The starting method of an AC single-phase motor is determined by several sources.
1. Working principle: When a single-phase sinusoidal current passes through the stator winding, the motor will generate an alternating magnetic field. The strength and direction of the magnetic field change sinusoidally with time, but the spatial orientation is fixed, so it is also called This magnetic field is an alternating pulsating magnetic field. This alternating pulsating magnetic field can be decomposed into two rotating magnetic fields with the same speed and opposite directions of rotation. When the rotor is stationary, the two rotating magnetic fields generate two torques in the rotor of equal magnitude and opposite directions, so that the combined The torque is zero, so the motor cannot spin.
2. Features: When a single-phase sinusoidal current passes through the stator winding, the motor will generate an alternating magnetic field. The strength and direction of this magnetic field change with a sinusoidal law with time, but the spatial orientation is fixed, so it is also called this. The magnetic field is an alternating pulsating magnetic field. This alternating pulsating magnetic field can be decomposed into two rotating magnetic fields with the same speed and opposite directions of rotation. When the rotor is stationary, the two rotating magnetic fields generate two torques in the rotor of equal magnitude and opposite directions, so that the combined The torque is zero, so the motor cannot spin. When we use external force to rotate the motor in a certain direction (such as clockwise rotation), the cutting magnetic field line between the rotor and the rotating magnetic field in the clockwise rotating direction becomes smaller; The motion of the cutting magnetic field lines becomes larger. In this way, the balance is broken, the total electromagnetic torque generated by the rotor will no longer be zero, and the rotor will rotate along the pushing direction.
When we usually repair electric fans, we have a deep understanding. When the starting capacitor of the fan motor is completely out of capacity or the starting winding is disconnected, the electric fan will not rotate when energized. At this time, we will find that the motor can be easily toggled when it is not powered on, and when powered on, the motor seems to be magnetically attracted, and the buzzing sound will run at a constant speed.
If it is a capacitor-started motor, the motor will slowly rotate after power-on until it reaches a certain speed. However, when the electric fan stops rotating, the indoor fan motor will stop rotating, directly substitute the motor to start, and directly substitute the motor to start. Only when we use a fan motor, we will find that when the motor is close to the fan, the entire motor will stop rotating.
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