Three-phase single-layer winding, three-phase double-layer winding and three-phase single-layer double-layer winding.
The common types of three-phase single-layer winding are equal width type, cross type and concentric type. Different types have different embedding rules, but the basic embedding rules are the same.
Single concentric winding
Concentric windings can be embedded with empty slots and hanging edges, but in practice, for convenience, the whole embedding method is usually adopted, that is, layered embedding. When the number of pole pairs p is even, the coil end of the winding is divided into two layers, forming a "biplane". Wherein each layer has one coil group for each phase; When the number of pole pairs p is odd, the end of the winding coil forms "three faces", and three-phase windings each occupy one layer. Although the whole embedding process is simple, the end lengths of each layer can not be equal for molding, so the three-phase parameters are unbalanced, which affects the electrical performance. When the electrical performance is required to be high, the empty slot hanging edge method can only be used, and the length of the three-phase end is equal by using the embedding law of the cross winding, thus ensuring the balance of the three-phase winding parameters. In fact, it is also cross-winding.
Three-phase double-layer winding
Three-phase large and medium-sized motors usually adopt double-layer winding embedding and overlapping coils.
Three-phase single-layer and double-layer winding is a kind of winding type with good performance, which evolved from overlapping short-distance winding. It combines the upper and lower in-phase effective edges of the double-layer winding into a single-layer large coil edge, so the total number of turns of the coil is less than that of the double-layer winding, which is convenient and time-saving. Moreover, the coil can adopt short pitch, which retains the advantages of double-layer short pitch winding to eliminate higher harmonics and improve electromagnetic performance, and is an advanced winding type.