FR-A800 Inverter for Wind/Unwind Applications

The FR-A800-R2R inverter offers a host of dedicated functions including automatic winding diameter calculations, automatic dancer speed control, and sensorless torque control to perform fast, smooth, and accurate winding and unwinding applications. These complex functions do not require additional sequence or motion control programming to implement because the FR-A800-R2R inverter has a built-in PLC, eliminating the need for a separate controller, and utilizes easy-to-use parameterization to set and enhance functions. Even without advanced knowledge of tension control, users can control winding/unwinding (roll-to-roll) easily with the dedicated functions.

Key Benefits

  • Dancer control function – PID control function keeps the dancer roll position and eliminates hunting, allowing for efficient wind/unwinding applications.
  • Winding diameter compensation function – Speed and torque is controlled to allow for changes in the diameter of the winding and unwinding shafts during operation for quick and easy system setup.
  • Tension control (inertia compensation/mechanical loss compensation) – Torque required for acceleration/deceleration and the mechanical loss compensation torque are controlled, keeping material tension constant and reducing wrinkling or deformations within the material roll.
  • Dancer PI automatic tuning function – Optimum PI gain is automatically set by the inverter, reducing system startup time.
  • Speed control proportional gain compensation function – Actual response level is corrected along with changes in the inertia ratio of the winding/unwinding shafts improving the tracking ability to automatically allow for changes in the diameter, contributing to overall cost savings of the system.
  • Speed Control and Gain Compensation – PID control utilizes the feedback from the detected dancer roll position or feedback from the tension sensor. Stable control can be achieved in combination with the winding diameter calculation. By adjusting the speed control proportional gain according to the winding diameter, the response level can be kept constant. The actual response level corrections along with the changes in the inertia ratio of the winding and unwinding shafts in order to improve the tracking ability to allow for the changes in the diameter.
  • Tension Sensor Feedback Torque Control – The output torque of a motor is controlled to maintain constant tension on the material, by raising the commanded torque to compensate for mechanical loss caused by factors such as friction on the dancer roll or winding/unwinding shaft. During acceleration/deceleration, constant tension is maintained on the material by adjusting the variable tension on the winding and unwinding sides. Adjusting the tension on the material, makes it possible to avoid imperfections such as wrinkles or deformation caused by the increase in diameter. The cushion time should be set for the tension command to avoid sudden changes in roll tension.

The article is taken from Mitsubishi Electric Website