The stepper driver is one of the key components in stepper system. As the diagram below, based on the pulse / direction instruction (thin current) from controller, the driver controls the motor coil current (strong current), thereby to control the rotation axis 's position and velocity. All of the drivers in China Stepper Motor Inc. utilize the advanced bi-polar constant current chopping mode to drive the stepper motor.

Stepper Driver 's Working Mode

  There are three basic driving modes for stepper motor: full step, half step & micro step. They are differing in current control precision in motor winding (i.e. excitation mode)

• Full Step Driving
  During full step operation, both full/half stepper and microstepping driver can be used for the same stepper motor, but with different effect. Based on the pulse/direction instruction, the stepper driver excitated the two-phase stepper motor 's two coils circularly (i.e. charging the coils to set current), with this driving mode, each pulse will make the motor run a basic step angle, i.e. 1.8o (the standard 2 phase motor runs at 200 step angle per revolution).
  
• Half Step Driving
  In uniphase excitation, the rotate shaft stop in the full step position, when the driver receive next pulse, the rotate axis will run half step and stop in the middle of two full step position on condition that excitated another phase and keep it in excitation status one by one. Keeping excitating the two-phase winding with uniphase and biphase repeatedly, the stepper motor will rotate at 0.90o per pulse in half step mode. All of the China Stepper Motor Inc.TM full and half step drivers can drive the motors with full and half step mode, which is selected by one of the driver 's switch-able switch. Compared with full step, half step is superiority with doubled precision and lower vibration during low operation, herein between full and half step mode, half step mode is usually preferable in actual operation.
  
• Microstepping Driving
  The microstepping drive has the advantage of least vibration when running at low speed & higher precision when positioning. When the low speed is needed (i.e. the rotate shaft work at speed less than 60 rpm), or the position precision is required to be less than 0.90 in stepping application, the microstepping driver is used widely. The basic principle is to control the motor 's two coils with precision current by sine and cosine step separately, thereby make one step angle divided by several micro stepping. As the diagram above, for instance 16 resolution step mode can make the stepper motor with standard 200 step/rev. to achieve the running precision at 200*16=3200 step/rev. (i.e. 0.1125”). China Stepper Motor Inc. can supply more than ten kinds of microstepping drivers with complete specification, superior performance, reliable quality and competitive price.

China Stepper Motor Inc.'s Advanced Technology in Microstepping Drive

  As one of the leading manufacturer of stepper motors and drivers in China, China Stepper Motor Inc. volume-produce the two-phase stepper driver with high ratio of performance-to-price, which is suitable for any 4, 6, and 8 leads homemade or imported motor. Some of the drivers utilize the patented technology from U.S. and the performance is highly predominant. While most of the drivers is developed by the Doctor & experts in internal China Stepper Motor Inc. which have gained Chinese patent and the ratio of performance-to-price is much more attracted.

Selection Principle Driver 's current： current is used to estimate the driver 's capacity and it is one of the most important parameter to select driver. Usually the driver 's max. current must be a little bit bigger than the nominal current, generally they are vary from 2.0A, 3.5A, 6.0A, 8.0A and so on. Driver 's power supply voltage： the power supply voltage is the criteria to estimate the driver 's capability of speed ascending. In general, the supply voltage vary from 24VDC, 40VDC, 80VDC, 110VAC and etc. Driver 's resolution： Resolution is the key factor to control precision, by increasing resolution, the precision can be improved. Furthermore, higher resolution can make the motor runs more stably. Usually the stepper motor vibrate at low frequency, however the vibration can be minimized by increasing the resolution, thereby make the motor running smoothly. Control Signal Interface Instruction  Difference Interface： Most China Stepper Motor Inc. drivers use difference interface circuit, set with photocoupler internally, long winding drivers receiving allowable, collector open loop & PNP output circuit signal, it is suitable for any controller interface, including Simens PLC. It is recommended to use long winding driver (e.g. AM26LS31) circuit, which is advantaged by anti interfere. Single / Double Pulse Mode： Most China Stepper Motor Inc. drivers can receive two kinds of pulse signal: one is pulse + direction (single pulse); another is positive pulse + negative pulse (double pulse) mode, it is selectable by the jump machine in the driver.