From the structural analysis of the rotor, we can divide the motor rotor into winding rotor and squirrel cage rotor. In comparison, due to the particularity of the production and manufacturing of the winding rotor, the degree of freedom of its structure and slot shape change is relatively small, so we will not discuss it specifically in this article. This article focuses on the relationship between the appearance of the squirrel cage rotor and the performance of the motor.
Open slot rotor and closed slot rotor. With the continuous implementation of environmental protection requirements for motors, many motor manufacturers have changed the original open slot cast aluminum rotors to closed slot rotors. In comparison, the quality visibility of the rotor lamination process is reduced, and more stringent processes are required to ensure it. Closed slot rotors can eliminate tooth harmonics and effectively improve the electromagnetic vibration and noise problems of motors; but the degree of sealing of closed slots is very particular, otherwise it will lead to low overall performance of the motor.
Straight slot and skewed slot rotor. Skewed slots are not used unless necessary, both from the perspective of motor manufacturing process control and overall performance indicators. However, in order to tend to eliminate the adverse effects of the motor, such as the electromagnetic noise of the motor, the rotor slots will be twisted to effectively reduce the impact of motor noise.
Deep slot rotor and double cage rotor. This type of rotor cannot be seen from the outer surface of the rotor. This measure is mainly used to solve the starting problem of industrial frequency motors, that is, through the skin effect of the current, the resistance of the rotor during the motor starting process is increased, thereby reducing the starting current of the motor, which is the same as the effect of starting a wound rotor in series with a resistor.
Herringbone slot rotor. When this type of rotor has an open slot, the distribution of the rotor bars can be clearly seen, that is, they diverge from the axial center of the rotor to both ends to achieve the twisting of the rotor in two directions. In addition to the special functions of the skewed slot rotor, this rotor also effectively eliminates the axial force generated by the skewed slot. However, for closed-slot herringbone rotors, it is not very obvious from the outside, but there may be faint traces after the rotor is turned. For large herringbone slot rotors, there is an obvious short-circuit ring at the axial center of the rotor, which is also a specific manifestation of the aluminum casting process of different manufacturers.
Post time: Feb-02-2025