Current flowing through a coil: When direct current (DC) or alternating current (AC) flows through a coil, a magnetic field is generated around the coil. The direction of the magnetic field is determined by the right-hand rule (hold the coil with your right hand, four fingers pointing in the direction of the current, and your thumb pointing in the direction of the magnetic field).
Magnetic field interaction: In a permanent magnet synchronous motor, the magnetic field generated by the coil interacts with the magnetic field of the permanent magnet; in an asynchronous motor, the rotating magnetic field generated by the stator coil induces current in the rotor coil, thus generating a rotor magnetic field. The interaction of these two magnetic fields produces torque.
Torque generation: The torque generated by the interaction of the magnetic fields drives the rotor to rotate, thereby realizing the conversion of electrical energy into mechanical energy.
Commutation or frequency conversion control: For DC motors, a commutator is needed to change the direction of the current to maintain continuous rotation; for AC motors, a frequency converter is used to control the current frequency to regulate the speed.
