How DC Motors Work
A ring-shaped permanent magnet is fixed in the DC motor, and the current passes through the coil on the rotor to generate an ampere force. When the coil on the rotor is parallel to the magnetic field, the direction of the magnetic field will change if it continues to rotate. Therefore, the brush at the end of the rotor is converted with The plates are alternately contacted, so that the current direction on the coil also changes, and the direction of the generated Lorentz force does not change, so the motor can keep rotating in one direction.
The working principle of the DC generator is to convert the alternating electromotive force induced in the armature coil into a DC electromotive force when it is drawn from the brush end by the commutator and the commutation effect of the brush.
The direction of the induced electromotive force is determined according to the right-hand rule (the magnetic field line points to the palm, the thumb points to the direction of movement of the conductor, and the other four fingers point to the direction of the induced electromotive force in the conductor).
The direction of force on the conductor is determined by the left-hand rule. This pair of electromagnetic forces forms a torque acting on the armature, which is called electromagnetic torque in a rotating electrical machine. The direction of the torque is counterclockwise, in an attempt to make the armature rotate counterclockwise. If this electromagnetic torque can overcome the resistance torque on the armature (such as resistance torque caused by friction and other load torques), the armature can rotate in a counterclockwise direction