Observer based robust tension control for a segmented stator coil winding machine

A control system for automatic regulation of the tension of the copper wire in a winding machine for segmented tooth stator coils of permanent magnet synchronous motors is presented. The use of a transducer to directly measure the tension force is avoided. Instead, an observer is used to estimate the tension force using a model of the permanent magnet synchronous tensioning motor, the only measurements being the rotor speed together with the direct axis and quadrature axis stator current components. This tension force estimate is then used as if it was a measurement to feed a second observer based on a complete model of the controlled plant, providing a state estimate. The control variables are the direct and quadrature axis stator voltage components. Forced dynamic control is applied to control the direct axis stator current component to nearly zero, as required for the vector control while observer based robust control is applied to control the tension force. The simulations predict that the system is very insensitive to winding feed speed variations and also to variations in the length of wire in tension feeding the stator segment coil being wound.