From the analysis of the selection of motor winding conductors, the stator part is mainly copper wire (early there were aluminum wire motors, and some small motors may still use aluminum wire), while the rotor part has cast aluminum rotors, cast copper rotors, copper bar rotors, wound rotors and permanent magnet rotors. First, from the analysis of the rotor bar structure, the cast copper rotor is the same as the cast aluminum rotor. The end rings at both ends of the rotor are connected to each bar to form a "cage type". The number of rotor pole pairs can change with the number of stator poles, but the performance of the whole machine is different under different pole numbers.

Secondly, the wound rotor can be a soft winding structure or a formed winding structure. The number of rotor poles is matched and wired according to the number of stator poles, that is, the number of poles of this rotor is fixed. Thirdly, we analyze the copper bar rotor. This type of rotor places the guide bar in the rotor core slot and connects it together through the end ring matching the guide bar. It is also a "cage-type" structure, but it is different from the process of cast copper rotor. This type of rotor is generally used in large-scale high-efficiency motors. The key process for manufacturing this type of rotor is the welding of the end ring and the guide bar. Some better motor manufacturers use medium-frequency welding, which better guarantees the welding quality. The overall welding effect is also very beautiful, but basically each specification of rotor needs to correspond to a set of molds. If there is no large batch, the manufacturing cost is relatively high. Finally, there is a wound motor rotor that uses copper bars, but the outside of the copper bars needs to be wrapped with insulating materials (glass fibers and insulating films) and matched with the insulation level of the stator. The wiring part is carried out according to the number of stator poles. In the manufacture of this rotor, welding is also a key point and a difficult point in quality control in motor manufacturing. The guide bar connection must pass through necessary auxiliary parts.

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