The magnetic field coil manufacturer tells you that this is the magnetic effect of the current. That is, if a straight metal wire passes an electric current, a circular magnetic field will be generated in the space around the wire. The magnetic field coil manufacturer tells you that the greater the current flowing through the wire, the stronger the magnetic field generated. The magnetic field forms a circle around the wire.

The magnetic field coil manufacturer tells you that the principle can be explained as Ampere's molecular current hypothesis: Ampere believes that there is a circular current - molecular current in the interior of atoms, molecules and other matter particles, making each particle a tiny magnet, and the two molecules of the molecule. The side is equivalent to two magnetic poles, but in fact the electrons in the molecule do not rotate around the nucleus, but the electron cloud formed by the probability of electrons appearing in space.
The magnetic field coil manufacturer tells you that a single-layer winding is a winding with only one effective side of the coil embedded in each stator slot, so the total number of coils is only half of the total number of slots in the motor. Magnetic field coil manufacturers tell you that the advantages of single-layer winding are that the number of winding coils is relatively simple; there is no interlayer insulation, so the utilization rate of the slot is improved; the single-layer structure will not cause interphase breakdown failure, etc.