Trends in motor winding technology

Trends in motor winding technology

Because of the higher performance density, brushless EC drives (electronically commutated motors) with permanent magnet rotors are increasingly used instead of the asynchronous technology. Owing to the compact design, the copper content can be cut in half in the best-case scenario. The manufacturers of electric motors also demand more flexibility of the production technology. For producing asynchronous motors, drawing-in systems are usually used that are initially winding air-core coils only to draw them later into the stator with a tool. In contrast, the concentrated winding of EC stators is more flexible in the manufacturing process, energy saving when implemented, better adjustable during operation and it requires less space.

Hairpin winding has been widely used in electric motors in the automotive sector. This winding method offers the advantage of automated winding process. However, the large size of the conductors are prone to proximity losses resulting in high winding AC loss. Similar method, plug-in winding, has been proposed where the coils are pre-made with plug-in features (male-female). Compared to hairpin, the plug-in method offers the advantages of automated winding process and small conductors size, however, the disadvantage of high contact resistivity in the plug-in connectors could result in a thermal hot spots.