As people continue to pursue motor efficiency, closed slot rotors are gradually recognized by motor manufacturers. For three-phase asynchronous motors, due to the existence of stator and rotor slots, pulsation loss will occur during rotation. If the rotor uses closed slots, the effective air gap is shortened and the pulsation of the air gap magnetic field is weakened, thereby reducing the exciting magnetic potential and the loss of the harmonic magnetic field, which helps to improve the motor performance.
Arch direction is an important parameter of closed slot rotors. Under the same rotor slot type, different arch heights will have different degrees of influence on motor performance. When closed slot rotors are stacked, there is no slot that cannot be seen, and it is difficult to check the neatness. It is easy to have hidden sawtooth problems, which increases uncontrollable factors.
The use of closed rotor slots will reduce the stray loss and iron loss of the motor, but will increase the rotor leakage reactance, resulting in a decrease in power factor, an increase in stator load current, and an increase in stator loss; the starting torque and starting current will decrease, and the slip rate will increase. Therefore, when using closed slots, the changes in various performance data should be considered at the same time to optimize the overall performance of the motor.
An induction motor is a motor that uses electromagnetic induction between the stator and rotor to induce current in the rotor to achieve electromechanical energy conversion. The stator of an induction motor consists of three parts: the stator core, the stator winding, and the frame. The rotor consists of the rotor core, the rotor winding, and the shaft. The rotor core is also part of the main magnetic circuit, generally made of 0.5mm thick silicon steel sheets, and the core is fixed to the shaft or rotor bracket. The entire rotor is cylindrical in appearance.
The rotor winding is divided into two types: cage type and winding type. Under normal circumstances, the rotor speed of the induction motor is always slightly lower or slightly higher than the speed of the rotating magnetic field (synchronous speed), so the induction motor is also called an “asynchronous motor”. When the load of the induction motor changes, the rotor speed and slip rate will change accordingly, causing the electromotive force, current and electromagnetic torque in the rotor conductor to change accordingly to meet the needs of the load. According to the positive and negative and size of the slip rate, the induction motor has three operating states: motor, generator and electromagnetic brake.
Post time: Apr-09-2025