Motor design requirements
5. As far as possible, use the parallel tooth trapezoidal groove
The silicon steel sheet works in the saturation section of the magnetization curve, and the number of ampere-turns per unit length of excitation increases with the increase of the magnetic flux density. In order to make full use of the internal space of the motor, the design of the motor always saturates the silicon steel sheet. If a trapezoidal tooth is used, the narrow portion of the tooth has a large magnetic flux density, and the number of excitation ampere increases greatly, and the power factor of the motor is lowered. If parallel teeth are used. Then, the magnetic flux density is uniform along the length of the tooth portion, and the number of ampoules consumed by the excitation is greatly reduced.
6. Do not have sharp corners on the groove edge
The design of the trough should be considered to facilitate the manufacture of the die. When the die is quenched. Cracks are often generated at the sharp corners of the grooves due to stress concentration. The corner also helps to extend the life of the die. The groove design should be rounded as much as possible at the edge, and the fillet radius should be no less than 1mm.
7. Try to replace the flat bottom slot with a round bottom slot
Advantages of the round bottom slot:
A. The round bottom groove can improve the filling of the wire, and the groove insulation is not easy to be damaged. In the case of the same groove fullness, the round bottom groove is easier than the flat bottom groove.
B. When the rotor is cast aluminum, the round bottom groove is better than the flat bottom groove aluminum water filling.
C. The round bottom groove is easier to mold than the flat bottom groove.
8. Motor core slot width should not be too large
The motor slot is too small and it is difficult to get off the line. The motor slot is too large, so that the air gap flux is unevenly distributed, the tooth harmonics are increased, and the additional loss is increased. The width of the slot of the semi-closed slot is generally 2 to 3 wires, which is about 3.5 mm. The low-pressure forming coil adopts a semi-opening groove structure with four component sides in the groove, so that the notch width is reduced to half of the groove width.
9. Do not use too many or too few stator slots
There are many stator slots in the motor, and the magnetomotive force and electromotive force waveform are good. The additional loss is small and the motor efficiency is high. However, the number of slots is large, the core teeth are too narrow, the stamping deformation is large, and the workability is poor. The number of slots also increases the cost of mold manufacturing. Regarding the problem of motor design, coil manufacturing and off-line man-hours increase. Generally speaking, the number of stator slots is large and the motor performance is good, but the cost is high. Generally, the asynchronous motor has a dispersion of q ≥ 2 per phase of each phase.
10. Air gap should not be too large or too small
The air gap is the gap between the stator and rotor of the motor. The air gap size has a great influence on the motor performance and manufacturing process. The air gap is large, the magnetic resistance is large, and the number of excitation ampere is increased, so that the excitation current of the motor increases and the power factor of the motor decreases. However, the air gap is large and the harmonic magnetic field is weakened, and the additional loss of the motor is reduced. The air gap is large, and the requirements for the coaxiality and assembly accuracy of the motor components are reduced; if the air gap is too small, the stator and rotor broom is easily caused, and the motor efficiency is lowered due to the increase of the additional loss.
