US Patent 11407536 Stretch wrapping machine with variable frequency drive torque control

A method, apparatus and program product utilize a torque control algorithm constrained by a speed window to control the dispense rate of a packaging material dispenser when wrapping a non-cylindrical load with packaging material. In particular, a dispenser motor of the packaging material dispenser that is controlled by a VFD may be driven to maintain a substantially constant torque, while also constrained to operate within a speed window that is based at least in part on a rate of relative rotation between the packaging material dispenser and the load.