Single-phase hood-pole asynchronous motor is the simplest single-phase motor, which can be divided into convex pole type and hidden pole type according to different magnetic pole types. Salient pole type according to the winding form can be divided into concentrated winding and distributed winding two kinds, rotor is a cage structure.
A small groove is provided at 1/3 to 1/4 of each magnetic pole of the single-phase hood-pole asynchronous motor, which divides the magnetic pole into two parts. The smaller part of the polar surface is equipped with copper short-circuit ring, as if this part of the magnetic pole is covered, so it is called cover pole motor.
When the stator winding of the covered pole motor enters the single-phase AC current, a continuous moving magnetic field will be formed in the air gap, which makes the cage rotor rotate by force.
In the process of ac current rising, magnetic flux increases, inductive electromotive force and current are generated in the short-circuit ring to prevent magnetic flux from entering the short-circuit ring. At this time, magnetic flux is mainly concentrated in the uncovered part of the magnetic pole.
When the AC current reaches the maximum value, the current and magnetic flux are basically unchanged, the electromotive force and current in the short-circuit ring are very small, and the magnetic flux is evenly distributed in the whole magnetic pole.
During the ac current descent, the magnetic flux decreases, and the electromotive force and current in the short-circuit ring prevent the flux from decreasing, so that the flux of the magnetic poles is concentrated in the part of the cover.
When the alternating current changes direction, the flux also moves from the uncovered part of the pole to the covered part so that the rotor rotates in the direction in which the magnetic field moves.
The above is the structure and working principle of the hood pole type single-phase motor.