I have a very basic knowledge of electronics in general.
I have recently purchased a NEMA17 bipolar 2-phase stepper motor with rated voltage of 2.8V, 1.68A/Phase, 1.8deg.
Now I have a dilema. What kind of power supply do I need for L298N to correctly drive the motor. I have old drill batteries that says 3.5Ah and both holds about 14-16Volts when charged. Then I have the battery charger that rates outputs 9-32V, 3.75A/95W max. I do have tons of mobile phone, scanner-printer, VCR power supplys around but as far as I understand I need at least 3.4A (1.68A/phase = 3.36A) psu, amarite?
in term of powering the stepper motor you could use any level of voltage higher then the rated voltage but control the current thru each winding. this will give you faster speed but will not over heat the stepper winding and ultimately causing it to fail. and yes you may use the battery charger for just one motor.
Ok,
Its getting confusing. The motor and driver works fine (driver gets really hot) using just 4xAA batteries but the motor has very little torque. But when I hook it up to 16V 3.5 drill battery it does not work, and the signal LEDs light up differently as opposed to 4AA`s. What am I missing?
ash901226:
in term of powering the stepper motor you could use any level of voltage higher then the rated voltage but control the current thru each winding. this will give you faster speed but will not over heat the stepper winding and ultimately causing it to fail. and yes you may use the battery charger for just one motor.
To clarify: this means use sense resistors (perhaps 0.1 ohm) to ground from pins 1 and 15, an RC low-pass filter perhaps
(to get the average current), measuring the voltage at the sense terminals with a couple of analog pins. PWM the drive to the L298 to keep
the current at the desired level. A fixed PWM level might be enough of course, you could experiment while monitoring
the current. You will need a faster PWM frequency than the Arduino default I believe, something more like 4 or 8kHz.
The L298 is a poor choice for low voltage motors as it loses 2 to 3V internally - it is going to run very hot whatever you do.
The motor will get hot - you don't have to run it at full rated current, note. Specific constant-current driver chips for bipolar
stepper motors are much to be prefered, less waste heat and you can get much better performance from the motor with
a high voltage supply. Pololu have a number of breakouts for these, IIRC the A4988 or some such.
