Hello, I am running a stepper motor using an ESP32 and the TMC2209 stepper driver set up for UART. Up until now, I have used a 12V power supply which worked fine for one motor. I now want to scale up to running four motors, each with their own driver. How do I handle power management here? Will a 24V 5A power supply be sufficient?
The motors I am using are NEMA 17 with a rated current of 1.68A. I am using microstepping (1/256) and the motors only need to turn slowly.
If 24V at 5A is indeed the way to go, is there anything I should do to distribute the power between the drivers, adding a capacitor for each, or similar?
No it's not that easy with steppers. To define the correct PSU for steppers you must look at the power the steppers need, not the current. So it's not sufficent to know the rated current, but also the resistance of the coils.
As a rough estimate, it can be assumed that one coil of a NEMA 17 stepper requires around 5W. So each stepper needs about 10W, with 4 motors its 40W. And you must take into account driver losses and a safety margin. A PSU that can deliver >80W should be sufficent.
But as already stated this is only a rough estimate. To be exact we need the resistance of the coils.
Yes, thats true, and it should positioned as close as possible to the driver.
With 1,68A this means 5,08W - nearly exact the estimation
I would recommend at least 100µF.
The rated current of the motor flows in both directions between the driver and the buffer capacitor. The direction of flow changes at quite a high frequency. The buffer capacitor must compensate for this, as modern power supplies units normally only supply current but cannot absorb any.
On the project I just built, I'm running two NEMA23 steppers with only 650mah of current between them, using a single 2209 chip and they run very smoothly. One of the things that 2209s are known for is their ability to drive motors with less power than most other systems. If you are running 4 motors off a single chip you would still be well under the rated capacity of the 2209 which I believe is 2a. If you're running them off 4 separate 2209s each should have a supply but it does not have to be very large. My motors are rated current/phase: 2.8A, Phase Resistance: 0.9ohms, Inductance: 2.5mH+/-20%(1KHz)
Are you able to control each motor individually (maybe a stupid question)? So far, using a 24V/5A power supply seems to work fine, but tbh I haven't driven the motors for long periods of time.
I have two of these, as I am running 8 motors from two ESP32s. I hope to be able to have PCB boards printed for future iterations.
I am using them to tune a self-built string instrument, so the motors (geared at 5:1) run at low speeds/high torque. They are very silent at the low speeds I need. I am using microstepping and UART communication.
I wish I could include a schematic but haven't gotten around to learning that yet.
