Performance and characteristics of three-phase single-layer winding end connection method
1. Equal width type (stacked type)
The coils are equidistant, with all coils having the same pitch, making the wire mold easy to adjust; the coil pitch is shorter than the pole pitch (full pitch), saving wire; a single-layer winding has fewer coils, saving time in winding, but with poorer electrical performance.
2. Concentric type
The winding is a single-layer wiring with a high slot fill factor; the average coil pitch is equal, the winding end length is large and consumes a lot of wire, and the leakage flux is large and the electrical performance is also poor; layered winding can be used to form "double-plane" or "triple-plane" windings, which makes winding convenient and is mostly suitable for two-pole motors.
3. Cross-type
The windings are of full pitch, but the average coil pitch is relatively short, resulting in less wire consumption. However, the number of coils and the pitch in each group are not equal, which increases the difficulty of the winding process. The slot fill factor is relatively high, resulting in poor electrical performance. In addition, the end connection method can also be a concentric cross type, that is, changing two coils of equal width into a concentric type.
4. Three-phase single-layer 4-pole 36-slot winding end connection method
Given the three-phase 4-pole 36-slot configuration, we know that the number of slots per pole phase of this winding is q=3. There are three possible ways to connect the ends, as shown in Figures (a), (b), and (c), where only one phase is connected.
In practice, the choice of which end connection method to use is not a consideration for repair personnel, but rather for designers. For repair personnel, the original design data is generally the crucial basis for rewinding the motor and cannot be altered.
5. Three-phase single-layer 4-pole 24-slot winding end connection method
Based on the two basic parameters of three-phase 4-pole 24-slot, the number of slots per pole phase can be calculated to be 2. According to the rules, there are three end connection methods, as shown in the figure below.
In summary, the above-mentioned single-layer winding types have advantages such as high slot utilization, low risk of phase-to-phase short circuits, fewer coils, and less winding time, and are widely used in small motors. In commonly used Y-series motors, single-layer lap windings are used for 4, 6, and 8-pole motors with q=2; single-layer cross windings are used for 2 and 4-pole motors with q=3; and concentric windings are used for 2-pole motors with q=4. These winding types are frequently seen in daily repair work. Furthermore, due to structural limitations, single-layer windings have thicker winding ends, making them difficult to shape and unable to utilize appropriate short pitch to improve the electromagnetic performance of the winding. This is why single-layer winding motors generally have poorer performance.
