Basic parameters of the windings of the basic knowledge of motor windings

31/05/2019

1. Mechanical angle and electrical angle
When the motor windings are distributed in the core slot, they must be embedded and connected according to a certain rule to output a symmetrical sinusoidal alternating current or generate a rotating magnetic field. In addition to being related to some other parameters, we also use the concept of electrical cost when reflecting the law of the relative position between coils and windings. It is known from mechanics that the circle can be equally divided into 360°, which is the mechanical angle usually mentioned. The angle unit for measuring electromagnetic relations in electrical engineering is called electrical angle. It divides the sinusoidal alternating current into 360° on the abscissa every week, that is, the conductor space changes correspondingly when passing a pair of magnetic poles. ° Electrical angle. Therefore, the relationship between the electrical angle and the mechanical angle in the motor is: electrical angle α = pole logarithm x P x 360 °. For example, for a two-pole motor, the pole pair p=1, then the electrical angle is equal to the mechanical angle. For a four-pole motor, p=2, then the motor has two pairs of magnetic poles on one circumference, and the corresponding electrical angle is 2×360°. =720°. And so on.

2, the pole distance (τ)
The pole pitch of the winding refers to the distance of each pole from the circumferential surface of the core. Generally speaking, it usually refers to the slot distance occupied by the center of two magnetic poles of the motor core. The stator core is calculated by the slot distance of the inner annular air gap surface; the rotor is calculated by the slot distance of the outer circumferential air gap surface of the iron core. Generally, there are two representation methods for the pole pitch, one is expressed by the length; the other is expressed by the number of slots, which is customarily expressed by the number of slots, and the general pole distance is τ=Z1/2p.

3, pitch (y)
The number of slots occupied by the two component sides of each coil of the motor winding is called the pitch, also called the span. When the coil element pitch is equal to the pole pitch pair, it is called the full-distance winding, y=τ; when the coil component pitch is less than the pole pitch, it is called the short-distance winding, y<τ; and when the coil component pitch is greater than the pole pitch, it is called the long distance. Winding y > τ. Because short-distance windings have many advantages such as short-end electromagnetic wire materials and high power factor, short-circuit windings are used in the double-stack windings with more applications.

4, winding coefficient
The winding coefficient refers to the product of the short-distance coefficient and the distribution coefficient of the AC distributed winding, that is,
Kdp1=Kd1Kp1.

5, slot angle (α)
The electrical angle between two adjacent slots of the motor core is called the slot angle, which is usually denoted by a, ie
α=total electrical angle/z1=p×360°/z1

6, phase belt
The phase band refers to the area occupied by each phase of the winding of each phase, usually expressed by the electrical angle or the number of slots. If the winding of the three-phase motor under each pair of poles is divided into six regions, then three at each pole. Since the groove angle α=360°P/Z, if the motor is 4 poles and 24 slots, the width of each phase per region is qα=Z/6P*360P/Z=60°, and the windings thus wound are called 60° phase winding. Because of the obvious advantages of 60° continuous phase windings, most of them are used in three-phase motors.

7, the number of slots per phase per phase (q)
The number of slots per phase per phase refers to the number of slots occupied by each phase of each phase winding. The number of coils to be wound in each phase of each phase winding is determined according to it. which is
q=Z/2Pm
 Z: number of core slots; 2P: number of motor poles; m motor phase number.
The result of the calculation, if q is an integer, is called an integer slot winding; if q is a fraction, it is called a fractional slot winding.

8, the number of conductors per slot
The number of conductors per slot of the motor winding shall be an integer, and the number of conductors per slot of the double winding shall also be an even integer. The number of conductors per slot of a wound rotor winding is determined by its open circuit voltage, and the number of conductors per slot of a medium-sized motor wound rotor must be equal to two. The number of conductors per slot of the stator winding can be calculated by:
               NS1=NΦ1m1a1/Z1
NS1: the number of conductors per slot of the stator winding;
NΦ1: the number of conductors per slot calculated by air gap magnetic density;
M1: the number of stator winding phases;
A1: the number of parallel branches of the stator windings;
Z1: Number of stator slots.

9, the number of serials per phase
The number of series conductors per phase refers to the number of bus turns in series for each phase winding in the motor. However, the number of serial bus turns is related to the number of parallel branches in each phase winding. If the number of parallel branches of the motor is one way, then all the series line turns of the coils of the motor should be added to form a phase. The number of bus turns in the winding. For example, the number of parallel branches in each phase winding of the motor, that is, the motor is 2-way connection, 3-way connection, etc., at this time, the number of series-connected conductors in each phase can only be determined by the number of turns connected in one of the windings. quasi. Since the number of series turns in each branch in the phase winding is the same, it is impossible to increase the series line after connecting them in parallel.

10, the total number of coils
The windings in the motor are composed of coils of various sizes and shapes. Since each coil has two components embedded in the core slot, that is, each coil is embedded in two slots. In a single-layer winding, since only one coil element side is embedded in each slot, the total number of coils is only equal to half of the total number of slots; in the double-layer winding, two coil elements are embedded in the upper and lower layers in each slot, so its The total number of coils is equal to the number of core slots.