Hardware Question for Motor Handling Geniuses...

General Discussion
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1

Okay and Hello Once More,

It is me. How can I pick a motor or a motor driver based on a controller? What is the data one can gather and how can one use it to handle deciphering what motor to pick and what motor driver to pick?

For instance:

My driver and PSU data…

  • PSU
    • 24v 14.6A
  • Driver
    • 18v to 50v
    • 0A to 3.5A

Supposedly, one can gather the millihenries of a two phase motor by adding a resistor in between two of one of the phases on an oscilloscope.

I am not quite sure exactly how to perform this specific test.

L = R * sqrt(3) / (2 * pi * f)

That is the test with the oscilloscope but it calls for a function generator too.

I will buy a LCR Meter. Blah.

Anyway, if you have any data on how to source a PSU, Motor Driver, and Stepper Motor, jump on in.

From the geckodrive website and their drivers I currently use, the data is this idea:

32 * (√mH inductance) = Power Supply Voltage

So, I think with an inductance test and depending on my output, I can decipher the PSU voltage needed but what else do I really need to gather?

There is a science behind it. It is not just vaguely pick driver, motor, psu. Also…I found that the PSU needs to have enough of the current to handle all of my three motors and then I multiply that by 1.2.

So: (5.6 * 2) * 1.2 = 13.44A

So: (4.5 * 1) * 1.2 = 5.4A

So: 13.44A + 5.4A = 18.84A

I need a 24v 18.84A PSU I guess to handle my motors. Now, onto driver theory. Do I pick Peak or RMS for the theory?

2

not an expert, but look at the motors stall current. if your driver can’t support the stall current, it will most likely fail.

1 Like
3

Expert or not, I will research stall current on these motors. Thank you.

Okay. I now know why (theory based here) my motors stalled without using a LCR tester. They had so much current going through the motors and the motors were generic (no data or datasheets) enough to stall at 0v.

1. voltage and coil resistance is what needs testing on motors.
   - Ohm's Law: I V/R
2. Why does this matter in motors, motor drivers, and PSU applications?
   - Stall current is how many amps the motor
     will draw when it tries to spin but cannot rotate. 
   - Load current is how many amps it will draw while it is 
     under a load of varying amounts.
3. What devices should be used to test for voltage and coil resistance?
   - Out in the world of testing electromechanical devices like
     two phase motors (bipolar stepper motors), testing for voltage can
     be done with a LCR Meter. 
   - In the defined definition, LCR or (L) Inductance, (C) Capacitance, and
     (R) Resistance testers complement the DMM (Digital Multimeter)
     and should be used with the device to be tested having the power off 
     when testing.

I say theory there in the above text because the motor was taken apart and with it being stalled, I moved it to recycling.