The stepper motor driver is an actuator that converts electrical pulses into angular displacements. When the stepper driver receives a pulse signal, it drives the stepper motor to rotate a fixed angle (called the "step angle") in the set direction, and its rotation is run at a fixed angle step by step. Can control the number of pulses to control the amount of angular displacement, so as to achieve the purpose of accurate positioning; at the same time by controlling the pulse frequency to control the motor speed and acceleration, so as to achieve speed and positioning purposes.
Stepper motor and stepper motor drive constitute stepper motor drive system. The performance of the stepper motor drive system depends not only on the performance of the stepper motor itself but also on the advantages and disadvantages of the stepper motor driver. The study of stepper motor drives is carried out almost simultaneously with the study of stepper motors.
Stepper motors are classified according to structure: stepper motors are also called pulse motors, including reactive stepper motor (VR), permanent magnet stepper motor (PM), hybrid stepping motor (HB) and so on.
(1) reactive stepping motor: also known as induction, hysteresis or magnetoresistive stepper motor. The stator and the rotor are made of soft magnetic material, the stator is evenly distributed on the large magnetic pole is equipped with multi-phase excitation winding, fixed, the rotor evenly distributed around the small teeth and groove, after the use of magnetic flux changes generated torque. Generally three, four, five, six phase; can achieve large torque output (power consumption, current up to 20A, drive voltage is high); step angle is small (minimum can be done 10 '); When there is no positioning torque; motor damping smaller, single-step operation (when the pulse frequency is very low) shock time is longer; start and run a higher frequency.
(2) permanent magnet stepper motor: usually the motor rotor made of permanent magnet material, soft magnetic material made of stator with multi-phase excitation winding, fixed, the rotor around the small teeth and groove, power after the use of permanent magnet and Stator current magnetic field interaction produces torque. (For example, 7.5 degrees, 15 degrees, 22.5 degrees, etc.); when the power is low, the output torque is small, the output power is small, the current is less than 2A, the driving voltage is 12V; Of the holding torque; start and run the frequency is low.
(3) hybrid stepping motor: also known as permanent magnetic reaction, permanent magnet induction stepper motor, mixed with permanent magnet and the advantages of the reaction. Its stator and four-phase reaction stepper motor is no different (but the same phase of the two poles relative, and the two poles on the winding generated N, S polarity must be the same), the rotor structure is more complex (rotor internal cylindrical permanent Magnet, both ends of the jacket soft magnetic material, surrounded by small teeth and groove). (The power consumption is relatively small); step angle than the permanent magnet type is small (usually 1.8 degrees); power failure when no power supply is more positive and negative pulse signal; Positioning torque; start and run a higher frequency; the development of a faster stepper motor.