Winding is one of the most important processes in the manufacturing process of electric motors, and with the development of electric motors, different “discipline categories” have been created.[1]

Stator winding is distinguished by the formation of magnetic poles

The stator winding can be divided into two types: The salient type and the Non-Salient type, according to the relationship between the number of poles and the actual number of poles formed by the distribution of windings.

Salient pole winding

In salient winding, each set of coils forms one pole, and the number of coils in the winding is equal to the number of poles.
In salient winding, in order to separate the polarity N and S, the current direction in two adjacent coils must be opposite, i.e. the two adjacent coils must be connected in such a way that the tail end connects to the tail end and the head end connects to the head end (in electrical terminology, “tail to tail, head to head”), i.e. reverse series connection.

Schematic of 2-Pole Salient Winding

Non-Salient winding

In a Non-Salient winding, each coil forms two poles, and the number of coils in the winding is half the number of poles because the other half of the poles are formed by the magnetic lines of force from which the coils generate the poles.
In a Non-Salient winding, the polarity of the poles formed by each coil is the same, so that the current in all coils is in the same direction, i.e. the two adjacent coils should be connected in such a way that the end is connected to the first end (in electrical terminology, “tail joint”), i.e. in a series connection.

Schematic of 4-pole Non-Salient Winding

The stator winding of the shape with the flush-mounted wiring distinguish

Stator windings can be divided into two categories: centralized and distributed, depending on the shape of the winding and the wiring method.

Centralized winding

The centralized winding generally consists of only one or several rectangular frame coils. After winding, the coil is wrapped and shaped with gauze tape, and then embedded in the core of the convex pole after dipping and drying. This type of winding is used in the excitation coils of DC motors, general-purpose motors, and the main pole winding of single-phase shaded-pole motors.

Distributed winding

The stator of a distributed winding motor has no convex pole palm, and each pole is composed of one or several coils wired in a certain pattern to form a coil group. According to the different forms of embedded wiring arrangement, the distributed winding can be divided into concentric and iterative.

Concentric winding

Concentric winding is the same coil group of several rectangular coils of different sizes, according to the same center of the position of the inlay arranged one by one into a zigzag type. Concentric winding is divided into single-layer and multi-layer.
Generally, single-phase motors and some small power three-phase asynchronous motors use this type of stator winding.

Iterative winding

Iterated winding is a type in which all coils have the same shape and size (except for single and double coils), and each slot is embedded with one coil side and evenly distributed one by one at the outer end of the slot. The iterative winding is divided into two types: single-layer iterative and double-layer iterative.
The single-layer iterative winding, or single iterative winding, is embedded with only one coil edge in each slot; the double-layer iterative winding, or double iterative winding, is embedded with two coil edges of different coil groups in each slot (divided into upper and lower layers).

The iterative winding has different variations of embedded wiring, and there are single and double coil cross-wiring arrangements and single and double-layer mixed wiring arrangements;
In addition, the embedded shape from the end of the winding is called chain winding, basket winding, in fact, all belong to the iterative winding. In general, the stator winding of a three-phase asynchronous motor is more often used in iterative winding.

Rotor winding

The rotor winding is basically divided into two types: squirrel-cage type and wire-wound type. The squirrel cage type has a simpler structure, and its winding used to be embedded with copper strips, but now most of them are cast aluminum, and the special double squirrel cage rotor has two sets of squirrel cage strips.
The winding rotor winding is the same as the stator winding, also divided into iterative and wave winding.

The wave winding is similar in appearance to the iterative winding, but the wiring is different in that the basic element is not a whole coil, but a single-turn unit coil, which is embedded and then welded one by one into a coil group.
Wave winding is generally used in rotor winding of large AC motors or armature winding of medium to large DC motors.[2]

7 types of stator winding methods

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