With the continuous pursuit of motor efficiency, closed-slot rotors are gradually recognized by motor manufacturers. For three-phase asynchronous motor, pulse vibration loss occurs when rotating due to the existence of stator and rotor tooth slots. If the rotor adopts a closed slot, the effective air gap is shortened, and the pulsation of the air gap magnetic field is weakened, so as to reduce the excitation magnetic potential and reduce the loss of harmonic magnetic field, which is helpful to improve the motor performance.
The arch direction of 3 phase induction motor is an important parameter of the closed grooved rotor. When the rotor groove type is the same, the selection of different arch heights will have different degrees of influence on the motor performance. It is difficult to check the uniformity of closed slot rotor because there is no notch, and it is easy to have hidden serrated problem and increase uncontrollable factors.
The use of rotor closed slot can not only reduce the stray loss and iron loss of the motor, but also increase the rotor leakage reactance, resulting in the decrease of power factor, the increase of stator load current and the increase of stator loss. Starting torque and starting current decrease, slip rate increases. Therefore, when using the closed slot, the change of the performance data should be considered at the same time, so that the overall performance of the motor is optimal.
Induction motor refers to a kind of motor that depends on electromagnetic induction between rotors to induce current in the rotor to achieve electro mechanical energy conversion. The stator of the induction motor consists of three parts: the stator core, the stator winding and the frame. The rotor consists of a rotor core, a rotor winding and a rotating shaft. The rotor core is also a part of the main magnetic circuit, generally composed of 0.5mm thick silicon steel sheets stacked, the core is fixed on the rotating shaft or rotor support. The exterior of the whole rotor is cylindrical.
Rotor windings are divided into two types: cage type and wound 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 “asynchronous motor”. When the load of the induction motor changes, the speed and slip rate of the rotor will change accordingly, so that the electromotive force, current and electromagnetic torque in the rotor conductor will change correspondingly to meet the needs of the load. According to the positive and negative slip rate and the size, the induction motor has three operating states: motor, generator and electromagnetic brake.
Post time: Sep-29-2024
