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The CPU of a power tool -Electric hand mixer hear is high quality stator and rotor
- Dec 06, 2018 -

The CPU of a power tool -Electric hand mixer hear is high quality stator and rotor

What is stator and rotor?

To put it simply: the fixed part of the motor is called the stator, on which the pair of DC-excited stationary main poles are mounted; and the rotating part (rotor-rotor) is called the armature core, which is mounted on it. The armature winding generates an induced electromotive force after being energized and acts as a rotating magnetic field. The electromagnetic torque is generated for energy conversion. The shape of the stator winding is distinguished from the embedded mode. The stator winding is different according to the shape of the coil winding and the embedded wiring. Divided into two types: centralized and distributed.

Centralized winding editing

The concentrated winding is applied to the salient pole stator, which is usually wound into a rectangular coil, and the warp yarn is wrapped and shaped, and then dried by dipping paint, and then embedded on the core of the convex magnetic pole. The excitation coils of general commutator motors (including DC motors and general purpose motors) and the main pole windings of single-phase shroud pole salient motors use concentrated windings.

Centralized windings usually have one coil per pole, but also in the form of a drain (hidden pole). For example, a frame-type shaded pole motor is a motor that uses two coils to form a two pole.

Distributed winding editing

The motor stator of the distributed winding has no convex poles, and each magnetic pole is composed of one or several coils to form a coil group according to a certain regularity. After being energized, magnetic poles of different polarities are formed, so it is also called a hidden pole type. According to the different arrangement of the embedded wiring, the distributed winding can be divided into two types: concentric and stacked.

(1) Concentric winding The concentric winding is composed of several coils of similar shape but different sizes, which are embedded in a return shape in the same central position. Concentric windings can be constructed as two- or three-plane windings depending on the wiring. The stator winding of a three-phase asynchronous motor of a general single-phase motor and a part of a low-power or large-span coil is of this type.

(2) Stacked windings The windings are generally formed by coils of the same shape and size, with one or two coil sides embedded in each slot, and uniformly distributed one by one at the outer ends of the slots. The stacked windings are divided into a single stack and a double stack. Each slot is embedded with only one coil side, which is a single-stack winding, or a single-stack winding; each slot is embedded in two coils of different coil groups when it is placed in the upper and lower layers of the slot, which is a double-stack winding, or It is called double stack winding. Depending on the way the embedded wiring changes, the stacked windings can be derived from cross-over, concentric crossover and single-dual hybrids. At present, the stator windings of the three-phase asynchronous motor with larger power are mostly double-stacked; while the small motors use the derivative type of the single-stack winding, but the single-stack winding is rarely used.

Rotor winding editing

The rotor winding of the AC asynchronous motor is divided into two types: the squirrel cage type and the winding type. The squirrel-cage structure is relatively simple. It is usually made of alloy aluminum cast into the inner core groove of the rotor and short-circuited by the end rings. It is also embedded with copper strips to re-solder the copper end rings. In order to improve the starting performance, the squirrel cage type can be made into special types such as deep trough and double squirrel cage. The wound rotor winding is the same as the stator winding. In addition to the various windings described above, a wave winding can be used. The corrugated winding is a single-turn or a few-turned rod-shaped unit coil. After being embedded, two components are welded at the end into one coil, and the whole winding is formed. The wiring principle is different from the above winding, but the shape and the double-stack winding similar. Waveform windings are commonly used in large AC motor rotor windings and armature windings of DC motors.

The different wiring forms of the stator windings can form different polarities, and the motors can be classified into two types according to their polarity.

1. Pseudo-polar winding

A motor stator having four salient poles, each of which forms a magnetic pole; and the adjacent coils form a different polarity; four poles are formed on the four salient poles. Therefore, in the galvanic winding, each set of coils forms a magnetic pole, that is, the number of coil groups of the winding is equal to the number of magnetic poles. In addition, in order for adjacent magnetic poles to exist in pairs of N and s polarities, the currents in the adjacent two sets of coils must be reversed. Therefore, the connection mode of two adjacent coil sets must be reversed in series, that is, in the electrical terminology, it is called "head joint" and "tail tail".

In fact, except for DC motors and single-phase salient pole-shielded motors, there is generally no protruding pole in the stator. This figure is a schematic drawing to illustrate the problem more vividly.

2. Bungee winding

Figure 2-2 is an image diagram of a stator of a four-pole winding. It can be seen from the figure that the polarities of the adjacent two sets of coils are the same, both are s poles. Due to the principle of repelling the same polarity, the magnetic field formed by the coils is returned to the closed magnetic circuit via the adjacent salient poles; thus, there is no coil. An opposite polarity N magnetic pole is produced on the salient pole. Therefore, in the buck-type winding, each coil group will form a pair of magnetic poles, and the number of coil groups per phase winding is half of the number of magnetic poles.

In the buck-type winding, since the polarity of the magnetic poles generated by each set of coils is the same, the current directions in all the coils are the same, that is, the adjacent two coil sets are connected in series, as shown in (b). This type of wiring is commonly known as "end-to-end", that is, "tail joint" connection.

The motor winding is a combination of a phase or a whole electromagnetic circuit formed by a coil group; and the coil group is formed by one or more coils being connected in series. Therefore, the coil is the basic component of the motor winding, and is also wound in a certain shape by an insulated wire (a circular or rectangular section wire). The coil can be a turn or can be wound by hundreds of turns. The number of turns depends mainly on the supply voltage and the parameters of the electromagnetic part of the motor and is determined by calculation.

There are many shapes of the motor coil, but the basic structure is composed of three parts, that is, the straight line embedded in the core groove is called the effective side, and one coil has two effective sides, which is an effective part for generating electromagnetic energy conversion; The part of the effective side is outside the slot at the ends of the core after the coil is fitted, and is called the end of the coil. It is an indispensable part of the coil, but it cannot be used for energy conversion; the lead is the head and tail of the coil after winding. It is also the connection point for the coil current.

The winding and embedding of the concentrated winding is relatively simple, but the efficiency is low and the running performance is also poor. Most of the current AC motor stators use distributed windings. According to different machine types, models and coil winding process conditions, the motors are designed with different winding types and specifications, so the technical parameters of the windings are also different.

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