Stepper motor is an electrical signal is transformed into mechanical angular displacement of the special motor. There is no winding of stepping motor rotor and uniform distribution system have several teeth, in the field winding on the stator. When a pulse input, the rotor is around a fixed point of view, its amount of angular displacement is proportional to the number of input pulses is strictly, also with the input pulse on time synchronization. When yuan pulse in winding power supply, under the stimulus of air-gap magnetic field can make the rotor to keep original, whereas in the positioning state.

Step by step electric machine machine size, the output torque can be divided into fast stepper motor and stepper motor power: according to the number of excitation phase can be divided into three phase, four, five, six or even eight phase stepper motor, etc.; According to its working principle is divided into magnetic Pao and reactive stepper motor.

Due to the amount of angular displacement of stepper motor and instruction is directly proportional to the number of the pulse and direction of rotation is associated with electricity phase sequence, so as long as the control input pulse number, frequency, and electrical windings phase sequence, can obtain the required corner size, speed and direction. The wide speed range, response spiderman, sensitivity, simple control system, and has certain precision, so they are widely used in open loop servo system.

1. The working principle of stepper motor

Despite the stepper motor is a lot of more phyletic, the basic principle of the essence is consistent. Now with three-phase reactive stepping motor as an example, illustrates its working principle.

In three of the stepper motor stator poles, it around has exciting winding, referred to as A phase, respectively, 8 and C phase. With isometric small teeth on the rotor has four teeth of the (figure). If the addition of A first on electrical impulses, the rotor of A 1, 3 two teeth were poles attract and aligned with the magnetic pole, then add those B on electrical impulses that has phase pole draws the nearest 2, 4 teeth in the past, so that the rotor along the counterclockwise around 30 °. In the same way, such as the addition of C on electrical impulses, the rotor turns 30 °. Then will A combined electrical impulses, the rotor continues to turn 30 °. So. As A - > B > C > A... In electricity, stepper motor as counterclockwise rotation.

2. The stepper motor driver

According to the working principle of stepper motor, we know that the angular displacement of stepper motor and the instruction is directly proportional to the number of the pulse and direction of rotation related to the current direction. So the stepper motor drive circuit, must be able to control stepping motor each phase excitation windings of electrical power change frequency, frequency and current order. The work done by pulse distributor and power amplifier by pulse command, according to certain order conduction or by the power amplifier, makes the corresponding excitation winding electric motor or power device is called pulse distributor, also called circular allocator. It is composed of gate, trigger the basic logic functions such as components. Stepper motor's forward and inversion, controlled by the direction of instruction. Angle and speed of step motor is determined by the command pulse frequency and the number of respectively.

Pulse distribution can be implemented by hardware or software. As a hardware, currently on the market for a dedicated distributor functional components for sale. Using special integrated circuits to improve system can take sex and reduce the system cost. With microcomputer control stepping motor, USES the assembly language programming to allocate pulse, pulse distribution is called software. This method is characterized by flexible control, high reliability, low manufacturing cost. Of course, it needs a complex program, need to take up a lot of memory units and operating time.