Clear Filters
Shop by Price
Shop by Brand
Tags

Stepper Motor Driver

Stepper Motor Driver info

Stepper motor performance is strongly dependent on the driver circuit. Torque curves may be extended to greater speeds if the stator poles can be reversed more quickly, the limiting factor being the winding inductance. To overcome the inductance and switch the windings quickly, one must increase the drive voltage. This leads further to the necessity of limiting the current that these high voltages may otherwise induce. L/R drivers and chopper drivers are widely used stepper motor drivers.

See more.

L/R driver circuit

L/R driver circuits are also referred to as constant voltage drives because a constant positive or negative voltage is applied to each winding to set the step positions. However, it is winding current, not voltage that applies torque to the stepper motor shaft. The current I in each winding is related to the applied voltage V by the winding inductance L and the winding resistance R. The resistance R determines the maximum current according to Ohm's law I=V/R. The inductance L determines the maximum rate of change of the current in the winding according to the formula for an inductor dI/dt = V/L. Thus when controlled by an L/R drive, the maximum speed of a stepper motor is limited by its inductance since at some speed, the voltage U will be changing faster than the current I can keep up. In simple terms the rate of change of current is L / R (e.g. a 10 mH inductance with 2 ohms resistance will take 5 ms to reach approx 2/3 of maximum torque or around 24 ms to reach 99% of max torque). To obtain high torque at high speeds requires a large drive voltage with a low resistance and low inductance.

With an L/R drive it is possible to control a low voltage resistive motor with a higher voltage drive simply by adding an external resistor in series with each winding. This will waste power in the resistors, and generate heat. It is therefore considered a low performing option, albeit simple and cheap.

Chopper drive circuits

Chopper drive circuits are referred to as constant current drives because they generate a somewhat constant current in each winding rather than applying a constant voltage. On each new step, a very high voltage is applied to the winding initially. This causes the current in the winding to rise quickly since dI/dt = V/L where V is very large. The current in each winding is monitored by the controller, usually by measuring the voltage across a small sense resistor in series with each winding. When the current exceeds a specified current limit, the voltage is turned off or "chopped", typically using power transistors. When the winding current drops below the specified limit, the voltage is turned on again. In this way, the current is held relatively constant for a particular step position. This requires additional electronics to sense winding currents, and control the switching, but it allows stepper motors to be driven with higher torque at higher speeds than L/R drives. Integrated electronics for this purpose are widely available.

Hide this content.

Show:
Sort By:
TinyG 6-Axis CNC Controller Board v8 is a high performance, USB based CNC 6-axis controller that sup..
$190.00
A4988 Stepper Motor Driver is a carrier board or breakout board for Allegro’s A4988 DMOS Microsteppi..
$4.50
DRV8825 Stepper Motor Controller is a breakout board for TI’s DRV8825 microstepping bipolar stepper ..
$6.00
TB6612FNG Dual Motor Driver is a motor driver breakout board to drive two bidirectional DC motors or..
$6.50
L9110S Motor Driver is a compact board that can be used to drive very small robots. This tiny module..
$4.50
The TB6612FNG is a great dual motor driver that is perfect for interfacing two small DC motors to a ..
$5.28
About the Product Pololu A4988 Stepper Motor Driver Carrier is a carrier board or break..
$19.00
EiBotBoard v.2.0 Motor Controller is a general purpose open source PIC18F46J50-based motor controlle..
$75.00