Stepper motors and their drivers

Other Hardware Motors, Mechanics, Power and CNC
1

Hi everyone,

I hope my message finds you well. I bought a stepper motor model: st-pm35-15-11c recently and I wanted to run it using a L298N stepper driver. The rated voltage for the motor is 12 V as it is written on the motor. When I set the voltage input to the driver to 12 V, the motor does not turn correctly. However, when I decrease it to around 5-6 V it starts to turn very well. What is the problem? I read somewhere that the inpit voltage should be always more than the rated voltage, something near double.

Thank you in advance

Best regards,
Masoud

2
  1. Links to datasheet of the stepper.
  2. L298N is not a genuine stepper driver. It's a dinosaur DC motor driver.

In what gutter journal did You read that? Doing like that is the best way to make toast of motors.

3

Thank you. Here is the link to its datasheet

What do you suggest instead? I used an Adafruit motor shield, and the results were the same. Though, I think that one also uses L298N.

Here it is noted that "This is due to the fact that stepper motors run better and far more efficiently when the voltage is several times higher than their rated voltage."

4

The L298 is ancient and very inefficient bi-polar technology. It will drop 2V to over 4V and dissipate that power as heat. They are, by today's standards, poor DC motor drivers and even worse stepper drivers.

That is true if using a coil current controlled stepper driver like the A4988 or DRV8825 (among others). You can supply the driver with the maximum voltage that the driver will allow to get the most speed and torque from the motor. Then the driver MUST be adjusted to limit the coil current.

Pololu has a good line of modern MOSFET output stepper drivers. Choose a driver based on the desired motor supply voltage and coil current limit (400mA max for the linked motor).

5

Thanks!
The datasheet confirm my suspicions, and the reply from @groundFungus. Put away the L298 and get a driver controlling the current to the stepper. 12 volt into the 4 ohm coils spells 3 amps, more than dangerously above the 400 mA specified in the datasheet.

Only listen to people You know have knowledge. There's a lot of crap, nonsense, out on the Internet.

6

Yes but You must use a driver with controlled current. The L298 doesn't do that. It just let all current through, and will overload itself.

7

Some reading for the OP:

Stepper motor basics tutorial.

Simple stepper test code.

8

Thanks to both of you. I understood well. I searched and repeated the things I saw on Youtube and every website. and nobody told a single thing about current and voltage and how we should manage it.

Thank you again