The three-phase asynchronous motor rotor core is slotted to embed the rotor winding or cast aluminum (or cast alloy aluminum, cast copper); the stator is usually slotted, and its function is also to embed the stator winding. In most cases, the rotor chute is used, because the inserting operation will be more difficult after the stator has the chute. What is the purpose of using the chute?
There are harmonics of various frequencies inside the motor. Because the stator adopts distributed short-distance windings, the amplitude of the harmonic magnetic potential of other frequencies except the tooth harmonics is greatly weakened. Since the tooth harmonic winding coefficient is equal to the fundamental wave winding coefficient, the tooth harmonic magnetic potential is hardly affected. Because the stator and rotor of the three-phase asynchronous motor are slotted, the magnetic resistance of the entire air gap circumference is uneven, and the electromagnetic torque and the induced electromotive force fluctuate accordingly when the motor is running.
After the rotor is slanted, the formed electromagnetic torque and induced electromotive force are similar to the average value of the same rotor bar evenly distributed in a circle, which can effectively weaken the harmonic electromotive force generated by the harmonic magnetic field of the teeth, thereby weakening these Additional torque caused by harmonic magnetic fields reduces electromagnetic vibration and noise. Although the rotor skewed slot will also reduce the fundamental wave electromotive force induced by the rotor, the generally selected skew slot degree is much smaller than the pole pitch, so it has little impact on the basic performance of the motor. Therefore, small and medium-sized cast aluminum rotor asynchronous motors Rotor chutes are commonly used.
The rotor blanks are punched by the usual method, and the rotor core is stacked with a dummy shaft with a linear oblique key. The oblique groove of the rotor core is also helical.
That is, the rotor blanks are punched by the usual method, and the rotor core is stacked with a false shaft with a helical oblique slot. The inclined groove of the rotor core is helical.
That is to say, the high-speed punching machine is equipped with the accessory of the punching slot, so that each punching rotor punches one sheet, and the punching die automatically moves a small distance along the punching direction. slope. The rotor blanks punched in this way can be optionally equipped with a slanted rotor core with a dummy shaft with a straight key. This kind of inclined slot rotor core is particularly beneficial to the copper bar rotor, because the inclined slot of the rotor iron core is not helical, but straight, which is convenient for the insertion of copper bars. However, the order and direction of the punching sheets punched in this way cannot be reversed, otherwise the laminated iron core cannot conform to the pattern.
There are not many manufacturers with high-speed punching machines with punching and inclined groove accessories, and it is difficult to manufacture spiral inclined keys. Many manufacturers use flat inclined keys to stack inclined groove rotor cores. The rotor slot bar cannot be used when the rotor core is selected with the straight oblique key. Because the groove shape is spiral at this time, and the groove bar is straight, it is impossible to use a straight groove bar to arrange the spiral groove shape. If slotted bars are to be used, the dimensions of the slotted bars must be much smaller than the rotor slots. It can only function as a slotted rod. Therefore, when selecting the rotor core with the oblique key, the oblique key plays both the role of skew and positioning. The problem encountered when using the linear oblique key to select the oblique groove rotor core is the interference between the helical skew of the punched keyway and the straight skew of the oblique key. That is, outside the middle of the rotor core, there should be interference between the punched keyway and the oblique key.
Post time: Jun-29-2022