Rockwell Automation WebPak 3000 DC Drive Application Workbook Version 1.1 - Manual (Page 81)

Using the WebPak 3000 Drive for Web Applications: The Basics A-3
A.2 Application Guidelines
Guidelines for the following applications are described in section A.2.1 through A.2.8:
• Speed regulators
• Current regulators
• Position regulators
• Tension regulators
• Voltage and field control
• Diameter calculator
• Flying splice unwinds
• Flying transfer winders
A.2.1 Speed Regulators
Most WebPak 3000 drives will be applied using speed loop control. The speed loop
operates with either analog tachometer or digital encoder feedback with a 10 ms
update rate.
A self-tuning algorithm is used to tune the WebPak 3000 speed loop and to calculate
the system inertia. The reflected load that is used in self-tuning a variable diameter
section unwind or winder is the empty core inertia. The system inertia can also be
entered through the OIM or WebPakCS software if this has already been manually
calculated. Otherwise, the system inertia calculated by the self-tuning algorithm will be
used by the drive.
Sections that use tension, position or current major loops are designed to operate in
cascade with the inner speed loop. The speed loop control algorithm includes
adaptive gain, which maximizes speed loop performance on a variable diameter
application. The adaptive gain profiler can be enabled or disabled via the OIM or
WebPakCS software.
Tension major loops are also designed to operate in a parallel operation. In parallel
operation, the tension loop error signal is used as an input to the high and low limits of
the speed loop regulator, and the speed loop runs in limit.
A.2.2 Current Regulators
Web transport systems have two types of applications that cover the majority of drives
configured as current regulators.
The primary application uses DC armature current closed loop control to profile motor
shaft torque and thereby establish web tension in a web process zone. This zone
could be a constant diameter section, such as a pull roll, or a variable diameter drive
section, such as an unwind or winder.
This control concept can be described as “open loop” tension control, since web
tension is indirectly controlled by feedback of motor torque.