The speed of the stepping motor depends on the pulse frequency, the number of rotor teeth and the number of beats. Its angular velocity is proportional to the pulse frequency and synchronized with the pulse in time. Therefore, when the number of rotor teeth and the number of running beats are fixed, the required speed can be obtained by controlling the pulse frequency. Since the stepper motor is started with the help of its synchronous torque, the starting frequency is not high in order to avoid losing step. Especially with the increase of power, the rotor diameter increases and the inertia increases. The starting frequency and the maximum operating frequency may differ by more than ten times.