Hello,

first post here.

I am somewhat confused by the guidance on line about voltages and currents, and please bear with me a little as I'm new to this.

1) the guidance seems to be to run steppers at a higher voltage (say 36v or 42v) as they will drive better at higher speed than trying to run the same driver at say 12 or 24V, given that this is correct, given

XL = 2*Pi*Freq*L

that would bode true, as Z = R + XL (ignoring Xc as it would be relatively small).

2) with regards to the TB6600 drives, the datasheet state that they can run drives up to 5A and ~45V, but the limiting power of the chips is 40W, so if you were running at drive at 42V, then is the limiting current of the drive 40W / 42V = ~0.95A?


3) if I was intending to use 3.1Nm stepper motors rated at 4.2A, 3.2mH, 0.65\Omega & 2.73V (in parrallel 4 wire arrangement), using TB6600's, the maximum driving voltage of these drives at 4.2A would be 40W / 4.2A = ~9.5V? Have I got something wrong here?


4) the limiting voltage guidance on these stepper motors is:

32 * \sqrt{L} = 32 * \sqrt{3.2mH} = 57V

or 25 * Motor Rated Voltage (2.73V) = 68.25V

5) The long and the short is can someone confirm that the TB6600's will never drive these steppers fully at a higher voltage that ~10V to achieve maximum torque?

I must admit at this point that as I got the common TB6600 smoke signal with one of these motors running at 42V I was more cautious with a second and placed a current meter on the stepper drive power supply feed to ensure that I'd got the current setting correct, but the stepper drive was only drawing about ~0.9A before it went into fault (thermal cutout) mode, (the motor was not moving at the time), which seems to tally with about 40W.

Would it be correct to presume that these drives should be drawing 4.2A even at 42V when measured on the drive supply side? Or have I misunderstood something? This being the case 4.2 * 42 would require a drive with a rating of better than ~176W! (quite a long way from a TB6600 rating + can't seem to see anything with that sort of rating).


Any guidance would be greatly appreciated.

(application is to direct drive a plasma table (timing belt drive) , however I'd like the flexibility to be able to pull the motors off and reuse them on maybe converting my mill and lathe in the future (direct drive application), and also be able to reuse my driver arrangement as space is at a premium in my garage and I can't accommodate 4 sets of drives for a plasma, 2 x mills and lathe)

Thanks

Brett