The working principle of the starter can be explained by the working principle of its main component DC motor. A DC motor is a device that converts electrical energy into mechanical energy. It is based on the principle that a charged conductor is subjected to electromagnetic forces in a magnetic field. Its working principle is shown in the figure. Because the torque generated by one coil is too small and the speed is unstable, in fact, there are many coils wound on the armature of the motor, and the number of commutation pieces also increases with the increase of the coils. So as to ensure that enough torque and stable speed are generated.