There are many structural forms and classification methods of stepping motors, which are generally divided into three types according to excitation mode: reluctance type, permanent magnet type and mixed magnet type; According to the number of phases, it can be divided into single-phase, two-phase, three-phase and multi-equivalent forms. The starting frequency characteristic of the stepping motor makes it impossible to reach the operating frequency directly when the stepping motor starts, but there should be a starting process, that is, gradually increasing the speed from a low speed to the operating speed.