time.
5.5.20.3 Open-loop torque mode
Open loop means there is no tension feedback signal. In this mode, stable tension can be achieved
by means of motor torque control. The rotation speed automatically changes with the linear speed of
material. The control basis is as follows: For a reel control system, the relationship between the
tension F of the roller with materials, present roll diameter D and output torque of the shaft is: T = F ×
D /2. If the output torque can be adjusted according to the variation of roll diameter, the tension can
be controlled. In order to ensure the constant tension in the process of acceleration and deceleration,
the internal friction compensation module and inertia compensation module have been built in the
VFD to calculate the real time rotation inertia, and compensate the torque according to the actual
speed change rate. The control principle is shown in the following figure.
Calculate the frequency
according to the tension
T=J*d
Ω/dt
+
+
Tension
reference
Rotational inertia of
mechanical system
Rotational inertia
of material
Basic reference
frequency
Inertia torque
compensation
Motor reference
frequency
+
+
Friction torque
compensation
+
+
Relevant modes:
(1) Linear speed input module: It has two functions: calculating the synchronous frequency in torque
control according to the linear speed, and calculating the roll diameter according to the linear speed.
(2) Tension setting module: Used to set the tension adapting to the control system. It needs to be
adjusted according to the actual situation. After confirmation, the value remains the same. In some
scenarios where the forming effect after winding needs to be improved, the tension taper function can
be used so that the tension decreases as the roll diamter increases.
(3) Real-time roll diameter calculation module: The calculation accuracy of roll diameter determines
the control performance. The roll diameter can be calculated according to the VFD output frequency
and the linear speed. In addition, it can also be calculated through the thickness or sensor. The linear
speed is widely used for the calculation. If the set linear speed is used for the calculation, you you
choose whether to enable the function of roll diameter change limiting.
(4) Torque compensation module: Torque compensation includes friction torque compensation and
